Greener Method for the Application of TiO<sub>2</sub> Nanoparticles to Remove Herbicide in Water

Hiep, Hoang; Tuan Anh, Pham; Dao, Van-Duong; Viet Quang, Dang

doi:https://doi.org/10.1155/2023/3806240

Journal of Analytical Methods in Chemistry

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Abstract Introduction Experimental Results and Discussion Conclusion Data Availability Conflicts of Interest Authors’ Contributions Acknowledgments References Copyright Related Articles

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Green Analytical Methods and Nanomaterials for Sample Preparation 2022

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Research Article | Open Access

Volume 2023 | Article ID 3806240 | https://doi.org/10.1155/2023/3806240

Greener Method for the Application of TiO₂ Nanoparticles to Remove Herbicide in Water

Hoang Hiep,¹Pham Tuan Anh,²Van-Duong Dao,²and Dang Viet Quang²

Academic Editor: Adrián Gutiérrez Serpa

Received30 Dec 2022

Revised22 May 2023

Accepted14 Jun 2023

Published11 Jul 2023

Abstract

TiO₂ nanoparticles have emerged as a great photocatalyst to degrade organic contaminants in water; however, the nanoparticles dispersed in water could be difficult to be recovered and potentially become contaminant. Herbicide like 2,4-dichlorophenoxyacetic acid (2,4-D) used in agriculture usually ends up with a large fraction remaining in water and sediment, which may cause potential risk to human health and the ecosystem. This study proposes a greener method to utilize TiO₂ as photocatalyst to remove 2,4-D from water. Accordingly, TiO₂ nanoparticles (10–45 nm) were synthesized and grafted on lightweight fired clay to generate a TiO₂-based floating photocatalyst. Experimental testing revealed that 60.2% of 2,4-D (0.1 mM) can be decomposed in 250 min under UV light with TiO₂-grafted lightweight fired clay floating on water. Degradation fits well into the pseudo-first-order kinetic model. The floating photocatalysts can degrade approximately 50% 2,4-D in 250 min under sunlight and the degradation efficiency is stable for cycles. The results revealed that the fabrication of floating photocatalyst could be a promising and greener way to remove herbicide contaminants in water using TiO₂.

1. Introduction

2,4-dichlorophenoxyacetic acid (2,4-D) is an herbicide agent that has been widely used to control broadleaf weeds in agriculture and urban landscape practices [1]. This chemical has been registered as an active ingredient in approximately 1500 herbicide formulations, with a large amount being produced and consumed worldwide every year [2]. In China, for example, 2,4-D production reached 40,000 tons/year in 2010 [3]; meanwhile, the consumption in the USA was about 13,000–15,000 tons annually in 2001 [2]. Herbicides are usually applied onto soil or sprayed over crops; therefore, they can reach superficial water and sediments [4]. It is estimated that 91.7% of 2,4-D ends up in surface and ground water due to its high solubility in water [5]. 2,4-D is a moderately persistent chemical, which can be decomposed by both photodegradation and microbial degradation at a very slow rate, with a half-life between 20 and 312 days [6]. 2,4-D contamination could be the source of health hazard to exposed animals and human, which may cause the endocrine disruption, reproductive disorder, genetic alterations, and carcinogenic effects [1]. Because of these environmental and health concerns, it is necessary to eliminate 2,4-D from water.

Photolysis and microbial degradation can occur naturally, however, at a slow rate, thus, it requires effective treatment technologies for the elimination of 2,4-D [4]. Removal of 2,4-D from water has been investigated with various treatment technologies such as adsorption [7–12], photo/oxidation [13, 14], electrochemical oxidation [15, 16], photocatalysis [17–22], and microbial degradation [23, 24]. In general, these technologies showed relatively high efficiency in the removal of 2,4-D from contaminated water. Activated carbon and metal organic frameworks, for example, can adsorb up to 352.9 mg/g and 556 mg/g, respectively [9, 11]. A photocatalyst based on TiO₂ can degrade 83% 2,4-D in 180 min under visible light. Electrochemical oxidation posed as a great treatment process that can reach 95.9% removal efficiency [15]. Even though these technologies efficiently remove 2,4-D, they may not be suitable for treatment of scattered or large water resources such as lake, river, irrigated water, and aquaculture water. These required more sustainable and cost-effective treatment technologies.

Floating photocatalyst-based water treatment technology (FPWT) that uses sunlight to breakdown pollutants has recently attracted great attention because of its potential for large-scale application, particularly to treat water resources that are contaminated with persistent organic pollutants (POPs) such as herbicides, pesticides, and antibiotics [25, 26]. These pollutants, which usually originated from agriculture, aquaculture, livestock, medicine, and chemical industries enter water reservoir and could not be removed by normal water treatment plants [1, 27, 28]. FPWT breaks POPs under sunlight using photocatalysts that are grafted on a floating substrate. When the floating photocatalysts (FPC) are dispatched to a water reservoir, it will float and continue degrading POPs under sunlight irradiation without any requirement of external intervention.

Several substrates including synthetic polymers [29–32], polymer composites [33–37], wood [38], ceramics and silica [39, 40], natural light-weight stones [41–43], and concrete [44] have been used to support photocatalysts. Testing in a laboratory revealed that FPWT effectively removes a variety of organic pollutants. TiO₂-PANI/cork FPC can decompose 95.2% methyl orange, 85.3% 4-nitrophenol, and over 60% of phenol, 2,4-dinitrophenol, toluidine, salicylic acid, and benzoic acid in 210 min under sunlight [33]. Ni-N-TiO₂ expanded graphite composite FPC removed 96.9% diesel oil after 5 h irradiation by visible light [34]. 98.1% methyl blue can be removed by B-N-TiO₂/expanded perlite FPC after 5 h under visible light [45]. 94.8% Congo red can be removed by TiO₂-loaded palm trunk after 150 h of irradiation by sunlight [38]. FPC also showed effective removal of NH₃ and naphthenic acids [25, 39].

Previous studies revealed that TiO₂ can effectively decompose 2,4-D in water [46, 47]. The decomposition efficiency may vary with the TiO₂ composition; pure anatase TiO₂ can remove 68.2–70.5%, but it increased to 92.7% as TiO₂ containing 8% rutile [46]. Obviously, TiO₂ powder can effectively remove 2,4-D; however, it could not be directly dispersed into water resources since it will require very large amount and could not be recovered. TiO₂ powder, consequently, is not feasible for the direct use to treat organic contaminants in large water reservoirs. Thus, the fabrication of FPC could be a greener and more feasible measure for the removal of 2,4-D and other organic pollutants from water using TiO₂. To the best of our knowledge, the application of FPC for the degradation of 2,4-D has not been investigated; therefore, the objective of this work is to graft TiO₂ onto LFC for TiO₂-based FPC production and investigate its potential for 2,4-D removal.

2. Experimental

2.1. Materials

Clay samples from Phu Tho province with the composition shown in Table 1 were purchased from a local supplier. Rice husk was collected from a local source in Hai Duong, Viet Nam. Clay samples were dried and ground to the particle size ≤63 μm while rice husk was crushed until the size of ≤0.5 mm. Tetraisopropyl orthotitanate (TTIP, 97%), isopropanol (IPA, 99.5%), acetyl acetone (ACAC, 99%), and 2,4-dichlorophenoxyacetic acid (2,4-D) were purchased from Sigma-Aldrich and used without further purification.

2.2. Preparation of Lightweight Fired Clay

LFC was prepared in accordance with previous publications [48, 49]. In a typical preparation process, desired amounts of clay and rice husk with a mass ratio of 1 : 1 were weighed and mixed well prior to the addition of water. The water quantity was sufficiently adjusted to ensure the plasticity of the clay mixture. The clay mixture was pelletized into spherical-like granules, which were then dried under sunlight for 2-3 days before being fired in a furnace. The firing process was conducted in two steps from the room temperature to 1200°C. The first step related to the temperature increment from the room temperature to 200°C at the ramping rate of 15°C/min and then to 1200°C at the ramping rate of 20°C/min. The temperature remained constant for 20 min and 10 min at the end of the first and second steps, respectively. After cooling down to room temperature, the LFC sample was stored for further characterization and experiments.

2.3. TiO₂ Synthesis

TiO₂ was prepared by a hydrothermal method adapted from [50] using tetra-isopropyl orthotitanate as a titanium precursor. Typically, a mixture of TTIP : ACA : IPA with a molar ratio of 1 : 1 : 30 was prepared by slow addition of TTIP into a 500 mL beaker containing ACA and IPA, followed by the introduction of a solution of 15 wt% water in IPA. The mixture was continuously stirred at room temperature for 30 min, transferred to a 500 mL hydrothermal reactor made of Teflon-lined stainless steel. The mixture was then hydrothermally treated by placing the reactor in an oven at 160°C for 9 h. Solid TiO₂ was separated and washed with plenty of ethanol and water by centrifugation. The obtained TiO₂ was dried at 90°C for 24 h for later characterization and fabrication of FPC.

2.4. Preparation of Floating Photocatalyst

FPC that is TiO₂-modified lightweight fired clay (TiO₂/LFC) was prepared according to a procedure described elsewhere [39]. First, 5 g TiO₂ was dispersed into 150 mL ethanol in a 500 mL beaker, followed by the adjustment of pH to ∼3.5 with dilute HNO₃. The mixture was sonicated for 30 min to generate a homogenous slurry, which was then gently mixed with 20 g of LFC granules in 2 h for TiO₂ to adsorb onto LFC. Subsequently, LFC granules were separated and dried in the oven for 2 h at 120°C prior to calcination at 450°C in 30 min. Finally, to remove any TiO₂ particles that were not grafted on the LFC surface, LFC granules were washed with distilled water for several times and again dried at 120°C for 2 h.

2.5. Photocatalytic Degradation Tests

Photocatalytic degradation was tested under UV light by a batch-wise method in an experimental chamber consists of a 6-place magnetic stirrer at the bottom and 10 fluorescent UV lamps (G8 W T5 from Sylvania producer with λ_max = 365 nm to 8 watt) mounted on the top. Over the magnetic stirrer, the energy density of 6.5 mW/cm² was determined by using a UVA-B light meter and an ILT 1400-A Radiometer Photometer. The chamber was constructed mainly by aluminium material and was completely covered by aluminium foil during testing. A similar experimental setup was used for the sunlight test; however, the chamber with UV light was removed for sunlight irradiation.

In a typical experiment, 0.5 g FPC and 50 mL of 2,4-D 0.1 mM solution (catalyst dose: 10 g/L) were added into a 250 mL beaker, stirred on a magnetic stirrer in the experimental chamber, and then the UV light was turned on. To follow the degradation progress, samples were extracted after a certain duration, filtered, and analyzed for 2,4-D concentration. Two FPC granule samples with average sizes of 5 mm and 8 mm were tested to evaluate the potential effect of granular size on its catalytic degradation activity. Blank and control experiments were conducted in the same procedure with no catalyst, pure TiO₂ (0.6 g/L) or LFC substrate (10 g/L). To study the recyclability of photocatalyst, FPC (8 mm) was recovered after the experiment, slightly washed with water, dried at 120°C for 2 h, and then reused in another cycle to examine any possible decrease in photocatalytic activities.

To conduct radical scavenging experiments, three radical scavengers, i.e., benzoquinone, EDTA, and isopropanol were captured to capture O⁻₂, h⁺, and OH, respectively. Accordingly, each scavenger was added to a beaker containing 2,4-D solution with FPC (8 mm), which was then placed in a UV chamber for 300 min and samples were taken for analyses. To further confirm the 2,4-D degradation, experiments were conducted 2,4-D solution (5 ppm) without scavenger and samples were collected for the analyses of total organic carbon.

2.6. Characterization

The specific surface areas of samples were analyzed by nitrogen adsorption/desorption method using Micromeritics TriStar II Plus. Samples were degassed at 250°C for 5 h prior to analysis and the surface area was determined by the BET method. X-ray diffraction (XRD) patterns were collected on the XRD D8 Advance Bruker using a Cu-Kα source. Scanning electron microscopy (SEM) images were observed on the JEOL 7500F coupled with energy-dispersive X-ray spectroscopy. Fourier transformer infrared spectroscopic studies were conducted on the FTIR 6300 spectrometer (Jasco). 2,4-D concentration was analyzed on an HPLC 5890 series II, Shimadzu using a UV detector at 285 nm, a Zipax SAX (duPont) C18 column, and solvent system including CH₃CN (A, 60%) and H₂O with 0.15% acetic acid (B, 40%) at a flow rate of 1 ml/min and an injection volume of 20 μl. Total organic carbon was analyzed on TOC Veolia/Suez Sievers M5310C Laboratory.

3. Results and Discussion

3.1. Material Characterization

TiO₂ photocatalyst and LFC floating substrate were prepared separately, and then TiO₂ was grafted on the LFC surface by an adsorption-calcination procedure without the addition of any binder. TiO₂ was prepared by a hydrothermal technique using TTIP as a titanium precursor. This method allows one to synthesize anatase or anatase/rutile mixed TiO₂ particles at relatively mild condition [50, 51]. The coexistence of the anatase/rutile phase reduces the band gap that enhances the photocatalytic activity of TiO₂ in the range of visible light [52, 53]. After hydrothermal treatment, TiO₂ nanoparticles were obtained with the particle size ranging from 10 to 45 nm. These particles tended to agglomerate into mesoporous powder, as shown in Figure 1(a). To evaluate the crystalline phases of TiO₂, an XRD pattern was collected and analyzed (Figure 2(a)). The resulting TiO₂ has a tetragonal structure of anatase corresponding to a PDF number of 01-078-2486. Characteristic diffraction at 25.3, 37.9, 48.1, and 62.9° are, respectively, assigned to the (101), (004), (200), and (204) crystal planes of anatase TiO₂.

(a)

(b)

(c)

(d)

Representative SEM images of the LFC surface are shown in Figure 1(b). LFC has a porous structure in which large pores can reach a size of ≈100 μm. Its highly porous structure gives it a low bulk density (<1 g/cm³). Higher magnification (Figure 1(b) inset) revealed that LFC constitutes of laminar structure of silicate that were interconnected into a highly porous network, similar observation in previous studies [54, 55]. This type of materials shows relatively good adsorption performance [54, 56]. Thus, the LFC surface was almost completely covered by TiO₂ nanoparticles as soon as it was contacted with TiO₂ slurry (Figure 1(c)). After calcination at, more and larger cracks appeared on the surface of the layer; however, the microstructure of TiO₂ was unchanged (Figure 1(d)). The interconnected TiO₂ nanoparticles percolated into pores and were deposited onto the LFC surface to form a porous layer. The degree of TiO₂ nanoparticle aggregation in the porous layer looks similar to that in the original TiO₂ powder. This restricted the accessibility to pores in the LFC structure, which resulted in a significant reduction in the surface area of LFC from 37.7 to 1.2 m²/g.

The presence of TiO₂ on LFC was asserted by the XRD study, as shown in (Figure 2). The XRD pattern of LFC exhibited peaks at 20.6, 26.5, 36.5, and 40.2°, which could be attributed to the diffraction of quartz. Diffraction at 30.9 and 40.8° corresponds to the mullite phase, which was upon the calcination. Most of these peaks decreased when LFC adsorbed TiO₂ slurry and calcined, except for the peak at 26.5° that belongs to the stable quartz phase. In addition, a novel and distinct peak emerged at 25.3° and some minor peaks at 37.9, and 48.1° that could be assigned to the characteristic diffraction of anatase TiO₂. This indicated that the TiO₂ was successfully grafted onto the LFC. Moreover, several additional minor peaks were observed at 27.7° on the calcined samples, which suggest the possible transformation of anatase to rutile TiO₂ during calcination.

The addition of TiO₂ onto LFC was further observed on the FTIR spectra of the samples. As shown in Figure 3, the vibration band at ∼3400 cm⁻¹ and 1630 cm⁻¹ attributed to O-H groups in the structure of TiO₂, LFC, and FPC and adsorbed water, respectively. The characteristic Si-O-Si bond (∼1080 cm⁻¹) of the LFC structure was remained after attachment of TiO₂. Particularly, the distinct vibration band belonging to the Ti-O-Ti bond (654.7 cm⁻¹) of anatase TiO₂ was reduced significantly but was detectable on the spectrum of FPC. This further confirmed the formation of the TiO₂ layer on the surface of the LFC. Elemental analyses by EDX indicated that the content of Ti increased from 0.82 wt% to 6.86 wt% after TiO₂ was grafted on the LFC surface (Figures 4(a) and 4(b)). Elemental mapping analyses revealed that TiO₂ distributed throughout the surface of the LFC substrate (Figures 4(c) and 4(d)). This is very meaningful to a floating catalyst that helps the catalyst stay active irrespective of the catalyst surface that receives the sunlight.

(a)

(b)

(c)

(d)

3.2. Photocatalytic Degradation toward 2,4-D

2,4-D degradation efficiency by photocatalysts is exhibited in Figure 5. A negligible decrease in 2,4-D concentration was detected after 250 min UV irradiation without catalyst. The test with LFC substrate showed a 4% reduction in the first 30 min and after that no considerable change was recorded. These suggested that the photolysis of 2,4-D occurred at a relatively slow rate and that the reduction in the presence of LFC substrate was due to its adsorption on LFC. Adsorption was also observed on FPC as the tests were conducted in the dark with a 4.5% and 9.6% reduction in 2,4-D concentration after 30 and 120 min, respectively. The adsorption of 2,4-D has very important role in the performance of FPC. This allows FPC to continuously attract pollutants from the water volume onto its surface for photocatalytic decomposition while floating on the surface without vigorous mixing.

(a)

(b)

The degradation efficiency increased sharply and reached 79.91% in the initial stage of 60 min as TiO₂ powder was used. The degradation occurred at slower rate in the later stage and reached 99.87% after 250 min. The slow degradation in the later stage is mostly due to the low 2,4-D concentration remained in the solution. This result revealed that the synthesized TiO₂ effectively decomposed the 2,4-D under UV radiation. The photocatalytic degradation was sustained as TiO₂ was grafted onto the floating structure of the LFC, however, at a slower rate. As seen in Figure 5(a), the 2,4-D removal efficiency reached only 21.7% after 60 min and 60.4% in 250 min. In this study, the quantity of TiO₂ in FPC used (0.057 g) is almost double that of TiO₂ powder (0.03 g), thus, the slow degradation rate is likely due to the less accessibility to photocatalytic sites in the floating catalyst compared with the TiO₂ powder. As added into water, TiO₂ particles in powder form can disperse throughout the water phase under mixing condition, thereby, 2,4-D can approach to TiO₂ particles instantly and then easily decomposed as TiO₂ particles are exposed to UV light. Meanwhile, the floating catalyst appears on water surface only, it takes time for 2,4-D molecules to migrate from bulk water to the surface of catalyst. This migration induces by 2,4-D concentration gradient and is rate-limiting process. The migration rate could be enhanced by the application of external forces, i.e., stirring or air bubbling; however, it could not be occurred instantly because of the long distance. Moreover, as FPC granules float on water, only about half of their surface area exposes to the light, which further limits the activity of floating catalyst. Even though the removal efficiency achieved by FPC was lower than that achieved by TiO₂ powder, it could be used to develop a sustainable water treatment technology. This method could considerably reduce the risk of secondary contamination and be particularly suitable for the treatment of large water resources, aquaculture, and agriculture water.

2,4-D degradation kinetics was investigated using the pseudo-first-order kinetic model, as given in the following equation:where r is reaction rate, C is 2,4-D concentration, t is reaction time, and k is pseudo-first-order rate constant. Solving equation (1) with the boundary conditions of t = 0, C_t = C₀, an integration form was obtained as the following equation:

The rate constant, k, can be determined by a linear plot of Ln (C_t/C₀) vs. time (t), as shown in Figure 5(b). R square and k values received from linear fitting are exhibited in Table 2. Rate constants were very small, only 1.98 × 10⁻⁶ min⁻¹ and 1.34 × 10⁻⁴ min⁻¹, in the case no catalyst and LFC were used in the experiments, respectively. Besides, the regression is very bad for those two cases with the correlation coefficients (R²) are −0.1967 and 0.32 only. Meanwhile, the degradation rate constant for TiO₂ powder was relatively high, reached 0.023 min⁻¹ with R² of 0.9589. Rate constants were 0.0036 min⁻¹ and 0.0038 min⁻¹ for FPC with granular sizes of 5 mm and 8 mm, respectively. The very close rate constants revealed that the variation in granule size from 5 to 8 mm caused no significant influence on their catalytic efficiency. The correlation coefficients reached 0.9878 and 0.9967 for FPC with granular sizes of 5 mm and 8 mm, respectively, indicated that the 2,4-D degradation on FPC fits well to the pseudo-first-order kinetic model. Simulation on 2,4-D degradation efficiency vs. time based on the pseudo-first-order kinetic model is presented in Figure 6(a). 2,4-D degradation trend resulted from the model is correlated well with that obtained from experiment. Accordingly, 90% of 2,4-D is expected to be decomposed in 640 min, equivalent to less than two sunny days depending on the location.

(a)

(b)

For large water resources such as agriculture, aquaculture, or reserve water resources, they may not require a significantly rapid treatment but rather a sustainable treatment method, and therefore, the application of the FPC could become suitable. However, to apply for this purpose, FPC must be active under the sunlight instead of UV light in the laboratory. In a previous work conducted by Shavisi et al., a floating catalyst based on P25 TiO₂ grafted lightweight expanded clay aggregates proved to efficient candidate for NH₄⁺ degradation under solar radiation with 96.5% NH₄⁺ removal [39]. By grafting TiO₂ synthesized from TTIP by the sol-gel method on palm trunk, Sboui et al. received a floating catalyst that can remove 98.2% Congo red after 210 min under solar radiation [38]. Several others demonstrated that the efficient degradation of organic compounds under sunlight can be achieved by grafting TiO₂ on a floating substrate for floating catalyst production [33, 35–37, 41, 44, 57].

To investigate the catalytic activity of FPC prepared in this study under sunlight, experiments has been conducted in the same protocol in laboratory except the light source was changed to natural sunlight with the measured radiation power of 6.71 mW/m². The result revealed that over 50% of 2,4-D was decomposed after 250 min. To evaluate the recyclability, photocatalysts were recovered, slightly washed, and dried before dispersing on water for another testing cycle. The performance of photocatalysts was assessed based on the change in degradation efficiency against 2,4-D after each cycle. Results obtained revealed that a negligible reduction in degradation efficiency (∼7.2%) was observed after 5 cycles (Figure 6(b)). This indicated that FPC is stable in experimental conditions in the laboratory. This work provided solid evidence to further confirm that FPWT could become a promising technology for water treatment.

It is well known that the radicals such as OH, O⁻₂, h⁺ generated during UV light irradiation are responsible for the photodegradation of 2,4-D. To elucidate the role of those radicals on the photodegradation, radical scavengers—benzoquinone, EDTA, and isopropanol— were used as scavengers to capture O⁻₂, h⁺, and OH, respectively. Experimental results showed that 2,4-D degradation efficiency slightly changes when benzoquinone was added, while the effect was significant as EDTA and isopropanol were used (Figure 7(a)). The 2,4-D degradation efficiency was reduced from 66% to 53.3% and 47.3% with the addition of EDTA and isopropanol, respectively. These results imply that h⁺ and OH radicals are the most influential radical on the 2,4-D degradation. This observation is in good agreement with a previous study where the contribution of ∙OH is dominant after 50 min irradiation on TiO₂/activated carbon system [21]. This suggests a mechanism for 2,4-D degradation over FPC, as described in equations (3)–(9). Under UV light, TiO₂ generates electrons and holes, which subsequently react with H₂O and O₂, to produce ∙OH and ∙O⁻₂ radicals. The radicals and h⁺ can oxidize 2,4-D molecules. Total organic carbon contents in the samples decreased significantly after UV irradiation (Figure 7(b)) indicating that 2,4-D was mineralized to CO₂ and H₂O.

(a)

(b)

4. Conclusion

A floating photocatalyst was successfully prepared by grafting TiO₂ on lightweight fired clay. In this study, TiO₂ nanoparticles were synthesized from TTIP by a hydrothermal process and grafted on floating substrate by an adsorption/calcination method. The resulting floating photocatalyst showed a great catalytic activity against 2,4-D with the degradation efficiency of 60% and 50% in 250 min under a UV radiation and sunlight, respectively. The photocatalytic degradation of 2,4-D on the floating catalyst is fitted well to the pseudo-first-order kinetic model with correlation coefficient (R²) of 0.9878 and 0.9967 and rate constant (k) of 0.0036 min⁻¹and 0.0038 min⁻¹ for catalyst granule with size 5 mm and 8 mm, respectively. Calculation based on the pseudo-first-order kinetic model indicated that 90% of 2,4-D can be treated within two days by sunlight using the floating catalyst. This demonstrated that a floating photocatalyst-based water treatment technology could be a feasible technology to degrade 2,4-D in water. The success of the work recommended a green approach to treat organic contaminants in large water resources, where they could not be treated efficiently by conventional technologies.

Data Availability

The data used to support the findings of this study are available within the article.

Conflicts of Interest

The authors declare that there are no conflicts of interest regarding the publication of this paper.

Authors’ Contributions

Hoang Hiep conceptualized the study, provided project administration and funding acquisition, revised the manuscript, and contributed to the final approval of the manuscript. Pham Tuan Anh performed experimental design, performed experimental conduction, contributed to data acquisition, and revised the manuscript. Dao Van-Duong contributed to work design, performed data interpretation, devised the work, and contributed to the final approval of the manuscript. Dang Viet Quang conceptualized the study, performed experimental design, contributed to data analysis, contributed to first draft, and contributed to the final approval of the manuscript.

Acknowledgments

This work was financially supported by a grant from Ministry of Science and Technology, Vietnam (Project number: NĐT/CZ/22/23).

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Copyright © 2023 Hoang Hiep et al. 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.

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Journal of Analytical Methods in Chemistry

Green Analytical Methods and Nanomaterials for Sample Preparation 2022

Greener Method for the Application of TiO2 Nanoparticles to Remove Herbicide in Water

Abstract

1. Introduction

2. Experimental

2.1. Materials

2.2. Preparation of Lightweight Fired Clay

2.3. TiO2 Synthesis

2.4. Preparation of Floating Photocatalyst

2.5. Photocatalytic Degradation Tests

2.6. Characterization

3. Results and Discussion

3.1. Material Characterization

3.2. Photocatalytic Degradation toward 2,4-D

4. Conclusion

Data Availability

Conflicts of Interest

Authors’ Contributions

Acknowledgments

References

Copyright

Greener Method for the Application of TiO₂ Nanoparticles to Remove Herbicide in Water

2.3. TiO₂ Synthesis