Degradation Of Endosulfan Research Articles

Activating 2D MoS2 by loading 2D Cu–S nanoplatelets for improved visible light photocatalytic hydrogen evolution, drug degradation, and CO2 reduction

Finding reliable photocatalysts capable of driving reactions using only sunlight is more needed than ever. A variety of strategies to harvest sunlight and convert it into chemical energy have been successfully utilized such as synthesizing nanostructures, using metal nanoparticles, doping, and others. In this work, we discover a facile way to anchor CuS nanoplatelets on 2D MoS2 by the solvothermal method using ethylene glycol (EG) as both a reduction agent and an exfoliating agent of bulk MoS2. Using CuS as a co-catalysis on MoS2 with their huge surface areas, led to improved photocatalytic activity for three different applications including H2 evolution, CO2 reduction, and endosulfan degradation. Specifically, Cu–S@MoS2 3% nanocomposite produced 9.86 μmol g−1 h−1 of H2, 0.48 μmol g−1 h−1 of CO and full decomposition of endosulfan within 6 h. The Cu-loaded MoS2 nanocomposites were thoroughly characterized by spectroscopic (including synchrotron-based spectroscopy) and microscopic methods to understand the formation of Cu–S during the solvothermal process. Moreover, the role of the EG during the synthetic procedure was revealed experimentally and studied theoretically via DFT simulations.

Exploring the potential of Halalkalibacterium halodurans laccase for endosulfan and chlorophacinone degradation: insights from molecular docking and molecular dynamics simulations

Pesticides are widely used in agriculture but at the same time, a majority of them are known to cause serious harm to health and the environment. In the recent past, laccases have been reported as key enzymes having the ability to degrade pollutants by converting them into less toxic forms. In this investigation, laccase from polyextremophilic bacterium Halalkalibacterium halodurans C-125 was analyzed for its structural, physicochemical, and functional characterization using in silico approaches. The 3D model of the said enzyme is unknown; therefore, the model was generated by template-independent modeling using ROBETTA, I-TASSER, and Alphafold server. The best-generated model from Alphafold with a confidence of 0.95 was validated from ERRAT and Verify 3D scores of 89.95 and 91.80%, respectively. The Ramachandran plot generated using the PROCHECK server further predicted the accuracy of the model with 93.7% and 5.9% of residues present in most favored and additional allowed regions of the plot respectively. The active sites, ion binding sites, and subcellular localization of laccase were also predicted. The generated model was docked with 121 pollutants (pesticides, insecticides, herbicides, fungicides, and rodenticides) for its degradation potential towards these pollutants. Two ligands chlorophacinone (based on the highest binding energy) and endosulfan (based on agricultural uses) were selected for molecular dynamic simulation studies. Endosulfan as a pesticide is banned but in some countries governments allow its use for special purposes which need serious consideration on developing bioremediation approaches for endosulfan degradation. MD simulation studies revealed that both chlorophacinone and endosulfan form hydrogen bonds and hydrophobic bonds with the active site of laccase and chlorophacinone-laccase complex were more stable in comparison to endosulfan. The present investigation provides insight into the structural features of laccase and its potential for the degradation of pesticides which can be further validated by experimental data. Communicated by Ramaswamy H. Sarma

Molecular insight into endosulfan degradation by Ese protein from Arthrobacter: Evidence-based structural bioinformatics and quantum mechanical calculations.

Endosulfan is an organochlorine insecticide widely used for agricultural pest control. Many nations worldwide have restricted or completely banned it due to its extreme toxicity to fish and aquatic invertebrates. Arthrobacter sp. strain KW has the ability to degrade α, β endosulfan and its intermediate metabolite endosulfate; this degradation is associated with Ese protein, a two-component flavin-dependent monooxygenase (TC-FDM). Employing in silico tools, we obtained the 3D model of Ese protein, and our results suggest that it belongs to the Luciferase Like Monooxygenase family (LLM). Docking studies showed that the residues V59, V315, D316, and T335 interact with α-endosulfan. The residues: V59, T60, V315, D316, and T335 are implicated in the interacting site with β-endosulfan, and the residues: H17, V315, D316, T335, N364, and Q363 participate in the interaction with endosulfate. Topological analysis of the electron density by means of the Quantum Theory of Atoms in Molecules (QTAIM) and the Non-Covalent Interaction (NCI) index reveals that the Ese-ligands complexes are formed mainly by dispersive forces, where Cl atoms have a predominant role. As Ese is a monooxygenase member, we predict the homodimer formation. However, enzymatic studies must be developed to investigate the Ese protein's enzymatic and catalytic activity.

Fermi level induced band edge alignment and band bending in Ag3PO4/Cu2O p-n heterojunction for proficient photocatalytic applications

Fabrication of binary p-n heterojunction and the band alignment at the interface of the individual semiconductor photocatalyst has been extensively studied to verify superior charge separation and migration capability in photocatalytic applications. Here, a simple wet chemical followed by a hydrothermal fabrication strategy was introduced for the development of the binary p-n Ag3PO4/Cu2O heterostructures. The tunable band structure of individual semiconductors with the work function (φ), witnessed a band bending at the space charge region. The bending at the interface induces a carrier concentration gradient and manifests a rectifying current transport diode. The fabricated p-n heterostructures and carrier migration between n-type Ag3PO4 and p-type Cu2O were verified by different morphological and physicochemical methods. The band banding at the interface, leading to a narrow depletion region, favors the tunneling of electron-hole pairs through a Z-scheme carrier transport mechanism. The electron-hole pair movement has further been confirmed by considering the band edge position after contact, photocatalytic scavengers, and the radical trapping experiment. The Ag3PO4/Cu2O p-n heterojunction photocatalyst manifested a 737.4 μmol g−1h−1 of H2 generation and 91% endosulfan degradation efficiency, these are 12 and 9 times higher than that of pure Ag3PO4. The p-n heterojunction photocatalyst displayed a higher current density with electron-hole migration efficiency, synergistically enhancing the catalytic activity through the interfacial space charge junction.

Turn Hazardous Endosulfan into S-Doped Alkynyl Carbon Material for Energy Storage and Hg(II) Adsorption via a Green Mechanochemical Process

Degradation of persistent organic pollutants (POPs), synthesis of advanced electrode materials, and treatment of heavy metal wastewater are important issues in energy and environment fields, which may be realized simultaneously through a multi-in-one interface strategy. Herein, an in situ S-doped alkynyl carbon material (SACM) was synthesized by co-milling hazardous endosulfan and CaC2. The solvent-free mechanochemical process is efficient, feasible, and green, whereby endosulfan is destructed completely under mild conditions without hazardous products and intermediates. The resultant SACM is a unique alkynyl-linked carbon skeleton with in situ S doping and multilayered structure. Furthermore, the SACM exhibits high supercapacitor performances with remarkable cycling stability and high specific capacitance (232.3 F cm–3), as well as excellent Hg(II) adsorptivity with pseudo-chemosorption behavior and high Hg(II) adsorbance (675.7 mg g–1). This work provides an integrated solution for the efficient degradation of hazardous endosulfan and a green synthesis of functional ACMs.

Biodegradation of Endosulfan-a Chlorinated Cyclodiene Pesticide by Indigenous Pseudomonas sp. MSCAS BT01.

Endosulfan remains as a lipophilic insecticide that causes serious medical problems because of biological stability and toxicity also found in air, water, soil sediments, and foodstuffs. Henceforward, the present study reveals a novel bacterial species isolated from pesticide-contaminated soil for enhanced endosulfan degradation. Next, isolated bacterial species was characterized with biochemical assays and 16S rRNA sequencing technique. Subsequently, the optimal conditions for endosulfan biodegradation such as pH, concentration of endosulfan, and bacterial growth were estimated with non-sulfur medium (NSM). Sequentially, the amount of endosulfan and compound degradation were analyzed through thin-layer chromatography and gas chromatography/mass spectrometry. Overall, the obtained results revealed the endosulfan acting as primary carbon source for bacterial growth. From the GC-MS analysis, the metabolic products released during endosulfan degradation by Pseudomonas sp. MSCAS BT01 were compared with standard GC-MS spectra. The highest (98%) endosulfan degradation was obtained at pH 7.0. The complete endosulfan degradation was achieved at 14th day of incubation and the less toxic endosulfan diol produced was observed via GC-MS. To conclude, the pesticide-contaminated isolate Pseudomonas sp. MSCAS BT01 emerged as a promising bioremediation tool and effectively employed to degrade endosulfan from contaminated soils, sediments, and wastewaters in the days yet to come.

Design and synthesis of g-C3N4/(Cu/TiO2) nanocomposite for the visible light photocatalytic degradation of endosulfan in aqueous solutions

The g-C3N4/Cu/TiO2 (graphitic-carbon nitride/copper/titanium dioxide) nanocomposite as a photocatalyst was developed to degrade endosulfan, a very poisonous pesticide, in an aqueous medium under visible light irradiation. The structure, morphology, and optical properties of the synthesized nanocomposite were determined using SEM, XRD, FT-IR, DRS, EDX, and PL. The obtained results showed that incorporating the Cu and TiO2 molecules onto g-C3N4 led to enhance absorption ability in the visible region, as well as improved the separation of photo-excited electron–holes. Some operational factors such as initial pesticide concentration, pH, and the presence of anions were studied in the photocatalytic degradation of endosulfan. The 60% photocatalytic performance was achieved by 80 min irradiation of the endosulfan solution, which was three times higher than pure g-C3N4. The improved photodegradation efficiency probably arose from the synergistic effect between three components of the composite photocatalyst.

Investigation of Endosulfan Removal and Metabolite Formation by Photocatalysis Process under UV-C Light Source Using Taguchi Experimental Design Program

ABSTRACT In this study, the efficiency of the synthesised Ag/TiO2/Fe3O4 catalyst in the removal of endosulfan and metabolite formation by the photocatalysis process, the effect, and optimisation of the ambient conditions were investigated under UV–C light source. Photocatalysis process for endosulfan removal and degradation to metabolites was optimised with Taguchi experimental design method and the results were evaluated statistically by analysis of variance. Light intensity, amount of catalyst, initial endosulfan concentration, pH, and time were chosen as controllable parameters. The highest S/N ratios on the based on parameters were obtained at 27 W light power, pH 4, 0.5 g/L catalyst amount, 60 min reaction time and 4 mg/L initial endosulfan concentration. Since these values, at which the highest removal rate will be achieved, were not found in the experimental design, a confirmation experiment was performed and the removal was obtained as 93.2%. It was found that the most effective parameters on the removal efficiency were the initial endosulfan concentration and pH, respectively. As a result of analysis of variance, Fcritical values showed that the effects of light power, catalyst amount and reaction time on endosulfan removal were not statistically significant. When the P values are examined, it is seen that there is a significant difference between the initial endosulfan concentration and the levels of the pH factor for endosulfan removal. No formations of endosulfan sulphate, endosulfan ether, and endosulfan lactone were observed at high concentrations while endosulfan was removed.

Facile synthesis and application of CdS/Bi20TiO32/Bi4Ti3O12 ternary heterostructure: A synergistic multi-heterojunction photocatalyst for enhanced endosulfan degradation and hydrogen evolution reaction

Facile fabrication of visible light responsive multicomponent heterostructure photocatalysts with synergistic photoelectron migration is an effective approach with potential application in water remediation and renewable energy generation. In this study, a series of ternary multi-heterojunction CdS/Bi20TiO32/Bi4Ti3O12 (CdSxBTC) photocatalysts were prepared by hydrothermal deposition of CdS nanoparticles (15–25 nm) over one pot combustion synthesized Bi20TiO32/Bi4Ti3O12 (BTC) nanostructures. Comprehensive characterization of the ternary composites revealed enhanced optical absorption, high interfacial contact, fast electron channelization and a prolonged excited state life time. The CdSxBTC composite materials displayed enhanced photocatalytic activity for endosulfan degradation (kapp value 6–12 times greater than pure semiconductors) and water splitting reaction (H2 production rate 1890 μmolg−1h−1 and apparent conversion efficiency 19%). The cell viability -study disclosed non-cytotoxic nature of the treated endosulfan solution. A synergistic Type-I bridged coupled Z-scheme electron migration process accounted for robust radical generation ability (•O2− and •OH) and photocatalytic activity of the ternary composites.

System biology analysis of endosulfan biodegradation in bacteria and its effect in other living systems: modeling and simulation studies

Endosulfan is a broadly applied cyclodiene insecticide which has been in use across 80 countries since last 5 decades. Owing to its recalcitrant nature, endosulfan residues have been reported from air, water and soil causing toxicity to various non-target organisms. Microbial decontamination of endosulfan has been reported previously by several authors. In the current study, we have evaluated the pathways of endosulfan degradation and its hazardous impact on other living beings including insects, humans, plants, aquatic life and environment by in-silico methods. For establishment of the endosulfan metabolism in different ecosystems, cell designer was employed. The established model was thereafter assessed and simulated to understand the biochemical and physiological metabolism of the endosulfan in various systems of the network. Topological investigation analysis of the endosulfan metabolism validated the presence of 207 nodes and 274 edges in the network. We have concluded that biomagnification of the endosulfan generally occurs in the various elements of the ecosystem. Dynamics study of endosulfan degrading enzymes suggested the important role of monooxygenase I, II and hydrolase in endosulfan bioremediation. Endosulfan shows toxicity in human beings, fishes and plants, however it is biodegraded by the microbes. To date, there are no reports of in- silico analysis of bioremediation of endosulfan and its hazardous effects on the environment. Thus, this report can be important in terms of modelling and simulation of biodegradation network of endosulfan and similar compounds and their impact on several other systems. Communicated by Ramaswamy H. Sarma

Natural attenuation and bioremediation of chlorpyrifos and endosulfan in periurban horticultural soils of Buenos Aires (Argentina) using microcosms assays

Chlorpyrifos and endosulfan degradations were compared at laboratory scale in three different soils: a conventional horticultural (SH), an accredited 25 year organic horticultural (SA) and a reference soil (SR) used as control. Chlorpyrifos and α-endosulfan degradation half-lives were, respectively, in the range 7.2 d – 9.8 d and 4.4 d – 6.6 d, finding no statistical difference for any soil. In the case of β-endosulfan, a difference was found in degradation half-lives, being: SR (25.8 d) < SA (49.1 d) < SH (102.1 d), indicating some difficulty, in the case of the traditional horticultural soil, to biodegrade this isomer. Three different biostimulants: poultry litter (CP), bokashi (fermented organic matter, BKS) and ramial chipped wood (BRF) were added to soil to explore the increase of chlorpyrifos and endosulfan biodegradation. While no improvement was observed for chlorpyrifos, all biostimulants favoured endosulfan degradation. In the case of BKS endosulfan half-life was reduced ca. three times (considering both isomers). Seed germination bioassays were performed using soil and biostimulant to evaluate potential ecotoxicological impacts. CP had a significant inhibitory effect on germination, hypocotyl elongation, radicle length and hypocotyl length, while BKS and BRF parameters were more similar to the control performance.

Bioremediation of an agricultural saline soil contaminated with endosulfan and Escherichia coli by an active surface agent induced in a Penicillium crustosum culture

This study evaluates the production of a biological active surface agent (BASA) through its surface tension (ST) and emulsifying activity (E24) for endosulfan degradation (ED) and Escherichia coli growth inhibition (EcGI) in an agricultural saline soil. The fungus, identified as Penicillium crustosum was isolated from the Citrus sinensis peel (CsP), then the surface properties were evaluated in 9 culture media through a Taguchi L9 experimental design. The culture conditions included: stirring speed, pH, carbon (C) and nitrogen (N) sources; being glucose, NH4N03, 120 rpm and pH of 5, the most significant parameters in the BASA production. The BASA identified as a lipopeptide type, showed a ST = 38 mN m−1 and E24=71%. Both properties were stable at 80 °C, while ST presented stability in the pH range of 2 – 12, and a saline concentration of 200 g L−1; E24 was also stable at a pH between 8–12. Further application of BASA and fungal inoculum to a contaminated agricultural saline soil presented an EcGI of 99.8% on the 8th day, and ED of 92.9 ± 4.7% in 30 days, respectively; being the first report that uses this fungus for pesticide and bacteria elimination from an agricultural saline soil.

Mycoremediation of an agricultural salty soil contaminated with endosulfan by Penicillium crustosum: and agronomic bioassays with Phaseolus leptostachyus

The fungus Penicillium crustosum was employed for endosulfan biodegradation, finding that sulphate endosulfan and mono alcohol endosulfan were the main compounds produced; therefore, an oxidative degradation pathway was suggested. A 93 ± 4.7% of Endosulfan degradation after one month of treatment of a highly salty agricultural soil was obtained, where ΔST was up to 17 ± 0.58 mN m−1, (related to the water value of 72 mNm−1), that was induced by the fungus during soil mycoremediation Additionally, an improvement in soil quality (reduction of clay proportion and salinity, as well as an increase of soluble phosphorus, carbon content and organic matter) was observed during the mycoremediation treatment. The phytotoxicity of the pesticide on Phaseolus leptostachyus was evaluated in the soil without the fungus addition (control), where the pesticide was translocated in the crop, presenting a negative effect in germination index, root length and weight, aerial weight, humidity, and proline content. This contrasted with the effect on the crop grown in the soil treated with P. crustosum, which had better agronomic characteristics. This is first report in which the effect of this property allows the pesticide biodegradation, due to a combined Endosulfan bioavailability and fungal biodegradation.

Evaluation of endosulfan degradation capacity by six pure strains isolated from a horticulture soil.

Endosulfan is an organochlorine pesticide included in the Stockholm Convention for Persistent Organic Compounds. The utilization of endosulfan as the sole source of carbon and its mineralization was evaluated using pure strains of Bacillus subtilis, Bacillus pseudomycoides, Peribacillus simplex, Enterobacter cloacae, Achromobacter spanius, and Pseudomonas putida, isolated from soil with historical pesticide use. The consumption of the α isomer of endosulfan by five of the six strains studied was higher than 95%, while B. subtilis degraded only 76% of the initial concentration (14mg/L). On the other hand, the degradation of the β isomer was approximately 86% of the initial concentration (6mg/L) by B. subtilis, P. simplex, and B. pseudomycoides and 95% by P. putida, E. cloacae, and A. spanius. The ability of A. spanius, P. simplex, and B. pseudomycoides to degrade endosulfan has not been previously reported. The production of endosulfan lactone by the Bacillus strains, as well as A. spanius and P. putida, indicated that endosulfan was degraded by the hydrolytic pathway.

Potential use of Solanum lycopersicum and plant growth promoting rhizobacterial (PGPR) strains for the phytoremediation of endosulfan stressed soil

This study aimed to assess the role of Solanum lycopersicum and plant growth promoting rhizobacterial (PGPR) strains to remove endosulfan present in the soil. S. lycopersicum was grown in endosulfan amended soil (5, 10, 25, and 50 mg kg−1) inoculated with PGPR strains for 40, 80, and 120 days. The influence of PGPR inoculation on endosulfan accumulation in plant tissues, endosulfan degradation in soil, and plant growth parameters were evaluated. The oxidative stress tolerance was assessed by determining the malondialdehyde formation in S. lycopersicum planted in endosulfan stressed soil inoculated with PGPR strains. The results showed that uptake of endosulfan followed root > shoot pathway in association with a reduction in endosulfan accumulation in inoculated plants as related to un-inoculated plants. Moreover, inoculation of PGPR strains showed a beneficial influence on the degradation of endosulfan, Bacillus sp. PRB101 showed maximum degradation (89% at 5 mg kg−1 of soil) of endosulfan at 120 days after sowing. Furthermore, the content of malondialdehyde was lower in inoculated plants as related to un-inoculated plants. Inoculation of PGPR strains efficiently enhanced plant biomass. The findings showed the effectiveness of PGPR strains to increase the decontamination of endosulfan stressed soil and decline endosulfan concentration in the plant tissues.

Kinetic Modeling of Endosulfan Degradation by Mixed Bacterial Culture

ABSTRACT A consortium of already isolated strains has been applied to degrade endosulfan. These were identified by 16S rRNA technique as Stenotrophomonas maltophilia EN-1, Pseudomonas sp. TAH and Enterobacter sp EN-2. Batch experiments were conducted to access the endosulfan degradation efficiency of consortium while using various concentrations of endosulfan (5, 25, 50, 75, 100 mg/L). Maximum degradation of about 85–90% was observed at a concentration of 100 mg/L after 96 hours of incubation while no degradation was observed in untreated ones (without consortium). Cell growth kinetic models were applied to explain the kinetic behaviors of bacterial consortium in batch study. Various kinetic parameters such as ‘µ max ’ and ‘Ks’ were determined having values of 0.9 h−1 and 7.9 mg/L respectively, that depicts the faster rate of endosulfan degradation by the selected bacterial consortium. Conversely, first-order kinetics was also well fitted in the experimental data using least squares regression (R 2) ranged from 0.09 to 0.95, which indicates that the endosulfan utilization was stimulated by a synergistic interaction of each bacterial strain in the consortium.

Bioremediation of Endosulfan Contaminated Soil by using Microbial Consortia in the Field

Objectives : The use of risky and persistent organochlorine pesticides was prohibited, but is still detected in many agricultural lands. In this study, Phanerochaete chrysosporium Y-2 (KCCM-10725P) and Streptomyces sp. MJM14747 (KACC 81078BP), which were finally selected among various candidate microorganisms, were applied to field soil and estimated the endosulfan removal rate.Methods : The field testing sites were set to an area of 3 m × 3 m, respectively. A 35% endosulfan emulsion was sprayed on both sites so that the final concentration was about 20 µg/g. Thereafter, 12 kg of original sawdust and 12 kg of sawdust loaded with microbial consortia were mixed at each of the two sites. During the test period for a total of 100 days, samples were taken every 30 days. Soil samples were extracted according to the QuEChERS AOAC method and analyzed by gas chromatography.Results and Discussion : The concentrations immediately after endosulfan emulsion treatment at both sites were detected as 21.2 µg/g and 21.9 µg/g, respectively. The removal rate of endosulfan at the site without microbial consortia treatment (Control) was about 21.9% until the 30th day, and 54.4% on the 100th day. On the other hand, the endosulfan removal rate on the 100th day of the site treated with microbial consortia was 89.5%, which was 1.6 times higher than that of the control site. On the 30th day, the removal rate was 56.8%, and the rate of degradation of endosulfan increased thereafter. Among the major components of endosulfan, the removal rate of α-endosulfan was higher than that of β-endosulfan. After 100 days, the removal rates of α-endosulfan and β-endosulfan were 98.0% and 83.5%, respectively.Conclusions : Streptomyces sp. MJM14747 showed good degradation ability in the presence of endosulfan at a high concentration of around 100 µg/g. Moreover, Phanerochaete chrysosporium Y-2 has a good performance in the removal of β-endosulfan, which is slow degrading components of endosulfan. Microbial consortia are expected to be applied not only to domestic and foreign agricultural land but also to overall bioremediation projects.

Degradation of endosulfan by a coupled treatments in a batch reactor with three electrodes

Endosulfan is one of the most important organochlorine pesticides, due is a persistence, bioaccumulation and toxicity (carcinogenic agent) is important remove this contaminant from wastewater. This work shows the results of the integrated three advanced oxidation process electrofenton/electrooxidation/ozonation (EF/EO/O3) to endosulfan degradation. Electrooxidation with Boron doped diamond (BDD) electrodes process achieved 49% of endosulfan degradation efficiency in 2 h, Ozonation process removed 62% in 2 h and electrofenton allows a 72% of endosulfan degradation efficiency. The integrated process EO/O3 improved the removal with 89% in 2 h but the EF/EO/O3 increases the removal to 92% and decreases the treatment time to only 1 h, optimizing the process with a lower energy consumption. The configuration of electrodes that improved de endosulfan degradation was iron (anode), graphite (cathode) and graphite (anode), the graphite electrodes achieved the higher H2O2 production and this is an advantage to the process, due this material is cheaper than BDD. The electrogeneration insitu of all oxidizing species allow that the process is sustainable.

Mechanism of visible-light-driven photocatalytic degradation of endosulfan pesticide by gold nanoparticles

Spherical shaped gold nanoparticles (GNPs) of size around ∼9 nm were successfully used for photocatalytic degradation of hazardous endosulfan (ES) pesticide. GNPs absorb sunlight at ambient condition in aqueous medium to enhance localized surface plasmon resonance (LSPR) which initiate hydrolysis, oxidation and reduction chemical reactions for the mineralization of ES molecules. Infrared transmittance spectra of GNPs treated ES solutions revealed formation of amorphous carbon and hydrocarbon as final reaction products indicating the nearly complete mineralization of ES as evidenced from their TEM images also. The disappearance of chloro carbon and sulphite functional groups peaks of ES in IR transmittance spectra confirmed their degradation. TEM images also support the optical absorption spectra consisting of inter-band and LSPR bands pertaining to individual and clustered GNPs ensembles. The redshift in LSPR absorption peak positions along minor and major axis of clustered GNPs ensembles is attributed to the change in GNPs polarizability on interaction with the electric component of visible light. The chemical reaction pathway for ES molecule degradation by the photocatalytic GNPs has been proposed in the light of inferences drawn from TEM images, IR transmittance and optical absorption spectra.

Synthesis, characterization and photocatalytic performance of iron molybdate (Fe2(MoO4)3) for the degradation of endosulfan pesticide

Iron molybdate was prepared via simple solution chemistry method and the photocatalytic degradation of a pesticide (endosulfan) was investigated under visible light irradiation. As-prepared (Fe2(MoO4)3) was characterized using scanning electron microscope (SEM), x-ray diffraction (XRD), energy dispersive x-ray spectra (EDX), diffused reflectance spectroscopy (DRS) and Zeta particle sizer techniques. The iron molybdate crystallite size was 36 nm, while grain size was in the range of 160–340 nm. The particles of polymetallic compound were spherical, highly porous and with fluffy texture indicating high surface area. DRS revealed Fe2(MoO4)3 was active under visible region since band gap value calculated was 2.7 eV. Response surface methodology (RSM) was employed for the optimization of photocatalytic activity (PCA) of Fe2(MoO4)3 as a function of catalyst dose, H2O2 dose, solution pH and concentration of endosulfan and up to 77% degradation was achieved at optimum conditions, which was monitored by UV/vis spectroscopy. In response to endosulfan degradation, the chemical oxygen demand (COD) and total organic carbon (TOC) were reduced up to 76% and 67%, respectively. Results revealed that iron molybdate is highly efficient photocatalyst for the degradation of endosulfan under solar light irradiation and could possibly be used for the treatment of endosulfan containing wastewater.