Degradation Of Dichlorvos Research Articles

Degradation effects on dichlorvos by a biocontrol strain, Trichoderma atroviride T23

Excessive use of organophosphate pesticides (OP), such as dichlorvos, in farming system poses a threat to human health through potential contamination of environment. To date, biodegradation has been prospected most promising approach to eliminate environmental OP residues. Trichoderma species as a biological control microorganism is often exposed to the chemical pesticides applied in environments, so it is necessary to understand the mechanism of degradation of dichlorvos by Trichoderma. In this study, dichlorvos significantly inhibited the growth, sporulation and pigmentation of T. atroviride T23, and the dichlorvos degradation activity of T23 required the initial induction effect of dichlorvos and the culture conditions, including the nutrient and pH values of the medium. Various changed primary and secondary metabolites released from T23 in the presence of dichlorvos were speculated as the energy and antioxidants for the strain itself to tolerate dichlorvos stress. The results showed that T23 could produce a series of enzymes, especially the intracellular enzymes, to degrade dichlorvos. The activities of the intracellular enzyme generated by T23 were differentially changed along time course and especially relied on initial dichlorvos concentration, ammonium sulfate and phosphate added in the medium. In conclusion, some dichlorvos-induced chemical degradation related enzymes of T23 were proved to be involved in the degradation of dichlorvos.

Optimizing the degradation of dichlorvos in aqueous solution using nZVI DTPA+H2O2 and its detection using ac conductivity measurement with the help of response surface methodology

Degradation of organic pollutants in wastewater is a common subject of discussion under advanced oxidation process. To detect the degradation of colourless organic pollutants conventional analytical techniques are available but their sophistication makes it difficult to pursue in all form of chemical laboratories. In the present study it was found that during degradation of Dichlorvos using diethylene triamine pent acetic acid (DTPA) stabilized nano zero valent iron (nZVI), COD removal and ac conductivity change has been done simultaneously. In this degradation study the heterogeneous Fenton type oxidation method was employed and an LCR circuit (which contains inductor, capacitor and resistor) was used to measure the ac conductivity. This study aims to find out a correlation between ac conductivity and COD removal using simple response surface methodology (RSM) so that the degradation of colourless pollutants can be estimated easily and also to identify the best processing parameters to optimise Dichlorvos degradation. It was found that COD removal in most of all cases, was more than 60% when the change in final ac conductivity more than 600% with respect to initial value. All of the experimental results were in good accord with the projected outcome.

Synergistic effects of the combined use of ozone and sodium percarbonate for the oxidative degradation of dichlorvos

Dichlorvos or 2,2-dichlorovinyl dimethyl phosphate (DDVP) is a chlorinated organophosphorus pesticide which is frequently detected in the aqueous environment. In this study, an environmentally friendly and highly efficient oxidant, i.e., sodium percarbonate (SPC, Na2CO3·1.5H2O2) was introduced to an ozonation process for the degradation of dichlorvos (DDVP). Experimental results revealed an enhancement of DDVP degradation efficiency via the O3/SPC process compared with O3 alone due to the generation of reactive species (OH and CO3−) under various conditions. Both processes fitted the pseudo-first-order kinetic model and the reaction rate constant of the O3/SPC process under low SPC dosage (30 mg L-1) was more than two times higher than for O3 alone. The DDVP removal performance was evaluated in terms of initial pH, O3 dosage, SPC dosage and water matrix. The pH played a significant role in DDVP degradation during the O3/SPC process, especially on the occurrence of the different types of reactive species. Based on radical scavenger experiments, OH were observed over the full pH range but dominated under neutral and alkaline conditions, while less oxidative CO3- emerged at lower pH. Furthermore, the complex matrix of real wastewater inhibited the oxidation process due to the competition for oxidative species between organic matter and DDVP. A modified kinetic model based on a steady-state hypothesis was established to predict DDVP degradation via the O3/SPC treatment and provided a fair result under different conditions. This observation suggested that eco-friendly SPC could be considered as a promising alternative for H2O2 in developing sustainable ozone-based oxidation processes for recalcitrant compounds elimination in wastewater treatment.

The stability of four organophosphorus insecticides in stored cucumber samples is affected by additives

The influence of some additives, including metal ions, antioxidants, enzyme inhibitors and organic solvents, on the storage stability of four organophosphorus pesticides in cucumber samples were investigated. It was found that metal ions, including Al3+, Fe3+, and Co2+, increased the stability of dichlorvos, malathion, and chlorpyrifos. Conversely, Al3+, Fe3+, Fe2+, and Co2+ caused catalytic degradation of diazinon. With the addition of organic solvents (CH2Cl2, CHCl3, CCl4, CH3OH and CH3COCH3), remaining of diazinon residues was higher (16-54%) after storage for seven days. CCl4 was associated with the highest retention of malathion, diazinon, and chlorpyrifos (33%, 48% and 44%, respectively) in samples. SDS also stabilized the pesticides since residues were, again, higher (13-38%) after seven days storage. Furthermore, addition of Al3+ and Fe3+ decreased peroxidase (POD) activity and inhibited degradation of dichlorvos and malathion. After 14days, lyophilization increased the pesticide residues remaining by 36%, 29%, and 58% for diazinon, malathion and chlorpyrifos, respectively. Overall, the stability of these pesticides during storage is impacted by water content and addition of exogenous substances. This could ensure higher quality of pesticide residue data in samples.

Aerobic dichlorvos degradation by Pseudomonas stutzeri smk: complete pathway and implications for toxicity in Mus musculus

Excess use of pesticides in agricultural field not only compromised soil fertility but also posed serious threat to water bodies and life in the surrounding environment. The leftover pesticide residue needs to be remediated effectively. Compared to physical, chemical and enzymatic remediation options the microbial remediation is more practical and sustainable. The Pseudomonas stutzeri smk strain was found to use dichlorvos as the solitary carbon source. Minimal medium supplemented with dichlorvos was used to test ability of bacterium to degrade pesticide aerobically. The metabolites produced by the bacterium were studied with UV-Vis spectrophotometry, HPLC, FTIR and GC-MS techniques. The toxicity studies of neat dichlorvos and P. stutzeri smk degraded metabolites were studied by subcutaneous injection in Mus musculus. The P. stutzeri smk strain was found to degrade as high as 80% of dichlorvos on 7th day of incubation, at 30 °C temperature and at pH 7. In five steps complete aerobic degradation of 2,2dicholorvinyl dimethyl phosphate (dichlorvos) resulted in production of free methyl and phosphate. The degradation intermediates produced are 2-Chlorovinyl dimethyl phosphate, vinyl dimethyl phosphate, dimethyl phosphate, methylphosphate and finally free phosphate. The histopathological analysis of liver, spleen and thymus of M. musculus were performed to study toxicity of dichlorvos and degraded metabolites. P. stutzeri smk could result highest aerobic degradation of dichlorvos to produce free methyl and phosphate. Degradation metabolites could reverse largely toxic effects of dichlorvos when studied in M. musculus.

Photocatalytic degradation of organophosphorus pesticide using semiconductor-sensitized composite in natural water: effect of oxidants

In this work, dichlorvos was degraded with photocatalytically active n-type semiconductors and p–n junction-type semiconductors. The p–n junction-type semiconductors such as GO–TiO2 (GO = graphene oxide) and GO–WO3 were synthesized by photodeposition method using commercial TiO2 and WO3. GO-doped nano-TiO2 was synthesized through sol–gel technique from titanium(IV) isopropoxide by hydrothermal treatment. The synthesized materials were characterized by different techniques such as XRD, UV, FTIR, SEM and TEM. In order to find out the photocatalytic ability towards degradation of dichlorvos, the experiment was carried out in an aqueous suspension under UV light in the presence of oxygen and oxidants such as H2O2 and K2S2O8. From the evaluation, GO–nano-TiO2 with H2O2 was found to be highly active that showed complete degradation of dichlorvos within 15 min under UV light.

Storage stability of three organophosphorus pesticides on cucumber samples for analysis

The residue sample storage stability of three organophosphorus pesticides, dichlorvos, diazinon, and malathion, under different conditions was investigated. The storage conditions studied included storage time, temperature, and sample form. The addition of extra enzyme to the samples was also studied to investigate its effect on stability. It was found that malathion was more unstable than dichlorvos and diazinon, there was an over 70% loss in 90 days even at −20 °C in coarsely chopped form. The pesticide residues were more stable when the cucumber was in homogenate form than coarsely chopped. Furthermore, the addition of catalase increased the degradation of malathion, where there was more decomposition with increasing levels of catalase. However, there was no obvious relationship between degradation of dichlorvos and diazinon and catalase concentration. Overall, this study revealed factors that can be optimized to increase the storage stability of organophosphorus pesticides, where enzyme was one of the main influencing factors.

Catalytic Degradation of Dichlorvos Using Biosynthesized Zero Valent Iron Nanoparticles.

The removal of dichlorvos contamination from water is a challenging task because of the presence of direct carbon to phosphorous covalent bond, which makes them resistant to chemical and thermal degradation. Although there have been reports in the literature for degradation of dichlorvos using nanomaterials, those are based on photocatalysis. In this paper, we report a simple and rapid method for catalytic degradation of dichlorvos using protein-capped zero valent iron nanoparticles (FeNPs). We have developed an unprecedented reliable, clean, nontoxic, eco-friendly, and cost-effective biological method for the synthesis of uniformly distributed FeNPs. Yeast extract was used as reducing and capping agent in the synthesis of FeNPs, and synthesized particles were characterized by the UV-visible spectroscopy, X -ray diffraction, Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). TEM micrographs reveal that the nanoparticles size is distributed in the range of 2-10 nm. Selected area electron diffraction pattern shows the polycrystalline rings of FeNPs. The mean size was found to be 5.006 nm from ImageJ. FTIR spectra depicted the presence of biomolecules, which participated in the synthesis and stabilization of nanoparticles. As synthesized, FeNPs were used for the catalytic degradation of dichlorvos in aqueous medium. The degradation activity of the FeNPs has been investigated by the means of incubation time effect, oxidant effect, and nanoparticle concentration effect. The ammonium molybdate test was used to confirm the release of phosphate ions during the interaction of dichlorvos with FeNPs.

Adsorption coupled photocatalytic degradation of dichlorvos using LaNiMnO6 perovskite nanoparticles supported on polypropylene filter cloth and carboxymethyl cellulose microspheres

Increasing pesticide application and improper wastewater disposal methods contaminate water resources and severely affect the ecology as well as environment. The present study is focused on the adsorption coupled photocatalytic degradation of dichlorvos using UV light in presence of LaNiMnO6 perovskite nanoparticles (Prv) supported on polypropylene filter cloth (PPPrv) and carboxymethyl cellulose (CMCPrv) microspheres. The synthesized LaNiMnO6 perovskite nanoparticles were characterized by XRD, FT‐IR, SEM and EDX. The adsorption percentage of DCV followed the order: CMCPrv (62.7%) > PPPrv (46.1%) > Prv (32.6%). Equilibrium studies suggested the heterogenous mode of adsorption. Pseudo‐first order exhibited the good linearity indicating the involvement of physical forces. Thermodynamics showed an endothermic and spontaneous nature of adsorption. The influences of various photocatalytic parameters viz., pH, irradiation time, initial DCV concentration, Prv loading and catalyst dosage on DCV degradation were investigated. Ex situ studies conducted for 8 h of sunlight exposure showed complete degradation of DCV present in industrial wastewater which was confirmed by GC‐MS analysis. The advantage of CMCPrv as supported catalyst is the easy separation and reuse for four cycles. The present work is the first report that signifies the potential efficacy of CMCPrv to serve as an effective remedial agent for DCV removal from contaminated water. © 2016 American Institute of Chemical Engineers Environ Prog, 36: 180–191, 2017

Photocatalytic Degradation of Dichlorvos using Graphite Oxide Based Catalysts

Photocatalytic Degradation of Dichlorvos using Graphite Oxide Based Catalysts

Degradation of dichlorvos using hybrid advanced oxidation processes based on ultrasound

Degradation of dichlorvos pesticide has been investigated in an ultrasonic bath having operating power of 150W and operating frequency of 36kHz with a capacity of 7L. All the experiments have been performed using 20mg/L solution of commercially available dichlorvos at an operating pH of 3 under ambient conditions. Different combined treatment processes such as ultrasound (US)/TiO2, solar/TiO2, US/solar/TiO2, US/H2O2, US/Fenton and US/ozone have been applied with an objective of achieving effective and complete degradation of dichlorvos. The removal of dichlorvos was found to be significant in the case of TiO2/solar (78.42%) and US/Fenton (81.19%) in 2h treatment as compared to only ultrasound (6.4%) or only TiO2 (3%) which is a clear indication of the efficacy of combined treatment processes. Complete degradation of dichlorvos was obtained by using combination of ozone and ultrasound. TOC analysis at optimum conditions was also performed to quantify the extent of mineralization and it has been observed that a maximum of 93% TOC reduction is obtained in the case of combination of ozone and ultrasound. Integral method of analysis was followed and it has been observed that pseudo-first order kinetics explains the degradation reaction very well. The present work has conclusively established that cavitation in the presence of additives can be effectively used for complete removal of dichlorvos pesticide at pilot scale operation.

In situ generated TiO2 over zeolitic supports as reusable photocatalysts for the degradation of dichlorvos

Materials based on titania supported on zeolitic matrices (HBETA, HY and HZSM5) were synthesized by in situ generation of TiO2. The supported catalysts characterized by XRD indicate the presence of the anatase phase alone. The materials were also characterized by FTIR, SBET, and UV-VIS DRS. A high TiO2 content produced lower degradation, due to the presence of TiO2 particle aggregates of greater size on the zeolite matrix surface, as evidenced by the calculated crystal size. TiO2/HBETA(20%) presented more activity than TiO2 supported on the other matrices due to higher adsorption of dichlorvos on HBETA. It has more surface area and a lower band gap value too, which makes it more effective. The mineralization degree is lower than the degradation percentage due to the formation of organophosphorous intermediates that are less toxic than the starting material. The complete degradation and mineralization of the pollutant was obtained in 360 and 540min of reaction with TiO2/HBETA(20%), respectively. This catalyst resulted in degradation percentages close to that of commercial TiO2 P25. The main advantage of supported catalysts is their easy separation and reuse, in this case resulting in a very low activity loss during eight cycles. These materials present suitable properties to be used as catalysts in the photocatalytic treatment of wastewater that contains pesticide dichlorvos in water.

VISIBLE LIGHT ACTIVECu2+/TiO2NANOCATALYST FOR DEGRADATION OF DICHLORVOS

The advantage of doping of TiO2with copper has been utilized for enhanced degradation of pesticide under visible light irradiation. The sol–gel method has been undertaken for the synthesis of copper-doped TiO2by varying the dopant loadings from 0.25 wt.% to 1.0 wt.% of Cu2+. The doped samples were characterized by UV-Visible Diffuse Reflectance Spectroscopy (DRS), N2adsorption–desorption (BET), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), and Energy Dispersive Spectrometry (EDS). The photocatalytic activity of the catalyst was tested by degradation of dichlorvos under visible light illumination. The results found that 0.75 wt.% of Cu2+doped nanocatalysts have better photo catalytic activity than the rest of percentages doped, undoped TiO2and Degussa P25. The reduction of band gap was estimated and the influence of the process parameters on photo catalytic activity of the catalyst has been explained.

Degradation of dichlorvos containing wastewaters using sonochemical reactors

The present work deals with application of sonochemical reactors for the degradation of dichlorvos containing wastewaters. The sonochemical reactor used in the work is a simple ultrasonic horn type operating at 20kHz with a power rating of 270W. The effect of different operating parameters such as operating pH, temperature and power density on the extent of degradation has been investigated initially followed by intensification studies using additives such as hydrogen peroxide, Fenton’s reagent and CCl4. It has been observed that low frequency sonochemical reactors can be effectively used for treatment of pesticide wastewaters and acidic conditions and optimum values of temperature and power dissipation favors the degradation of dichlorvos. The efficacy of sonochemical reactors can be further enhanced by using different additives at optimized loadings. Complete removal of the pesticide at the given loading has been obtained using an optimized combination of ultrasound and Fenton’s chemistry. The controlling mechanism for the sonochemical degradation has been confirmed to be the free radical attack based on the studies involving radical scavengers. The novelty of the present work is clearly established as there have been no earlier studies dealing with degradation of dichlorvos pesticide using sonochemical reactors operating at low frequency which offers distinct advantage in terms of cost and the stability of the reactor.

Degradation of dichlorvos using hydrodynamic cavitation based treatment strategies

The degradation of an aqueous solution of dichlorvos, a commonly used pesticide in India, has been systematically investigated using hydrodynamic cavitation reactor. All the experiments have been carried out using a 20 ppm solution of commercially available dichlorvos. The effect of important operating parameters such as inlet pressure (over a range 3–6 bar), temperature (31 °C, 36 °C and 39 °C) and pH (natural pH = 5.7 and acidic pH = 3) on the extent of degradation has been investigated initially. It has been observed that an optimum value of pressure gives maximum degradation whereas low temperature and pH of 3 are favorable. Intensification studies have been carried out using different additives such as hydrogen peroxide, carbon tetrachloride, and Fenton’s reagent. Use of hydrogen peroxide and carbon tetrachloride resulted in the enhancement of the extent of degradation at optimized conditions but significant enhancement was obtained with the combined use of hydrodynamic cavitation and Fenton’s chemistry. The maximum extent of degradation as obtained by using a combination of hydrodynamic cavitation and Fenton’s chemistry was 91.5% in 1 h of treatment time. The present work has conclusively established that hydrodynamic cavitation in combination with Fenton’s chemistry can be effectively used for the degradation of dichlorvos.

Kinetics and mechanism for degradation of dichlorvos by permanganate in drinking water treatment

The degradation kinetics and mechanism of dichlorvos by permanganate during drinking water treatment were investigated. The reaction of dichlorvos with permanganate was of second-order overall with negligible pH dependence and an activation energy of 29.5 kJ·mol −1. At pH 7.0 and 25 °C, the rate constant was 25.2 ± 0.4 M −1 s −1. Dichlorvos was first degraded to trimethyl phosphate (TMP) and dimethyl phosphate (DMP) simultaneously which approximately accounted for <5% and ≥95% with respect to phosphorus mass, respectively. Further oxidation of DMP generated a final byproduct, monomethyl phosphate (MMP). MMP was for the first time identified as a major byproduct in chemical oxidation of dichlorvos. The kinetic model based on degradation mechanism and determined reaction rate constants allowed us to predict the evolution of dichlorvos and its byproduct concentrations during permanganate pre-oxidation process at water treatment plants. These results suggest that even though the dichlorvos concentration in surface water complies with the surface water quality standards of China (50 μg L −1), its concentration after conventional water treatment will most probably exceed the drinking water quality standards (1 μg L −1). Moreover, luminescent bacteria test shows that the acute toxicity of dichlorvos solution evidently increased after permanganate oxidation.

Removal of mixed pesticides from drinking water system by photodegradation using suspended and immobilized TiO2

Lindane (1α, 2α, 3β, 4α, 5α, 6β-hexachloro cyclohexane), methyl parathion (O,O-dimethyl-O-4-nitrophenyl phosphorothioate) and dichlorvos (2,2-dichlorovinyl-O-O-dimethyl phosphate) are removed from water individually and as a mixture by photo degradation using suspended and immobilized forms of TiO2 (Degussa P-25). Studies were conducted to optimize the coating thickness of immobilized photo catalyst. The rate of degradation of pesticides was compared in both suspended and immobilized TiO2 systems. Degradation studies of mixed pesticides were carried out with low concentrations (1.0 and 2.5 mg/L) of pesticides. Only three intermediate byproducts such as methyl paraoxon, O,O,O-trimethyl phosphonic thionate and p-nitrophenol were observed during the methyl parathion degradation in suspended, immobilized TiO2 systems and mixed pesticides degradation studies. At the end of the reaction methyl parathion and its by-products were completely degraded. During lindane degradation hexachloro cyclohexane, pentachloro cyclohexane, hexachloro benzene, 1-hydroxy 2,3,4,5,6-chlorocyclohexane, 1-hydroxy 2,3,4,5,6-chlorobenzene, pentachloro cyclopentadiene, 1,2,3,4,5-hydroxy cyclopentene and 1,2,3-hydroxy cyclobutane were identified in suspended and immobilized TiO2 systems, whereas only hexachloro cyclohexane, pentachloro cyclohexane, hexachloro benzene and pentachloro cyclopentadiene were observed during mixed pesticides degradation. No intermediate by-product was observed during the photo degradation of dichlorvos. Langmuir-Hinshelwood pseudo first order kinetic equation showed that there was not much change in the rates of degradation in both suspended and immobilized TiO2 systems irrespective of the pesticide. During mixed pesticides degradation, the degradation pattern was not similar to that of single pesticide.

The photocatalytic degradation of dichlorvos under solar irradiation

The photocatalytic degradation of the organophosphorous pesticide dichlorvos (DDVP) in suspended TiO 2 was studied under solar irradiation. It is completely oxidized following a pseudo-first-order kinetic with a characteristic half-life time t 1/2. The mineralization product formation followed the same kinetic order, Cl − ion being totally released, whereas PO 4 3− only partially, due to formation of phosphate organic stable intermediates. Starting from various initial DDVP concentrations we used Langmuir–Hinshelwood equation to calculate K ad the adsorption–desorption equilibrium constant, k r the rate of the oxidation reaction and t 1 / 2 * the corresponding half-life time. The variation of t 1 / 2 * and t 1/2 versus DDVP concentration suggests that there is no competition between the parent pollutant and its oxidation byproducts for the OH radical consumption. The addition of low concentration of H 2O 2 enhanced the oxidation effect on DDVP degradation.

Kinetics and Mechanism of Degradation of Dichlorvos in Aqueous Solutions Containing Reduced Sulfur Species

Reactions of dichlorvos with five reduced sulfur species (hydrogen sulfide, bisulfide, thiosulfate, thiophenol, and thiophenolate) were examined in well-defined anoxic aqueous solutions to investigate their role in its degradation. Reactions were monitored at varying concentrations of reduced sulfur species over pH range to obtain the second-order reaction rate constants. Experiments at 25 degrees C demonstrated that degradation of dichlorvos promoted by bisufide, thiosulfate, and thiophenolate were of much greater importance than hydrolysis under the experimental conditions in our study. In contrast, hydrogen sulfide and thiophenol were not effective in the degradation of dichlorvos. The activation parameters of the reaction of dichlorvos with bisulfide, thiosulfate, and thiophenolate were also determined from the measured second-order rate constants over a temperature range of 12-50 degrees C. The relative reactivity of the reduced sulfur species decreases in the following order: PhS- > HS- approximately equal to S2O3(2-). When the second-order rate constants at 25 degrees C are multiplied by the environmentally relevant concentration of the reduced sulfur species, predicted half-lives of dichlorvos ranged from hours to days. The results indicated that reduced sulfur species could play a very important role in the chemical fate of dichlorvos in coastal marine environments.

Isolation and Characterization of a Dichlorvos-Degrading Strain DDV-1 of Ochrobactrum sp.

ABSTRACT The objective of this research was to isolate a dichlorvos (2,2-dichlorovinyl dimethyl phosphate)-degrading strain of Ochrobactrum sp., and determine its effectiveness in remediation of a dichlorvos-contaminated soil. A dichlorvos-degrading bacterium (strain DDV-1) was successfully isolated and identified as an Ochrobactrum sp. based on its 16S rDNA sequence analysis. Strain DDV-1 was able to utilize dichlorvos as a sole carbon source, and the optimal pH and temperature for its cell growth and degradation were 7.0 and 30 °C, respectively. Also, the growth and degradation of strain DDV-1 showed the same response to dissolved oxygen. In addition, the soil degradation test indicated that in soil spiked with 100 mg L−1 or 500 mg L−1 dichlorvos and inoculated with 0.5% or 1.0% (v/v) strain DDV-1, complete degradation of dichlorvos could be achieved in 24 h. The present study showed that strain DDV-1 was a fast dichlorvos-degrading bacterium in soil. However, further research will be needed to clarify the degradation pathway and the properties of the key enzymes involved in its biodegradation.