Degradation Of Methyl Parathion Research Articles

Improving thermostability, solvent tolerance, and reusability of methyl parathion hydrolase through immobilization into the metal-organic framework ZIF-8

The metal-organic framework (MOF) ZIF-8 has found extensive application in the medicinal and agricultural fields. This study aimed to immobilize the methyl parathion hydrolase (MPH) enzyme from Azohydromonas australica (Azau-MPH) within ZIF-8 using an in-situ synthesis method. Interestingly, the immobilized Azau-MPH (abbreviated as Azau-MPH@ZIF-8) exhibited enhanced thermostability and tolerability towards organic solvents compared to the free enzyme. Moreover, Azau-MPH@ZIF-8 retained more than 50% of its initial activity after six cycles, demonstrating its desirable reusability. To further improve the recyclability and catalytic activity of the immobilized enzyme, we introduced magnetic Fe3O4 nanoparticles into the immobilization carrier. Notably, the resulting Azau-MPH@(Fe3O4@ZIF-8) biocomposite displayed superior catalytic activity and stability when compared to Azau-MPH@ZIF-8. In practical applications, we employed Azau-MPH@ZIF-8 for cyclic degradation of methyl parathion (20 mg/L) in cherries, and it exhibited exceptional degradation ability. Hence, both Azau-MPH@ZIF-8 and Azau-MPH@(Fe3O4@ZIF-8) hold great promise as valuable biodegradation tools against MP contamination.

Rational design and fabrication of novel MnSeO3/GO nanocomposites for catalysis applications: Analysis of degradation efficacy, stability and degradation pathway

The MnSeO3/GO nanocomposites were effectively synthesized using a hydrothermal technique. The structural analyses of the heterogeneous catalyst were validated through the utilization of diverse characterization techniques, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet–visible diffuse reflectance spectroscopy (UV-DRS), and energy-dispersive X-ray spectroscopy (EDX) investigations. The surface of graphene oxide (GO) exhibits well-aggregated MnSeO3 particles, as shown by the utilization of analytical techniques such as FT-IR,EDX, and SEM. The structural characteristic of the sample demonstrated a satisfactory synthesis process, resulting in well-formed crystals and high purity of the final products. The results of the morphological study suggest that MnSeO3nanorods are formed, characterized by the presence of small particles on their surface. Simultaneously, the formation of GO nanosheets exhibiting pronounced aggregation occurred, potentially attributed to the influence of van der Waals forces. The optical properties of different samples were determined and the values are 2.06 eV for MnSeO3 and 1.81 eV for MnSeO3/GO. The photodegradation process of antibiotic drug Cefuroxime (CEF) and pesticide Methyl parathion (MP) was investigated using UV–visible spectroscopy, with the involvement of MnSeO3/GO nanocomposites. The results demonstrate a photocatalytic activity over 90 % during a time frame of 50 and 60 min under visible light exposure for CEF and MP degradation. In the field of scavenger research, the hydroxide radical assumes a prominent role in the mechanism of photodegradation. In addition, the stability of the photocatalyst were determined by recycle analysis. The analysis of the intermediates resulting from photocatalytic degradation was conducted by GC–MS investigations.

Oxygen defect rich Bi2S3/SnS2/Bi-self doped Bi2W2O9 multijunction photocatalyst for enhanced degradation of methyl parathion and H2 evolution

In this study, a facile in situ co-assembly technique is developed for one pot fabrication of Bi2S3/SnS2/Bi2W2O9 multijunction photocatalyst. Initially, Aurivillius phase Bi2W2O9 with nanoplate morphology is prepared by combustion synthesis route. The hydrothermal co-deposition of SnS2 and Bi2S3 phase led to the formation of the ternary composite photocatalyst. During hydrothermal treatment, substantial microstructural reorganization of the BWO phase occurred resulting in exfoliation of the nanoplates to high aspect ratio nanosheets followed by substitution of Bi5+ ions in the [W2O7]2- bilayer of the BWO structure. The Bi-self doping phenomena also resulted in creation of oxygen vacancy in the BWO lattice. Morphological investigations revealed intimate interfacial contact among hexagonal SnS2 nanoplates, Bi2S3 nanorods and Bi-doped Bi2W2O9 nanosheets. The oxygen vacancy (OV) and Bi self-doping endow improved photoelectrochemical properties and enhanced photocatalytic activity towards methyl parathion photodegradation (kapp = 0.013 min−1) and hydrogen evolution (0.92 mmolg-1h−1). The optimal BS15BWO photocatalyst exhibited nearly 13 and 32 times higher photocatalytic activity for methyl parathion photodegradation and H2 evolution reaction in comparison to the pure components. The robust generation of •OH and •O2− radicals and improved charge channelization through a type-I conjugated dual S-scheme electron migration mechanism accounted for the improved photocatalytic activity of the ternary composite.

Insights into the role of oxidation and adsorption for degradation of methyl parathion by ferrate (VI)

Methyl parathion (MP), as a widely used organophosphorus pesticide, posed a great threat for the aquatic environment because of its high toxicity and bioaccumulation. Ferrate (Fe(VI)) has received extensive attention in the environmental field in recent years as a green and efficient, multifunctional strong oxidant. In this study, Fe(VI) was used to degrade MP, and its performance and mechanism were comprehensively investigated. MP can be entirely eliminated within 5 min ([Fe(VI)] = 150 μM, [MP] = 10 μM and initial pH = 8.0). Moreover, Fe(VI) performed significantly better oxidation capacity than potassium permanganate and sodium periodate. MP degradation efficiency by Fe(VI) markedly improved with increasing Fe(VI) dosage or decreasing solution pH. And Cl−, Ca2+ and Mg2+ exhibited negligible effects on MP degradation, while HA and HCO3− showed slightly inhibition. Fe(VI) and in situ formed iron nanoparticles contributed to the high removal of total organic carbon (TOC) mainly through oxidation and adsorption, achieving a maximum of 44%. Based on the nine by-products identified, three MP conversion pathways were proposed, and a significant reduction in the toxicity of Fe(VI)-degraded MP was detected with luminescent bacteria. With their unique advantages of multifunction in water treatment, Fe(VI) systems may be a viable method for the elimination of micropollutants.

Fabrication of FeVO4/RGO Nanocomposite: An Amperometric Probe for Sensitive Detection of Methyl Parathion in Green Beans and Solar Light-Induced Degradation.

Pesticide usage is one of the significant issues in modern agricultural practices; hence, monitoring pesticide content and its degradation is of utmost importance. A novel and simple one-pot deep eutectic solvent-based solvothermal method has been developed for the synthesis of FeVO4/reduced graphene oxide (FeV/RGO) nanocomposite. The band gap of FeV decreased upon anchoring with RGO. Enhanced activity in the detection and photocatalytic degradation has been achieved in the FeV/RGO nanocomposite compared to pure FeV and RGO. FeV/RGO was used to modify glassy carbon electrode (GCE), and the fabricated electrode was evaluated for its electrochemical detection of methyl parathion (MP). The amperometric technique was found to be more sensitive with a 0.001-260 μM (two linear ranges; 0.001-20 and 25-260 μM) wide linear range and low limit of detection value (0.70 nM). The practical applicability of modified GCE is more selective and sensitive to real samples like river water and green beans. Photocatalytic degradation of MP has been examined using FeV, RGO, and FeV/RGO nanocomposite. FeV/RGO managed to degrade 95% of MP under solar light in 80 min. Degradation parameters were optimized carefully to attain maximum efficiency. Degradation intermediates were identified using liquid chromatography-mass spectrometry analysis. The degradation mechanism has been studied in detail. FeV/RGO could serve as a material of choice in the field of electrochemical sensors as well as heterogeneous catalysis toward environmental remediation.

Proteomic analysis of Burkholderia zhejiangensis CEIB S4–3 during the methyl parathion degradation process

Methyl parathion is an organophosphorus pesticide widely employed worldwide to control pests in agricultural and domestic environments. However, due to its intensive use, high toxicity, and environmental persistence, methyl parathion is recognized as an important ecosystem and human health threat, causing severe environmental pollution events and numerous human poisoning and deaths each year. Therefore, identifying and characterizing microorganisms capable of fully degrading methyl parathion and its degradation metabolites is a crucial environmental task for the bioremediation of pesticide-polluted sites. Burkholderia zhejiangensis CEIB S4–3 is a bacterial strain isolated from agricultural soils capable of immediately hydrolyzing methyl parathion at a concentration of 50 mg/L and degrading the 100% of the released p-nitrophenol in a 12-hour lapse when cultured in minimal salt medium. In this study, a comparative proteomic analysis was conducted in the presence and absence of methyl parathion to evaluate the biological mechanisms implicated in the methyl parathion biodegradation and resistance by the strain B. zhejiangensis CEIB S4–3. In each treatment, the changes in the protein expression patterns were evaluated at three sampling times, zero, three, and nine hours through the use of two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), and the differentially expressed proteins were identified by mass spectrometry (MALDI-TOF). The proteomic analysis allowed the identification of 72 proteins with differential expression, 35 proteins in the absence of the pesticide, and 37 proteins in the experimental condition in the presence of methyl parathion. The identified proteins are involved in different metabolic processes such as the carbohydrate and amino acids metabolism, carbon metabolism and energy production, fatty acids β-oxidation, and the aromatic compounds catabolism, including enzymes of the both p-nitrophenol degradation pathways (Hydroquinone dioxygenase and Hydroxyquinol 1,2 dioxygenase), as well as the overexpression of proteins implicated in cellular damage defense mechanisms such as the response and protection of the oxidative stress, reactive oxygen species defense, detoxification of xenobiotics, and DNA repair processes. According to these data, B. zhejiangensis CEIB S4–3 overexpress different proteins related to aromatic compounds catabolism and with the p-nitrophenol degradation pathways, the higher expression levels observed in the two subunits of the enzyme Hydroquinone dioxygenase, suggest a preferential use of the Hydroquinone metabolic pathway in the p-nitrophenol degradation process. Moreover the overexpression of several proteins implicated in the oxidative stress response, xenobiotics detoxification, and DNA damage repair reveals the mechanisms employed by B. zhejiangensis CEIB S4–3 to counteract the adverse effects caused by the methyl parathion and p-nitrophenol exposure.

Study of detoxification of methyl parathion by dielectric barrier discharge (DBD) non-thermal plasma at gas-liquid interface：mechanism and bio-toxicity evaluation

Methyl parathion (MP) as an organophosphorus pesticide has been used in the control of agricultural pests and diseases. Due to its high toxicity and persistence in the environment, MP may pose threat to human health when it is released into environmental water. For MP treatment, people have found that oxidative degradation of MP may generate some intermediates which are more toxic than MP itself, such as methyl paraoxon. Herein, we proposed a new method of applying dielectric barrier discharge (DBD) non-thermal plasma technology to treat MP in aqueous solution, and investigated the influences of different gases, pH value, discharge voltage/power, and main active species on the MP removal efficiency. In particular, the safety of DBD treatment was concerned with analysis of the biological toxicity of the byproducts from the DBD oxidation, and the DBD-induced degradation together with the involved mechanism was explored therein. The results showed that the production of toxic intermediates could be effectively suppressed or avoided under certain treatment conditions. As such, this work demonstrates that the proper application of DBD plasma technology with necessary caution can detoxify methyl parathion effectively, and also provides a practical guide for low-temperature plasma application in treatment of various organophosphorus pesticides in agricultural wastewater.

Metabolic Engineering of Escherichia coli for Methyl Parathion Degradation.

Organophosphate compounds are widely used in pesticides to control weeds, crop diseases, and insect pests. Unfortunately, these synthetic compounds are hazardous and toxic to all types of living organisms. In the present work, Escherichia coli was bioengineered to achieve methyl parathion (MP) degradation via the introduction of six synthetic genes, namely, opdS, pnpAS, pnpBS, pnpCS, pnpDS, and pnpES, to obtain a new transformant, BL-MP. MP and its subsequent decomposition intermediates were completely degraded by this transformant to enter the metabolites of multiple anabolic pathways. The MP-degraded strain created in this study may be a promising candidate for the bioremediation of MP and potential toxic intermediates.

Visible-light-driven photocatalytic degradation of methyl parathion as chemical warfare agent simulant by NiO/Bi2MoO6 heterojunction photocatalyst

Chemical warfare agents are considered the most lethal and sinister pollutants with incapacitating effects on humans and the environment. This study has reported a new NiO/Bi2MoO6 heterojunction photocatalyst capable of degrading methyl parathion (MP) as a nerve agent simulant. The NiO/Bi2MoO6 photocatalyst with nanoscale morphology was prepared using a solvothermal method and characterized using FE-SEM, EDS, TEM, HRTEM, XRD, UV-Vis spectroscopy and photoelectrochemical measurements. The conjugation of NiO with Bi2MoO6 nanostructures decreased the bandgap energy from 2.88 and 2.61 eV. The photoluminescence studies proved that the recombination of the charge carriers is slower in NiO/Bi2MoO6 nanocomposite compared to the pristine Bi2MoO6. Response surface methodology was used to consider the effect of pertinent factors (such as time, organophosphate concentration, pH, and photocatalyst dosage on the degradation reaction of MP. The photodegradation of the organophosphorus compound follows pseudo-first-order kinetics with a high rate constant of 1.7 × 10−3 min−1. According to the obtained results, NiO/Bi2MoO6 photocatalyst degraded more than 95% of MP around 120 min. The synthesized nanocomposite showed favorable performance for removing chemical pollutants with potential applications in visible-light-induced environmental remediation.

Performance evaluation of Zr(CUR)/NiCo2S4/CuCo2S4 and Zr(CUR)/CuCo2S4/Ag2S composites for photocatalytic degradation of the methyl parathion pesticide using a spiral-shaped photocatalytic reactor.

Zr(CUR)/NiCo2S4/CuCo2S4 and Zr(CUR)/CuCo2S4/Ag2S ternary composites were synthesized as efficient photocatalysts, and well characterized through XRD, FTIR, DRS, FE-SEM, EDS, and EDS mapping techniques. The potential of a spiral-shaped photocatalytic reactor was evaluated for degradation of the methyl parathion (MP) pesticide using synthesized photocatalysts under visible light irradiation. Computational fluid dynamics (CFD) was applied for analysis of the hydrodynamics behaviour and mass transport occurring inside the reactor. The experiments were performed based on a developed CCD-RSM model, while the desirability function (DF) was used for optimization of the process. Findings showed that the highest MP degradation percentage was 98.70% at optimal operating values including 20 mg L-1, 0.60 g L-1, 8 and 40 min for MP concentration, catalyst dosage, pH, and reaction time, respectively. This study clearly demonstrated that high degradation efficiency can be achieved using a spiral-shaped photocatalytic reactor rather than a traditional annular reactor at same conditions. The increase in reaction rate is related to the higher average turbulence kinetic energy in the spiral-shaped reactor over the traditional reactor, which results in the increased diffusivity and improves the mass and momentum transfer.

Visible light photocatalytic degradation of methyl parathion as chemical warfare agents simulant via GO-Fe3O4/Bi2MoO6 nanocomposite

• New ternary GO-Fe 3 O 4 /Bi 2 MoO 6 nanocomposite was successfully prepared. • Successful degradation of methyl parathion in the presence of GO-Fe 3 O 4 /Bi 2 MoO 6 nanocomposite. • More than 95% of methyl parathion was degraded in less than 140 mins using GO-Fe 3 O 4 /Bi 2 MoO 6 nanocomposite. • The band gap energy of Bi 2 MoO 6 nanostructures was decreased from to 2.52 eV after doped with GO and Fe 3 O 4 . Chemical warfare agent simulants present significant risks for humans, animals, and the environment. In this work, GO-Fe 3 O 4 /Bi 2 MoO 6 nanocomposite was synthesized and fully characterized by FE-SEM, FT-IR, BET, XRD, VSM, and UV–Vis spectroscopy and used as a potential photocatalyst for degradation of methyl parathion as a chemical warfare agent simulant. The effect of pertinent factors (pH, the amount of catalyst, and organophosphate concentration) in the synthesis process was studied using a central composite design by response surface methodology. The band gap of the synthesized GO-Fe 3 O 4 /Bi 2 MoO 6 nanocomposite was 2.5 eV, appropriate for visible light photocatalytic activity. According to the obtained results, after 120 min, GO-Fe 3 O 4 /Bi 2 MoO 6 photocatalyst showed more than 95% degradation efficiency for methyl parathion as a chemical warfare agent simulant. The magnetic characteristic of the synthesized photocatalyst helped its recovery from the solution after the reaction. According to the obtained data, GO-Fe 3 O 4 /Bi 2 MoO 6 nanocomposite could degrade methyl parathion (efficiency more than 90%) even after five consecutive runs. The GO-Fe 3 O 4 /Bi 2 MoO 6 nanocomposite shows promising performance for catalytic degradation of methyl parathion with the possibility to expand its application for other toxic chemicals removal.

Rational design of novel 3D flower-like praseodymium molybdate anchored graphitic carbon Nitride: An efficient and sustainable photocatalyst for mitigation of carcinogenic pollutants

The rational design of heterostructured praseodymium molybdate@polymeric graphitic carbon nitride (Pr6MoO12@g-C3N4) was effectively designed by a new chemical strategy in a hydrothermal environment and followed by an ultrasound-assisted route. The features of the as-fabricated Pr6MoO12@g-C3N4 nanocomposite was broadly investigated by various standard characterization techniques like p-XRD,SEM, TEM, XPS, BET, PL,UV-DRS. The fabricated photocatalyst was demonstrated that high crystallinity and crystalline size was 46.7 nm. Furthermore, the 50 mg catalyst and 5 ppm (mg/L) of pollutant concentration were optimized conditions for the highest photocatalytic decomposition results. Interestingly, the Pr6MoO12@g-C3N4 composite synergistic photocatalytic abilities via excellent reusable stability towards the degradation of ciprofloxacin (CIP) and methyl parathion (MPT) as removal of aquatic pollutants. More distinctively, the Pr6MoO12@g-C3N4 nanocomposite was deliberate in the decolouration rate of CIP and MPT under visible light radiation: 98 % CIP and 97 % of MPT degradation in just 70 and 40 min respectively. A plausible charge separation/transfer pathway where redox species experiments implicate •OH is the most essential role while h + and O2•−contributed to a lesser extent in the catalytic process. This research work presented a versatile nature of the Pr6MoO12@g-C3N4 heterostructured material for energy harvesting and application in environmental crises.

Mechanism of unactivated peroxymonosulfate-induced degradation of methyl parathion: Kinetics and transformation pathway

Although various activated peroxymonosulfate (PMS) processes have been applied widely for the destruction of recalcitrant organics due to its high generation potential of various electrophiles reactive oxygen species (e.g., sulfate and hydroxyl radicals and singlet oxygen), non-radical-based PMS reactions with pollutants are poorly understood. Especially, relatively little information exists on the reactivity of PMS towards organic ester compounds such an organophosphorus pesticides (OPPs). Herein, we systematically studied the unactivated PMS-induced transformation of methyl parathion, a stubborn and toxic OPP. Specifically, direct reaction rather than electrophile radical-based oxidation was responsible for the rapid degradation of methyl parathion. The contribution of the produced singlet oxygen (1O2) from the self-decomposition of PMS to methyl parathion degradation can be neglected. The degradation rate constant (kobs) was strongly dependent on PMS loading and solution pH. The implication of the PMS reaction with methyl parathion for environment treatment was further evaluated by investigating the effects of common water matrices such as sediment humic acids, Cl−, and natural water. The identified metabolic products revealed that exposure to PMS resulted in hydrolysis and oxidation to methyl parathion. Further study demonstrated that PMS was also capable of effectively oxidizing other typical OPPs without explicit activation. This study provides novel insights into the reaction of methyl parathion with PMS, which indicate feasibility for the decontamination of OPP-contaminated environments.

Transcriptomic analysis of Burkholderia cenocepacia CEIB S5-2 during methyl parathion degradation.

Methyl parathion (MP) is a highly toxic organophosphorus pesticide associated with water, soil, and air pollution events. The identification and characterization of microorganisms capable of biodegrading pollutants are an important environmental task for bioremediation of pesticide impacted sites. The strain Burkholderia cenocepacia CEIB S5-2 is a bacterium capable of efficiently hydrolyzing MP and biodegrade p-nitrophenol (PNP), the main MP hydrolysis product. Due to the high PNP toxicity over microbial living forms, the reports on bacterial PNP biodegradation are scarce. According to the genomic data, the MP- and PNP-degrading ability observed in B. cenocepacia CEIB S5-2 is related to the presence of the methyl parathion-degrading gene (mpd) and the gene cluster pnpABA'E1E2FDC, which include the genes implicated in the PNP degradation. In this work, the transcriptomic analysis of the strain in the presence of MP revealed the differential expression of 257 genes, including all genes implicated in the PNP degradation, as well as a set of genes related to the sensing of environmental changes, the response to stress, and the degradation of aromatic compounds, such as translational regulators, membrane transporters, efflux pumps, and oxidative stress response genes. These findings suggest that these genes play an important role in the defense against toxic effects derived from the MP and PNP exposure. Therefore, B. cenocepacia CEIB S5-2 has a great potential for application in pesticide bioremediation approaches due to its biodegradation capabilities and the differential expression of genes for resistance to MP and PNP.

Cu2O nanoparticles for the degradation of methyl parathion.

Methyl parathion (MP) is one of the most neurotoxic pesticides. An inexpensive and reliable one-step degradation method of MP was achieved through an aqueous suspension of copper(I) oxide nanoparticles (NPs). Three different NPs sizes (16, 29 and 45 nm), determined with X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM), were synthesized using a modified Benedict’s reagent. 1H nuclear magnetic resonance (NMR) results show that the hydrolytic degradation of MP leads to the formation of 4-nitrophenol (4-NPh) as the main product. While the P=S bond of MP becomes P=O, confirmed by 31P NMR. Although Cu2O is a widely known photocatalyst, the degradation of methyl parathion was associated to the surface basicity of Cu2O NPs. Indirect evidence for the basicity of Cu2O NPs was achieved through UV–vis absorption of 4-NPh. Likewise, it was shown that the surface basicity increases with decreasing nanoparticle size. The presence of CuCO3 on the surface of Cu2O, identified using X-ray photoelectron spectroscopy (XPS), passivates its surface and consequently diminishes the degradation of MP.

Carbon Catabolite Repression of Methyl Parathion Degradation in a Bacterial Isolate Characterized as a Cupriavidus sp. LMGR1

Among the mixture of carbon compounds, bacteria have the ability to select energetically efficient substrate as a preferred carbon source. This specific behavior often limits the use of pollutants as a secondary carbon source by bacteria grown with preferred carbon source and the pollutants. Therefore, to develop an efficient bioremediation technology for removal/degradation of organophosphorus pesticide methyl parathion (MP) from agricultural soils, a soil bacterial strain (LMGR1) capable of degrading MP and p-nitrophenol was isolated and identified as a Cupriavidus oxalaticus based on biochemical (carbon utilization pattern) and molecular analysis (16S rRNA gene sequence), but the phylogenetic analysis revealed a distinct position, and the name was designated as Cupriavidus sp. LMGR1. The effect of preferred carbon source on degradation was also investigated. The bacterium assimilated the pesticide as a sole source of carbon and consumes about 100 mg L−1 of MP within 6 to 7 h of incubation. Furthermore, the methyl parathion hydrolase (MPH) enzyme (localized in the periplasm of bacterium) activity was induced by the carbon deficiency instead of substrate. Determination of kinetic parameters, i.e., Vmax and Km for MPH enzyme in the extracted periplasmic protein indicated significant higher affinity towards the substrate. The reduced MPH activity in the bacterium grown in presence of preferred carbon source indicated the role of carbon catabolite repression in regulation of pesticide degradation. Thus, the bacterium has prodigious capability to be used as a bioremediation agent, but the availability of preferred carbon source may affect its potential in field application.

Cascade degradation of organophosphorus pollutant by photoenzymatic integrated nanocatalyst

AbstractBACKGROUNDAs visible‐light photocatalytic semiconductors, BiOBr‐based catalysts have a promising application prospect for the degradation of dyes and pollutants in wastewater. Enzyme catalysis has become a promising technology in the degradation of organophosphorus pollutants due to excellent activity and specificity. Herein, a photoenzymatic integrated nanocatalyst of organophosphorus hydrolase (OPH) immobilized on BiOBr (OPH@BiOBr) was successfully synthesized for the cascade degradation of methyl parathion under visible light.RESULTSThe obtained OPH@BiOBr could degrade methyl parathion into para‐nitrophenol (p‐NP) by hydrolyzing the PS bond using OPH, and then converting the produced p‐NP into a less toxic substance through photocatalysis of BiOBr. After 3 h of reaction, methyl parathion was degraded into hydroquinone and nearly 80% of the produced p‐NP was further degraded at the same time. The OPH@BiOBr nanocatalyst could be recycled five times and still retained 83% of its initial activity.CONCLUSIONSA novel photoenzymatic integrated nanocatalyst was developed for cascade degradation of methyl parathion under visible light. This represents the first attempt at eliminating pesticide residues by combining enzyme with photocatalyst through a cascade reaction. Considering the fact that wastewater may have pesticide residues, photoenzymatic integrated catalysts will be useful for the degradation of pollutants. The unique flower‐like structure of the nanocatalyst could not only improve photocatalytic activity but also protect enzyme molecules so as to complete the cascade degradation. In addition, with the development of enzyme engineering and photocatalysis, the integrated nanocatalysts that combine photocatalyst with enzyme will have more and more application in the fields of energy and the environment. © 2020 Society of Chemical Industry

Sono-coprecipitation synthesis of ZnO/CuO nanophotocatalyst for removal of parathion from wastewater.

Semiconductor photocatalysis is an effective method used to degrade organophosphorus compounds. Here, the potential of a commonly mixed oxide semiconductor, ZnO/CuO, has been examined to degrade methyl parathion. Sono-coprecipitation method was used to provide ZnO/CuO nanocomposites, and it was applied to photocatalytic and sono-photocatalytic degradation of methyl parathion under solar light irradiation. Powder x-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), the Brunauer-Emmett-Teller (BET) surface area, field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM) were used to characterize the synthesized samples. The optimal experimental conditions such as ZnO/CuO photocatalyst 90:10M ratios, the initial concentration of 20mg/L parathion, 1g/L photocatalyst loading, no compressed air sparging, pH of 8, and ultrasonic power (60W and 80kHz) were used to degrade the parathion effectively. The parathion was fully (100% removal) degraded after 60min sono-photoirradiation in the optimal experimental conditions. A real water sample was used to examine the ability of the ZnO/CuO photocatalyst 90:10 to remove the parathion in the water-soluble ions. Graphical abstract.

Fabrication of Pt-Pd@ITO grown heterogeneous nanocatalyst as efficient remediator for toxic methyl parathion in aqueous media.

In this study, nano-sized ITO supported Pt-Pd bimetallic catalyst was synthesized for the degradation of methyl parathion pesticide, a common extremely toxic contaminant in aqueous solution. On the characterization with different techniques, a beautiful scenario of honeycomb architecture composed of ultra-small nanoneedles or fine hairs was found. Average size of nanocatalyst also confirmed which was in the range of 3-5nm. High percent degradation (94%) was obtained in 30s using 1.5 × 10- 1mg of synthesized nanocatalyst, 0.5mM NaBH4, and 110W microwave radiations power. Recyclability of nanocatalyst was efficient till 4th cycle observed during study of reusability. The supported Pt-Pd bimetallic nanocatalyst on ITO displayed many advantages over conventional methods for degradation of methyl parathion pesticide, such as high percent degradation, short reaction time, small amount of nanocatalyst, and multitime reusability. Graphical abstract Schematic illustration of reaction for degradation of methyl parathion.

Effective oxidation of methyl parathion pesticide in water over recycled glass based-MCM-41 decorated by green Co3O4 nanoparticles

Pieces of glass as solid wastes were recycled in the synthesis of highly order MCM-41 that decorated by green fabricated Co3O4 nanoparticles using the green extract of green tea leaves forming novel green nano-composite. The synthetic Co3O4/MCM-41 exhibit high surface area, low bandgap energy (1.63 eV), and typical spherical morphology decorated by Co3O4 nanoparticles. The composite was evaluated as green photocatalyst in effective oxidation of methyl parathion pesticide in the presence of a visible light source. The degradation results revealed complete removal of 50 mg/L and 100 mg/L after 60 min and 90 min, respectively using 0.25 of the catalyst at pH 8. The detection of the TOC in the treated methyl parathion solution gives strong indications about the formation of organic intermediate compounds during the oxidation steps. The main detected intermediate compound are C6H5OH(NO2), C6H5OH, (CH3O)3P(S), C6H4(OH)2, C6H3(OH)3, C6H4(NH2)OP(O)(OCH3)2, (CH3O)2P(O)OH, (CH2)2C(OH)OH(CHO)OC(O), and HO2C(CH2)2C(O)CHO. The detected intermediate compounds converted into SO42−, PO43−, NO3−, and CO2 under the extensive photocatalytic of them over Co3O4/MCM-41. The oxidizing species trapping test verified the controlling of the methyl parathion degradation pathway by the hydroxyl radicals. Finally, the composite showed significant reusability properties and applied five times in the oxidation of methyl parathion with considerable degradation percentages.