Degradation Of Methyl Parathion Research Articles

Photodecomposition of organic phosphorus in aquatic solution under solar irradiation with nitrate: Kinetics and influencing water parameters

The transformation of organic phosphorus plays an important role in the phosphorus cycle in the natural environment. In this study, a series of laboratory‐based experiments were conducted to address the influence of nitrate ( ) photochemical activity on the transformation of methyl parathion under solar irradiation. It is demonstrated that the photodecomposition of methyl parathion by obeys pseudo‐first‐order reaction kinetics, with the photodecomposition rate increasing with concentration. The photodecomposition rates of methyl parathion by were strongly influenced by pH, concentration of humic acid and Fe3+. Higher concentrations of Fe3+ and lower concentrations of humic acid accelerated the photodegradation induced by . Moreover, compared to alkaline media the acidic media can enhance the rate of methyl parathion degradation. Formation of the hydroxyl radical (•OH) was identified through the measurement of photoluminescence spectra (PL) using terephthalic acid as the trapping molecule. The primary transformation pathways of methyl parathion in the presence of under solar irradiation were proposed through the qualitative and quantitative analysis of byproducts. Intermediates, such as paraoxon, 4‐nitrophenol and orthophosphate, were identified, and a mineralization pathway from methyl parathion to orthophosphate was proposed. © 2016 American Institute of Chemical Engineers Environ Prog, 36: 404–411, 2017

Photocatalytic degradation of Acephate, Omethoate, and Methyl parathion by Fe3O4@SiO2@mTiO2 nanomicrospheres

A novel magnetic mesoporous nanomicrospheres Fe3O4@SiO2@mTiO2 were synthetized and characterized by a series of techniques including FE-TEM, EDS, FE-SEM, PXRD, XPS, BET, TGA as well as VSM, and subsequently tested as a photocatalyst for the degradation of Acephate, Omethoate, and Methyl parathion under UV irradiation. The well-designed nanomicrospheres exhibit a pure and highly crystalline anatase TiO2 layer, large specific surface area, and high-magnetic-response. Photocatalytic degradation of the three organophosphorus pesticides (OPPs) and the formation intermediates were identified using HPLC, TOC-Vcpn, IC, pH meter and GC–MS. Acephate, Omethoate, and Methyl parathion disappeared after 45min, 45min, and 80min UV illumination, respectively. At the end of the treatment, the total organic carbon (TOC) of the OPPs was reduced 80–85%. The main mineralization products were SO42−, NO3− and PO43− and Omethoate additionally formed NO2−. Based on the results, we proposed the photocatalytic degradation pathways for Acephate, Omethoate, and Methyl parathion.

Microwave-induced carbon nanotubes catalytic degradation of organic pollutants in aqueous solution

In this study, a new catalytic degradation technology using microwave induced carbon nanotubes (MW/CNTs) was proposed and applied in the treatment of organic pollutants in aqueous solution. The catalytic activity of three CNTs of 10–20nm, 20–40nm, and 40–60nm diameters were compared. The results showed that organic pollutants such as methyl orange (MO), methyl parathion (MP), sodium dodecyl benzene sulfonate (SDBS), bisphenol A (BPA), and methylene blue (MB) in aqueous solution could be degraded effectively and rapidly in MW/CNTs system. CNTs with diameter of 10–20nm exhibited the highest catalytic activity of the three CNTs under MW irradiation. Further, complete degradation was obtained using 10–20nm CNTs within 7.0min irradiation when 25mL MO solution (25mg/L), 1.2g/L catalyst dose, 450W, 2450MHz, and pH=6.0 were applied. The rate constants (k) for the degradation of SDBS, MB, MP, MO and BPA using 10–20nm CNTs/MW system were 0.726, 0.679, 0.463, 0.334 and 0.168min−1, respectively. Therefore, this technology may have potential application for the treatment of targeted organic pollutants in wastewaters.

Abiotic degradation of methyl parathion by manganese dioxide: Kinetics and transformation pathway

Methyl parathion, a widely used insecticide around the world, has aroused gradually extensive concern of researchers due to its degradation product such as methyl paraoxon, with higher toxicity for mammals and more recalcitrant. Given the ubiquity of manganese dioxide (MnO2) in soils and aquatic sediments, the abiotic degradation of methyl parathion by α-MnO2 was investigated in batch experiments. It was found that methyl parathion was decomposed up to 90% by α-MnO2 in 30 h and the removal efficiency of methyl parathion depended strongly on the loading of α-MnO2 and pH value in the solution where the reactions followed pseudo-first-order model well. The coexisting metal ions (such as Ca2+, Mg2+ and Mn2+) weakened markedly the degradation of methyl parathion by α-MnO2. However, the effect of dissolved organic matter (HA-Na) on reaction rates presented two sides: to improve hydrolysis rate but deteriorate oxidation rate of methyl parathion. Based on the degradation products identified by gas chromatography–mass spectrometer (GC/MS) and liquid chromatography high-resolution mass spectrometer (LC/HRMS), both hydrolysis and oxidation processes were proposed to be two predominant reaction mechanisms contributing to methyl parathion degradation by α-MnO2. This study provided meaningful information to elucidate the abiotic dissipation of methyl parathion by manganese oxide minerals in the environment.

Characterization and comparison of putative Stenotrophomonas maltophilia methyl parathion hydrolases

ABSTRACTThree Stenotrophomonas maltophilia isolates, KKWT11, CBF10-1, TTF10, were collected from organophosphate (OP)-contaminated soil in the Houston metropolitan area. A conserved metallo-β-lactamase (MBL) enzyme purported to function as a methyl parathion hydrolase was identified and found to be distantly homologous to the characterized Pseudomonas sp. WBC-3 methyl parathion hydrolase and shared no significant homology with other organophosphate hydrolases. Following expression of MBL enzymes cloned from S. maltophilia strains KKWT11, CBF10-1, and TTF10, respectively, an enzymatic preference for paraoxon was observed, with concentrations of 70, 40, and 30 µM of p-nitrophenol (PNP) formed after 48 h. Comparatively limited hydrolysis against the phosphorothioate methyl parathion was recorded with concentrations of PNP ranging from 9.5 to 3.5 µM after 48 h. A coexpressive construct harboring a modified organophosphorus hydrolase enzyme and the CBF10-1 MBL enzyme yielded only a slight improvement in degradation of methyl parathion, resulting in 75 µM of PNP formed compared with 69 µM formed by the organophosphorus hydrolase (OPH) control over 48 h. These results suggest that S. maltophilia MBL enzymes are currently insufficient for broad-spectrum hydrolysis of phosphorothioate insecticides. Future studies will thus seek to elucidate their catalytic efficiency against other notable phosphotriester oxons, including chlorpyrifos oxon, and malaoxon.

Genetically engineered Pseudomonas putida X3 strain and its potential ability to bioremediate soil microcosms contaminated with methyl parathion and cadmium.

A multifunctional Pseudomonas putida X3 strain was successfully engineered by introducing methyl parathion (MP)-degrading gene and enhanced green fluorescent protein (EGFP) gene in P. putida X4 (CCTCC: 209319). In liquid cultures, the engineered X3 strain utilized MP as sole carbon source for growth and degraded 100 mg L(-1) of MP within 24 h; however, this strain did not further metabolize p-nitrophenol (PNP), an intermediate metabolite of MP. No discrepancy in minimum inhibitory concentrations (MICs) to cadmium (Cd), copper (Cu), zinc (Zn), and cobalt (Co) was observed between the engineered X3 strain and its host strain. The inoculated X3 strain accelerated MP degradation in different polluted soil microcosms with 100 mg MP kg(-1) dry soil and/or 5 mg Cd kg(-1) dry soil; MP was completely eliminated within 40 h. However, the presence of Cd in the early stage of remediation slightly delayed MP degradation. The application of X3 strain in Cd-contaminated soil strongly affected the distribution of Cd fractions and immobilized Cd by reducing bioavailable Cd concentrations with lower soluble/exchangeable Cd and organic-bound Cd. The inoculated X3 strain also colonized and proliferated in various contaminated microcosms. Our results suggested that the engineered X3 strain is a potential bioremediation agent showing competitive advantage in complex contaminated environments.

Reactivity and reusability of immobilized zinc oxide nanoparticles in fibers on methyl parathion decontamination

Zinc oxide (ZnO) nanoparticles were used as the photocatalyst to develop self-decontaminating fibers for potential use as chemical protective materials. Since ZnO is an effective photocatalyst for degradation of organophosphate, it was incorporated in electrospun polyacrylonitrile (PAN) fibers. Photocatalytic degradation of methyl parathion, an organophosphate, upon exposure to ZnO-PAN fibers was evaluated and found to be effective for reuse for up to five exposure cycles. High performance liquid chromatography, UV-vis spectroscopy, calculations of octanol–water partition coefficients, and 31P NMR spectroscopy were used to determine that hydrolysis is the probably mechanism for photocatalytic degradation.

Dual-functional OPH-immobilized polyamide nanofibrous membrane for effective organophosphorus toxic agents protection

In both civilian and military domains, the increasing use of highly toxic organophosphates (OPs) has created an urgent demand for developing an effective method that could protect the human body from OP poisoning. In this study, a novel dual-functional protecting material with both OP filtration and degradation functions was designed and fabricated. The filtration function was endowed by the electrospinning polyamide 66 (Nylon 66, PA-66) nanofibrous membrane, while the OP degradation function was based on the immobilization of organophosphorus hydrolase (OPH) on membrane through glutaraldehyde (GA) crosslinking. A systematic study of the relationship between the membrane structure, filtration ability and OP degradation activity revealed that PA-66 nanofibrous enzyme with 20μm thickness exhibited perfect uniform morphology, and the particle filtration efficiency was over 99%. The nanofibrous enzyme exhibited a specific activity of 41U/g; the enzyme activity recovery was 53.3%, and the methyl parathion (MP) degradation efficiency was 40%. Moreover, the nanofibrous enzyme expressed excellent organic solvent stability; approximately 70% of its initial activity was retained after incubation in xylene solvent for 24h at 25°C. The residual activity was 40% after being stored for 30d at 25°C. After 10 repeated uses, the residual activity of the nanofibrous membrane was 37%. This study demonstrated the application potential of dual-functional PA-66 nanofibrous enzyme in biochemical protection, aimed at various military and civilian applications.

Degradation studies of methyl parathion with CuBTC metal-organic framework

Degradation of methyl parathion (MP) adsorbed in metal-organic framework (MOF-199) cages was studied using solid-state 31P nuclear magnetic resonance (NMR), Raman spectrometry, and solvent extractions. MP degradation was confirmed to be occurring when adsorbed in CuBTC MOF (MOF-199). Over 67 days of treatment, NMR results show that constitutional isomerization is an early mechanism of methyl parathion degradation with smaller amounts of oxidation (methyl paraoxon) and direct hydrolysis of MP followed by hydrolysis of these early degradation products. Raman spectrometry after 5 days and water extractions after 5 and 35 days supported this conclusion. 4-Nitrophenyl, a common MP degradation product, was observed with the amount increasing with exposure time or higher MP loading. Degradation of organic compounds such as methyl parathion, in addition to the selective physisorption, demonstrates the usefulness of MOF-199 for potential applications in protective materials and filtration.

Electrochemical Oxidation of Methyl Parathion at a Boron-Doped Diamond Electrode

The commercial plaguicide methyl parathion (MP) is electrochemically degraded in a divided H-type cell equipped with two boron doped diamond electrodes, BDDE and a Nafion cation exchange membrane. High removals (i.e., >90%) of total organic carbon, TOC and of chemical oxygen demand, COD were obtained after 180 min at a current density, j of 5 mA/cm2 with a specific energy consumption, Esp of ca. 200 kWh per kg of COD degraded. These results show that the anodic oxidation route may be an efficient alternative for MP degradation in polluted waters.

Genetically modified microorganism Spingomonas paucimobilis UT26 for simultaneously degradation of methyl-parathion and γ-hexachlorocyclohexane

Bioremediation of pesticide residues by bacteria is an efficient and environmentally friendly method to deal with environmental pollution. In this study, a genetically modified microorganism (GMM) named UT26XEGM was constructed by introducing a parathion hydrolase gene into an initially γ-hexachlorocyclohexane (γ-HCH) degrading bacterium Spingomonas paucimobilis UT26. In order to reduce its potential risk of gene escaping into the environment for the public concern on biosafety, a suicide system was also designed that did not interfere with the performance of the GMM until its physiological function was activated by specific signal. The system was designed with circuiting suicide cassettes consisting of killing genes gef and ecoRIR from Escherichia coli controlled by Pm promoter and the xylS gene. The cell viability and original degradation characteristics were not affected by the insertion of exogenous genes. The novel GMM was capable of degrading methyl-parathion and γ-HCH simultaneously. In laboratory scale testing, the recombinant bacteria were successfully applied to the bioremediation of mixed pesticide residues with the activity of self-destruction after 3-methylbenzoate induction.

Sol-gel immobilisation of methyl parathion degrading bacteria isolated from agricultural areas of Pakistan

The following areas are discussed in this paper: immobilisation of bacterial consortium in sol-gel; methyl parathion degradation and bioremediation applications; evaluation of indigenous bacterial isolates of contaminated soils. Bacterial strains were isolated from agricultural areas of Pakistan which were contaminated with methyl parathion. A bacterial consortium of seven (out of 64) Enterobacteriaceae isolates including Citrobacter, Enterobacter and Proteus vulgaris capable of degrading methyl parathion (enzyme activity ranging 410–675 mU mL−1 for individual isolates and 982 mU/mL for consortium) was selected and subsequently immobilised in tetraethyl orthosilicate (TEOS) and sodium-silicate-based sol-gel matrices. Cell viability of suspended and immobilised bacterial consortium was monitored using a minimal salt medium supplemented with methyl parathion. The results indicate that sol-gel immobilisation can be helpful to increase the shelf life of methyl parathion degrading bacterial strains along with preservation of biological activity for bioremediation applications in field.

Optimization of methyl parathion biodegradation and detoxification by cells in suspension or immobilized on tezontle expressing the opd gene

The goal of this study was to optimize methyl parathion (O,O-dimethyl-O-4-p-nitrophenyl phosphorothioate) degradation using a strain of Escherichia coli DH5α expressing the opd gene. Our results indicate that this strain had lower enzymatic activity compared to the Flavobacterium sp. ATCC 27551 strain from which the opd gene was derived. Both strains were assessed for their ability to degrade methyl parathion (MP) in a mineral salt medium with or without the addition of glucose either as suspended cells or immobilized on tezontle, a volcanic rock. MP was degraded by both strains with similar efficiencies, but immobilized cells degraded MP more efficiently than cells in suspension. However, the viability of E. coli cells was much higher than that of the Flavobacterium sp. We confirmed the decrease in toxicity from the treated effluents through acetylcholinesterase activity tests, indicating the potential of this method for the treatment of solutions containing MP.

Electrochemical degradation of the insecticide methyl parathion using a boron-doped diamond film anode

Methyl parathion is one of the most toxic of the organophosphate insecticides. While this agent continues to be used, natural waters in agricultural areas are likely to contain significant amounts of the biocide, representing a threat to beneficial insects, freshwater organisms, birds and mammals. The electrochemical oxidation of methyl parathion in acidic medium has been studied using a boron-doped diamond (BDD)/Ti anode under galvanostatic current control. Chronoamperometry showed that significant oxidation of reference standard methyl parathion commenced at 1.8V vs Ag/AgCl, while spectrophotometric studies revealed that the absorbance of a commercial formulation of the insecticide decayed according to time in electrolysis. Electrochemical degradation experiments were performed in a laboratory-constructed polypropylene cell in which solutions containing methyl parathion (equivalent to 60mgL−1) were subjected to electrolytic treatment at different current densities (5, 10, 25, 50 and 100mAcm−2). High performance liquid chromatographic analysis demonstrated that 81.2% of the insecticide was removed in 180min at an applied current density of 100mAcm−2, and a compound, identified from its UV spectrum as 4-nitrophenol, was formed either as an intermediate or as a byproduct. Under these conditions, mineralization efficiency (determined by total organic carbon analysis) was 67.6%, and the toxicity of the original electrolyte against the bioluminescent bacterium Vibrio fischeri was reduced considerably by the electrochemical treatment. It is concluded that electrooxidation using BBD/Ti electrodes represents an appropriate method for the removal of methyl parathion from contaminated waters.

Interfacial interaction between methyl parathion-degrading bacteria and minerals is important in biodegradation

In the present study, the influence of kaolinite and goethite on microbial degradation of methyl parathion was investigated. We observed that the biodegradation process was improved by kaolinite and depressed by goethite. Calorimetric data further showed that the metabolic activities of degrading cells (Pseudomonas putida) were enhanced by the presence of kaolinite and depressed by the presence of goethite. A semipermeable membrane experiment was performed and results supported the above observations: the promotive effect of kaolinite and the inhibition of goethite for microbial degradation was not found when the bacteria was enclosed by semipermeable membrane and had no direct contact with these minerals, suggesting the important function of the contact of cellular surfaces with mineral particles. The relative larger particles of kaolinite were loosely attached to the bacteria. This attachment made the cells easy to use the sorbed substrate and then stimulated biodegradation. For goethite, small particles were tightly bound to bacterial cells and limited the acquisition of substrate and nutrients, thereby inhibiting biodegradation. These results indicated that interfacial interaction between bacterial cells and minerals significantly affected the biodegradation of pesticides.

Electrochemical degradation of methyl parathion

This paper describes the degradation of commercially available methyl parathion by electro oxidation using Ti/RuO2 as anode, stainless steel as cathode and sodium chloride as a supporting electrolyte. Experiments were carried out at constant flow rate and various current densities such as 10, 12 and15 A/dm2 and various concentrations of sodium chloride. At regular time intervals, reduction of chemical oxygen demand (COD) has been investigated. From the results, addition of 14 g/l g of sodium chloride and applied current density of 15 A/dm2 give better degradation performance than the other. In addition to that degradation of methyl parathion was carried out at different pH ranges such as 4, 7 and 10 at standardised current density of 15 A/dm2. Results indicate that degradation of methyl parathion was more effective when the pH of the solution was at 4. The degradation of methyl parathion has been analysed by high performance liquid chromatography (HPLC), NMR, UV-Vis spectra, FT-IR and TOC.

Identification of water-borne bacterial isolates for potential remediation of organophosphate contamination

Three water-borne bacterial isolates were collected from the Houston metropolitan area. Each isolate was capable of growing upon carbon limited media inoculated with the organophosphorus (OP) compound paraoxon. All isolates were able to efficiently metabolize paraoxon and, to a lesser degree, methyl parathion to p-nitrophenol. 16S rDNA genome sequencing with universal bacterial primers identified the isolates as species belonging to the genera Aeromonas, Steno- trophomonas, or Exiguobacterium. All screened isolates harbor organophosphorus degradation (opd) genes that are approximately 99% similar over approximately 660 base pairs sequenced to one first isolated from Sphingobium fuliginis ATCC 27551 (formerly Flavobacterium sp. ATCC 27551). Additionally, two isolates KKWT11, identified as a putative Senotro- phomonas maltophilia, and KKBO11, identified as a putative Exiguobacterium indicum, were found to possess genomic DNA that closely matched a metallo- beta-lactamase that has been reported to function as a methyl parathion degradation (mpd) gene suggesting that both of these strains are prime candidates for wastewater remediation of a broad range of OP compounds.

Electrochemical monitoring of methyl parathion degradation based on carbon fiber microelectrodes (CFME)

The electrochemical degradation of methyl parathion (MP) has been investigated by using carbon fiber microelectrodes (CFME) as working electrode and acetate buffer pH 5.2 as supporting electrolyte. pnitrophenol (PNP) and p-aminophenol (PAP) recognized as by-products of MP degradation process have been detected and identified in real time using square wave voltammetry. This study shows for the first time that CFME could be used to follow MP degradation in real time and to identify its stables metabolites.Keywords: Organopollutants, decomposition, p-nitrophenol, p-aminophenol, Cyclic voltammetry, Square wave voltammetry

Degradation of methyl parathion using hydrodynamic cavitation: Effect of operating parameters and intensification using additives

Methyl parathion (C8H10NO5PS), which is an organophosphorus pesticide that has been widely used as an agricultural insecticide in India, can result in significant water pollution due to its biorefractory nature and longer stability. In the present work, degradation of methyl parathion has been investigated using hydrodynamic cavitation reactors with possible intensification studies using different approaches. Effect of different parameters like operating pressures (1–8bar), operating temperatures (sets of intense cooling, moderate cooling and uncontrolled operation) and initial pH (2.2–8.2) has been investigated initially. Under the optimized set of operating parameters, the effect of process intensifying parameters like hydrogen peroxide (25–200mg/l), carbon tetrachloride (1–6g/l) and Fenton’s reagent (H2O2:FeSO4 ranging from 1:1 to 1:6) on the extent of degradation has been investigated. Effect of radical scavengers like sodium bicarbonate and tert-butanol on the extent of degradation was also investigated with an objective of establishing the controlling mechanism. More than 90% degradation of methyl parathion was achieved using combination of hydrodynamic cavitation with H2O2 and Fenton’s reagent. TOC analysis at optimum conditions was also performed to quantify the extent of mineralization and it has been observed that a maximum of 76% TOC reduction is obtained. The study has also focused on the determination of intermediate products formed during the degradation. It has been established that hydrodynamic cavitation in the presence of additives can be effectively used for complete removal of methyl parathion.

Effect of pH on the Degradation of Aqueous Organophosphate (methylparathion) in Wastewater by Ozonation

Degradation of O,O-dimethyl -O-4-nitrophenylphosphorothioate (methylparathion) by ozonation in aqueous solution was studied in a batch reactor under constant ozone dosage and variable pH conditions. The effectiveness of the process was estimated based on the degree of COD (chemical oxygen demand) reduction and conversion of methylparathion. It was observed that ozonation is more effective at alkaline reaction of medium than other conditions. The degree of methylparathion conversion achieved after 120 minutes of the process at pH 9 was 98% compared to 81% and 60% at pH 7 and 3, respectively. Another parameter used to quantify the methylparathion during ozonation was the pseudo first order rate constant k (1/min). Results showed that the rate constant of the process was approximately much higher at pH 9 compared to pH 7 and 3. A significant improvement in chemical oxygen demand removal was observed at pH above 7. At pH 9, the reduction in chemical oxygen demand at the end of the process reached 93%. The methylparathion degradation intermediate products were analyzed by gas chromatography–mass spectrometry (GC–MS). The main intermediate product was p-nitrophenol. The result of the study concludes that ozonation is an effective process for the treatment of organophosphate (methylparathion) contaminated wastewater.