Synthesis and Characterization of <i>Parthenium hysterophorus</i>-Mediated ZnO Nanoparticles for Methylene Blue Dye Degradation

Nzilu, Dennis; Madivoli, Edwin; Makhanu, David; Wanakai, Sammy; Kirui, Gideon; Mwangi, Vincent; Kareru, Patrick

doi:https://doi.org/10.1155/2024/1088430

Journal of Chemistry

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

Research Article | Open Access

Volume 2024 | Article ID 1088430 | https://doi.org/10.1155/2024/1088430

Synthesis and Characterization of Parthenium hysterophorus-Mediated ZnO Nanoparticles for Methylene Blue Dye Degradation

Dennis Nzilu,¹Edwin Madivoli,¹David Makhanu,²Sammy Wanakai,¹Gideon Kirui,¹Vincent Mwangi,¹and Patrick Kareru¹

Academic Editor: Liviu Mitu

Received05 Sept 2023

Revised14 Nov 2023

Accepted26 Dec 2023

Published03 Jan 2024

Abstract

Herein, zinc oxide nanoparticles (ZnO NPs) were synthesized using Parthenium hysterophorus whole plant aqueous extract as reducing and capping agents. The synthesized ZnO NPs were characterized via UV-Vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and dynamic light scattering (DLS). An intrinsic optical absorbance of ZnO NPs occurred at 337 nm in the UV-Vis spectrum. The FTIR analysis revealed the presence of secondary metabolites responsible for reducing and stabilizing the nanoparticles. Furthermore, SEM and TEM images revealed that ZnO NPs were spherical with an average particle size of 38 nm. The XRD analysis revealed that ZnO NPs had a hexagonal wurtzite crystal structure with a crystallite size of 42.6 nm. The synthesized nanoparticles were investigated for degradation ability against methylene blue dye at varying conditions of ZnO NPs’ dosage, methylene blue concentrations, pH, temperature, and interaction time. Degradation efficiency of 55.69% was obtained at optimal conditions using 50 mg of ZnO NPs, 5 mg/L of MB dye concentration, and pH 12 and at 65°C within 32 minutes. Due to their novel green synthesis route, Parthenium hysterophorus-mediated ZnO NPs are promising candidates for removing persistent organic dyes from aquatic environments.

1. Introduction

Aquatic pollution by industrial effluents and emissions from wastewater treatment plants is a serious threat facing humanity and the ecosystem [1, 2]. Among the industrial wastewater contaminating our water systems are organic dyes from textile, cosmetic, paper, plastic, and pharmaceutical factories [3–5]. These organic dyes endanger water quality, and some, such as methylene blue, are nonbiodegradable and toxic because of their mutagenic and carcinogenic properties, threatening human health [6].

Chemical, physical, and biological methods are conventional methods employed in wastewater treatment to remove contaminants, including dyes [5]. However, these methods have drawbacks in removing the contaminants at low concentrations. Recently, researchers have embraced green nanotechnology to develop materials in nanoscale size that can effectively remediate the pollutants before being discharged into the water system [7–11]. Chemical, biological, and physical methods are the primary methods employed in the synthesis of nanoparticles [11, 12]. Chemical and physical processes of synthesizing nanoparticles include coprecipitation, pyrolysis, thermal decomposition, sol-gel, solvothermal, laser ablation, and ball milling [13, 14]. However, both chemical and physical processes of synthesizing nanomaterials have drawbacks of using toxic chemicals and being time-consuming, energy inefficient, and cost-ineffective [14–16]. Researchers find biological methods for synthesizing nanomaterials more attractive because they are environmentally friendly and cost-effective [16, 17]. Biological methods involve the use of microorganisms and plants. However, the use of microorganisms is characterized to be labor-intensive and involves delicate procedures in microbe isolation, growth, maintenance, longer synthesis time, and the possibility of forming toxic byproducts [18, 19]. To promote environmentally friendly chemistry, using aqueous plant extracts in synthesizing metallic nanoparticles is preferred because of their cost-effectiveness, simplicity, little or no toxicity in products, and ease in large-scale production of nanoparticles [15, 18–21].

Zinc oxide nanoparticles (ZnO NPs) find wide application in cosmetic, photocatalysis, plasmonic, sensors, pure water technologies, and optoelectronics, among others [14, 22]. The ZnO NPs possess improved chemical and physical properties which make them suitable for removing pollutants from the environmental compartments [14, 22]. The use of plant extracts for synthesizing ZnO NPs makes the process cost-effective and nontoxic to carry out [23].

Therefore, this study reports a simple, cost-effective, environmentally friendly, and easy approach to decontaminating a highly toxic MB dye from our wastewater system using readily available plant materials, Parthenium hysterophorus, as raw materials, which are renewable and biodegradable, for preparing the ZnO NPs. Parthenium hysterophorus plant is an invasive weed that abundantly grows in cultivated and agricultural lands and along the roadsides [24]. Previous studies report that Parthenium hysterophorus possesses medicinal and bioherbicidal properties [25, 26]. The phytochemical profiling of the Parthenium hysterophorus shows the presence of tannins, flavonoids, phenols, saponins, and terpenoids, essential for reducing, capping, and stabilizing metal ions from high oxidation state to zero-valent species [25]. The synthesized ZnO NPs were characterized via UV-Vis spectroscopy, FTIR, SEM, TEM, XRD, and DLS techniques and investigated on their ability to degrade methylene blue (MB) dye. The catalytic properties of ZnO NPs against MB dye were also explored at varying conditions of pH, ZnO NP dosage, MB dye concentration, interaction time, and temperature. The study places ZnO NPs obtained in Parthenium hysterophorus-mediated synthesis as powerful plant-based nanoparticles that aim to reduce increasing aquatic pollution from dyes, a significant issue currently pressing humanity. In this light, a comparative overview of the efficiency of Parthenium hysterophorus-mediated ZnO NPs in the removal of MB dye with other nanomaterials that have previously been studied for the removal of MB dye in aquatic systems is provided in this study.

2. Experimental Methods

2.1. Materials

Zinc nitrate hexahydrate (96%), hydrogen peroxide (30% w/w), and methylene blue dye (82%) were procured from Legacy Lab Africa Limited, Kenya. The materials were used as procured without any form of purification.

2.2. Sample Collection and Preparation

The Parthenium hysterophorus plant sample was collected from Kalimoni, Juja, Kiambu County, Kenya. Mr. John Kamau authenticated the plant sample, and a voucher specimen was deposited at Jomo Kenyatta University of Agriculture and Technology (JKUAT) Botany Herbarium and assigned accession number DMN-JKUATBH/001/2023A-C as described in our previous study [24]. The sample was washed with running tap water, rinsed with distilled water, and shed-dried for two weeks at room temperature [26]. We followed the methods of Datta et al. in which the dry sample was ground to a fine powder by using a milling machine, after which the phytochemicals were extracted by dissolving 20 g of the plant sample in 200 mL of distilled water [26]. The extraction was carried out at 45°C for 45 minutes and stored at 4°C in a freeze drier before further being used to synthesize zinc oxide nanoparticles [26].

2.3. Preparation of Zn Ions Solution and Synthesis of ZnO NPs

0.01 M zinc solution of zinc nitrate hexahydrate (Zn (NO₃)₂.6H₂O) was prepared by using distilled water. The nanoparticles were synthesized by modification of a previously established protocol of Iqbal et al. and Naseer et al. in which the zinc ions solution was mixed with plant extract in a ratio of 1 : 4 and heated in a hot plate at 60°C for 1 hour with constant stirring [27, 28]. The formation of ZnO NPs was monitored by color change and UV-Vis spectrophotometric measurement [28–30].

2.4. Characterization of ZnO Nanoparticles

2.4.1. UV-Vis Analysis

The UV-Vis absorption analysis of ZnO NPs was performed by scanning a double beam UV 1800 UV-Vis spectrophotometer (Shimadzu, Japan) to confirm their surface plasmonic resonance at 200–800 nm wavelength range [24].

2.4.2. FTIR Analysis

The functional groups present on the surface of the ZnO NPs were acquired by Bruker Tensor II FT-IR spectrophotometer (Bruker, Ettlingen, Germany). The samples were directly placed on the sample holder, pressed, and scanned in the frequency range of 4000−400 cm⁻¹ [31, 32].

2.4.3. XRD Analysis

The crystallinity nature of the nanoparticles was determined by using X-ray diffraction, and the diffractograms were obtained by using a Bruker D8 Advance Diffractometer (Bruker, Ettlingen, Germany) with a copper tube operating under a voltage and current of 40 kV and 40 mA. The samples were irradiated with a monochromatic CuKα radiation of 0.1542 nm, and the diffractograms were acquired between 2θ values of 5°–90° at 0.05° intervals with a measurement time of 1 second per 2θ intervals. The nanoparticles’ crystalline size was calculated by using the Debye Scherrer’s equation as follows:where D is the average particle size (nm), K is a constant equal to 0.94, λ is the wavelength of X-ray radiation, β is full-width at half maximum of the peak in radians, and theta is the diffraction angle (degree) [24, 29, 33].

2.4.4. SEM Analysis

The surface morphology analysis of the nanoparticles was visualized by using the Tescan Mira3 LM FE scanning electron microscope (Tescan, Brno-Kohoutovice, Czech Republic), operating under an accelerating voltage of 3 kV. Before analysis, the samples were sputter coated with 4 nm gold to avoid charging effects by using a AGB7340 Agar Sputter Coater (Agar Scientific, Essex, United Kingdom) [32, 34].

2.4.5. TEM Analysis

Surface morphology and shape of the nanoparticles were observed using TEM and was performed on a Tecnai G2 Spirit (Thermo Fischer Scientific, Oregon USA) under an operating voltage of 120 kV equipped with Veleta 2048 × 2048 wide angle and Eagle 4096 × 4096 bottom mount detectors. The dry samples were suspended in ultrapure water (Barnstead GenPure, Thermo Scientific, Germany) and ultrasonicated to obtain a solution that was drop casted on 300 mesh carbon films before analysis [32, 34].

2.4.6. DLS Analysis

To determine the particle size distribution and polydispersity index of the suspended nanoparticles, the metallic nanoparticles were resuspended in ultrapure water (18 MΩ·cm Barnstead GenPure UV-TOC, Thermo Scientific, Germany) and ultrasonicated to obtain a solution of suspended nanoparticles. The solutions were filtered through 0.25 μM PTFE syringes into glass vials, and 45 μL of each solution was transferred onto quartz cuvettes before analysis. The particle size distribution and polydispersity index were then measured by using a Beckman Coulter DelsaMax PRO dynamic light scattering analyzer (Beckman Coulter, Indianapolis, United States) [35, 36].

2.5. Degradation Studies

Methylene blue (MB) dye was used as a model organic dye in the degradation studies using ZnO NPs. The degradation of MB dye was monitored by using a UV-Vis spectrophotometer by measuring the change in absorbance of the dye alone; the dye spiked with hydrogen peroxide and the dye spiked with hydrogen peroxide and ZnO NPs at a constant time of 150 minutes. The degradation studies of MB dye by ZnO NPs were also conducted at varying reaction conditions, including the concentration of the MB dye solution, the dosage of ZnO NPs, interaction time, pH, and temperature [37–39]. The recyclability capability of ZnO NPs in the degradation of MB dye was also investigated in this study [17, 39–42]. For this study, 5 mg/L of the MB dye solution was prepared as the standard MB concentration except where the variation of MB concentration was studied. The degradation efficiency was calculated by using the following equation, where is the absorbance of MB at time = 0, and is the absorbance after a particular time, t [24]:

The kinetics of degradation of MB dye was determined by assuming a pseudo-first-order kinetic model (equation (3)) and a pseudo-second-order kinetic model (equation (4)) [38, 40, 41].where = is the absorbance of MB at time = 0, = is the absorbance after a particular time, and t = is the time in minutes.

The thermodynamics of the degradation reaction was determined by using the linear form of Van’t Hoff ‘s equation to obtain the change in heat and enthalpy of the reaction as follows:where and are the change in heat and entropy of the degradation reaction, respectively. The T is the temperature in Kelvin, and R is the universal gas constant [38, 43].

3. Results and Discussion

3.1. Biosynthesis of ZnO NPs

Parthenium hysterophorus aqueous extract contains phytochemicals such as saponins, flavonoids, terpenoids, and phenols [25]. These phytochemicals contain functional groups, which, upon reaction with zinc metal solution, reduce Zn²⁺ to Zn⁰, as previously described in the biosynthesis mechanism of metallic nanoparticles [44–46]. Figure 1 illustrates a generalized mechanism for the synthesis of Parthenium hysterophorus-mediated ZnO NPs.

3.2. Visual and UV-Vis Spectral Analysis of ZnO NPs

Figure 2 depicts the formation of ZnO NPs by color change and observation of the intrinsic optical absorbance band by UV-Vis spectrum.

As can be seen in Figure 2, the color changed from brown to dark brown after the zinc ion solution was mixed with Parthenium hysterophorus aqueous extract. This color change can be attributed to secondary metabolites in the aqueous extract that reduces zinc ions (Zn²⁺) into Zn⁰ species [47]. Furthermore, the formation of ZnO NPs was confirmed by its intrinsic optical absorbance band by UV-Vis spectrophotometer centered at 337 nm. Our synthesis of ZnO NPs agreed with UV-Vis results from previous studies [27, 28, 47, 48].

3.3. FTIR Analysis

Figure 3 compares the IR spectra of Parthenium hysterophorus aqueous extract and ZnO NPs identified by infrared spectrometry.

As can be seen in Figure 3, the plant extract has peaks at 3299 cm⁻¹, 1632 cm⁻¹, 1362 cm⁻¹, and 1222 cm⁻¹. These peaks are attributable to broad O-H, C=O, and C-N stretching bands characterized by phenols, flavonoids, and amine metabolites in the plant extract [26]. A slight shift in the functional groups present in the extract was evident in the IR spectra of the ZnO NPs, indicating that some metabolites bonded or capped ZnO during its formation [49]. Observable vibration bands in ZnO NPs spectra were at 3173 cm⁻¹, 2923 cm⁻¹, 1591 cm⁻¹, 1375 cm⁻¹, 1259 cm⁻¹, 1001 cm⁻¹, 809 cm⁻¹, and 543 cm⁻¹. Three new peaks appeared in the IR spectra of ZnO NPs at 1001 cm⁻¹, 809 cm⁻¹, and 543 cm⁻¹. The peak at 1001 cm⁻¹ showed that ZnO NPs underwent C-H bending. The peak at 543 cm⁻¹ was characteristic of the Zn-O stretching vibration band. The FTIR analysis showed the role of functional groups in the plant metabolites as reducing and capping agents in forming ZnO NPs, which were consistent with previous studies using plant extracts as sources of reducing and capping agents in the formation of ZnO NPs [28, 40, 47, 49].

3.4. SEM Analysis

Figure 4 shows the SEM micrograph of ZnO NPs and the histogram used to determine particle size distribution using ImageJ software.

The surface morphology from the SEM micrograph revealed that the ZnO NPs were nearly spherical. These findings agreed with previous studies, which showed that ZnO NPs synthesized using the coffee leaf extract and Elaeagnus angustifolia leaf extracts were spherical [27, 48]. The micrograph revealed less evidence of agglomeration of the nanoparticles, which indicates that the synthesis method was effective in obtaining highly homogenous nanoparticles with desired catalytic properties [26, 49, 50]. The particle diameter size ranged from 10 to 70 nm, with the average particle size diameter of the ZnO NPs calculated using ImageJ software being 38.47 nm. The particle diameter size was in the range of previously prepared ZnO NPs [12, 51].

3.5. TEM Analysis

Figure 5 depicts the TEM images and particle diameter size distribution histogram of the synthesized ZnO NPs.

As shown in Figure 5, the TEM images were spherical with little agglomeration evidence, which agrees with SEM image results. The average particle size of the nanoparticles was calculated from ImageJ data to be 7.54 nm. These results agree with previous studies that synthesized ZnO NPs using coffee leaf extract [48].

3.6. XRD Analysis

Figure 6 illustrates the XRD diffractogram patterns of ZnO NPs obtained from a powder diffractometer.

The XRD diffractogram reveals 11 peaks at 31.74°, 34.40°, 36.4°, 47.56°, 56.73°, 62.88°, 66.55°, 68.05°, 69.22°, 72.54°, and 77.05° obtained between 20 and 80 2θ degrees. The 2θ values correspond to (100), (002), (101), (102), (110), (103), (200), (112), (201), (004), and (202) crystallographic planes, respectively, which correspond to the International Center for Diffraction Data (ICDD) database for ZnO NPs [27, 48, 49]. These crystallographic planes reveal that the ZnO NPs had a hexagonal wurtzite structure [12, 48, 49]. The crystallite size was calculated by using the Debye Scherrer equation and was found to be of 42.6 nm. In a previous study, the particle size of ZnO NPs was 66.43 nm [52]. In another study, the crystalline particle size of ZnO NPs was calculated to be 52.23 nm [47]. Therefore, we confirm the formation of ZnO NPs from the XRD pattern.

3.7. DLS Analysis

Figure 7 depicts the size distribution of ZnO NPs as observed by using the dynamic light scattering (DLS) technique.

The particle size distribution revealed that the particles were polydisperse, with most of the particles below 500 nm. The polydispersity index (PDI) obtained in the DLS determination was ≤0.3, which proved that the particles were polydisperse. In contrast, individual groups of particles were monodisperse, supporting possible particle agglomeration [49, 53]. The monodispersity of the particles shows that the particles were homogenous, which is desired in the catalytic activity of the nanoparticles.

4. Degradation Studies of Methylene Blue Dye

Figure 8(a) shows the UV-Vis spectrum of MB alone observed after 150 min, Figure 8(b) shows the changes in absorbance intensity of MB after it is reacted with 1 mL of H₂O₂, and Figure 8(c) shows the changes in absorbance intensity of MB after it is reacted with 1 mL of H₂O₂ and 10 mg of ZnO NPs.

(a)

(b)

(c)

As shown in Figure 8(a), there was no observable change in absorption intensity for the MB dye after 150 minutes. However, spiking the same amount of MB dye with 1 mL hydrogen peroxide, there was a slight decrease in the absorbance intensity of the dye as shown in Figure 8(b). A significant change in the absorbance intensity of the MB dye was obtained when the same amount of the MB dye was reacted with 1 mL of H₂O₂ and 10 mg of ZnO NPs as shown in Figure 8(c). This indicated that the ZnO NPs have the catalytic properties to degrade the MB dye [39, 54]. The degradation studies were then investigated by varying MB dye concentration, pH, ZnO NP dosage, temperature, and interaction time [37–39].

4.1. Effect of MB Dye Concentration on Degradation Efficiency of ZnO NPs

To study the influence of dye concentration on the degradation efficiency of ZnO NPs, the study was conducted using 2.5 mg/L, 5 mg/L, 7.5 mg/L, 10 mg/L, and 12.5 mg/L concentrations, and their effect on degradation efficiency is depicted in Figure 9.

The concentration of dyes affects the activity of the nanoparticles because of the saturation of active sites at higher dye concentrations. It was observed that the percentage of degradation of MB dye decreased as the dye concentration increased. At 2.5 mg/L of MB dye, the degradation percentage was 35.03%, while at 12.5 mg/L (the highest concentration of MB dye used for this study), the degradation percentage was 14.68%. The decrease in the efficiency of ZnO NPs in MB degradation studies can be attributed to the saturation of the nanoparticles’ active sites by more MB dye molecules [40, 55]. Simultaneously, more molecules of MB dye were available with insufficient active sites on the surface of the nanoparticles because the ZnO NPs were saturated [55]. The MB solution’s absorbance increased as the MB dye concentration increased. This means that the nanoparticles become highly saturated at higher concentrations of MB dye, and little dye breakdown occurs.

4.2. Effect of Nanoparticle Dosage on Degradation Efficiency of ZnO NPs

In this study, the dosage of ZnO NPs was conducted at 10 mg, 20 mg, 30 mg, 40 mg, and 50 mg, and their degradation efficiency was determined within 2.5 hours, and the results are illustrated in Figure 10.

It was observed that the percentage of degradation of MB dye increased proportionally to the dosage of the ZnO NPs. The degradation percentage increased from 22.32% at 10 mg to 44.52% at 50 mg within 2.5 hours. The increase in degradation percentage of MB upon increasing the amount of ZnO NPs was probable because, at higher ZnO NPs dosage, the total surface area of the nanoparticles was higher, making more active sites available to bind the MB dye molecules [3, 56]. The decrease in absorbance at a higher nanoparticle dose (50 mg) revealed that the MB dye molecules were degrading towards completion because more active sites were present on the surface of the nanoparticles to bind, interact, and result in the degradation of MB dye [40]. Our results agreed with previous studies which reported that the degradation efficiency increased as the amount of the nanoparticles was increased against the same amount of the pollutant [3, 24, 40, 50, 55, 56].

4.3. Effect of Interaction Time on Degradation Efficiency of ZnO NPs

Figure 11 illustrates the effect of interaction time on the percentage of degradation of MB dye by ZnO NPs.

It was observed that as the interaction time of MB dye with ZnO NPs was increased, the degradation percentage increased from 18.09% at 30 min to 56.87% within 360 minutes. The corresponding absorbance of MB decreased as the reaction time increased, implying that molecules were allowed enough time to interact with the surface of ZnO NPs and break down. The increase in the degradation percentage of MB dye was also supported in previous studies employing ZnO NPs [12, 50].

4.4. Effect of pH on Degradation Efficiency of ZnO NPs

To monitor the optimal pH that results in the higher degradation of MB using ZnO NPs, the solution pH was adjusted to pH 2, 4, 8, and 12, and their effect on the degradation efficiency is depicted in Figure 12.

The acidic conditions of the MB dye solution were adjusted using 0.1 M of HCl, while the basic conditions of the MB dye were adjusted using 0.1 M of NaOH. At pH 2 and 4, the degradation efficiency was 26.00% and 29.91%, respectively. At pH 8 and 12, the degradation efficiency was 45.34% and −114.72%, respectively. The interaction of the acid and the base resulted in the generation of free radicals from the hydrogen peroxide used as a catalyst and radical generator for this reaction. In acidic pH 2 and 4, the degradation efficiency could be attributed to the increase in hydrogen radicals generated from H₂O₂ and the positive charge imparted on the surface of nanoparticles, which activates the active sites to improve reaction with the dye molecules [55]. In basic pH 8 and 12, degradation efficiency was attributed to the generation of hydroxyl radicals, which increased the degradation ability of the nanoparticles towards the MB molecules [3]. Uniquely, at pH 12, a negative percentage of degradation was observed within the 2.5 hours used for this study. At pH 12, it implies that MB dye molecules were destroyed to yield probable degradation products with higher absorbance than those obtained in other pH values.

4.5. Effect of Temperature on Degradation Efficiency of ZnO NPs

The temperature of the MB dyes was varied at 25°C, 35°C, 45°C, 55°C, and 65°C, and the highest degradation efficiency was observed at higher temperatures, as illustrated in Figure 13.

The temperature significantly influences the activation of the surface of nanoparticles and, therefore, improves the degradation efficiency of ZnO NPs on the degradation of MB dye. The increase in temperature was observed to increase the percentage of degradation of MB dye to 53.08% at 65°C, which is attributed to the Brownian motion, which increases the kinetic energy of MB dye molecules [38]. Another probable reason for the increase in degradation efficiency at higher temperatures is that the MB dye molecules have enough energy to react and undergo degradation [53].

The change in heat and entropy of the reaction was obtained by Van’t Hoff’s plot of , as shown in Figure 14.

Figure 14 shows that the degradation of MB dye using ZnO NPs was an endothermic reaction, demonstrating that the MB degradation rate increases as the temperature increases. The change in the heat of the degradation reaction was determined experimentally and calculated from the slope of Van’t Hoff’s plot to be 14.199 kJ·mol⁻¹, and the change in entropy was calculated from the intercept value to be 1.37264 J·K⁻¹. The entropy indicated enhanced system disorder due to the increase in temperature resulting from the breakdown of the MB dye molecules [57].

4.6. Degradation of MB Dye Using ZnO NPs at Optimal Conditions

The degradation of MB dye by ZnO NPs was also investigated by combining all the conditions that resulted in the highest degradation efficiency of MB dye, as described in the previous section. Figure 15 depicts the change in absorption intensity of MB dye obtained using 5 mg/L concentration of MB dye, temperature maintained at 65°C, 50 mg of ZnO NPs, and solution at pH 12.

As shown in Figure 15, a significant change in the absorption intensity of MB dye was observed to occur within 32 minutes in optimal conditions described in this study. Degradation efficiency of 55.69% was obtained under the combined optimal conditions.

5. Kinetics of Degradation of Methylene Blue Dye

The kinetics of degradation of MB dye using ZnO NPs was determined by fitting the pseudo-first-order and pseudo-second-order kinetics at 298, 308, 318 328, and 338 K, and the results are depicted in Table 1 and Figures 16 and 17.

The kinetic data were analyzed to fit the pseudo-first-order other than the pseudo-second-order because most R² (correlation coefficient) values were higher compared to the R² of the pseudo-second-order kinetic model. From this determination, it can be concluded that the degradation of MB was highly dependent on temperature. The increase in temperature increases the reacting molecules’ Brownian motion, resulting in the highest degradation efficiency [58, 59]. Figure 16 shows the first-order kinetic plots of , and Figure 17 shows the second-order kinetic plots of

6. Functional Group Analysis of ZnO NPs after Degradation Studies

The analysis of changes in the frequencies of functional groups present in ZnO NPs after degradation studies with MB dye was investigated. The IR spectra in Figure 18 show changes in the peaks before and after degradation studies.

The frequencies of functional groups in the IR spectrum of ZnO NPs before degradation were observed at 3173 cm⁻¹, 2923 cm⁻¹, 1591 cm⁻¹, 1375 cm⁻¹, 1259 cm⁻¹, 1001 cm⁻¹, 809 cm⁻¹, and 543 cm⁻¹. The peak at 3173 cm⁻¹ was attributed to the O-H group of phenols and 2923 cm⁻¹ was due to the C-H band, while the bands at 1375 cm⁻¹ and 1259 cm⁻¹ were characteristic of C-N. The peak at 1001 cm⁻¹ and 809 cm⁻¹ was attributed to C=C bending vibration. The peak at 543 cm⁻¹ was characteristic of Zn-O stretching vibration [3, 49]. The shifts in the IR spectrum of ZnO NPs after degradation studies with MB dye were observed at 3023 cm⁻¹, 2958 cm⁻¹, 1734 cm⁻¹, 1447 cm⁻¹, 1364 cm⁻¹, 1215 cm⁻¹, 1095 cm⁻¹, 891 cm⁻¹, and 521 cm⁻¹. The peaks at 3023 cm⁻¹ were due to O-H of phenols, the band at 2958 cm⁻¹ was due to C-H band, 1734 cm⁻¹ was attributable to C=O, 1445 cm⁻¹ band was attributable to C-H bending, and the bands at 1364 cm⁻¹ and 1215 cm⁻¹ were attributable to C-N stretching band. The 1095 cm⁻¹ and 891 cm⁻¹ peaks were due to C-O and C=C bending bands, respectively. The characteristic peak at 521 cm⁻¹ was associated with Zn-O vibration bands. The slight changes in the frequencies of the functional groups after reaction with MB dye indicated that a molecule of MB was adsorbed onto the surface of the ZnO NPs, which resulted in a slight shift in the functional group frequencies and their intensities after degradation [60].

7. Recyclability of ZnO NPs

The recyclability ability of ZnO NPs was investigated experimentally in four cycles for MB dye degradation. The recyclability studies were conducted under the same conditions (20 mg of ZnO NPs and 5 mg/L of MB concentration). The degradation cycle was determined at constant time (2.5 hours), after which the solution was decanted and washed with water, and the nanoparticles were dried at 80°C in an oven for 6 hours [48]. The degradation of MB was observed by the change in intensity of the absorbance monitored using a UV-Vis spectrophotometer, and the results are plotted as shown in Figure 19. After each cycle, fresh 5 mg/L of MB solution was spiked with 1 mL of H₂O₂. As observed in Figure 19, the percentage of degradation of MB decreased after each cycle of using the ZnO NPs.

The decrease in the degradation efficiency of ZnO NPs with multiple uses in the recyclability process indicates a loss in the catalytic potential of the nanoparticles [17]. The reduction in degradation efficiency of ZnO NPs can be attributed to the loss of nanoparticle catalytic ability during the separation, washing, and drying procedures after each application cycle [45, 61]. These procedures result in a decrease in the number of active sites available on the surface of ZnO NPs to interact with the fresh MB dye molecules. We also performed FTIR analysis to get insights into the stability of the nanoparticles by observing structural changes of ZnO NPs after their use in the first cycle and after their fourth cycle, and the results are depicted in Figure 20.

The structure of ZnO NPs from the IR spectrum revealed that no remarkable changes in the functional groups were observed for a single cycle and when four recyclability processes were used during the degradation of MB dye. This can support that the ZnO NPs exhibited strong stability and were not altered after several uses, a valuable characteristic of nanoparticles [13, 62].

8. Mechanism of Degradation of Methylene Blue Dye Using ZnO NPs

The mechanism of degradation of MB dye by ZnO NPs has been explained in previous studies [11, 50, 63–66]. The incident light leads to the excitation of an electron from the valence band (VB) to the conduction band (CB) on the ZnO NPs surface, leading to the creation of a positive hole in the VB [50, 63, 64]. The electron on the CB is taken up by oxygen adsorbed onto the surface of ZnO NPs, generating a superoxide anion radical . The anion radical is then involved in the degradation of MB dye [64, 67]. The positive holes in the valence band react with H₂O₂ used as a radical generator on the surface of ZnO NPs to produce OH radical which reacts with the dye, leading to the generation of degradation products. The positive hole in the VB then moves onto the surface of ZnO NPs, releasing more oxygen that produces . A similar process repeats itself to produce OH radicals, which are involved in the degradation of MB dye. Consequently, the acts as the oxidizing agent and interacts with the , leading to the significant generation of OH radicals that react with MB dye adsorbed onto the surface of the ZnO NPs, enhancing the oxidation of MB dye [65]. The mechanisms of degradation of MB dye by ZnO NPs can be illustrated using the steps shown in the following equations:

Figure 21 further provides an illustration of the probable mechanism of degradation of MB by ZnO NPs.

The ZnO NPs prepared using plant extracts have been reported to be less toxic than chemically prepared ZnO NPs [68, 69]. The reducing agents such as hydroxyl radicals and superoxide radical anions reduce the methylene blue dye to less toxic degradation products such as carbon dioxide and water which are less harmful and environmentally friendly [33, 50, 68–71].

9. Comparative Overview of Degradation Efficiency of MB Dye Using Other Nanomaterials

Table 2 provides an overview of previously utilized nanomaterials in removing MB dye from aquatic systems and their performance efficiency. From Table 2, it can be concluded that ZnO NPs prepared from Parthenium hysterophorus aqueous extract are attractive in the degradation of MB dye and thus are promising in future exploitation of biosynthesized nanoparticles in environmental remediation of dyes.

Our study confirms that aqueous extract from the Parthenium hysterophorus plant can act as reducing, capping, and stabilizing agents in the formation of ZnO nanoparticles. The presence of secondary metabolites makes Parthenium hysterophorus a potential universal candidate in the formation of other nanoparticles in an eco-friendly and cost-effective manner.

10. Conclusion

ZnO NPs were successfully synthesized using an aqueous extract of the Parthenium hysterophorus plant as a reducing, capping, and stabilizing agent. The ZnO NPs were analyzed via UV-Vis spectroscopy, which revealed an intrinsic optical absorbance band associated with ZnO NPs that occurred at 337 nm. The functional group analysis by FTIR confirmed the presence of secondary metabolites in the extract, which were responsible for reducing Zn²⁺ to Zn⁰, with a characteristic Zn-O vibration band being observed at 543 cm⁻¹. SEM and TEM analyses revealed that the ZnO NPs were spherical with an average particle size of 38 nm. The XRD analysis confirmed the hexagonal wurtzite structure of ZnO NPs, and the crystallite size calculated using the Debye Scherrer equation was 42 nm. The pH, temperature, dosage of ZnO NPs, concentration of MB solution, and interaction time influenced the degradation ability of ZnO NPs against MB dye. Under optimal conditions set at 65°C, pH 12, 50 mg of ZnO NPs, and 5 mg/L of MB dye concentration, a degradation efficiency of 55.69% was obtained within 32 minutes. The stability of ZnO NPs after multiple uses was confirmed by running an FTIR analysis in which there were no observable changes in the position of the functional groups. Therefore, Parthenium hysterophorus-mediated ZnO NPs demonstrated to be fruitful in degrading MB dye making the nanoparticles suitable for addressing aquatic pollution by dyes. However, future prospects should consider understanding the toxicity profile of the degradation products on the environment and encapsulation of the ZnO NPs with polymeric adsorbents to enhance their degradation efficiency, recyclability, and large-scale application. The green synthesis of ZnO NPs is still in its early stages and should be exploited by using other plant materials and studied in the degradation of other organic dyes before they are deployed in large-scale waste water treatment.

Data Availability

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

Conflicts of Interest

The authors declare that they have no conflicts of interest.

Authors’ Contributions

Dennis M. Nzilu conceptualised the study, developed the methodology, curated the data, and wrote the original draft. Edwin S. Madivoli conceptualised the study and collected the resources. David S. Makhanu supervised the study. Sammy I. Wanakai curated the data and visualised the study. Gideon K. Kiprono investigated the study. Vincent N. Mwangi visualised the study. Patrick K. Gachoki supervised the study. All authors have read and agreed on the final version of the manuscript.

Acknowledgments

The authors thank the Department of Chemistry, College of Pure and Applied Sciences, Jomo Kenyatta University of Agriculture and Technology, for providing laboratory facilities to conduct this research. The authors are also thankful to the Federal Commission of Scholarships (FCS) for a one-year exchange program at the University of Fribourg, Switzerland, and the Swiss National Science Foundation under grant number IZSEZ0_200290 that enabled access to various analytical instruments at Prof. Katharina Fromm Laboratory, Chemistry Department, University of Fribourg.

References

N. B. E. Badr, K. M. Al-Qahtani, S. O. Alflaij, S. F. Al-Qahtani, and M. A. Al-Saad, “The effect of industrial and sewage discharges on the quality of receiving waters and human health, Riyadh City-Saudi Arabia,” The Egyptian Journal of Aquatic Research, vol. 46, no. 2, pp. 116–122, 2020.
View at: Publisher Site | Google Scholar
R. I. L. Eggen, J. Hollender, A. Joss, M. Schärer, and C. Stamm, “Reducing the discharge of micropollutants in the aquatic environment: the benefits of upgrading wastewater treatment plants,” Environmental Science and Technology, vol. 48, no. 14, pp. 7683–7689, 2014.
View at: Publisher Site | Google Scholar
N. Choudhary, V. K. Yadav, H. Ali et al., “Remediation of methylene blue dye from wastewater by using zinc oxide nanoparticles loaded on nanoclay,” Water (Switzerland), vol. 15, no. 7, p. 1427, 2023.
View at: Publisher Site | Google Scholar
V. Katheresan, J. Kansedo, and S. Y. Lau, “Efficiency of various recent wastewater dye removal methods: a review,” Journal of Environmental Chemical Engineering, vol. 6, no. 4, pp. 4676–4697, 2018.
View at: Publisher Site | Google Scholar
H. B. Slama, A. C. Bouket, Z. Pourhassan et al., “Diversity of synthetic dyes from textile industries, discharge impacts and treatment methods,” Applied Sciences, vol. 11, no. 14, pp. 1–21, 2021.
View at: Publisher Site | Google Scholar
B. Lellis, C. Z. Fávaro-Polonio, J. A. Pamphile, and J. C. Polonio, “Effects of textile dyes on health and the environment and bioremediation potential of living organisms,” Biotechnology Research and Innovation, vol. 3, no. 2, pp. 275–290, 2019.
View at: Publisher Site | Google Scholar
T. Ilame and A. Ghosh, “The promising applications of nanoparticles for synthetic dyes removal from wastewater: recent review,” Management of Environmental Quality: An International Journal, vol. 33, no. 2, pp. 451–477, 2022.
View at: Publisher Site | Google Scholar
P. Kumari, M. Alam, and W. A. Siddiqi, “Usage of nanoparticles as adsorbents for waste water treatment: an emerging trend,” Sustainable Materials and Technologies, vol. 22, Article ID e00128, 2019.
View at: Publisher Site | Google Scholar
D. M. Nzilu, E. S. Madivoli, D. S. Makhanu et al., “Environmental remediation using nanomaterial as adsorbents for emerging micropollutants,” Environmental Nanotechnology, Monitoring & Management, vol. 20, Article ID 100789, 2023.
View at: Publisher Site | Google Scholar
V. B. Shet, P. S. Kumar, R. Vinayagam et al., “Cocoa pod shell mediated silver nanoparticles synthesis, characterization, and their application as nanocatalyst and antifungal agent,” Applied Nanoscience, vol. 13, no. 6, pp. 4235–4245, 2023.
View at: Publisher Site | Google Scholar
S. Shah, S. A. Shah, S. Faisal et al., “Engineering novel gold nanoparticles using Sageretia thea leaf extract and evaluation of their biological activities,” Journal of Nanostructure in Chemistry, vol. 12, no. 1, pp. 129–140, 2022.
View at: Publisher Site | Google Scholar
S. Faisal, N. S. Al-Radadi, H. Jan et al., “Curcuma longa mediated synthesis of copper oxide, nickel oxide and Cu-Ni bimetallic hybrid nanoparticles: characterization and evaluation for antimicrobial, anti-parasitic and cytotoxic potentials,” Coatings, vol. 11, no. 7, pp. 849–922, 2021.
View at: Publisher Site | Google Scholar
H. Jan, M. A. Khan, H. Usman et al., “The Aquilegia pubiflora (Himalayan columbine) mediated synthesis of nanoceria for diverse biomedical applications,” Royal Society of Chemistry Advances, vol. 10, no. 33, pp. 19219–19231, 2020.
View at: Publisher Site | Google Scholar
M. I. Khan, S. Shah, S. Faisal et al., “Monotheca buxifolia driven synthesis of zinc oxide nano material its characterization and biomedical applications,” Micromachines, vol. 13, no. 5, pp. 668–716, 2022.
View at: Publisher Site | Google Scholar
S. Faisal, H. Jan, S. A. Shah et al., “Bio-catalytic activity of novel mentha arvensis intervened biocompatible magnesium oxide nanomaterials,” Catalysts, vol. 11, no. 7, pp. 780–818, 2021.
View at: Publisher Site | Google Scholar
R. Shah, S. A. Shah, S. Shah, S. Faisal, and F. Ullah, “Green synthesis and antibacterial activity of gold nanoparticles of digera muricata,” Indian Journal of Pharmaceutical Sciences, vol. 82, no. 2, pp. 374–378, 2020.
View at: Publisher Site | Google Scholar
M. Khan, P. Ware, and N. Shimpi, “Synthesis of ZnO nanoparticles using peels of Passiflora foetida and study of its activity as an efficient catalyst for the degradation of hazardous organic dye,” Applied Sciences, vol. 3, no. 5, pp. 528–617, 2021.
View at: Publisher Site | Google Scholar
H. Sridevi, M. R. Bhat, P. S. Kumar, N. M. Kumar, and R. Selvaraj, “Structural characterization of cuboidal α-Fe2O3 nanoparticles synthesized by a facile approach,” Applied Nanoscience, vol. 13, no. 8, pp. 5605–5613, 2023.
View at: Publisher Site | Google Scholar
N. E. Zikalala, S. Azizi, S. A. Zikalala et al., “An evaluation of the biocatalyst for the synthesis and application of zinc oxide nanoparticles for water remediation—a review,” Catalysts, vol. 12, pp. 1442–1511, 2022.
View at: Publisher Site | Google Scholar
J. Singh, T. Dutta, K. H. Kim, M. Rawat, P. Samddar, and P. Kumar, “Green” synthesis of metals and their oxide nanoparticles: applications for environmental remediation,” Journal of Nanobiotechnology, vol. 16, no. 1, p. 84, 2018.
View at: Publisher Site | Google Scholar
S. O. Aisida, K. Ugwu, P. A. Akpa et al., “Biosynthesis of silver nanoparticles using bitter leave (Veronica amygdalina) for antibacterial activities,” Surfaces and Interfaces, vol. 17, Article ID 100359, 2019.
View at: Publisher Site | Google Scholar
S. Faisal, M. Rizwan, R. Ullah et al., “Paraclostridium benzoelyticumbacterium-mediated zinc oxide nanoparticles and their in vivo multiple biological applications,” Oxidative Medicine and Cellular Longevity, vol. 2022, Article ID 5994033, 15 pages, 2022.
View at: Publisher Site | Google Scholar
H. Jan, M. Shah, A. Andleeb et al., “Plant- based synthesis of zinc oxide nanoparticles (ZnO-NPs) using aqueous leaf extract of Aquilegia pubiflora: their antiproliferative activity against HepG2 cells inducing reactive oxygen species and other in vitro properties,” Oxidative Medicine and Cellular Longevity, vol. 2021, Article ID 4786227, 14 pages, 2021.
View at: Publisher Site | Google Scholar
D. M. Nzilu, E. S. Madivoli, D. S. Makhanu, S. I. Wanakai, G. K. Kiprono, and P. G. Kareru, “Green synthesis of copper oxide nanoparticles and its efficiency in degradation of rifampicin antibiotic,” Scientific Reports, vol. 13, no. 1, Article ID 14030, 2023.
View at: Publisher Site | Google Scholar
T. Tafese Bezuneh, “Phytochemistry and antimicrobial activity of Parthenium hysterophorus L.: a Review,” Science Journal of Analytical Chemistry, vol. 3, no. 3, p. 30, 2015.
View at: Publisher Site | Google Scholar
A. Datta, C. Patra, H. Bharadwaj, S. Kaur, N. Dimri, and R. Khajuria, “Green synthesis of zinc oxide nanoparticles using Parthenium hysterophorus leaf extract and evaluation of their antibacterial properties,” Journal of Biotechnology & Biomaterials, vol. 07, no. 03, pp. 2–8, 2017.
View at: Publisher Site | Google Scholar
J. Iqbal, B. A. Abbasi, T. Yaseen et al., “Green synthesis of zinc oxide nanoparticles using Elaeagnus angustifolia L. leaf extracts and their multiple in vitro biological applications,” Scientific Reports, vol. 11, no. 1, pp. 20988–21013, 2021.
View at: Publisher Site | Google Scholar
M. Naseer, U. Aslam, B. Khalid, and B. Chen, “Green route to synthesize zinc oxide nanoparticles using leaf extracts of Cassia fistula and Melia azadarach and their antibacterial potential,” Scientific Reports, vol. 10, no. 1, pp. 9055–9110, 2020.
View at: Publisher Site | Google Scholar
V. V. Ukidave and L. T. Ingale, “Green synthesis of zinc oxide nanoparticles from Coriandrum sativum and their use as fertilizer on Bengal Gram, Turkish Gram, and Green Gram plant growth,” International Journal of Agronomy, vol. 2022, Article ID 8310038, 14 pages, 2022.
View at: Publisher Site | Google Scholar
M. A. Abomuti, E. Y. Danish, A. Firoz, N. Hasan, and M. A. Malik, “Green synthesis of zinc oxide nanoparticles using Salvia officinalis leaf extract and their photocatalytic and antifungal activities,” Biology, vol. 10, no. 11, p. 1075, 2021.
View at: Publisher Site | Google Scholar
E. S. Madivoli, P. G. Kareru, A. N. Gachanja, S. M. Mugo, and D. S. Makhanu, “Synthesis and characterization of dialdehyde cellulose nanofibers from O. sativa husks,” Applied Sciences, vol. 1, no. 7, pp. 723–727, 2019.
View at: Publisher Site | Google Scholar
L. K. Kian, M. Jawaid, H. Ariffin, and O. Y. Alothman, “Isolation and characterization of microcrystalline cellulose from roselle fibers,” International Journal of Biological Macromolecules, vol. 103, pp. 931–940, 2017.
View at: Publisher Site | Google Scholar
T. H. Abdullah, T. Hussain, S. Faisal et al., “Green synthesis and characterization of copper and nickel hybrid nanomaterials: investigation of their biological and photocatalytic potential for the removal of organic crystal violet dye,” Journal of Saudi Chemical Society, vol. 26, no. 4, Article ID 101486, 2022.
View at: Publisher Site | Google Scholar
B. V. Otenda, P. G. Kareru, E. S. Madivoli, A. M. Salim, J. Gichuki, and S. I. Wanakai, “Starch-hibiscus-cellulose nanofibrils composite films as a model antimicrobial food packaging material,” Journal of Natural Fibers, vol. 19, no. 15, pp. 12371–12384, 2022.
View at: Publisher Site | Google Scholar
E. S. Madivoli, P. G. Kareru, A. N. Gachanja et al., “Adsorption of selected heavy metals on modified nano cellulose,” International Research Journal of Pure and Applied Chemistry, vol. 12, no. 3, pp. 1–9, 2016.
View at: Publisher Site | Google Scholar
E. S. Madivoli, P. G. Kareru, and K. Fromm, Versatility of Cellulose Stimuli Responsive Membranes in the Detection of Dimethylamine, Springer, Berlin, Germany, 2022.
K. M. Reza, A. Kurny, and F. Gulshan, “Parameters affecting the photocatalytic degradation of dyes using TiO2: a review,” Applied Water Science, vol. 7, no. 4, pp. 1569–1578, 2017.
View at: Publisher Site | Google Scholar
N. Goyal, D. Rastogi, M. Jassal, and A. K. Agrawal, “Kinetic studies of photocatalytic degradation of an Azo dye by titania nanoparticles,” Research Journal of Textile and Apparel, vol. 26, no. 4, pp. 500–514, 2022.
View at: Publisher Site | Google Scholar
M. Kgatle, K. Sikhwivhilu, G. Ndlovu, and N. Moloto, “Degradation kinetics of methyl orange dye in water using trimetallic Fe/Cu/Ag nanoparticles,” Catalysts, vol. 11, no. 4, p. 428, 2021.
View at: Publisher Site | Google Scholar
S. Alkaykh, A. Mbarek, and E. E. Ali-Shattle, “Photocatalytic degradation of methylene blue dye in aqueous solution by MnTiO₃ nanoparticles under sunlight irradiation,” Heliyon, vol. 6, no. 4, Article ID e03663, 2020.
View at: Publisher Site | Google Scholar
H. Etay, A. Kumar, and O. Yadav, “Kinetics of photocatalytic degradation of methylene blue dye in aqueous medium using ZnO nanoparticles under UV radiation,” Journal of Analytical and Pharmaceutical Research, vol. 12, no. 1, pp. 32–37, 2023.
View at: Publisher Site | Google Scholar
R. Chowdhury, A. Khan, and M. H. Rashid, “Green synthesis of CuO nanoparticles using: Lantana camara flower extract and their potential catalytic activity towards the aza-Michael reaction,” Royal Society of Chemistry Advances, vol. 10, no. 24, pp. 14374–14385, 2020.
View at: Publisher Site | Google Scholar
I. S. Wanakai, G. P. Kareru, M. D. Sujee, S. E. Madivoli, M. E. Gachui, and K. P. Kairigo, “Kinetics of rifampicin antibiotic degradation using green synthesized iron oxide nanoparticles,” Chemistry Africa, vol. 6, no. 2, pp. 967–981, 2022.
View at: Publisher Site | Google Scholar
N. Matinise, X. G. Fuku, K. Kaviyarasu, N. Mayedwa, and M. Maaza, “ZnO nanoparticles via Moringa oleifera green synthesis: physical properties & mechanism of formation,” Applied Surface Science, vol. 406, pp. 339–347, 2017.
View at: Publisher Site | Google Scholar
N. Mayedwa, N. Mongwaketsi, S. Khamlich, K. Kaviyarasu, N. Matinise, and M. Maaza, “Green synthesis of nickel oxide, palladium and palladium oxide synthesized via Aspalathus linearis natural extracts: physical properties & mechanism of formation,” Applied Surface Science, vol. 446, pp. 266–272, 2018.
View at: Publisher Site | Google Scholar
D. Hassan, A. T. Khalil, J. Saleem et al., “Biosynthesis of pure hematite phase magnetic iron oxide nanoparticles using floral extracts of Callistemon viminalis (bottlebrush): their physical properties and novel biological applications,” Artificial Cells, Nanomedicine and Biotechnology, vol. 46, no. 1, pp. 693–707, 2018.
View at: Publisher Site | Google Scholar
A. Jayachandran, A. Tr, and A. S. Nair, “Green synthesis and characterization of zinc oxide nanoparticles using Cayratia pedata leaf extract,” Biochemistry and Biophysics Reports, vol. 26, Article ID 100995, 2021.
View at: Publisher Site | Google Scholar
Q. Wang, S. Mei, P. Manivel, H. Ma, and X. Chen, “Zinc oxide nanoparticles synthesized using coffee leaf extract assisted with ultrasound as nanocarriers for mangiferin,” Current Research in Food Science, vol. 5, no. May, pp. 868–877, 2022.
View at: Publisher Site | Google Scholar
S. Alamdari, M. S. Ghamsari, C. Lee et al., “Preparation and characterization of zinc oxide nanoparticles using leaf extract of Sambucus ebulus,” Applied Sciences, vol. 10, no. 3620, pp. 1–19, 2020.
View at: Publisher Site | Google Scholar
S. Faisal, H. Jan, S. A. Shah et al., “Green Synthesis of zinc oxide (ZnO) nanoparticles using aqueous fruit extracts of Myristica fragrans: their characterizations and biological and environmental applications,” Omega, vol. 6, no. 14, pp. 9709–9722, 2021.
View at: Publisher Site | Google Scholar
H. Hameed, A. Waheed, M. S. Sharif et al., “Green synthesis of zinc oxide (ZnO) nanoparticles from green algae and their assessment in various biological applications,” Micromachines, vol. 14, no. 5, p. 928, 2023.
View at: Publisher Site | Google Scholar
A. Umamaheswari, S. L. Prabu, S. A. John, and A. Puratchikody, “Green synthesis of zinc oxide nanoparticles using leaf extracts of Raphanus sativus var. Longipinnatus and evaluation of their anticancer property in A549 cell lines,” Biotechnology Reports, vol. 29, Article ID e00595, 2021.
View at: Publisher Site | Google Scholar
D. Jain, A. A. Bhojiya, H. Singh et al., “Microbial fabrication of zinc oxide nanoparticles and evaluation of their antimicrobial and photocatalytic properties,” Frontiers in Chemistry, vol. 8, pp. 778–811, 2020.
View at: Publisher Site | Google Scholar
A. Riapanitra, K. Riyani, and T. Setyaningtyas, “Photocatalytic and kinetics study of copper oxide on the degradation of methylene blue dye,” Proceedings of the Soedirman International Conference on Mathematics and Applied Sciences, vol. 5, pp. 3–7, 2022.
View at: Publisher Site | Google Scholar
A. Salama, A. Mohamed, N. M. Aboamera, T. A. Osman, and A. Khattab, “Photocatalytic degradation of organic dyes using composite nanofibers under UV irradiation,” Applied Nanoscience, vol. 8, no. 1–2, pp. 155–161, 2018.
View at: Publisher Site | Google Scholar
Z. Z. Vasiljevic, M. P. Dojcinovic, J. D. Vujancevic et al., “Photocatalytic degradation of methylene blue under natural sunlight using iron titanate nanoparticles prepared by a modified sol-gel method: methylene blue degradation with Fe2TiO5,” Royal Society Open Science, vol. 7, no. 9, Article ID 200708, 2020.
View at: Publisher Site | Google Scholar
H. N. Bhatti, Z. Iram, M. Iqbal, J. Nisar, and M. I. Khan, “Facile synthesis of zero valent iron and photocatalytic application for the degradation of dyes,” Materials Research Express, vol. 7, no. 1, Article ID 015802, 2020.
View at: Publisher Site | Google Scholar
R. Surakasi, Y. S. Rao, A. K. Sanuj, P. P. Patil, A. Jayaganthan, and R. Hechhu, “Methylene blue dye photodegradation during synthesis and characterization of WO₃ nanoparticles,” Adsorption Science and Technology, vol. 2022, Article ID 2882048, 10 pages, 2022.
View at: Publisher Site | Google Scholar
K. A. Isai and V. S. Shrivastava, “Photocatalytic degradation of methylene blue using ZnO and 2%Fe–ZnO semiconductor nanomaterials synthesized by sol–gel method: a comparative study,” Applied Sciences, vol. 1, no. 10, pp. 1247–1311, 2019.
View at: Publisher Site | Google Scholar
T. Ainane, F. Khammour, M. Talbi, and M. Elkouali, “A novel bio-adsorbent of mint waste for dyes remediation in aqueous environments: study and modeling of isotherms for removal of methylene blue,” Oriental Journal of Chemistry, vol. 30, no. 3, pp. 1183–1189, 2014.
View at: Publisher Site | Google Scholar
N. Z. Zainuri, N. H. H. Hairom, D. A. B. Sidik, N. Misdan, N. Yusof, and A. W. Mohammad, “Reusability performance of zinc oxide nanoparticles for photocatalytic degradation of POME,” E3S Web of Conferences, vol. 34, pp. 02013–02019, 2018.
View at: Publisher Site | Google Scholar
S. Sankar Sana, R. Haldhar, J. Parameswaranpillai, M. Chavali, and S. C. Kim, “Silver nanoparticles-based composite for dye removal: a comprehensive review,” Cleaner Materials, vol. 6, Article ID 100161, 2022.
View at: Publisher Site | Google Scholar
A. Kulis-Kapuscinska, M. Kwoka, M. A. Borysiewicz et al., “Photocatalytic degradation of methylene blue at nanostructured ZnO thin films,” Nanotechnology, vol. 34, no. 15, Article ID 155702, 2023.
View at: Publisher Site | Google Scholar
M. Saeed, M. Usman, and A. U. Haq, “Catalytic degradation of organic dyes in aqueous medium,” Photochemistry and Photophysics-Fundamentals to Applications, 2018, https://www.intechopen.com/chapters/60313.
View at: Publisher Site | Google Scholar
S. Venkatesan, S. Suresh, P. Ramu, J. Arumugam, S. Thambidurai, and N. Pugazhenthiran, “Methylene blue dye degradation potential of zinc oxide nanoparticles bioreduced using Solanum trilobatum leaf extract,” Results inChemistry, vol. 4, Article ID 100637, 2022.
View at: Publisher Site | Google Scholar
U. Wijesinghe, G. Thiripuranathar, F. Menaa, H. Iqbal, A. Razzaq, and H. Almukhlifi, “Green synthesis, structural characterization and photocatalytic applications of ZnO nanoconjugates using Heliotropium indicum,” Catalysts, vol. 11, no. 7, p. 831, 2021.
View at: Publisher Site | Google Scholar
U. Wijesinghe, G. Thiripuranathar, H. Iqbal, and F. Menaa, “Biomimetic synthesis, characterization, and evaluation of fluorescence resonance energy transfer, photoluminescence, and photocatalytic activity of zinc oxide nanoparticles,” Sustainability, vol. 13, no. 4, pp. 2004–2022, 2021.
View at: Publisher Site | Google Scholar
L. M. Mahlaule-Glory and N. C. Hintsho-Mbita, “Green derived zinc oxide (ZnO) for the degradation of dyes from wastewater and their antimicrobial activity: a review,” Catalysts, vol. 12, no. 8, 2022.
View at: Publisher Site | Google Scholar
J. Gangwar, A. Pratap Singh, N. Marimuthu, and J. Kadanthottu Sebastian, “Environmentally sustainable zinc oxide nanoparticles for improved hazardous textile dye removal from water bodies,” AQUA—Water Infrastructure, Ecosystems and Society, vol. 72, no. 7, pp. 1198–1210, 2023.
View at: Publisher Site | Google Scholar
J. Gangwar and J. K. Sebastian, “Unlocking the potential of biosynthesized zinc oxide nanoparticles for degradation of synthetic organic dyes as wastewater pollutants,” Water Science and Technology, vol. 84, no. 10–11, pp. 3286–3310, 2021.
View at: Publisher Site | Google Scholar
B. Gherbi, S. E. Laouini, S. Meneceur et al., “Effect of pH value on the bandgap energy and particles size for biosynthesis of ZnO nanoparticles: efficiency for photocatalytic adsorption of methyl orange,” Sustainability, vol. 14, no. 18, p. 11300, 2022.
View at: Publisher Site | Google Scholar
R. Vinayagam, B. Singhania, G. Murugesan et al., “Photocatalytic degradation of methylene blue dye using newly synthesized zirconia nanoparticles,” Environmental Research, vol. 214, Article ID 113785, 2022.
View at: Publisher Site | Google Scholar
S. Modi, V. K. Yadav, A. Amari et al., “Photocatalytic degradation of methylene blue dye from wastewater by using doped zinc oxide nanoparticles,” Water, vol. 15, no. 12, p. 2275, 2023.
View at: Publisher Site | Google Scholar
Z. Kalaycıoğlu, B. Özuğur Uysal, Ö. Pekcan, and F. B. Erim, “Efficient photocatalytic degradation of methylene blue dye from aqueous solution with cerium oxide nanoparticles and graphene oxide-doped polyacrylamide,” Omega, vol. 8, no. 14, pp. 13004–13015, 2023.
View at: Publisher Site | Google Scholar
L. M. Mahlaule-Glory, S. Mapetla, A. Makofane, M. M. Mathipa, and N. C. Hintsho-Mbita, “Biosynthesis of iron oxide nanoparticles for the degradation of methylene blue dye, sulfisoxazole antibiotic and removal of bacteria from real water,” Heliyon, vol. 8, no. 9, pp. 105366–e10623, 2022.
View at: Publisher Site | Google Scholar

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Copyright © 2024 Dennis Nzilu 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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