Removal Of Diazinon Research Articles

Degradation of organophosphorus pesticide diazinon using activated persulfate: Optimization of operational parameters and comparative study by Taguchi's method

The degradation of organophosphorus insecticide diazinon as the major concern of the present study was scrutinized. Advanced oxidation processes (AOPs) as a dominant route to degradation was considered. Also, to create the robust hydroxyl radicals for decontamination, sodium persulfate was used. Activation of persulfate was utilized both thermally and by UV light. UV-LEDs were applied instead of conventional UV lamps. Besides, use of periodic-based irradiation showed that more energy-saving itinerary could be provided utilizing UV-LEDs. In ruin procedures, the effect of individual and collaborative factors such as temperature, time, UV light intensity, oxidant and diazinon concentration was investigated. Furthermore, to optimize influential parameters, the Taguchi method was practiced. As a result, temperature has been shown to be the most effectual factor by 82.99% contribution. It was also found that the sum of the diazinon was efficiently reduced by the UV/thermal/S2O82- process. The most important mechanistic aspect of diazinon removal was also found to be a substitution reaction of sulfur by oxygen to form diazoxon through oxidation.

Evaluation of Diazinon Adsorption from Water Solutions Using Magnetic Carbon Nano-Tubes with Fe3O4

Background and objective: Insecticides are one of the most important pollutants in water. Diazinon is one of the phosphorus pesticides that can be found in aquatic ecosystems in Iran. The toxic effect of diazinon is inhibition of the enzyme acetyl cholinesterase (Ache). In this study, MWCNT/ Fe3O4 efficiency was investigated. Materials and Methods: In this study, co-precipitation method was used for the Fe3O4 synthesis on multiwall carbon nanotube. The pH, contact time, adsorbent dose, pollutant concentrations and temperature parameters were investigated. Diazinon was measured by Gas chromatography method. Results: The results showed that the optimum conditions for diazinon removal were pH 6, contact time of 15 minutes, andn adsorption dose of 0.6 g/l. So, the absorption efficiency increases with increasing of temperature and decresing of pollutant concentration. The diazinon adsorption corresponded with Freundlich isotherm (R2> 0.99) more than Langmuir isotherm model (R2> 0.90). Conclusion: The results show that the magnetic carbon nanotubes with Fe3O4 can be suitable adsorbent for diazinon removal from aquatic environment.n

Photocatalytic degradation of diazinon by illuminated WO3 nanopowder

In this study, photocatalytic degradation of diazinon as a model phosphorothioate insecticide by tungsten oxide nanopowder under UV irradiation was investigated. Effect of operational parameters including WO3 dosage, pH, initial diazinon concentration, and organic compounds (humic acid, oxalic acid, phenol, ethylenediaminetetraacetic acid (EDTA)) on the photocatalytic degradation of diazinon was studied. Degradation efficiency of diazinon by WO3/UV process was more effective than WO3-alone and UV-alone. As the nanocatalyst dosage increased, the photocatalytic degradation of the diazinon decreased. Removal efficiency was decreased by increasing pH and initial diazinon concentration. The reaction rate constant (kobs) was decreased from 0.1233 to 0.0001/min, and the value of electrical energy per order (EEo) was increased from 38.93 to 48,000 (kWh/m3) with increasing initial diazinon concentration from 5 to 50 mg/L, respectively. The photocatalytic degradation of diazinon was increased in the presence of oxalic acid and EDTA, while different trend was observed in the presence of phenol and humic acid. Proper photocatalytic activity was observed even after five successive cycles. Finally, UV/WO3 is identified as a promising technique for the removal of diazinon with high efficiency in a short reaction time.

Removal of Diazinon from Aqueous Solutions in Batch Systems Using Cu-modified Sodalite zeolite: An Application of Response Surface Methodology

In this work, perlite was used as a low-cost source of Si and Al in the synthesis of sodalite zeolite using hydrothermal synthesis method. Cu2O nanoparticles were coated on a bed of sodalite zeolite and used as an adsorbent for removal of diazinon from aqueous solutions. To analyze the process, a significant variable .i.e. removal efficiency (%) of diazinon and three dependent parameters as the process responses were examined through a central composite design (CCD) under the response surface methodology (RSM). The optimum conditions included contact time of 23.62 min, an adsorbent amount of 0.22 g and temperature 29.28 oC. The percentage removal of diazinon in batch administrations was 97.24.

Degradation and mineralization of diazinon pesticide in UVC and UVC/TiO2 process

The performance of photolytic and photocatalytic degradation and mineralization of diazinon in water using UVC and UVC/TiO2 process in batch condition was investigated, determining the effects of different parameters. The best pH in removal of diazinon by UVC-Photolysis and UVC/TiO2 process is equal to 5 and optimum amount of catalyst was calculated as 150 mg/L. The results showed that diazionon completely degraded after 30 min at 100 mg/L TiO2 and pH 5. The presence of anionic species promoted the photolysis efficiency to degrade diazinon from 52 to 80%, lowering the UVC/TiO2 ability to degrade and mineralize diazinon from 97 to 62%, on the other hand. Mineralization of diazinon by photocatalyst process proved to be 2.5 times higher than of photolysis. Moreover, the reduction pattern in the photocatalysis and photolysis processes were better described by pseudo-first- and second-order kinetics model with a reaction rate constant of 0.094 and 0.0029, respectively.

Degradation and detoxification of diazinon by sono-Fenton and sono-Fenton-like processes

The degradation of the organophosphorus pesticide diazinon by means of sono-Fenton and sono-Fenton-like systems was investigated in this study. The effects of a combination of transition metals, the concentration of Fenton’s reagent and temperature on diazinon degradation were examined. An initial concentration of 50mgL−1 diazinon was used in this study as a model solution. For the sono-Fenton and sono-Fenton-like experiments, an ultrasonic probe at a frequency of 20kHz was employed. The optimal experimental conditions were determined to be as follows: 20mgL−1 Fe2+, 150mgL−1 H2O2, 25°C and pH3. According to the results, the diazinon removal efficiency after 60min was 98.3%, and the mineralization efficiency was 29.9%. It was also found that the toxicity of the diazinon solution was efficiently reduced by a sono-Fenton process. The most important mechanism of degradation was the substitution of sulfur by oxygen on the PS bond in diazinon through oxidation.

Adsorptive removal of diazinon: kinetic and equilibrium study

The adsorption of diazinon on bentonite acid treated with dilute H2SO4 solutions has been studied. Bentonite activated with 0.06 N sulfuric acid showed a higher efficiency in removing diazinon from aqueous solutions and was selected for further investigation. The effect of initial diazinon concentration, contact time, pH, and adsorbent dosage on the adsorption was studied in a batch mode process. Equilibrium data were analyzed by the Langmuir, Freundlich, Temkin, and Dubinin–Radushkevitch isotherm models. Langmuir isotherm provided the best fit to the equilibrium data with maximum adsorption capacity of 5.56 mg/g. The kinetic data were found to follow closely the pseudo-second-order model. The sorption process was found to be controlled by both film and pore diffusion with film diffusion at the earlier stages followed by pore diffusion at the later stages. Thermodynamics studies revealed the spontaneous and exothermic nature of the sorption process.

Photocatalytic degradation and mineralization of diazinon in aqueous solution using nano-TiO2(Degussa, P25): kinetic and statistical analysis

In this study, photocatalytic degradation of diazinon was investigated using nano-TiO2, Degussa P25, as a photocatalyst and the effects of some operational parameters such as aeration, pH, photocatalyst concentration, and the irradiation time were also examined. Dispersive liquid-liquid microextraction technique was used to extract and pre-concentration of residual diazinon from the liquid samples and all experiments were carried out by gas chromatography. Amount of degradation and mineralization were determined by gas chromatograph with flame ionization detector (GC/FID) and COD measurements, respectively. The optimum condition for degradation of diazinon has been obtained in the pH 6, [nano-TiO2] = 0.2 g/L, and [time] = 120 min. In the optimal condition the removal efficiency of diazinon and COD were 99.64 and 65%, respectively. The results have shown that the nano-TiO2, aeration and time of reaction have a positive effect on photocatalytic degradation of diazinon and COD removal. Statistical analysis showed that the maximum removal of diazinon and COD were due to UV irradiation (71%, 41%), exposure time (16%, 39%), aeration (7%, 4%), and increased concentration of nano-TiO2 (0.4%, 2%), respectively; and the kinetics of photodegradation were found to follow a first-order kinetic model and the constant rate, at optimal condition, was 0.038 (min−1).

Removal of Diazinon from aqueous solution by electrocoagulation process using aluminum electrodes

Electrocoagulation (EC) is an electrochemical method to treat polluted wastewaters and aqueous solutions. In this paper, the removal of Diazinon was studied by EC on aluminum electrode. The effect of several parameters such as initial concentration of Diazinon, current density, solution conductivity, effect of pH, and electrolysis time were investigated on EC performance. The obtained results showed that the removal efficiency of EC depends on the current density, initial concentration of Diazinon and electrolysis time. The optimum pH is 3 and also the solution conductivity has no significant effect on removal efficiency.

Remediation of contaminated water from nitrate and diazinon by nanofiltration process

Nitrate and diazinon pesticide is among the environmental challenges which enter water resources, mostly as a result of agricultural activities. In this study, the effects of diazinon concentration, nitrate concentration and pH on the efficiency of simultaneous removal of contaminants from polluted water were investigated, applying a commercial polyamide nanofilter. Each factor was considered in three levels where diazinon concentration, nitrate concentration and solution pH were in the range of 10–1,000 μg/L, 40–160 mg/L and 5–9, respectively. The experiments were conducted at constant pressure of 6 bar. The response surface method was adopted in the experimental design to obtain the impact of mentioned factors. It was found that increasing diazinon concentration and pH enhance the pesticide removal efficiency up to 94%, while increasing nitrate concentration increases the commercial nanofilter efficiency from 80 to 85%. The diazinon removal percentage at optimum condition was estimated to be about 93% at diazinon concentration of about 90 μg/L, nitrate concentration of about 80 mg/L and pH of 9.

Removal of the insecticide diazinon from liquid media by free and immobilized Streptomyces sp. isolated from agricultural soil

From an agricultural soil that had received continuous applications of organophosphorus pesticides, 30 actinobacteria strains were isolated. Two strains, identified as Streptomyces sp. AC1-6 and Streptomyces sp. ISP4, were selected because of their tolerance to diazinon and based on the relationship between diazinon removal and microbial growth. In liquid medium with diazinon at concentrations of 25 and 50 mg L(-1), both strains were able to remove approximately 40-50% and 70-90% of the initial diazinon after 24 and 96 h of incubation, respectively. This diazinon removal was accompanied by microbial growth of the strains, an initial pH decrease, and glucose consumption in the liquid medium. Evaluation of the diazinon removal achieved by the free actinobacteria and Streptomyces sp. AC1-6 immobilized on alginate beads revealed that the immobilized cells exhibited a 60% higher diazinon removal compared with the free cells. The reusability of the encapsulated biomass was confirmed, and a diazinon removal rate of more than 50% was obtained after the second batch. This work constitutes one of the few reports that describe Streptomyces strains as diazinon degraders. Given the high diazinon removal found, the streptomycetes exhibit suitable potential as diazinon-degrading actinobacteria for elimination of diazinon from liquid residues.

Chlorine dioxide treatment for the removal of pesticide residues on fresh lettuce and in aqueous solution

The effectiveness of chlorine dioxide (CD) to remove phorate and diazinon residues on fresh lettuce and in aqueous solution was investigated. The results indicated that CD (20 mg/L) added in tap water can significantly improve the removal of phorate and diazinon on lettuce (p < 0.05), as compared to tap water wash. The study in aqueous solutions suggested that addition of CD could increase the removal rates of phorate and diazinon by 40–80% and 10–20% more than that in tap water without CD, respectively, indicating CD can result in the degradation of the both pesticides. The removal of the both pesticides in aqueous solutions was influenced by concentration of CD, pH value, treatment time, initial concentration and kind of pesticides. The degradation efficiency increased with the concentration of CD and treatment time, and the least removal rates of the both pesticides were obtained in the aqueous solution at pH 4.6. Furthermore, the lower initial concentration of pesticides, the higher degradation rate would be obtained. The degradation kinetics of both pesticides were fitted to the first-order kinetics model well, and the kinetics parameters indicated that phorate was much easier to be degraded than diazinon. The degradation products of both pesticides were identified by GC–MS, phorate and diazinon were oxidized to phorate sulfoxide and phoratoxon sulfoxide, diazoxon, respectively. The present study validates the application of CD treatment as a safe and promising method for the removal of pesticides on fresh fruits and vegetables.

Removal of diazinon and 2,4-dichlorophenoxyacetic acid (2,4-D) from aqueous solutions by granular-activated carbon

In this paper, batch removal of diazinon and 2,4-dichlorophenoxyacetic acid (2,4-D) from aqueous solution by granular-activated carbon was investigated. The required concentrations of toxins were prepared by appropriate dilution of the stock standard solution. There was a significant relationship between chemical oxygen demand (COD) and toxins concentration and that COD was measured instead of direct analysis of toxins. For all the concentrations tested, removal efficiency increased by increasing contact time for both toxins. The highest removal efficiency of 90% for 2,4-D and 88% for diazinon obtained in 50-min contact time. The highest value of toxin removal for both toxins occurred at pH=6. Based on the results obtained, one can conclude that granular-activated carbon has high efficiency in 2,4-D and diazinon removal from aqueous solution.

The Role of Naturally Occurring River Biofilms on the Degradation Kinetics of Diazinon

AbstractRiver biofilms are dominant riverine biota with diverse microorganisms. They have been found to contribute greatly to river self‐purification for removal of nutrients and organic matter. This study intended to investigate the ability of naturally occurring river biofilms with changing seasons for the removal of the organophosphorus pesticide diazinon. Natural river biofilms from spring showed higher ability to remove diazinon (99.9% removal) than those from winter (77%) with light exposure. In contrast to control sets without biofilms under irradiation, 27% of diazinon removal in spring and 22% in winter may result from microbial activity within biofilms. Removal of diazinon by river biofilms could be attributed mostly to degradation due to low sorption capacity of biofilms. Spring biofilms had higher dissipation rates (0.265 and 0.486 d−1 for biofilms with different growth periods) than winter ones (0.099 and 0.119 d−1) according to first order model. Higher ability of diazinon removal by spring biofilms may be explained by their higher bacterial and algal biomass comparing to winter biofilms. Naturally occurring river biofilms played a significant role in degradation of diazinon, particularly for those grown in spring. Their potential for use in the treatment of diazinon‐contaminated water has been demonstrated.

Removal of diazinon by various advanced oxidation processes

AbstractDiazinon is a widely used organophosphorus insecticide that is an important pollutant in aquatic environments. The chemical removal of diazinon has been studied using UV radiation, ozone, Fenton's reagent, UV radiation plus hydrogen peroxide, ozone plus hydrogen peroxide and photo‐Fenton as oxidation processes. In the photodegradation process the observed quantum yields had values ranging between 2.42 × 10−2 and 6.36 × 10−2 mol E−1. Similarly, the ozonation reaction gave values for the rate constant ranging between 0.100 and 0.193 min−1. In the combined systems UV/H2O2 and O3/H2O2 the partial contributions to the global oxidation reaction of the direct and radical pathways were deduced. In the Fenton's reagent and photo‐Fenton systems, the mechanism of reaction has been partially discussed, and the predominant role of the radical pathway pointed out. Additionally, the rate constant for the reaction between diazinon and the hydroxyl radicals was determined, with the value 8.4 × 109 L mol−1 s−1 obtained. A comparison of the different oxidation systems tested under the same operating conditions revealed that UV radiation alone had a moderate oxidation efficiency, which is enhanced in the case of ozone, while the most efficient oxidant is the photo‐Fenton system. Copyright © 2007 Society of Chemical Industry

Efficacy evaluation of low-concentration of ozonated water in removal of residual diazinon, parathion, methyl-parathion and cypermethrin on vegetable

The present study investigated the degradation of four pesticides by low-concentration of dissolved ozone in order to establish the effect of operational parameters. The results indicated that dissolved ozone (initial concentration of 1.4 mg/l) was effective to oxidize 60–99% of 0.1 mg/l aqueous diazinon, parathion, methyl-parathion and cypermethrin shortly within 30 min. The feasibilities of applying low dissolved levels of ozone in water (1.4–2.0 mg/l) to remove the target pesticides residing on vegetable surface ( Brassica rapa) were studied. Ozonated water was mostly effective in cypermethrin removal (>60%). The efficacy highly depended on the dissolved ozone levels. Higher temperature enhanced the efficacy in pesticide removal; however, the solubility of ozone in water is inversely proportional to temperature. The maximal efficacy for diazinon removal was detected to be at 15–20 °C. Major limitation factors for residual pesticide removal are temperature, concentration of ozone gas applied and concentration of dissolved ozone established.

Field and laboratory study of pesticide leaching in a Motupiko silt loam (Nelson) and in a Waikiwi silt loam (Southland)

Selected pesticides were applied to a Motupiko silt loam located near Wakefield, Nelson, and a Waikiwi silt loam located near Invercargill, Southland, New Zealand, along with bromide as a tracer. Atrazine, bromacil, diazinon, hexazinone, and terbuthylazine were applied to both sites, with procymidone also being applied to the Nelson site, and trifluralin being applied to the Southland site. The persistence and transport behaviour of these compounds were monitored for 15 months using a combination of soil sampling down to a maximum of 1 m and 8 suction cups at each site located between 0.2 and 1.3 m down the profile. The bromide tracer had moved below 0.8 m within 9 months at the Nelson site and below 1.0 m within 12 months at the Southland site. Hexazinone was the most mobile of the pesticides, followed by bromacil at both sites. Diazinon and atrazine dissipated rapidly at both sites, while trifluralin and, to a lesser extent, terbuthylazine and bromacil data indicated some volatilisation losses. The diazinon removal was probably a combination of degradation and volatilisation. There was evidence of some preferential flow at the Southland site, as rainfall was heavy at the time of pesticide application. The Koc values from the sorption isotherms were generally similar to literature values for the Waikiwi soil but were much higher for the Motupiko soil. The exception was diazinon, for which the Koc values were much lower than the literature values for both sites.

Changes in diazinon concentrations during shower and plunge dipping of Merino sheep

The rate of removal of diazinon from solution (stripping) during dipping of adult short wool Merino sheep was similar in a standard and modified Buzacott 60R shower dip. During 12 min showering, dip concentration fell from about 100 mg/L to about 20 mg/L. Addition of insecticide concentrate (reinforcement) and sufficient fresh solution to re-establish original sump volume (topping up or replenishment) at this point restored dip concentration but was contrary to product label instructions. Adherence to the label directions to reinforce and top up after the sump was depleted by 25% (after 2 pens of sheep in the case of the standard dip) caused dip concentration to drop below the limit of quantification (10 mg/L). Similarly, current directions for continuous replenishment (commonly referred to as constant replenishment) shower dipping failed to offset diazinon stripping. Continuous replenishment plunge dipping with diazinon for the control of lice on sheep is an off-label use of the product; however, we demonstrated that a working concentration of about 100 mg diazinon /L (the nominal rate for lice control) was maintained in a 5000 L non-draining dip if charged and replenished at 200 mg diazinon/L. By maintaining 100 mg/L, this regimen was more likely to eradicate lice from sheep. This work also identified, by calculation, large and potentially significant variations in the dose of diazinon applied per sheep due to the application method, reinforcement practice and whether the sheep were treated early or late in the dipping sequence.