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Journal of Chemistry
Volume 2019, Article ID 4816849, 20 pages
https://doi.org/10.1155/2019/4816849
Review Article

Nanoparticles Used for Extraction of Polycyclic Aromatic Hydrocarbons

Department of Chemistry, Faculty of Science and Arts, Al Baha University, Qilwah, P.O. Box 1988, Al Baha, Saudi Arabia

Correspondence should be addressed to Hiba Abdalla Mahgoub; moc.oohay@alladbaabih

Received 8 December 2018; Revised 19 April 2019; Accepted 6 May 2019; Published 27 May 2019

Academic Editor: Maurice Millet

Copyright © 2019 Hiba Abdalla Mahgoub. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This article offers a review on the application of nanoparticles (NPs) that have been used as sorbents in the analysis of polycyclic aromatic hydrocarbons (PAHs). The novel advances in the application of carbon NPs, mesoporous silica NPs, metal, metal oxides, and magnetic and magnetised NPs in the extraction of PAHs from matrix solutions were discussed. The extraction techniques used to isolate PAHs have been highlighted including their advantages and limitations. Methods for preparing NPs and optimized conditions of NPs extraction efficiency have been overviewed since proper extraction procedures were necessary to achieve optimum analytical results. The aim was to provide an overview of current knowledge and information in order to assess the need for further exploration that can lead to an efficient and optimum analysis of PAHs.

1. Introduction

Polycyclic aromatic hydrocarbons (PAHs) comprise a large group of organic compounds containing two or more fused benzene rings connected in linear, angular, or cluster arrangements. They have high melting and boiling points, low volatility, and are relatively insoluble in water. Their solubility decreases with increasing number of aromatic rings. They are highly soluble in organic solvents and are lipophilic. PAHs with more than five rings occur as solids, whereas those with less than five rings occur in the vapour and particulate phases [1]. These compounds are ubiquitous in the environment and can originate from both natural and anthropogenic sources. Globally, the major contributors to environmental PAHs include burning coal and biofuels, vehicle emissions, and biomass burning (agricultural waste, deforestation, and wildfires) [2, 3]. Recently, PAHs have received considerable attention as significant pollutants that contaminate our environment. More than 80% of inputs of PAHs to the environment are influenced by atmospheric deposition as reported by the Federal Environmental Agency of Germany [4]. They show high persistency and low biodegradability in the environment. In addition, PAHs are present in environmental matrices in trace levels, and due to their lipophilic property, they show high affinity for organic matter. The behaviour and toxicity of individual PAHs in the environment depend on their size, and the smallest ones (less than three benzene rings) are more soluble in water and can break down quickly via dissolution, volatilisation, and microbial degradation which make them acutely toxic to fish and aquatic organisms [5]. PAHs with 3 to 5 benzene rings are less water soluble and accumulate in the tissues of aquatic organisms and stick to solid particles. Larger-size PAHs (greater than 5 benzene rings) do not break down quickly and can persist for years especially in sediments [6]. Some of these larger compounds are known to cause cancer and affect DNA [7]. Alkylated PAHs have also been shown to be more toxic than the parent compounds (nonalkylated PAHs), and they are formed during the diagenesis process and usually coexist with their parent compounds in the environment [8]. More than 100 PAHs have been characterised in nature, and 16 of which were classified as priority pollutants due to their wide distribution and toxicity (Figure 1) [9]. The U.S. Environmental Protection Agency (US EPA) has classified PAHs into three groups based on their carcinogenic tendencies (Table 1) [10]. Group B2 consists of substances that are probable human carcinogens, group C contains substances with possible carcinogenic effects in humans, and group D contains substances not classifiable as to human carcinogenicity. US EPA has also developed toxicity equivalence factors (TEFs) based on carcinogenicity for the quantification of the PAHs toxicity level (Table 2) [11]. Furthermore, these compounds are known to induce the formation of cancer after chronic exposure [12]. In addition, exposure to high levels of PAHs has been shown to produce immunosuppressive effects causing oxidative stress during its metabolism [13]. Among all PAHs, benzo(a)pyrene is the greatest carcinogen based on a number of studies demonstrating the carcinogenicity in human and animal species. It has been found that human exposure to different PAH mixtures containing benzo(a)pyrene increases the cancer risks in the lung and skin [14].

Figure 1: Chemical structure of the 16 PAHs listed in US EPA priority pollutants: (a) naphthalene; (b) acenaphthylene; (c) acenaphthene; (d) fluorene; (e) phenanthrene; (f) anthracene; (g) fluoranthene; (h) pyrene; (i) benzo(a)anthracene; (j) chrysene; (k) benzo(b)fluoranthene; (l) benzo(k)fluoranthene; (m) benzo(a)pyrene; (n) dibenzo(a,h)anthracene; (o) benzo(g,h,i)perylene; (p) indeno(1,2,3-cd)pyrene.
Table 1: EPA classification of PAHs.
Table 2: Toxicity equivalent factors (TEFs) of PAHs [11].

Different regulatory agencies have defined the maximum allowable level of PAHs in the environment due to their adverse effects on human health [15]. The Occupational Safety and Health Administration (OSHA) permissible exposure level for PAHs in the workplace is 0.2 mg/m3 for eight hours of workday [16]. The annual mean target value of benzo(a)pyrene of 0.7 to 13 × 10−7 mg/m3 was established by European countries [17]. The World Health Organization (WHO) recommended a health-based guideline value of 1 × 10−6 mg/m3 benzo(a)pyrene for an ambient air [18]. US EPA has defined the maximum allowable concentration of PAHs in soil and water, as shown in Table 3 [9]. Due to their ecological risks, toxicity, and adverse health effects in humans, the monitoring and detection of PAHs from the environment has attracted worldwide concern.

Table 3: Maximum allowable concentrations (MACs) of PAHs in water and soil [9].

2. PAHs Extraction Techniques

As mentioned, PAHs are released to the environment through natural and anthropogenic sources. Human exposure to PAHs is usually through water, air, food, and soil. Exposure routes include inhalation, ingestion, and dermal contact in both occupational and nonoccupational settings (Figure 2). The analysis of water samples requires isolation of PAHs from the sample matrix before instrumental analysis. PAHs have low solubility in water, and thus, they are usually present in trace quantity in water samples (sea, rivers, lakes, surface and groundwater, industrial waste, and drinking water). Different extraction techniques have been applied to isolate PAHs from water samples [19], among them include solid phase extraction (SPE) [20, 21], solid-phase microextraction (SPME) [22, 23], dispersive microsolid phase extraction (D-µ-SPE) [24], stir bar sorptive extraction (SBSE) [25, 26], cloud point extraction (CBE) [27], liquid-liquid extraction (LLE) [28], and dispersive liquid-liquid microextraction combined microsolid-phase extraction (DLLME/SPE) [29]. Owing to their presence in trace quantity, the extraction method of PAHs from water samples should be of high enrichment factors for the target analyte in order to be in a detectable level of the instrument used for analysis [30]. An effective method should provide good accuracy, low limit of detection, and high recovery of the target analyte. Table 4 shows the limit of detection and recovery percent of different PAHs extraction techniques from water samples. The most commonly used methods for preconcentration of PAHs in drinking water are SPE and LLE [3335] and have been recommended by US EPA (methods 8310 and 8100).

Figure 2: Sources and routes of exposure of PAHs to human.
Table 4: Some PAHs extraction techniques.

On the contrary, it has been reported that SPME is suitable for extraction of low-molecular-weight (less than four rings) PAHs associated with airborne particles [36]. The extract from airborne particulate matter represents a complex matrix in trace amounts which contain N2, O2, sulfur heterocompounds, and saturated hydrocarbons which lead to difficulties in identification of PAHs [37]. To eliminate interference that affects PAHs detection, a cleanup procedure was recommended after liquid extraction [38]. The analysis of PAHs in the solid samples also required pretreatment extraction to transfer PAHs into a solvent. Different methods have been used for extraction of PAHs from soil and sediments, and some of them are soxhlet extraction [39], pressurised fluid extraction, microwave extraction [40], ultrasonic extraction [41], solid-phase microextraction, and micellar solid-phase microextraction [42, 43]. Table 5 shows a summary of the main techniques for the extraction of organic compounds from environmental matrices [44]. Most of the extraction techniques are nonselective and produce an extract with a large amount of the matrix effect; therefore, a cleanup step is necessary to isolate PAHs from the matrix effect prior to instrumental determination [45]. The choice of the extraction method depends mainly on the sample matrix, operation cost, simplicity of operation, and availability of the standardised method. Some of the standardised methods for the determination of PAHs in various matrices are presented in Table 6. Although these techniques provide good accuracy and low limits of detections, they are often time-consuming and some of them generate large solvent wastes (Table 4). In this regard, a new adsorbent attached to nanoparticles (NPs) has gained a great consideration as a novel extraction technique focused on the isolation of PAHs as target analytes from complex matrices. NPs with a structural characterisation ranging from 1 to 100 nm in size have become of great scientific interest as they are effectively a bridge between bulk materials and atomic or molecular structures. NPs are unique because of the following properties: presence of a large surface area, high absorption capacity, quantum effect production, ability to form suspensions, quantum confinement in semiconductor particles, surface plasmon resonance in some metal particles, and superparamagnetism in magnetic materials [47]. NPs have amorphous or crystalline form, and their surfaces can act as carriers for gases or liquid droplets. Owing to their distinctively large surface area, high sorption capacity, favorable thermal features, and the possibility for surface functionalisation, NPs have shown great promise in analytical application especially in sample treatment. The physicochemical properties of NPs can be controlled through surface modification, insertion of suitable components, or structural design. In addition, multifunctional NPs (hybrid NPs) have exceptional properties due to their combination of targeting specificity, magnetic properties, and analytical capability [47]. On the contrary, the adsorption process is a promising technology owing to its low cost, high efficiency, and simplicity of operation for removing trace levels of organic and inorganic pollutants from effluents. In the adsorption mechanism, the adsorbate is accumulated on the adsorbent surface through molecular interaction and diffusion of sorbate molecules from the surface into the interior of sorbent materials either by monolayer or by multilayer [48]. The adsorption process is generally classified as physisorption in which an adsorbate is attached to the surface by weak Van der Waals forces and chemisorption in which adsorbate is tethered to the surface through covalent bonding or due to electrostatic attraction [49].

Table 5: Classification of the main extraction techniques, characteristics, and applications [44].
Table 6: Standardized methods for PAHs determination in various matrices [46].

3. Methods for Preparing Nanoparticles

The synthetic methods for preparing NPs were classified as either the bottom-up method which involves building up of the atom or molecular constituent using chemical or biological procedures or the top-bottom method which involves making a smaller structure from a uniform piece of material using a physical (mechanical) or chemical means to create nanostructures [50]. However, the top-bottom approach for the generation of uniform NPs faces some difficulties like the introduction of an internal stress, structural defect, and contaminations in addition to the consumption of energy to maintain high pressure and temperature used in synthetic procedures. Although the bottom-up approach produces NPs with more precise structures, shape, size, and chemical composition with low cost for high volume, the use of toxic solvents and generation of hazardous by-products are its drawbacks [51]. Table 7 presents different methods used in the synthesis of NPs including their advantages and limitations. Different routes with various strategies have been applied for the synthesis of NPs, and these include chemical, physical, and biological routes (Figure 3). The chemical route is fast and inexpensive and can produce a large number of NPs, but this route leads to the creation of a non-ecofriendly environment since toxic chemicals were used to stabilise and cap NPs. Fabrication of NPs by using the physical method is usually expensive and time- and energy-consuming and involves complex experimental instrument in comparison with biological methods which are easy, cost-effective, and ecofriendly [52]. The green synthesis (biosynthesis) of NPs is a bottom-up approach that uses microbes, enzymes, or phytochemicals for the reduction of metal compounds into their respective NPs [53]. The green method is easy and efficient, eliminates the use of toxic chemicals, consumes less energy, and produces safer products and by-products. The biological method is used in various areas such as pharmaceuticals, cosmetics, foods, and medical applications.

Table 7: Advantages and disadvantages of some methods of preparing NPs.
Figure 3: Different routes for synthesis of nanoparticles.

Recently, there is a greater interest in green synthesis of NPs [5456]. Gold NPs were synthesized by using plant extracts as both the reducing and capping agents [57]. Pomegranate peels extract was used as a reducing and capping agent for the synthesis of proanthocyanidin-functionalised gold NPs via the hydrothermal method [58]. Also, iron oxide NPs (IONPs) were synthesized at room temperature by using pomegranate peel extracts for removal of pyrene and benzo(a)pyrene from water samples with a removal rate of 98.5 and 99%, respectively [59]. Metal and metal oxide NPs have been widely used for the isolation of PAHs. Metal oxide NPs are usually prepared by hydrothermal synthesis which can easily be obtained through the hydrothermal treatment of peptised precipitates of a metal precursor with water [60, 61]. The hydrothermal method can be useful to control grain size, particle morphology, crystalline phase, and surface chemistry through regulation of the solution composition, pressure, solvent properties, additives, and aging time [62]. Carbon-based nanomaterials including graphene, fullerene, and nanotube have been used as adsorbents for PAHs due to their availability, ease of preparation, stable structure, and high sorption capacity. Graphene NP can be prepared from distinct carbon-containing precursors by the chemical method. A reaction of potassium with CO2 led to the formation of 3D honeycomb-like structured graphene [63]. Surface oxygen groups can be introduced to graphene edges (Figure 4). PAH-based metal complexes can be prepared by the inclusion of heteroatoms (Ru or Pd) (Figure 5). These heteropolyaromatic compounds result from the FeCl3 catalysed oxidative cyclodehydrogenation of 1,2-dipyramidyl-3,4,5,6-tetra-(4-tert-butylphenyl) benzene. Three new C-C bonds are formed that lock the two pyrimidines in a molecular platform comprising eight fused aromatic rings flanked by two remaining uncyclised phenyl rings [65]. Oxidation of graphene produces graphene oxide (Figure 6). Using ππ stacking interaction and van der Waals’ forces, adsorption of pollutant on the graphene oxide nanosheet (GONSs) can be realised (Figure 7) [66]. Carbon nanotubes (CNTs) are members of the fullerene structural family, and they can be single-walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs) [67] (Figure 8). CNTs can be prepared by decomposition of hydrocarbon molecules on a metal catalyst surface, and the formed CNT hangs down from the catalyst particle and captures it in the growth process (Figure 9). The CNT growth is accompanied by a charge of catalyst particle “spherical-elongated-spherical” [64]. Also, CNTs can be prepared from ethanol using iron or cobalt acetate as the catalyst, and horizontally or vertically ordered arrays of CNTs can be obtained on SiO2 from xylene as the carbon source and ferrocene as the catalyst [64]. CNTs can be functionalised to introduce various functional groups that provide new adsorption sites. Hydroxyl and carbonyl groups can be easily introduced to CNTs via oxidation.

Figure 4: Surface oxygen groups on graphene edge: (a) carboxyl; (b) lactone; (c) hydroxyl; (d) lactol, (e) carboxylic anhydride; (f) quinone; (g) carbonyl; (h) ether.
Figure 5: (a, b) Ruthenium and (c) palladium-graphene complex [64].
Figure 6: Schematic structure of graphene (a) and graphene oxide (b) [49].
Figure 7: Schematic representation of possible interactions between GONSs and pollutants [66].
Figure 8: Schematic of (a) SWCNTs and (b) MWCNT [68].
Figure 9: Proposed mechanism for SWCNT growth on Au supporting Ni nanocatalyst by the electrochemical process [64].

Novel approaches in improving the use of NPs include incorporating a magnetic material such as Fe3O4. The method includes the use of adsorbents attached to NPs that can be separated by a magnetic field. The surface modification of magnetic NPs (MNPs) with a suitable coating is very important to get an efficient extraction of the target analyte and prevents agglomerisation/aggregation of MNPs by van der Waals’ forces or magnetostatic interaction [69]. The magnetic particles in nanoscales can be synthesized by different methods such as chemical (coprecipitation of hydroxides), hydrothermal synthesis, sol-gel transformation, and ball milling [70]. A novel approach for the preparation of the SPE sorbent (1,4,7,10-tetrabenzyl-1,4,7,10-tetraazacyclododecane) (TBCD)/MNP was developed. The four benzyl groups provide the TBCD functionalised Fe3O4 with strong adsorption capacity for PAHs due to their ππ stacking interaction which increases the selectivity of the synthesized material to the target analyte [71]. The TBCD/MNP was prepared by a bottom-up chemical strategy, TBCD was chemically bonded to the surface of prepared MNPs through the quaternisation reaction, as illustrated in Figure 10, and the extraction process scheme is illustrated in Figure 11.

Figure 10: Preparation scheme of Fe3O4/TBCD MNP [71].
Figure 11: Scheme of the extraction process of PAHs by Fe3O4/TBCD MNP [71].

4. Nanoparticles for Extraction of PAHs

The search for a suitable adsorbent that can effectively isolate PAHs from environmental samples is a priority and that is because PAHs are hydrophobic and tend to coextract with a large amount of matrix effects, have a very low charge, and exist in the environment as mixtures and in trace amounts. The synthesis of nanosorbents coated with functional organic moieties and the fabrication of molecular imprinted polymers for PAHs forms part of the progress in the analysis of PAHs [72]. Different NPs adsorbents have been investigated and applied for isolation of PAHs from a sample matrix, and these include mesoporous silica NP, carbon NP, metal and metal oxide NP, and magnetic and magnetised NP. Some properties of these nanoparticles adsorbents are summarised in Table 8.

Table 8: Some properties of nanoparticles adsorbents for PAH extraction.
4.1. Mesoporous Silica NP

Mesoporous silica NPs (MSNPs) are chemically and thermally stable nanomaterials having pores in the range of 2–50 nm. The unique properties of MSNPs make them highly attractive in many diverse fields of science, industry, and technology [73, 74]. These nanomaterials are synthesized by condensation reactions of tetraethyl orthosilicate in the presence of a surfactant such as cetyltrimethylammonium bromide under acidic or basic catalysis [75]. MSNPs are considered excellent carriers for drug delivery because of their textural properties which increase the loading amount of drug inside the pore channels, and drug diffusion kinetics can be controlled due to the functionalised silanol group [76, 77]. MSNPs have been applied for isolation of PAHs from environmental water samples. Different surfactants have been found to increase adsorption capacity values such as dodecylamine and tetramethylammonium [78, 79]. Cyclodextrin-functionalised MSNPs was used for removal of 5 PAHs from aqueous solution with adsorption capacities of 0.3 and 1.56 mg·g−1 [80]. Recently, the magnetised form of mesoporous silica has been applied for the adsorption of pyrene [81]. Magnetised silica NPs using cholesterol as a functionalising agent was applied for extraction of 7 PAHs, and the limit of detection (LOD) was between 0.50 and 1.0 ng·g−1 [82]. N-methylimidazole-coated MSNPs was also used for extracting 13 PAHs with an extraction efficiency of 75–102% [83]. Silica has been applied in surface modification due to its availability, cheapness, good chemical stability, biocompatibility, and flexibility. In different methods of extraction of PAHs by using magnetic NP (Fe3O4), the unprotected particles can easily be oxidised under harsh extraction conditions and lose magnetism when used in long term, and silica has been chosen as the most ideal substance to solve this problem [84, 85].

4.2. Metal and Metal Oxide NPs

Unfunctionalised metal and metal oxide NPs have been used in the extraction of PAHs from environmental samples. Gold and titanium oxide NPs have been reported with the recoveries of 83.3–100% and LOD value of 0.9–59 ng·L−1, respectively [86, 87]. Among the metals and metal oxides which have been used for the isolation of PAHs are gold and silver NPs due to the ease of preparation and strong affinity to PAHs which allow extraction and preconcentration of these compounds from drinking water [88, 89]. Silane-based 3-mercaptopropyltrimethoxysilane and thiolated agents have been reported for functionalising gold NPs [90]. The thiol-based coated NPs recorded LODs of 0.8–60 ng·L−1 for 16 PAHs with a total recovery of 44.6–90.5%. Gold immobilised magnetic mesoporous silica NPs were applied for extraction of PAHs from seawater samples, and the results indicated good recovery efficiencies ranging from 91.4 to 104.2% with a detection limit in the range 0.002–0.004 µg·L−1 [91]. Several kinds of modified Au and Ag substrates have been developed to adsorb PAHs close to the surface of the metal for the label-free surface-enhanced Raman spectroscopy (SERS) detection. Among these are thio-functionalised Fe3O4@Ag core-shell magnetic NPs [92], humic acid-modified Ag NPs [93], and Ag NPs functionalised with dithiocarbamate [94]. However, excessive modifying reagents may adsorb PAHs and reduce the sensitivity of SERS. Au NPs decorated with glycidyl methacrylate-ethylene dimethacrylate (GMA-EDMA) were reported for SERS detection of anthracene, phenanthrene, and pyrene in water samples with LODs of 0.93 × 10−7, 4.5 × 10−7, and 1.1 × 10−7, respectively [95]. Inorganic-organic hybrid nanocomposite has been used as a fiber coating for SPME of PAHs. It is composed of ZnO NPs, polythiophene, and hexagonally ordered silica (ZnO/PT/SBA-15) [96]. The material was successfully applied in HS-SPME due to its thermal stability, and detection limits were found between 8.2 and 20 pg·mL−1. Table 9 shows some metal and metal oxide NPs used in the extraction of PAHs. To enhance the selectivity of metal and metal oxide NPs, they can be functionalised with organic frameworks. This involves incorporating metal ions or metal oxides into organic ligands that have an affinity for the target analyte. The organic ligand acts by providing interaction sites for PAHs while the metal and metal oxide NPs increase the surface area of the interaction. When organic ligand functionalised metal and metal oxide NPs also contain magnetic components, the adsorption can be achieved by dispersing them in solution and then can be easily separated from the matrix by applying an external magnet.

Table 9: Some metal and metal oxide NPs used in the extraction of PAHs.
4.3. Carbon NPs

Carbon-based nanomaterials form a diverse group of nanomaterials, and these include graphene, carbon black, graphene oxide, and carbon nanotubes. All have been reported as sorbents in the analysis of PAHs (Table 10). Application of carbon NPs (CNPs) in SPE and SPME has shown higher extraction yields and thermal stability compared to other materials such as polydimethylsiloxane (PDMS) and PDMS/divinylbenzene [110]. The characteristic structures and electronic properties of CNPs allow them to interact strongly with organic molecules via hydrogen bonding, π–π stacking, and electrostatic and van der Waals’ forces. Depending on the synthesis process, multiwalled carbon nanotubes (MWCNTs), fullerene, graphene platelets, or carbon nanohorns can be generated [111]. The surface of CNPs can be modified with oxygen-containing groups such as carboxylic, carbonyl, and hydroxyl to make them more hydrophilic materials suitable for sorption of relatively low-molecular-weight and polar compounds [112]. Fullerene has been applied successfully in headspace in-tube extraction of eight PAHs with LODs ranging from 10 to 300 ng·L−1 [113]. Carbon black was used to adsorb benzopyrenes with well-known toxic properties on its surface, and this is due to its hydrophobic character [114]. Graphene is a two-dimensional nanomaterial composed of a single layer of carbon atoms and can be chemically functionalised through graphene oxide with ease. Owing to the similarity in the chemical structure, it is common to treat graphene as the parent form of graphite, fullerenes, and carbon nanotubes. Graphene nanomaterials have been used for the adsorption of phenanthrene [115], and in this manner, graphene nanosheets and graphene oxide show better adsorption capacities than those of carbon nanotubes and granular activated carbon in the presence of synthetic organic contaminants [116]. Despite its high adsorption capacity, graphene tends to aggregate, and some researchers tried to combine it with other nanomaterials to solve this problem. Zhao et al. [117] introduce hydrophilic sulfonic acid groups to the surface of graphene which increased the adsorption capacity for naphthalene (2.326 mmol·g−1) and 1-naphthol (2.407 mmol·g−1) [117]. Graphene oxide contains many oxygen functional groups such as epoxy and hydroxyl groups which enable good dispersion of it in many solvents compared with graphene [118]. Graphene oxide nanosheet bonded with silica-coated Fe3O4 microparticles and graphene oxide surface modified with 2-phenylethylamine were reported for the extraction of 10 PAHs from aqueous matrices with an LOD value of 0.005–0.1 µg·L−1 [119]. Graphene oxide embedded in silica fiber was also reported for extraction of PAHs from river and pond water with an LOD value of 0.005–0.08 µg·L−1 [120]. A significant advantage of graphene is that it can be synthesized from graphite, a very common and cheap material without using a metal catalyst.

Table 10: Some CNPs used in the extraction of PAHs.

Carbon nanotubes (CNTs), especially multiwall CNTs (MWCNTs), have attracted great attention in different research fields as sorbent materials due to their physical and chemical properties and hydrophobic and π–π interactions with PAHs [121, 122]. MWCNTs have been used as sorbents packed inside a porous polypropylene membrane in SPE microcolumns for monitoring PAHs in water samples [123, 124]. The results show an LOD of 4.2–46.5 ng/L [125]. Also, MWCNTs have been combined with polyvinyl alcohol cryogel (MWCNTs/PVA) to form composites used for extraction and preconcentration of PAHs in water samples [109]. Despite the wide uses of MWCNTs composites in PAHs extraction, different limitations were reported, and these include technically complex and longtime of preparation with high costs, in addition to their agglomeration due to their high hydrophobic nature which hinders the PAHs adsorption processes [126, 127]. Recently, the combination of MWCNTs composite and MNPs can be promising to overcome these limitations [128]. MWCNT oxide immobilised on pyrrole MNPs (Fe3O4@PPy-MWCNT) have been used in MSPE for extraction and preconcentration of five PAHs from environmental water samples with LODs of 0.1–0.3 µg·L−1 [129]. Another composite made by caging Fe3O4 NPs and MWCNTs into calcium alginate beads was used for extraction of benzo(a)anthracene, benzo(a)pyrene, and benzo(a)fluoranthene from water samples with LODs of 5, 5, and 10 ng·L−1, respectively [130]. On the contrary, CNTs may affect bioavailability and toxicity of organic contaminants in the environment [131133]. Recent studies have reported the influence of MWCNTs on the fate of PAHs and other organic contaminants. MWCNTs minimise the toxicity of highly bioavailable PAHs in a sandy loam soil and increase pyrene degradation in a sandy clay loam soil [134]. A novel application of CNPs is the combination of magnetisation and functionalisation of their surface with organic groups that have an affinity for PAHs. As mentioned, the major challenge with the application of CNPs is their tendency to aggregate in aqueous solutions due to the hydrophobic nature of their surfaces. Coating on other NPs materials such as silica and magnetite or the incorporation of a small hydrophilic group such as sulfonic acid can be used to solvate CNPs.

4.4. Magnetic and Magnetised NP

Another new trend is to couple different NPs with a magnetic material such as magnetite Fe3O4 and maghemite Y-Fe2O3. This technique is based on the use of magnetic nanoparticles (MNPs) which provide rapid extraction ability and excellent efficiency. The method includes the use of adsorbents attached to nanoparticles that can be separated by a magnetic field. The surface modification of MNPs with a suitable coating is very important to get an efficient extraction of target analytes and prevent agglomerisation/aggregation of MNPs by van der Waals’ forces or magnetostatic interaction [69]. Metal/metal oxides, silica, or graphene organic functionalised framework can be dopped with Fe3O4. The coating of nanomaterials by inorganic substances (e.g., silica, MnO2, graphene, and carbon nanotubes) and organic substances (e.g., molecularly imprinted polymers, chitosan, polypyrrole, and surfactants) stabilises the magnetic shell and prevents their oxidation providing different applications. Different organic functional groups such as 1,3,5-triformylphloroglucinol, styrene-divinylbenzene, tert-butyl methacrylate, octadecyl-3-methylimidazolium, and 1,3,5-benzenetricarboxylic acid have been used as modifiers for NPs surface due to their affinity for PAHs. Fe3O4 magnetic NPs modified with polyfuran (PFu/Fe3O4) was used as an adsorbent for the magnetic solid-phase extraction of some PAHs in water and urine samples, the LODs range was 0.02–0.05 ng·mL−1, and the relative recovery was between 87.3 and 99.2% [135]. Some drawbacks of reported modified sorbents include tedious preparation and time-consuming and usually involve toxic reagents. Fats and oils were used as economical and ecofriendly hydrophobising agents in modifying the surface of MNPs. Among them is the palm fatty acid used to functionalise MNPs (MNP-FA) [136] (Table 4). Also, another green method used for the reduction of PAHs in marine sediment was enhanced by using magnetic bamboo biochar [137]. Wood biochar supported by magnetite NPs (Fe3O4-WB) was found as an efficient catalyst for the removal of high-ring PAHs with the highest degradation rates for the 6-, 5-, and 4-ringed PAHs being 90, 84, and 87%, respectively [138]. Polydopamine coated Fe3O4 NPs (Fe3O4/PDA) has been successfully used as an adsorbent for determination of trace PAHs in environmental samples. Fe3O4/PDA adsorbents are environmentally friendly and simple, and no toxic materials or organic solvents were used [139]. Magnetic and magnetised NPs are the most used nanosorbents in the isolation of PAHs (Table 11). Magnetic NPs can be attached to the desired molecules, conferring magnetic properties to the targets and then with a rapid and simple separation by using an external magnetic field.

Table 11: Some magnetic and magnetised NPs used in the extraction of PAHs.

5. Optimisation Conditions of NP Efficiency

Several parameters such as desorption solvent, type and amount of adsorbent, pH, and ionic strength can affect the extraction efficiency of NPs. In order to obtain quantitative recoveries, selection of an appropriate desorption solvent to elute the target analytes from adsorbent is necessary. Organic solvents like hexane, acetone, methanol, toluene, dichloromethane, ethyl acetate, acetonitrile, and a mixture of them have been used for desorbing PAHs. The effect of desorption solvent volume should be investigated to improve the elution of an analyte from the adsorbent. Nonpolar organic solvents were found to improve the recovery toward PAHs with a higher ring number [144]. In the extraction of PAHs from water samples by using synthesized MWC nanotube oxide immobilised in the pyrrole magnetic NPs, seven organic solvents which had a broad range of polarities were used for desorption of the adsorbed PAHs. 2-Propanol was chosen as the best elution solvent [129]. In another study where a nanocomposite consisting of silica-coated magnetite and phenyl functionalised graphene oxide used for extraction of PAHs from an aqueous matrix, a mixture of acetonitrile : tetrachloroethylene (CAN : C2Cl4) has shown a better elution capability toward all PAHs [119]. Acetonitrile was selected as the best desorption solvent for 6 PAHs extracted from water samples by using polydopamine-coated Fe3O4 NP (Fe3O4/PDA) [71].

Type and amount of nanomaterials will also influence the analyte desorption. For PAHs, MWCNTs composites were described as less prone to aggregation than single-walled CNTs [128, 145]. Other studies show that Fe3O4/CNS/PPy sorbent exhibits the higher extraction efficiency for PAHs compared to the Fe3O4/PPy sorbent [141]. The main advantages of NPs adsorbents are the large surface area and high extraction capacity. Therefore, better extraction capacity can be achieved with fewer amounts of NPs compared to microsized sorbents. In many studies, it has been observed that the peak area of PAHs increases as the amount of nanosorbent increases. This is due to accessible active sites of adsorbents for interaction with the analyte; after that, the extracted amount of PAHs was almost constant; hence, the suitable amount of NPs can be optimised [136]. In another study where the silica-based organic-inorganic nanohybrid material (NH2-SBA-15) was used for removal of naphthalene, acenaphthylene, and phenanthrene from wastewater, the removal efficiency was increased significantly as the adsorbent amount increased due to the increase in the contact surface of the adsorbent and greater availability of adsorbent [146].

Effect of salt concentration is commonly studied in many extraction methods in order to enhance enrichment performance. This can be achieved by decreasing the solubility of the analytes in the aqueous phase and enhancing their partitioning onto the sorbent or organic phase. The solubility of PAHs decreases with increasing molecular weight or number of aromatic rings [147]. Higher recoveries were obtained for PAHs with four or more aromatic ring at a lower amount of salt. In contrast, the PAHs with a lower number of rings (3 rings) and high amount of salt result in better extraction efficiency. It has been observed in another study that the adsorption capacity of pyrene increased when the concentration of KCl increased. This result was attributed to the salting-out effect. Since the adsorption mechanism of pyrene was mainly caused by hydrophilic interaction, as the ionic strength increased, the solubility of pyrene and the activity coefficients in solution decreased which induce the adsorption of pyrene [148].

The effect of pH on extraction efficiency was studied. The pH ranges of 3–11 have been studied for PAHs, and no significant effect of pH on extraction efficiency was observed [119]. PAHs exist as neutral molecules in aqueous solutions and π–π interactions between adsorbent and PAHs are not affected by changing the pH value. On the contrary, NPs functionalised with palm fatty acid (MNP/FA) and high recoveries of four selected PAHs were obtained at pH 6.5 and lower recoveries were observed when pH was higher or lower. This can be explained by considering the charged species and charge density on the surface of the nanosorbent [136]. It has also been observed that the adsorption capacity of pyrene onto SBA-15 and MCM-41 decreased when the pH values increased in a single system. This result was explained by the electrostatic interaction between adsorbents and contaminants. The change of pH values affects the electrical conductivity of the surface of SBA-15 and MCM-41 greatly. Pyrene has an electron-rich π-ring; therefore, the electrostatic attraction between pyrene and the two adsorbents is weakened, resulting in a decrease in the adsorption capacity for pyrene [148]. The pH of the solution affected the surface charge of the adsorbents and the degree of ionisation and speciation of different pollutants. The removal rate of 3 PAHs (naphthalene, acenaphthylene, and phenanthrene) was increased at a lower pH, and this is due to the formation of NH3+ on the surface of the nanohybrid adsorbent (NH2-SBA-15). Consequently, the electrostatic interaction between surface charges of the adsorbent and PAHs increased due to the π-electron-rich character of PAHs [146].

6. Conclusion

Recently nanotechnology is one of the most active areas in modern science and its development is impacting human life. Novel applications of NPs are renovated in various fields such as health, environment, drug-gene delivery, biomedical food and feed, mechanics, optics, and chemical and space industries. NPs are known to have unique properties owing to their high surface area and sorption capacity; they have been successfully applied in the isolation of PAHs from sample matrix solutions. The extraction techniques used to isolate PAHs have been highlighted including their advantages and limitations. Different methods for NPs synthesis have been discussed in this paper, and it is necessary to develop the nonhazardous and green biological methods for NPs synthesis. Challenges in the application of adsorbents for PAHs are related to the lack of functional groups on PAHs that can be targeted. Nanosorbents that have been applied in the analysis of PAHs were reviewed, and these include mesoporous silica NPs, CNTs, metal and metal oxides, novel advancements of NPs functionalised with organic groups that have a high affinity for PAHs, and application of magnetic and magnetised NPs to improve extraction efficiency. One of the most important issues that need more investigation is how to make safe disposal of NPs. The effect of the prolonged exposure to NPs on human health and the environment needs to be assessed completely before their large-scale production. The small size of NPs allows them to easily access the skin, lung, and brain and causes adverse effects [149]. Green synthesis of NPs can be developed as an alternative to produce more environmentally friendly NPs.

Conflicts of Interest

The author declares that there are no conflicts of interest regarding the publication of this article.

Acknowledgments

The author would like to thank the Faculty of Science and Arts, Al Baha University, Qilwah.

References

  1. T. Abdulazeez, “Polycyclic aromatic hydrocarbons,” A Review. Lawal, Cogent Environmental Science, vol. 3, Article ID 1339841, 2017. View at Publisher · View at Google Scholar
  2. H. Shen, R. Wang, D. Zhu et al., “Global atmospheric emissions of polycyclic aromatic hydrocarbons from 1960 to 2008 and future predictions,” Environmental Science & Technology, vol. 47, no. 12, pp. 6415–6424, 2013. View at Publisher · View at Google Scholar · View at Scopus
  3. A. Ramesh, A. Archibong, D. Hood, Z. Guo, and B. Loganathan, “Global environmental distribution and human health effects of polycyclic aromatic hydrocarbons,” in Global Contamination Trends of Persistent Organic Chemicals, B. G. Loganathan and P. K. S. Lam, Eds., pp. 95–124, CRC Press, Boca Raton, FL, USA, 2011. View at Google Scholar
  4. Umweltbundesamt–UBA (The Federal Environment Agency), “Polycyclic aromatic hydrocarbons: harmful to the environment! toxic! inevitable?” Section IV, vol. 2, no. 3, pp. 1–24, 2016. View at Google Scholar
  5. C. D. Greer, P. V. Hodson, Z. Li, T. King, and K. Lee, “Toxicity of crude oil chemically dispersed in a wave tank to embryos of Atlantic herring (Clupea harengus),” Environmental Toxicology and Chemistry, vol. 31, no. 6, pp. 1324–1333, 2012. View at Publisher · View at Google Scholar · View at Scopus
  6. CCME (Canadian Council of Ministers of the Environment), Canadian soil quality guidelines for carcinogenic and other polycyclic aromatic hydrocarbons (environmental and human health effects). Scientific Supporting Document. CCME (Canadian Council of Ministers of the Environment), 2008.
  7. I. Hussein and M. Mansour, “A review on polycyclic aromatic hydrocarbons: source, environmental impact, effect on human health and remediation,” Egyptian Journal of Petroleum, vol. 25, no. 1, pp. 107–123, 2016. View at Publisher · View at Google Scholar · View at Scopus
  8. A. Abiodun, O. Oluranti, and A. Okoh, “Analytical methods for polycyclic aromatic hydrocarbons and their global trend of distribution in water and sediment: a review,” in Recent Insights in Petroleum Science and Engineering, IntechOpen Limited, London, UK, 2018. View at Publisher · View at Google Scholar
  9. ATSDR, Agency for Toxic Substances and Disease Registry, Toxicological Profile for Polycyclic Aromatic Hydrocarbons, ATSDR, Atlanta, Georgia, 2006.
  10. US Environmental Protection Agency, Deposition of Air Pollutants to the Great Waters, Office of Air Quality Planning and Standards, Research Triangle Park, NC, USA, 1994, First Report to Congress. EPA-453/R-93-055.
  11. IARC (International Agency for Research on Cancer), Monographs on the Evaluation of Carcinogenic Risks to Humans, vol. 92, IARC (International Agency for Research on Cancer), Lyon, France, 2010, http://monographs.iarc.fr/ENG/Monographs/vol92/index.php.
  12. WHO, Health Risks of Persistent Organic Pollutants from Long-Range Transboundary Air Pollution, World Health Organization, Geneva, Switzerland, 2003.
  13. V. K. Singh, D. K. Patel, R. Jyoti, S. Ram, N. Mathur, and M. K. J. Siddiqui, “Blood levels of polycyclic aromatic hydrocarbons in children and their association with oxidative stress indices: an Indian perspective,” Clinical Biochemistry, vol. 41, no. 3, pp. 152–161, 2008. View at Publisher · View at Google Scholar · View at Scopus
  14. U.S. EPA (US Environmental Protection Agency), “Guidelines for carcinogen risk assessment (final),” U.S. Environmental Protection Agency, Risk Assessment Forum, Washington, DC, USA, 2005, Report EPA/630/P-03/001F. View at Google Scholar
  15. H. A. Mahgoub and N. A. Salih, “Concentration level of polycyclic aromatic hydrocarbons emitted from oud incense: Al-Baha city, Southwest Saudi Arabia,” Modern Chemistry & Applications, vol. 05, no. 1, p. 201, 2017. View at Publisher · View at Google Scholar
  16. Occupational Safety and Health Administration (OSHA), Coal Tar Pitch Volatiles, Method 5023, Issue 2, 1993, https://www.cdc.gov/niosh/docs/2003-154/pdfs/5023.pdf.
  17. P. Ballesta, D. Saeger, and D. Kotzias, State of the Art of the PAHs’ Analysis in Ambient Air, Commiss European Communities, Ispra, Italy, 1999.
  18. C.-E. Boström, P. Gerde, A. Hanberg et al., “Cancer risk assessment, indicators, and guidelines for polycyclic aromatic hydrocarbons in the ambient air,” Environmental Health Perspectives, vol. 110, no. 3, pp. 451–488, 2002. View at Publisher · View at Google Scholar
  19. A. Hiba, “Extraction techniques for determination of polycyclic aromatic hydrocarbons in water samples,” International Journal of Science and Research, vol. 5, pp. 268–272, 2015. View at Publisher · View at Google Scholar
  20. W. Kanchanamayoon and N. Tatrahun, “Determination of polycyclic aromatic hydrocarbons in water samples by solid phase extraction and gas chromatography,” World Journal of Chemistry, vol. 3, no. 2, pp. 51–54, 2008. View at Google Scholar
  21. P. Sibiyaa, M. Potgietera, E. Cukrowskaa, J. Jönssonb, and L. Chimukaa, “Development and application of solid phase extraction method for polycyclic aromatic hydrocarbons in water samples in Johannesburg area, South Africa,” South African Journal of Chemistry, vol. 65, pp. 206–213, 2012. View at Google Scholar
  22. Q. Li, X. Xu, L. F. Sen-Chun, and X. Wang, “Determination of trace PAHs in seawater and sediment pore-water by solid-phase microextraction (SPME) coupled with GC/MS,” Science in China Series B: Chemistry, vol. 49, no. 6, pp. 481–491, 2006. View at Publisher · View at Google Scholar · View at Scopus
  23. X. Yan, D. Wu, H. Peng, K. Ding, C. Duan, and Y. Guan, “Array capillary in-tube solid-phase microextraction: a rapid preparation technique for water samples,” Journal of Chromatography A, vol. 1244, pp. 69–76, 2012. View at Publisher · View at Google Scholar · View at Scopus
  24. A. Abdulmumin, B. Chanbasha, A. Amjad, and A. Abdul Rahman, “Determination of polycyclic aromatic hydrocarbons in water using nanoporous material prepared from waste avian egg shell,” Journal of Nanomaterials, vol. 2012, Article ID 305691, 7 pages, 2012. View at Publisher · View at Google Scholar · View at Scopus
  25. K. Rami, B. Helene, L. Karyn, T. Jan, and L. Stephane, “Chemical characterization of oil-water system using stir bar sorptive extraction (SBSE)-thermal desorption (TD)- gas chromatography mass spectrometry (GCMS),” in Proceedings of the Thirty-Fifth AMOP Technical Seminar on Environmental Contamination and Response, pp. 994–1000, Ottawa, Canada, June 2012.
  26. C. Margoum, C. Guillemain, X. Yang, and M. Coquery, “Stir bar sorptive extraction coupled to liquid chromatography-tandem mass spectrometry for the determination of pesticides in water samples: method validation and measurement uncertainty,” Talanta, vol. 116, pp. 1–7, 2013. View at Publisher · View at Google Scholar · View at Scopus
  27. C. Fai, J. Wong, C. Huie, and M. Choi, “On-line flow injection-cloud point preconcentration of polycyclic aromatic hydrocarbons coupled with high-performance liquid chromatography,” Journal of Chromatography A, vol. 1214, no. 1-2, pp. 11–16, 2008. View at Publisher · View at Google Scholar · View at Scopus
  28. K. Farshid, H. Amir, and M. Rokhsareh, “Determination of polycyclic aromatic hydrocarbons (PAHs) in water and sediments of the Kor River, Iran,” Middle-East Journal of Scientific Research, vol. 10, no. 1, pp. 1–7, 2011. View at Google Scholar
  29. Z.-G. Shi and H. K. Lee, “Dispersive liquid−liquid microextraction coupled with dispersive μ-solid-phase extraction for the fast determination of polycyclic aromatic hydrocarbons in environmental water samples,” Analytical Chemistry, vol. 82, no. 4, pp. 1540–1545, 2010. View at Publisher · View at Google Scholar · View at Scopus
  30. G. Kiss, Z. Varga-Puchony, and J. Hlavay, “Determination of polycyclic aromatic hydrocarbons in precipitation using solid-phase extraction and column liquid chromatography,” Journal of Chromatography A, vol. 725, no. 2, pp. 261–272, 1996. View at Publisher · View at Google Scholar · View at Scopus
  31. M. Poulain, G. Rodier, C. Canaff, V. Ruban, and A. Ambles, “Quantification of polynuclear aromatic hydrocarbons in retention pond waters using gas chromatography-tandem mass spectrometry,” Austin Chromatography, vol. 1, no. 3, p. 5, 2014. View at Google Scholar
  32. E. Manoli, C. Samara, I. Konstantinou, and T. Albanis, “Polycyclic aromatic hydrocarbons in the bulk precipitation and surface waters of Northern Greece,” Chemosphere, vol. 41, no. 12, pp. 1845–1855, 2000. View at Publisher · View at Google Scholar · View at Scopus
  33. A. Filipkowska, L. Lubecki, and G. Kowalewska, “Polycyclic aromatic hydrocarbon analysis in different matrices of the marine environment,” Analytica Chimica Acta, vol. 547, no. 2, pp. 243–254, 2005. View at Publisher · View at Google Scholar · View at Scopus
  34. S. Triantafyllaki and M. Dassenakis, “Determination of polycyclic aromatic hydrocarbons in seawater by high performance liquid chromatography with photodiode array and fluorescence detection,” in Proceedings of the 9th International Conference on Environmental. Science and Technology, pp. 939–944, Rhodes Island, Greece, September 2005.
  35. J. Hassan, M. Izadi, and S. Homayonnejad, “Application of low density homogeneous liquid-liquid extraction combined with GC for TPH and PAH determination in semi-micro solid samples,” Journal of the Brazilian Chemical Society, vol. 24, no. 4, pp. 639–644, 2013. View at Publisher · View at Google Scholar · View at Scopus
  36. A. Björseth, A. Lunde, and A. Lindskog, “Long-range transport of polycyclic aromatic hydrocarbons,” Atmospheric Environment, vol. 13, no. 1, pp. 45–53, 1979. View at Publisher · View at Google Scholar · View at Scopus
  37. G. Grossi, J. Lichtig, and P. Krauβ, “PCDD/F, PCB and PAH content of Brazilian compost,” Chemosphere, vol. 37, no. 9–12, pp. 2153–2160, 1998. View at Publisher · View at Google Scholar · View at Scopus
  38. A. L. Spongberg and J. D. Witter, “Pharmaceutical compounds in the wastewater process stream in Northwest Ohio,” Science of the Total Environment, vol. 397, no. 1–3, pp. 148–157, 2008. View at Publisher · View at Google Scholar · View at Scopus
  39. T. Oluseyi, K. Olayinka, B. Alo, and R. Smith, “Comparison of extraction and clean-up techniques for the determination of polycyclic aromatic hydrocarbons in contaminated soil samples,” African Journal of Environmental Science and Technology, vol. 5, no. 7, pp. 482–493, 2011. View at Google Scholar
  40. EPA (Environmental Protection Agency), Method 3500C: Organic Extraction and Sample Preparation, Environmental Protection Agency, Washington, DC, USA, 2007, https://www.epa.gov/sites/production/files/2015-12/documents/3500c.pdf.
  41. C.-D. Dong and C.-W. Chen, “Determination of polycyclic aromatic hydrocarbons in industrial harbor sediments by GC-MS,” International Journal of Environmental Research and Public Health, vol. 9, no. 6, pp. 2175–2188, 2012. View at Publisher · View at Google Scholar · View at Scopus
  42. V. Pino, J. H. Ayala, A. M. Afonso, and V. González, “Micellar microwave-assisted extraction combined with solid-phase microextraction for the determination of polycyclic aromatic hydrocarbons in a certified marine sediment,” Analytica Chimica Acta, vol. 477, no. 1, pp. 81–91, 2003. View at Publisher · View at Google Scholar · View at Scopus
  43. A. Nikolaou, M. Kostopoulou, G. Lofrano, and S. Meric, “Determination of PAHs in marine sediments: analytical methods and environmental concerns,” Global NEST Journal, vol. 11, no. 4, pp. 391–405, 2009. View at Google Scholar
  44. S. Hugo, R. Márquez, M. Tovar, M. Montoya, J. Álvarez, and J. Sánchez, “Recent advances for polycyclic aromatic analysis in airborne particulate matter,” in Hydrocarbon Pollution and its Effect on the Environment, IntechOpen Limited, London, UK, 2018, https://www.intechopen.com/online-first/recent-advances-for-polycyclic-aromatic-analysis-in-airborne-particulate-matter/. View at Google Scholar
  45. E. Pakpahan, M. Isa, and S. Kutty, “Polycyclic aromatic hydrocarbons in petroleum sludge cake: extraction and origin—a case study,” International Journal of Applied Science and Technology, vol. 1, no. 5, pp. 201–207, 2011. View at Google Scholar
  46. L. Donta, Polycyclic Aromatic Hydrocarbons (PAH) Factsheet, European Union JRC 66955, Joint Research Center, Institute for Reference Materials and Measurements, Geel, Belgium, 4th edition, 2011.
  47. P. Krystyna, “Nanomaterials in extraction techniques,” in Advanced Environmental Analysis: Applications of Nanomaterials, C. M. Hussain and B. Kharisov, Eds., vol. 1, Royal Society of Chemistry, London, UK, 2017, http://www.rsc.org. View at Google Scholar
  48. R. Bushra, A. Ahmeda, and M. Shahadatb, “Mechanism of adsorption on nanomaterials,” in Advanced Environmental Analysis: Applications of Nanomaterials, C. M. Hussain and B. Kharisov, Eds., vol. 1, Royal Society of Chemistry, London, UK, 2017, http://www.rsc.org. View at Google Scholar
  49. S. Hamidreza, G. Ali, V. Gupta et al., “The role of nanomaterials as effective adsorbents and their applications in wastewater treatment,” Journal of Nanostructure in Chemistry, vol. 7, no. 1, pp. 1–14, 2017. View at Publisher · View at Google Scholar
  50. S. Shei and I. Chang, “Review of production routes of nanomaterials,” in Commercialization of Nanotechnologies–A Case Study Approach, D. Barbazon et al., Ed., Springer International Publishing, Manhattan, NY, USA, 2018, ISBN: 978-3-319-56978-9. View at Google Scholar
  51. A. Saad, “A Brief review on nanoparticles: types of platforms, biological synthesis and applications,” Research & Reviews: Journal of Material Sciences, vol. 6, no. 2, pp. 109–116, 2018. View at Publisher · View at Google Scholar
  52. P. Singh, Y.-J. Kim, D. Zhang, and D.-C. Yang, “Biological synthesis of nanoparticles from plants and microorganisms,” Trends in Biotechnology, vol. 34, no. 7, pp. 588–599, 2016. View at Publisher · View at Google Scholar · View at Scopus
  53. S. Iravani and B. Zolfaghari, “Green synthesis of silver nanoparticles using pinus eldarica bark extract,” BioMed Research International, vol. 2013, Article ID 639725, 5 pages, 2013. View at Publisher · View at Google Scholar · View at Scopus
  54. V. Dhand, L. Soumya, S. Bharadwaj, S. Chakra, D. Bhatt, and B. Sreedhar, “Green synthesis of silver nanoparticles using Coffea arabica seed extract and its antibacterial activity,” Materials Science and Engineering: C, vol. 58, pp. 36–43, 2016. View at Publisher · View at Google Scholar · View at Scopus
  55. S. Saif, A. Tahir, T. Asim, and Y. Chen, “Plant mediated green synthesis of CuO nanoparticles: comparison of toxicity of engineered and plant mediated CuO nanoparticles towards daphnia magna,” Nanomaterials, vol. 6, no. 11, p. 205, 2016. View at Publisher · View at Google Scholar · View at Scopus
  56. S. Patra, S. Mukherjee, A. K. Barui, A. Ganguly, B. Sreedhar, and C. R. Patra, “Green synthesis, characterization of gold and silver nanoparticles and their potential application for cancer therapeutics,” Materials Science and Engineering: C, vol. 53, pp. 298–309, 2015. View at Publisher · View at Google Scholar · View at Scopus
  57. S. Iravani, “Green synthesis of metal nanoparticles using plants,” Green Chemistry, vol. 13, no. 10, pp. 2638–2650, 2011. View at Publisher · View at Google Scholar · View at Scopus
  58. B. Linhai, S. Tan, Q. Meng et al., “Green synthesis, characterization and application of proanthocyanidins-functionalized gold nanoparticles,” Nanomaterials, vol. 8, p. 53, 2018. View at Publisher · View at Google Scholar · View at Scopus
  59. H. Saad, A. Hussein, and M. Mansour, “Removal of pyrene and benzo(a)pyrene micropollutant from water via adsorption by green synthesized iron oxide nanoparticles,” Advances in Natural Sciences: Nanoscience and Nanotechnology, vol. 9, no. 1, Article ID 015006, 2018. View at Publisher · View at Google Scholar · View at Scopus
  60. X. Chen and S. S. Mao, “Titanium dioxide nanomaterials: synthesis, properties, modifications, and applications,” Chemical Reviews, vol. 107, no. 7, pp. 2891–2959, 2007. View at Publisher · View at Google Scholar · View at Scopus
  61. J. Yang, S. Mei, and J. M. F. Ferreira, “Hydrothermal synthesis of TiO2 nanopowders from tetraalkylammonium hydroxide peptized sols,” Materials Science and Engineering: C, vol. 15, no. 1-2, pp. 183–185, 2001. View at Publisher · View at Google Scholar · View at Scopus
  62. O. Carp, C. Huisman, and A. Reller, “Photoinduced reactivity of titanium dioxide,” Progress in Solid State Chemistry, vol. 32, no. 1-2, pp. 33–177, 2004. View at Publisher · View at Google Scholar · View at Scopus
  63. W. Wei, B. Hu, F. Jin et al., “Potassium-chemical synthesis of 3D graphene from CO2 and its excellent performance in HTM-free perovskite solar cells,” Journal of Materials Chemistry A, vol. 5, no. 17, pp. 7749–7752, 2017. View at Publisher · View at Google Scholar · View at Scopus
  64. B. Kharisov and O. Kharissova, Carbon Allotropes: Metal-Complex Chemistry, Properties and Applications, Springer Nature Switzerland AG, Basel, Switzerland, 2019.
  65. S. Draper, D. Gregg, E. Schofield et al., “Complexed nitrogen heterosuperbenzene: the coordinating properties of a remarkable ligand,” Journal of the American Chemical Society, vol. 126, no. 28, pp. 8694–8701, 2004. View at Publisher · View at Google Scholar · View at Scopus
  66. J.-G. Yu, L.-Y. Yu, H. Yang et al., “Graphene nanosheets as novel adsorbents in adsorption, preconcentration and removal of gases, organic compounds and metal ions,” Science of the Total Environment, vol. 502, pp. 70–79, 2015. View at Publisher · View at Google Scholar · View at Scopus
  67. A. Astefanei, M. T. Núñez, and M. Galceran, “Characterisation and determination of fullerenes: a critical review,” Analytica Chimica Acta, vol. 882, pp. 1–21, 2015. View at Publisher · View at Google Scholar · View at Scopus
  68. K. Zare, V. K. Gupta, O. Moradi et al., “A comparative study on the basis of adsorption capacity between CNTs and activated carbon as adsorbents for removal of noxious synthetic dyes: a review,” Journal of Nanostructure in Chemistry, vol. 5, no. 2, pp. 227–236, 2015. View at Publisher · View at Google Scholar
  69. G. Giakisikli and A. N. Anthemidis, “Magnetic materials as sorbents for metal/metalloid preconcentration and/or separation. A review,” Analytica Chimica Acta, vol. 789, pp. 1–16, 2013. View at Publisher · View at Google Scholar · View at Scopus
  70. N. Kandpal, N. Sah, R. Loshali, R. Joshi, and J. Prasad, “Co-precipitation method of synthesis and characterization of iron oxide nanoparticles,” Journal of Scientific & Industrial Research, vol. 73, pp. 87–90, 2014. View at Google Scholar
  71. M. Sarno, E. Ponticorvo, C. Cirillo, and P. Ciambelli, “Magnetic nanoparticles for pahs solid phase extraction,” Chemical Engineering Transactions, vol. 47, pp. 313–318, 2016. View at Google Scholar
  72. N. Somandla, L. Madikizela, E. Cukrowska, and L. Chimuka, “Recent advances in the adsorbents for isolation of polycyclic aromatic hydrocarbons (PAHs) from environmental sample solutions,” Trends in Analytical Chemistry, vol. 99, pp. 101–116, 2018. View at Publisher · View at Google Scholar · View at Scopus
  73. S.-H. Wu, C.-Y. Mou, and H.-P. Lin, “Synthesis of mesoporous silica nanoparticles,” Chemical Society Reviews, vol. 42, no. 9, pp. 3862–3875, 2013. View at Publisher · View at Google Scholar · View at Scopus
  74. T. Asefa and Z. Tao, “Biocompatibility of mesoporous silica nanoparticles,” Chemical Research in Toxicology, vol. 25, no. 11, pp. 2265–2284, 2012. View at Publisher · View at Google Scholar · View at Scopus
  75. Y. Wan and D. Zhao, “On the controllable soft-templating approach to mesoporous silicates,” Chemical Reviews, vol. 107, no. 7, pp. 2821–2860, 2007. View at Publisher · View at Google Scholar · View at Scopus
  76. E. Tasciotti, X. Liu, R. Bhavane et al., “Mesoporous silicon particles as a multistage delivery system for imaging and therapeutic applications,” Nature Nanotechnology, vol. 3, no. 3, pp. 151–157, 2008. View at Publisher · View at Google Scholar · View at Scopus
  77. M. V. Speybroeck, V. Barillaro, T. D. Thi et al., “Ordered mesoporous silica material SBA-15: a broad-spectrum formulation platform for poorly soluble drugs,” Journal of Pharmaceutical Sciences, vol. 98, no. 8, pp. 2648–2658, 2009. View at Publisher · View at Google Scholar · View at Scopus
  78. J. A. S. Costa, R. A. de Jesus, C. M. P. Romão, and L. P. C. Romao, “Efficient adsorption of a mixture of polycyclic aromatic hydrocarbons (PAHs) by Si-MCM-41 mesoporous molecular sieve,” Powder Technology, vol. 308, pp. 434–441, 2017. View at Publisher · View at Google Scholar · View at Scopus
  79. R. S. Araújo, D. C. S. Azevedo, C. L. Cavalcante, A. Jiménez-López, E. Rodríguez-Castellón, and O. Castellon, “Adsorption of polycyclic aromatic hydrocarbons (PAHs) from isooctane solutions by mesoporous molecular sieves: influence of the surface acidity,” Microporous and Mesoporous Materials, vol. 108, no. 1–3, pp. 213–222, 2008. View at Publisher · View at Google Scholar · View at Scopus
  80. T. Fuat and T. Uyar, “Cyclodextrin-functionalized meso structured silica nanoparticles for removal of polycyclic aromatic hydrocarbons,” Journal of Colloid and Interface Science, vol. 497, pp. 233–241, 2017. View at Publisher · View at Google Scholar · View at Scopus
  81. Z. Zhang, X. Hou, X. Zhang, and H. Li, “The synergistic adsorption of pyrene and copper onto Fe(III) functionalized mesoporous silica from aqueous solution,” Colloids and Surfaces A: Physicochemical and Engineering Aspects, vol. 520, pp. 39–45, 2017. View at Publisher · View at Google Scholar · View at Scopus
  82. Z. Yan, J. Yuan, G. Zhu et al., “A new strategy based on cholesterol-functionalized iron oxide magnetic nanoparticles for determination of polycyclic aromatic hydrocarbons by high-performance liquid chromatography with cholesterol column,” Analytica Chimica Acta, vol. 780, pp. 28–35, 2013. View at Publisher · View at Google Scholar · View at Scopus
  83. F. Galan, V. Bernab, R. Lucena et al., “Sensitive determination of polycyclic aromatic hydrocarbons in water samples using monolithic capillary solid-phase extraction and on-line thermal desorption prior to gas chromatography-mass spectrometry,” Journal of Chromatography A, vol. 1218, no. 14, pp. 1802–1807, 2011. View at Publisher · View at Google Scholar · View at Scopus
  84. Y. Jiao, S. Fu, L. Ding et al., “Determination of trace leaching phthalate esters in water by magnetic solid phase extraction based on magnetic multi-walled carbon nanotubes followed by GC-MS/MS,” Analytical Methods, vol. 4, no. 9, pp. 2729–2734, 2012. View at Publisher · View at Google Scholar · View at Scopus
  85. S. Yan, T.-T. Qi, D.-W. Chen, Z. Li, X.-J. Li, and S.-Y. Pan, “Magnetic solid phase extraction based on magnetite/reduced graphene oxide nanoparticles for determination of trace isocarbophos residues in different matrices,” Journal of Chromatography A, vol. 1347, pp. 30–38, 2014. View at Publisher · View at Google Scholar · View at Scopus
  86. H. Wang and A. D. Campiglia, “Determination of polycyclic aromatic hydrocarbons in drinking water samples by solid-phase nanoextraction and high-performance liquid chromatography,” Analytical Chemistry, vol. 80, no. 21, pp. 8202–8209, 2008. View at Publisher · View at Google Scholar · View at Scopus
  87. B. B. Kefi, L. L. El Atrache, H. Kochkar, and A. Ghorbel, “TiO2 nanotubes as solid-phase extraction adsorbent for the determination of polycyclic aromatic hydrocarbons in environmental water samples,” Journal of Environmental Sciences, vol. 23, no. 5, pp. 860–867, 2011. View at Publisher · View at Google Scholar · View at Scopus
  88. A. Dios and M. Garcia, “Multifunctional nanoparticles: analytical prospects,” Analytica Chimica Acta, vol. 666, no. 1-2, pp. 1–22, 2010. View at Publisher · View at Google Scholar · View at Scopus
  89. S. Vasileva, A. Olenin, G. Romanovskaya et al., “Adsorption preconcentration of pyrene by silver nanoparticles and its determination in aqueous solutions,” Journal of Analytical Chemistry, vol. 64, no. 12, pp. 1244–1250, 2009. View at Publisher · View at Google Scholar · View at Scopus
  90. O. Péron, E. Rinnert, M. Lehaitre, P. Crassous, and C. Compère, “Detection of polycyclic aromatic hydrocarbon (PAH) compounds in artificial sea-water using surface-enhanced Raman scattering (SERS),” Talanta, vol. 79, no. 2, pp. 199–204, 2009. View at Publisher · View at Google Scholar · View at Scopus
  91. M. Ali, E. Khojastehb, T. Kayyalb, and A. Jabbari, “Magnetic solid phase extraction using gold immobilized magnetic mesoporous silica nanoparticles coupled with dispersive liquid–liquid microextraction for determination of polycyclic aromatic hydrocarbons,” Journal of Chromatography A, vol. 1364, pp. 20–27, 2014. View at Publisher · View at Google Scholar · View at Scopus
  92. J. Du and C. Jing, “Preparation of thiol modified Fe3O4@Ag magnetic SERS probe for PAHs detection and identification,” The Journal of Physical Chemistry C, vol. 115, no. 36, pp. 17829–17835, 2011. View at Publisher · View at Google Scholar · View at Scopus
  93. Y. Xie, X. Wang, X. Han et al., “Selective SERS detection of each polycyclic aromatic hydrocarbon (PAH) in a mixture of five kinds of PAHs,” Journal of Raman Spectroscopy, vol. 42, no. 5, pp. 945–950, 2010. View at Publisher · View at Google Scholar · View at Scopus
  94. L. Guerrini, J. V. Garcia-Ramos, C. Domingo, and S. Sanchez-Cortes, “Sensing polycyclic aromatic hydrocarbons with dithiocarbamate-functionalized Ag nanoparticles by surface-enhanced Raman scattering,” Analytical Chemistry, vol. 81, no. 3, pp. 953–960, 2009. View at Publisher · View at Google Scholar · View at Scopus
  95. W. Xuan, W. Hao, H. Zhang et al., “Analysis of polycyclic aromatic hydrocarbons in water with gold nanoparticles decorated hydrophobic porous polymer as surface-enhanced Raman spectroscopy substrate,” Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, vol. 139, pp. 214–221, 2015. View at Publisher · View at Google Scholar · View at Scopus
  96. M. M. Abolghasemi, V. Yousefi, and B. Hazizadeh, “An inorganic-organic hybrid material based on ZnO nanoparticles anchored to a composite made from polythiophene and hexagonally ordered silica for use in solid-phase fiber microextraction of PAHs,” Microchimica Acta, vol. 181, no. 5-6, pp. 639–645, 2014. View at Publisher · View at Google Scholar · View at Scopus
  97. T. Yu, M. Sun, X. Wang, C. Luo, and J. Feng, “A nanospherical metal–organic framework UiO-66 for solid-phase microextraction of polycyclic aromatic hydrocarbons,” Chromatographia, vol. 81, no. 7, pp. 1053–1061, 2018. View at Publisher · View at Google Scholar · View at Scopus
  98. G. Adrián, P. Tabares, V. Pino, F. Moreno, and A. Abizanda, “Silver nanoparticles supported onto a stainless steel wire for direct-immersion solid-phase microextraction of polycyclic aromatic hydrocarbons prior to their determination by GC-FID,” Microchimica Acta, vol. 185, no. 7, p. 341, 2018. View at Publisher · View at Google Scholar · View at Scopus
  99. H. Yunrui, Q. Zhoua, and G. Xiec, “Development of micro-solid phase extraction with titanate nanotube array modified by cetyltrimethylammonium bromide for sensitive determination of polycyclic aromatic hydrocarbons from environmental water samples,” Journal of Hazardous Materials, vol. 193, pp. 82–89, 2011. View at Publisher · View at Google Scholar · View at Scopus
  100. Y. Liu, J. Zhang, F. Zhao, and B. Zeng, “Electrodeposition of self-assembledpoly(3,4-ethylenedioxythiophene) @gold nanoparticles on stainlesssteel wires for the headspace solid-phase microextraction and gas chromatographic determination of several polycyclic aromatic hydrocarbons,” Journal of Chromatography A, vol. 1471, pp. 80–86, 2016. View at Publisher · View at Google Scholar · View at Scopus
  101. P. Di, J. Wang, C. Chen, C. Huang, Q. Cai, and S. Yao, “Ultrasonic assisted extraction combined with titanium-plate based solid phase extraction for the analysis of PAHs in soil samples by HPLC-FLD,” Talanta, vol. 108, pp. 117–122, 2013. View at Publisher · View at Google Scholar · View at Scopus
  102. L. Hongmei, W. Daoai, J. Li, S. Liua, X. Liua, and S. Jiang, “A novel TiO2 nanotube array/Ti wire incorporated solid-phase microextraction fiber with high strength, efficiency and selectivity,” Journal of Chromatography A, vol. 1217, no. 12, pp. 1898–1903, 2010. View at Publisher · View at Google Scholar · View at Scopus
  103. W. Huiyong and D. Andres, “Direct determination of benzo(a)pyrene in water samples by a gold nanoparticle-based solid phase extraction method and laser-excited time-resolved Shpol’skii spectrometry,” Talanta, vol. 83, no. 1, pp. 233–240, 2010. View at Publisher · View at Google Scholar · View at Scopus
  104. M. Sarno, E. Ponticorvo, C. Cirillo, and P. Ciambelli, “Polycyclic aromatic hydrocarbons extraction based on graphene coated magnetic alloy nanoparticles,” Chemical Engineering Transactions, vol. 60, pp. 145–150, 2017. View at Google Scholar
  105. W. Hong, X. Wang, B. Liu et al., “Flow injection solid-phase extraction using multi-walled carbon nanotubes packed micro-column for the determination of polycyclic aromatic hydrocarbons in water by gas chromatography–mass spectrometry,” Journal of Chromatography A, vol. 1217, no. 17, pp. 2911–2917, 2010. View at Publisher · View at Google Scholar · View at Scopus
  106. M. Jiping, R. Xiaoa, J. Li, J. Yub, Y. Zhanga, and L. Chen, “Determination of 16 polycyclic aromatic hydrocarbons in environmental water samples by solid-phase extraction using multi-walled carbon nanotubes as adsorbent coupled with gas chromatography–mass spectrometry,” Journal of Chromatography A, vol. 1217, no. 34, pp. 5462–5469, 2010. View at Publisher · View at Google Scholar · View at Scopus
  107. S. Rui, L. Yanb, T. Xub, D. Liub, Y. Zhua, and J. Zhoub, “Graphene oxide bound silica for solid-phase extraction of 14polycyclic aromatic hydrocarbons in mainstream cigarette smoke,” Journal of Chromatography A, vol. 1375, pp. 1–7, 2015. View at Publisher · View at Google Scholar · View at Scopus
  108. K.-J. Huang, Y.-J. Liu, J. Li, T. Gan, and Y.-M. Liu, “Ultra-trace determination of polycyclic aromatic hydrocarbons using solid-phase extraction coupled with HPLC based on graphene-functionalized silica gel composites,” Analytical Methods, vol. 6, no. 1, pp. 194–201, 2014. View at Publisher · View at Google Scholar · View at Scopus
  109. P. Kueseng, C. Thammakhet, P. Thavarungkul, and P. Kanatharana, “Multiwalled carbon nanotubes/cryogel composite, a new sorbent for determination of trace polycyclic aromatic hydrocarbons,” Microchemical Journal, vol. 96, no. 2, pp. 317–323, 2010. View at Publisher · View at Google Scholar · View at Scopus
  110. M. Valcárcel, S. Cárdenas, B. M. Simonet, Y. Moliner-Martínez, and R. Lucena, “Carbon nanostructures as sorbent materials in analytical processes,” TrAC Trends in Analytical Chemistry, vol. 27, no. 1, pp. 34–43, 2008. View at Publisher · View at Google Scholar · View at Scopus
  111. B.-T. Zhang, X. Zheng, H.-F. Li, and J.-M. Lin, “Application of carbon-based nanomaterials in sample preparation: a review,” Analytica Chimica Acta, vol. 784, pp. 1–17, 2013. View at Publisher · View at Google Scholar · View at Scopus
  112. K. Pyrzynska, “Carbon nanotubes as sorbents in the analysis of pesticides,” Chemosphere, vol. 83, no. 11, pp. 1407–1413, 2011. View at Publisher · View at Google Scholar · View at Scopus
  113. B. Osorio, T. Hüffer, P. Mettig, B. Schilling, M. Jochmann, and T. Schmidt, “Investigation of carbon-based nanomaterials as sorbents for headspace in-tube extraction of polycyclic aromatic hydrocarbons,” Analytical and Bioanalytical Chemistry, vol. 409, no. 15, pp. 3861–3870, 2017. View at Publisher · View at Google Scholar · View at Scopus
  114. P. Borm, G. Cakmak, E. Jermann et al., “Formation of PAH-DNA adducts after in vivo and vitro exposure of rats and lung cells to different commercial carbon blacks,” Toxicology and Applied Pharmacology, vol. 205, no. 2, pp. 157–167, 2005. View at Publisher · View at Google Scholar · View at Scopus
  115. J. Zhao, Z. Wang, Q. Zhao, and B. Xing, “Adsorption of phenanthrene on multilayer graphene as affected by surfactant and exfoliation,” Environmental Science & Technology, vol. 48, no. 1, pp. 331–339, 2014. View at Publisher · View at Google Scholar · View at Scopus
  116. Z. Yang, O. Guven, and T. Karanfil, “Adsorption of halogenated aliphatic contaminants by graphene nanomaterials,” Water Research, vol. 79, pp. 57–67, 2015. View at Publisher · View at Google Scholar · View at Scopus
  117. G. Zhao, L. Jiang, Y. He et al., “Sulfonated graphene for persistent aromatic pollutant management,” Advanced Materials, vol. 23, no. 34, pp. 3959–3963, 2011. View at Publisher · View at Google Scholar · View at Scopus
  118. D. Chen, H. Feng, and J. Li, “Graphene oxide: preparation, functionalization, and electrochemical applications,” Chemical Reviews, vol. 112, no. 11, pp. 6027–6053, 2012. View at Publisher · View at Google Scholar · View at Scopus
  119. M. Shokouh, H. Sereshti, and M. Ahmadvand, “A nanocomposite consisting of silica-coated magnetite and phenyl-functionalized graphene oxide for extraction of polycyclic aromatic hydrocarbon from aqueous matrices,” Journal of Environmental Sciences, vol. 55, pp. 164–173, 2016. View at Publisher · View at Google Scholar · View at Scopus
  120. L. Xu, J. Feng, J. Li, X. Liu, and S. Jiang, “Graphene oxide bonded fused-silica fiber for solid-phase microextraction-gas chromatography of polycyclic aromatic hydrocarbons in water,” Journal of Separation Science, vol. 35, no. 1, pp. 93–100, 2012. View at Publisher · View at Google Scholar · View at Scopus
  121. W.-D. Wang, Y.-M. Huang, W.-Q. Shu, and J. Cao, “Multiwalled carbon nanotubes as adsorbents of solid-phase extraction for determination of polycyclic aromatic hydrocarbons in environmental waters coupled with high-performance liquid chromatography,” Journal of Chromatography A, vol. 1173, no. 1-2, pp. 27–36, 2007. View at Publisher · View at Google Scholar · View at Scopus
  122. B. Rodríguez, A. Herrera, M. Asensio, and J. Hernández, “Recent applications of carbon nanotube sorbents in analytical chemistry,” Journal of Chromatography, vol. 1357, pp. 110–146, 2014. View at Publisher · View at Google Scholar · View at Scopus
  123. J. Ma, R. Xiao, J. Li, J. Yu, Y. Zhang, and L. Chen, “Determination of 16 polycyclic aromatic hydrocarbons in environmental water samples by solid-phase extraction using multi-walled carbon nanotubes as adsorbent coupled with gas chromatography-mass spectrometry,” Journal of Chromatography A, vol. 1217, no. 34, pp. 5462–5469, 2010. View at Publisher · View at Google Scholar · View at Scopus
  124. H. Wu, X. Wang, B. Liu et al., “Flow injection solid-phase extraction using multi-walled carbon nanotubes packed micro-column for the determination of polycyclic aromatic hydrocarbons in water by gas chromatography-mass spectrometry,” Journal of Chromatography A, vol. 1217, no. 17, pp. 2911–2917, 2010. View at Publisher · View at Google Scholar · View at Scopus
  125. L. Guo and H. K. Lee, “Development of multiwalled carbon nanotubes based micro-solid-phase extraction for the determination of trace levels of sixteen polycyclic aromatic hydrocarbons in environmental water samples,” Journal of Chromatography A, vol. 1218, no. 52, pp. 9321–9327, 2011. View at Publisher · View at Google Scholar · View at Scopus
  126. M. Moazzen, R. Ahmadkhaniha, M. E. H. Gorji, M. Yunesian, and N. Rastkari, “Magnetic solid-phase extraction based on magnetic multi-walled carbon nanotubes for the determination of polycyclic aromatic hydrocarbons in grilled meat samples,” Talanta, vol. 115, pp. 957–965, 2013. View at Publisher · View at Google Scholar · View at Scopus
  127. H. C. Menezes, S. M. R. de Barcelos, D. F. D. Macedo et al., “Magnetic N-doped carbon nanotubes: a versatile and efficient material for the determination of polycyclic aromatic hydrocarbons in environmental water samples,” Analytica Chimica Acta, vol. 873, pp. 51–56, 2015. View at Publisher · View at Google Scholar · View at Scopus
  128. I. Ana, J. Francisco, Z. Mohammed, C. Rosa, and R. Ángel, “Magnetic nanoparticles-carbon nanotubes hybrid composites for selective solid-phase extraction of polycyclic aromatic hydrocarbons and determination by ultra-high performance liquid chromatography,” Analytical and Bioanalytical Chemistry, vol. 409, no. 21, pp. 5125–5132, 2017. View at Publisher · View at Google Scholar · View at Scopus
  129. S. Meysam, M. Ahmad, and A. Hamid, “Synthesis of Fe3O4@PPy–MWCNT nanocomposite and its application for extraction of ultra-trace amounts of PAHs from various samples,” Journal of the Iranian Chemical Society, vol. 14, no. 3, pp. 623–634, 2017. View at Publisher · View at Google Scholar · View at Scopus
  130. B. Opas and K. Proespichaya, “Extraction of polycyclic aromatic hydrocarbons with a magnetic sorbent composed of alginate, magnetite nanoparticles and multiwalled carbon nanotubes,” Microchimica Acta, vol. 182, no. 7-8, pp. 1519–1526, 2015. View at Publisher · View at Google Scholar · View at Scopus
  131. P. Oleszczuk, I. Jośko, and B. Xing, “The toxicity to plants of the sewage sludges containing multiwalled carbon nanotubes,” Journal of Hazardous Materials, vol. 186, no. 1, pp. 436–442, 2011. View at Publisher · View at Google Scholar · View at Scopus
  132. X. Xia, X. Chen, X. Zhao, H. Chen, and M. Shen, “Effects of carbon nanotubes, chars, and ash on bioaccumulation of perfluorochemicals by Chironomus plumosus larvae in sediment,” Environmental Science & Technology, vol. 46, no. 22, pp. 12467–12475, 2012. View at Publisher · View at Google Scholar · View at Scopus
  133. D. Volder, S. Tawfick, R. Baughman, and A. Hart, “Carbon nanotubes: present and future commercial applications,” Science, vol. 339, no. 6119, pp. 535–539, 2013. View at Publisher · View at Google Scholar · View at Scopus
  134. S. Babina, T. Anderson, V. Acosta, P. Payton, and E. Cañas, “The influence of multiwalled carbon nanotubes on polycyclic aromatic hydrocarbon (PAH) bioavailability and toxicity to soil microbial communities in alfalfa rhizosphere,” Ecotoxicology and Environmental Safety, vol. 116, pp. 143–149, 2015. View at Publisher · View at Google Scholar · View at Scopus
  135. A. Amiri, M. baghayeri, and M. Kashmari, “Extraction and determination of polycyclic aromatic hydrocarbons in water and urine samples using magnetic nanoparticles modified with polyfuran,” in Proceedings of the 7th Seminar of Chemistry and Environment, pp. 26-27, Baqiyatallah University of Medical Science, Asan, Korea, September 2015.
  136. S. K. M. Rozi, H. R. Nodeh, M. A. Kamboh, N. S. A. Manan, and S. Mohamad, “Novel palm fatty acid functionalized magnetite nanoparticles for magnetic solid-phase extraction of trace polycyclic aromatic hydrocarbons from environmental samples,” Journal of Oleo Science, vol. 66, no. 7, pp. 771–784, 2017. View at Publisher · View at Google Scholar · View at Scopus
  137. C.-D. Dong, C.-W. Chen, and C.-M. Hung, “Synthesis of magnetic biochar from bamboo biomass to activate persulfate for the removal of polycyclic aromatic hydrocarbons in marine sediments,” Bioresource Technology, vol. 245, pp. 188–195, 2017. View at Publisher · View at Google Scholar · View at Scopus
  138. C.-D. Dong, C.-W. Chen, C.-M. Kao, C.-C. Chien, and C.-M. Hung, “Wood-biochar-supported magnetite nanoparticles for remediation of PAH-contaminated estuary sediment,” Catalysts, vol. 8, no. 2, p. 73, 2018. View at Publisher · View at Google Scholar · View at Scopus
  139. W. Yixuan, S. Wanga, H. Niua et al., “Preparation of polydopamine coated Fe3O4 nanoparticles and their application for enrichment of polycyclic aromatic hydrocarbons from environmental water samples,” Journal of Chromatography A, vol. 1283, pp. 20–26, 2013. View at Publisher · View at Google Scholar · View at Scopus
  140. H. Wang, X. Zhao, W. Meng et al., “Cetyltrimethylammonium bromide-coated Fe3O4 magnetic nanoparticles for analysis of 15 trace polycyclic aromatic hydrocarbons in aquatic environments by ultraperformance, liquid chromatography with fluorescence detection,” Analytical Chemistry, vol. 87, no. 15, pp. 7667–7675, 2015. View at Publisher · View at Google Scholar · View at Scopus
  141. A. Sajjad, A. Amiri, and F. Ghaemi, “Development of novel magnetic solid-phase extraction sorbent based on Fe3O4/carbon nanosphere/polypyrrole composite and their application to the enrichment of polycyclic aromatic hydrocarbons from water samples prior to GC–FID analysis,” Journal of the Iranian Chemical Society, vol. 15, no. 1, pp. 153–161, 2018. View at Publisher · View at Google Scholar · View at Scopus
  142. E. Tahmasebi and Y. Yamini, “Facile synthesis of new nano sorbent for magnetic solid-phase extraction by self assembling of bis-(2,4,4-trimethyl pentyl)-dithiophosphinic acid on Fe3O4@Ag core@shell nanoparticles: characterization and application,” Analytica Chimica Acta, vol. 756, pp. 13–22, 2012. View at Publisher · View at Google Scholar · View at Scopus
  143. R. Wang and Z. Chen, “A covalent organic framework-based magnetic sorbent for solid phase extraction of polycyclic aromatic hydrocarbons, and its hyphenation to HPLC for quantitation,” Microchimica Acta, vol. 184, no. 10, pp. 3867–3874, 2017. View at Publisher · View at Google Scholar · View at Scopus
  144. K. Li, H. Li, L. Liu, Y. Hashi, T. Maeda, and J.-M. Lin, “Solid-phase extraction with C30 bonded silica for analysis of polycyclic aromatic hydrocarbons in airborne particulate matters by gas chromatography-mass spectrometry,” Journal of Chromatography A, vol. 1154, no. 1-2, pp. 74–80, 2007. View at Publisher · View at Google Scholar · View at Scopus
  145. M. Virginia, M. Zougagh, and R. Ángel, “Hybrid nanoparticles based on magnetic multiwalled carbon nanotube-nano C18 SiO2 composites for solid phase extraction of mycotoxins prior to their determination by LC-MS,” Microchimica Acta, vol. 183, no. 2, pp. 871–880, 2016. View at Publisher · View at Google Scholar · View at Scopus
  146. A. Balati, A. Shahbazi, M. M. Amini, and S. H. Hashemi, “Adsorption of polycyclic aromatic hydrocarbons from wastewater by using silica-based organic-inorganic nanohybrid material,” Journal of Water Reuse and Desalination, vol. 5, no. 1, pp. 50–63, 2015. View at Publisher · View at Google Scholar · View at Scopus
  147. M. Tobiszewski and J. Namieśnik, “PAH diagnostic ratios for the identification of pollution emission sources,” Environmental Pollution, vol. 162, pp. 110–119, 2012. View at Publisher · View at Google Scholar · View at Scopus
  148. L. Haiyan, M. Zhai, H. Chen, C. Tan, X. Zhang, and Z. Zhang, “Systematic investigation of the synergistic and antagonistic effects on the removal of pyrene and copper onto mesoporous silica from aqueous solutions,” Materials, vol. 12, no. 3, p. 546, 2019. View at Publisher · View at Google Scholar · View at Scopus
  149. R. Radhika, P. Loganathan, K. Logavaseekaran, R. Nithiya, and V. Jayabharathi, “Green synthesis of nanoparticles their chartacterization & application,” World Journal of Pharmacy and Pharmaceutical Sciences, vol. 5, no. 5, pp. 454–478, 2016. View at Google Scholar