Initial Diazinon Concentration Research Articles

Removal of diazinon from aqueous solutions using 3D electrochemical system including a nanocomposite of microbial cellulose/nanomagnetite

In this study, with the aim of improving of the diazinon removal efficiency, a 3D electrochemical system was provided including microbial cellulose/Fe3O4 (MC/Fe3O4) nanocomposite. The MC/Fe3O4 nanocomposite was utilized for the activation of persulfate (PS) in the diazinon decomposition process. The characterization of the MC/Fe3O4 nanocomposite was determined by FE-SEM, FT-IR, XRD and TGA analysis. The operating variables including initial pH, NaCl concentration, PS concentration, initial diazinon concentration, current density and time were investigated. The proposed 3D electrochemical system in the optimal conditions of 10 mg/L initial diazinon concentration, pH 3, 0.2 g/L NaCl, 0.07 mmol/L PS, 3.54 mA/cm2 current density and energy consumption of 12.61 kWh/m3 during 60 min reached to the complete removal of diazinon and 84.4 % TOC removal. According to the obtained results, the MC/Fe3O4 nanocomposite has the high efficiency of diazinon and TOC removal, as well as the consumption of NaCl, PS and lower energy in a shorter period of time compared to general electrochemical processes. Therefore, the reactions provide not only on the surface of the main electrodes but also on the surface of the particle electrode. It can improve the performance of electroabsorption and electrocatalysis in the chemical electrooxidation system.

Removal of diazinon from aqueous solutions using alternating current in a three-dimensional electrochemical system containing MC/Fe3O4 nanocomposites

This study aims to determine diazinon removal using a three-dimensional electrochemical system supplied with alternating current (AC), which uses Fe3O4 magnetite nanoparticles immobilized on microbial cellulose (MC). The nanocomposites are used as catalysts to activate persulfate and produce sulfate radicals for diazinon removal. The surface properties and morphology of MC/Fe3O4 nanocomposites were determined by Fourier Transform Infrared Spectroscopy (FT-IR), Field Emission Scanning Electron Microscopes (FE-SEM), Thermo-Gravimetric Analysis (TGA), and X-Ray Diffraction (XRD) techniques. The studied variables were initial pH (3–9), diazinon concentration (10–40 mg/l), persulfate concentration (0.5–0.8 mmol/l), Na2SO4 concentration (0.1–0.7), MC/Fe3O4 nanocomposite concentration (01–0.3 g/l), voltage (1–7 V), and time (0−60). The obtained results indicated that the 3D electrochemical system could lead to complete removal in the presence of the MC/Fe3O4 catalyst in optimal conditions (10 mg/l initial diazinon concentration, 0.5 g/l Na2SO4, pH of 3 ± 0.5, 0.7 mmol/l PS, 0.25 g/l MC/Fe3O4, and 5 V AC) during 60 min. The energy consumption in this system was calculated 0.35 KW h/m3. The role of each process involved in diazinon removal and the reaction kinetics were also provided in this study.

Mineralization of diazinon by low-cost CuO-Kaolin nanocomposite under visible light based RSM methodology: Kinetics, cost analysis, reaction pathway and bioassay

A convenient and low-cost co-precipitation method was utilized for stabilization of CuO nanoparticles on Kaolin. The prepared CuO-Kaolin was characterized by XRD, FT-IR, SEM, EDX and pHPZC techniques. In this empirical study, response surface methodology (RSM) based central composite design (CCD) was applied for optimization of operational factors in the photocatalytic removal of Diazinon (DZ). Under optimum conditions, i.e. initial pH=7, initial DZ concentration=30 mg L-1, photocatalyst amount=0.4g L-1 and in the presence of oxalic acid, folic acid and sodium carbonate=5 mg L-1, about 87.23 % DZ removal was achieved by CuO-Kaolin after 180 min of reaction. The ANOVA results of the polynomial model prove that the model is quite meaningful (F-value> 0.001 and P-value< 0.0001). Further, estimated electrical energy per order consumption (EEO) for visible light (VIS)/CuO-Kaolin system was calculated as 213.66 kWh m−3 with operational cost (OC) utilization of 52.053 USD kg−1 that was revealed this process is highly feasible and economic comparing with other photocatalytic processes (VIS/CuO, VIS/Kaolin and VIS). Ten cycle experiments confirmed that the CuO-Kaolin propounded a satisfied stability and recycling potency. By applying the OFAT technique, 96.05 % of DZ degradation and 79.19 % of DZ mineralization could be achieved after 180 min. The five main compounds produced during the VIS/CuO-Kaolin embracing 2-isopropyl-6-methyl-4-pyrimidinol (IMP), diethyl phosphonate, diazoxon, hydroxydiazinon, and diazinon methyl ketone are formed in the path of DZ degradation. The results of toxicity in the photocatalytic removal of DZ by D. magna showed LC50 and TU 48 h equal to 18.79 and 5.32 vol percent.

Design and modeling of diazinon degradation in hydrous matrix by Ni-doped ZnO nanorods under ultrasonic irradiation: process optimization using RSM (CCD), kinetic study, reaction pathway, mineralization, and toxicity assessment.

In first, the Ni-doped ZnO nanorods used as an appeal sonocatalyst was synthesized through co-precipitation method. Afterwards, the crystalline structure, functional groups, surface morphology, and elemental composition were characterized by a set of analysis. Removal of diazinon ((DZ) as a renowned pesticide) was investigated using sonocatalytic performance of US/Ni-doped ZnO system. In this empirical study, response surface methodology (RSM) based central composite design (CCD) was applied for optimization of operational factors. Under the optimum conditions such as initial pH = 5, initial DZ concentration = 15mg L-1, sonocatalyst dosage = 1g L-1, and in the presence of organic compounds (oxalic acid, humic acid, and folic acid) = 3mg L-1, the sonocatalytic degradation of DZ after 15min was 82.29%. The F-value (6.64) and P-value (< 0.0001) for DZ degradation in the quadratic model imply the proposed model was significant. A-factor (pH) considers as a prominent factor owing to having the highest F-value. In addition, the sonocatalytic data in this study exhibited valid fitting for the first order kinetic model (R2 > 0.98). After six consecutive cycles, the Ni-doped ZnO nanorods could be recyclable for sonocatalytic degradation of DZ. The five main compounds produced during the US/Ni-doped ZnO embracing 2-isopropyl-6-methyl-4-pyrimidinol (IMP), diethyl phosphonate, diazoxon, hydroxyldiazinon, and diazinon methyl ketone are formed in the path of DZ degradation. OFAT style also revealed 99.99% of DZ degradation with 73.26% of mineralization rate in optimum status. The Ni-doped ZnO presented agreeable sonocatalytic facility in the refinement of real water and wastewater matrix. Finally, the results of toxicity evaluation (Daphnia magna) in the sonocatalytic degradation of DZ (by US/Ni-doped ZnO system) showed that the toxicity of the DZ solution lessened under US waves (LC50 and TU 48h equal to 36.472 and 2.741 volume percent, respectively).

Experimental and numerical study on diazinon removal using plasma bubble column reactor: Modeling, kinetics, mechanisms, and degradation products

Diazinone is the most commonly used pesticide worldwide. In this study, experimental and numerical analyses were employed to model and optimize the degradation and mineralization of diazinon using remotely generated non-thermal atmospheric pressure plasma. The initial concentration of diazinon, pH of the medium, and flow rate of the plasma feeding gas were considered as the salient factors in the modeling and optimization processes. To our knowledge, this study is the first report on the effects of gas composition and flow rate on the type and concentration of remotely generated reactive nitrogen and oxygen species (RNOS). An air gas composition was adopted as the feeding gas for a custom-made dielectric barrier discharge (DBD) plasma generator. Remotely generated gas plasma was introduced into the reactor through a diffuser located at the bottom of the column reactor, and the degradation of diazinon and its derived products was monitored using GC-MS. The decrease in the total organic carbon (TOC) content of the samples due to plasma treatment was traced using a TOC analyzer. Although 83.11% degradation was observed, the maximum TOC removal using this method was only 39.22%. Subsequently, response surface methodology (RSM) was employed to mathematically model the process and observe the correlations between different parameters. Our results suggested a quadratic model for the degradation and TOC removal of the given treatment methods, which further indicated that the initial concentration of the analyte and pH influenced the degradation efficiency. However, the gas flow rate was identified as an important factor in TOC removal. The energy yield of the treatment procedure was 46.2 (gTOCkW−1h−1), suggesting the potential of DBD plasma for the treatment of diazinon-polluted water.

Sonophotocatalytic degradation and operational parameters optimization of diazinon using magnetic cobalt–graphene nanocomposite as a catalyst

Adopting the hydrothermal method, the cobalt ferrite nanocomposite was loaded onto graphene (G–CoFe2O4) and the material thus produced was first characterized and then employed as a sonophotocatalyst to assist in the degradation of diazinon (DZN) at different operational parameters. Further, response surface methodology was used for the optimization and modeling of the operational parameters. From the statistical analysis of the analysis of variance (ANOVA), the quadratic model was observed to give a good fit with the experimental data, barring the catalyst dose (P value = 0.194) and the initial concentration of DZN (P value = 0.20), significantly affected the efficiency of the DZN degradation. Complete DZN degradation was achieved under the conditions of pH 3, time 100 min, DZN concentration 10 mg/L, temperature 50 °C, and the G–CoFe2O4 dose of 0.99 g/L. Reduction in the DZN degradation rate was observed, falling below 10% during the eight consecutive cycles, giving proof of the stability and adequate recyclability of the G–CoFe2O4. Biodegradability related to the five–day biochemical oxygen demand/chemical oxygen demand (BOD5/COD) ratio increased from 0.15 to 0.58, with the corresponding 90.95% total organic carbon (TOC) and 96.41% COD being removed. The toxicity evaluated using the inhibition growth rate of Escherichia coli (E. coli) showed high ability of the suggested treatment system to lower the toxicity, when compared to photocatalysis and photolysis. On using the analytical methods, the presence of the mineral ions such as NH4+, NO3−, SO42−, and PO43− appeared to act as good indicators of mineralization.

Novel catalytic degradation of Diazinon with ozonation/mg-Al layered double hydroxides: optimization, modeling, and dispersive liquid-liquid microextraction.

In this study MgAl- layered double hydroxides (MgAl-LDH) nanoparticles were prepared by a simple and fast co-precipitation method and used as a catalyst in the ozonation process to degrade diazinon from aqueous solutions. The structure of the synthesized MgAl-LDH was investigated by X-ray diffraction pattern (XRD) and field emission scanning electron microscope-energy dispersive spectroscopy (FESEM-EDX). The response surface methodology (RSM) was used to investigate the effects of different parameters including of reaction time, initial diazinon concentration, pH, and LDH dose on the removal of diazinon by MgAl-LDH catalytic ozonation process. Central Composite Design (CCD) was employed for the optimization and modeling of the process. Dispersive liquid-liquid microextraction (DLLME) method was used to extract diazinon from aqueous samples. The GC-Mass analysis was performed to determine intermediate compounds during diazinon degradation reactions. To evaluate the process performance, TOC and COD removal were measured under optimum conditions. The highest removal efficiency of 92% was observed in optimum conditions as follow; initial diazinon concentration: 120mg/L, pH: 8.25, LDH dose: 750mg/L, and reaction time: 70min. The quadratic model was obtained with a good fit. The removal of COD and TOC were 80% and 74%, respectively. This process can be suggested and used in the treatment of various industrial wastewaters. The online version contains supplementary material available at 10.1007/s40201-021-00687-w.

Photocatalytic Degradation of Diazinon with a 2D/3D Nanocomposite of Black Phosphorus/Metal Organic Framework

Metal–organic frameworks (MOFs) are promising materials for the removal and photodegradation of pesticides in water. Characteristics such as large surface area, crystalline structure and catalytic properties give MOFs an advantage over other traditional adsorbents. The application of MOFs in environmental remediation is hindered by their ability to only absorb in the UV region. Therefore, combining them with an excellent charge carrier 2D material such as black phosphorus (BP) provides an attractive composite for visible-light-driven degradation of pesticides. In the study, a nanocomposite of black phosphorus and MIL-125(Ti), defined as BpMIL, was prepared using a two-stage hydrothermal and sonication route. The as-prepared composite was characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS) and photoluminescence (PL) spectroscopy. These techniques revealed that the circular and sheet-like morphology of the nanocomposites had minimum charge recombination, allowing them to be effective photocatalysts. Furthermore, the photocatalysts exhibited extended productive utilization of the solar spectrum with inhibited recombination rate and could be applied in visible-light-driven water treatment. The photodegradation of diazinon in water was studied using a series of BpMIL (4%, 6% and 12% by mass) nanocomposites as a photocatalyst. The optimal composite was determined to be 4%BpMIL. The degradation parameters were optimized and these included photocatalyst dosage, initial diazinon concentration and pH of the solution. The optimal conditions for the removal and degradation of diazinon were: neutral pH, [diazinon] = 20 mg/L, photocatalyst dosage = 0.5 g/L, achieving 96% removal of the pesticide after 30 min with 4%BpMIL, while MIL-125(Ti) showed 40% removal. The improved photodegradation efficiency of the 4%BpMIL composite was attributed to Ti3+-Ti4+ intervalence electron transfer and the synergistic effect between MIL-125(Ti) and BP. The photodegradation followed pseudo-first-order kinetics with a rate constant of 1.6 × 10−2 min−1.

Equilibrium, kinetic and thermodynamic study of diazinon adsorption from water by clay/GO/Fe3O4: Modeling and optimization based on response surface methodology and artificial neural network

In this study, a new magnetic composite consisted of clay/graphene oxide/Fe3O4 was used for elimination of Diazinon (pesticide) from aqueous solutions. Analysis of the structural properties and surface morphology of the composite showed that the composite was well-synthesized and had a crystalline and multilayere structure. Magnetic saturation value was determined to be 39.9 emu/g. Its pHZPC value and active surface area was 7.1 and 185.7m2/g, respectively.In order to investigate the effects of pH, temperature, contact time, initial concentration of Diazinon and composite dosage on adsorption efficiency and modeling adsorption process, the response surface methodology-central composite design (RSM-CCD) and artificial neural network methods (ANN) were used. The results obtained through analysis using response surface methodology showed that the maximum amount of adsorption was 98.79% at 25.91 °C, while pH, initial concentration, contact time, and adsorbent dose were 6.9, 1.2 ppm, 24.6 min, and 1.1 g/L, respectively. Comparison between results obtained from CCD modeling and artificial neural network proved that both methods had high ability to predict the adsorption process but the CCD method had higher coefficient of determination and lower error. The equilibrium and kinetic study of the process showed that the Langmuir-Freundlich isotherm model, pseudo-second-order, and Elovich kinetics are all suitable for expressing the adsorption process. In addition, the adsorption mechanism obeyed double-exponential model that combines external and internal diffusions.Results of thermodynamic study suggested that the Diazinon adsorption on clay/GO/Fe3O4 was a spontaneous and exothermic process. The results of the equilibrium process study revealed that the adsorption process was physical and desirable. Therefore, the adsorption-desorption process was performed which showed that the composite was reusable up to 20 cycles.

High effective removal of diazinon from aqueous solutions using the magnetic tragacanth-montmorillonite nanocomposite: isotherm, kinetic, and mechanism study.

Health and environmental impact of pesticide contamination of groundwater has been reported repeatedly in many studies. The removal of diazinon from agricultural wastewater is still of great interest due to using widely in many developing countries. In the presented study, the magnetic tragacanth-montmorillonite nanocomposite was utilized as an adsorbent to remove diazinon from an aqueous solution. The adsorbent properties were characterized using FE-SEM, EDX, FTIR, XRD, BET, and VSM techniques. The influence of adsorbent dosage, pH, contact time, and initial concentration of diazinon was studied in a batch system. Different adsorption kinetics and isotherm models were used to describe the kinetic and equilibrium data. The results indicated that the adsorption kinetic was fitted better with a Elovich kinetic model, and the adsorption isotherm was well described by the Langmuir-Freundlich model, and the maximum adsorption capacity was 416mgg-1. According to Weber and Morris's model and Boyd plot, the results demonstrated that the adsorption kinetic was controlled simultaneously by film diffusion and intraparticle diffusion. Besides, a thermodynamic study showed that the removal of diazinon is an endothermic process. Considering the results, magnetic tragacanth-montmorillonite nanoadsorbent has a high capability to remove diazinon from aqueous solution.

PANI/g-C3N4/CeO2 Nanocomposite for Photodegradation of Diazinon in Aqueous Solution

Diazinon is one of organophosphate pesticides which it is classified as a relatively dangerous substance (Class II by WHO). The PANI/g C3N4/ CeO2 nanocomposite was synthesized by in situ polymerization method to determine the efficiency of photocatalytic degradation of diazinon. The photocatalytic activities efficiencies of the supported and unsupported nanocomposites were evaluated using diazinon as a model pollutant. The superior photocatalytic effect of the PANI/g C3N4/CeO2 nanocomposite is attributed to the synergistic effect of PANI and g C3N4/CeO2 which promotes migration efficiency of the photogenerated carriers on the g C3N4/CeO2 nanocomposite interface. The effects of pH, initial diazinon concentration, catalyst load, hydrogen peroxide as well as effect of other organic compound were investigated using photocatalytic degradation of PANI/g C3N4/CeO2. The results obtained indicate the efficient degradation at pH= 6 which extent to 94.08 %, at 10 ppm extent to 88.9%, at 0.1 g/L extent to 97.48 %; were as increasing the concentration of hydrogen peroxide, the percent of degradation of diazinon increased due to the increased reaction between hydrogen peroxide and electron in the conduction band of PANI/g-C3N4/CeO2. Hydrogen peroxide can effectively inhibited electron hole recombination. Therefore hydrogen peroxide is better electron acceptor than dissolved oxygen; it acts as an alternative electron acceptor to oxygen. The effect of different organic compound on the photocatalytic degradation of diazinon; organic compound such as phenol, citric acid, EDTA and oxalic acid were examined, the result indicated that photocatalytic degradation was negatively affected in the presence of all organic compounds.

Organophosphorus Diazinon Pesticide Removing from Aqueous Solution by Zero-Valent Iron Supported on Biopolymer Chitosan: RSM Optimization Methodology

In this study, chitosan/zero-valent iron nanoparticle (CS/nZVI) composite was synthesized for the removal of diazinon as an organophosphorus pesticide from aqueous solution. Characterizations of the synthesized composite were identified by the scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), vibrating sample magnetometer (VSM), Brunauer–Emmett–Teller (BET), thermogravimetric analysis (TGA), and differential scanning calorimetric (DSC). The surface area was obtained 90.164 m2 g−1 and 92.142 m2 g−1 by the BET method and Langmuir plot, respectively. The surface area, volume, and pore diameter of CS/nZVI were found 86.923 m2 g−1, 0.1623 cm3 g−1, and 1.85 nm, respectively from the pore size distribution curves using the Barrett–Joyner–Halenda (BJH) formula. The analysis of samples was accomplished with gas chromatography (GC). Response surface methodology (RSM) based on the central composite design (CCD) was applied to design the experiments, and survey the effects of factors on the adsorption efficiency. Analysis of variance (ANOVA) indicated that pH, adsorbent dosage, and initial concentration had a significant influence on the removal performance using the second-order polynomial model. The highest removal percent of the CCD method was equal to 96.95% in the optimum conditions. The effect of experimental variables such as contact time, pH, adsorbent dosage, and initial concentration of diazinon on the removal of diazinon was investigated. Results showed that the contact time of 20 min, pH 4.6, CS/nZVI dosage of 0.05 g, and initial diazinon concentration of 100 mg l−1 were achieved as optimum conditions. In addition, the adsorption data fitted well with the pseudo-second-order kinetic model (R2 = 0.9989) and Freundlich isotherm (R2 = 0.9629). Eventually, the results of diazinon removal from the aqueous real samples revealed the great applicability of CS–nZVI for the removal of diazinon.

Fe3O4@SiO2 magnetic nanocomposites as adsorbents for removal of diazinon from aqueous solution: isotherm and kinetic study

PurposeThe purpose of this study was to the synthesis of Fe3O4@SiO2 nanocomposites and using it as an adsorbent for removal of diazinon from aqueous solutions. Structural characteristics of the synthesized magnetic nanocomposite were described by Fourier transform infrared spectroscopy and scanning electron microscopy.Design/methodology/approachThe effects of different parameters including pH (2-10), contact time (1-180 min), adsorbent dosage (100-2000 mg L−1) and initial diazinon concentration (0.5–20 mg L−1) on the removal processes were studied. Finally, isotherm and kinetic and of adsorption process of diazinon onto Fe3O4@SiO2 nanocomposites were investigated.FindingsThe maximum removal efficiency of diazinon (96%) was found at 180 min with 1000 mg L−1 adsorbent dosage using 0.5 mg L−1 diazinon concentration at pH = 7. The experimental results revealed that data were best fit with the pseudo-second-order kinetic model (R2 = 0.971) and the adsorption capacity was 10.90 mg g−1. The adsorption isotherm was accordant to Langmuir isotherm.Originality/valueIn the present study, the magnetic nanocomposites were synthesized and used as an absorbent for the removal of diazinon. The developed method had advantages such as the good ability of Fe3O4@SiO2 nanocomposites to remove diazinon from aqueous solution and the magnetic separation of this absorbent that make it recoverable nanocomposite. The other advantages of these nanocomposites are rapidity, simplicity and relatively low cost.

Removal of inorganic and organic phosphorus compounds from aqueous solution by ferrihydrite decoration onto graphene.

Existing research on phosphorus removal from wastewater mostly focused on inorganic phosphorus while ignoring organic phosphorus, which has potential bioavailability. This study aims to provide an innovation for the development of advanced treatment material for both inorganic and organic phosphorus removal in water. In this study, ferrihydrite loaded on the graphene oxide (FeOOH-GO) composite adsorbent was synthesized by surface precipitation method, and its ability to remove both phosphate and diazinon as forms of inorganic and organic phosphorous from water was investigated. Characterization of the loaded composite using X-ray diffraction (XRD), scanning electron microscope (SEM), and Fourier transform-infrared spectroscopy (FTIR) indicated that FeOOH was successfully loaded onto graphene. The results of batch adsorption experiments showed that the adsorbent could remove both inorganic and organic phosphorus compounds simultaneously from water. When FeOOH content is 40%, the equilibrium adsorption amount of FeOOH-GO composite adsorbent for phosphate and diazinon was 5.81 and 23.20mgg-1, respectively. Environmental parameters such as pH and initial concentration have important influence on phosphorus removal by FeOOH-GO composite adsorbent and the removal efficiency of the inorganic and organic phosphorus from water decreases by increasing the initial concentration of phosphate and diazinon and the pH. It was concluded that the FeOOH-GO composite adsorbent has great potential to remove both inorganic and organic phosphate simultaneously from contaminated water.

Photocatalytic Degradation of Commercial Diazinon Pesticide Using C,N-codoped TiO&lt;sub&gt;2&lt;/sub&gt; as Photocatalyst

Diazinon (C12H21N2O3PS) is an effective pest controller that has been frequently used by farmers in agriculture. It is a nonspecific and highly toxic pesticide having low persistence in the environment and categorized as moderately hazardous class II. The degradation of commercial diazinon in aqueous solution was investigated by photocatalysis using low-energy activated C,N-codoped TiO2 as catalyst under visible-light. The influence of some parameters, i.e., catalyst concentration, the initial concentration of diazinon, initial pH of diazinon, and irradiation time on the diazinon degradation was studied. The amount of diazinon degradation was strongly influenced by all the above parameters. The results show that titania-modified enhanced the degradation percentage of diazinon, from 44.08% without a catalyst to 86.93% by adding 12 mg C,N-codoped TiO2 catalyst after 30 minutes visible-light irradiation. UV-visible spectrophotometer, HPLC, and COD analysis verified that diazinon was successfully degraded under photocatalysis visible.

Electrochemical degradation of diazinon from aqueous media using graphite anode: Effect of parameters, mineralisation, reaction kinetic, degradation pathway and optimisation using central composite design

ABSTRACT In this study, the experimental data were collected in a laboratory-scale batch reactor equipped with a graphite electrode as anode and an SS316 electrode as a cathode. The central composite design (CCD) was selected for evaluation of the effect of different parameters (j = 1–8 mA/cm2, initial diazinon concentration = 30–90 mg/L, pH = 3–11, and electrolysis time = 30–90 min) and their interactions on the electrochemical degradation of the diazinon. The results showed that the degradation of diazinon and removal of COD reached 87.6% and 77.81%, respectively. The kinetic studies were indicative of the suitability of the pseudo-first-order kinetic (R2 > 0.98) for the explanation of data obtained from the degradation of diazinon and removal of COD on the graphite electrode. The AOS parameters in the outlet effluent of the electrochemical process with graphite anode were increased from −0.73 to +0.58, indicating the biodegradability of the diazinon by the electrochemical system. The intermediate produced during the electro-oxidation process were diazinon, O,O-diethyl O-(4-ethylpyrimidin-2-yl) phosphorothioate, O,O-diethyl O-(pyrimidin-2-yl) phosphorothioate, O-methyl O-(pyrimidin-2-yl) O-hydrogen phosphorothioate, O-(pyrimidin-2-yl) O-hydrogen phosphonothioate, pyrimidin-2-yl hydrogen phosphonate, 1,3-dioxan-2-ol, 1λ3,3 λ3-dioxine, and ethane-1,2-diol. Finally, diazinon was completely degraded using hydroxyl radicals produced by the electrochemical process and converted into CO2 and H2O products.

Purification of diazinon pesticide by sequencing batch moving-bed biofilm reactor after ozonation/Mg-Al layered double hydroxides pre-treated effluent

The catalytic ozonation process (COP) using MgAl-layered double hydroxide (MgAl-LDH) nanoparticles was used as a pre-treatment of the sequencing batch moving-bed biofilm reactor (SBMBBR) to degrade diazinon pesticide from aqueous solutions. The structure of the synthesized MgAl-LDH was investigated by X-ray diffraction pattern (XRD), field-emission scanning electron microscope (FESEM), energy dispersive spectroscopy (EDS) mapping, and Fourier-transform infrared spectra (FTIR). The response surface methodology (RSM) was adopted to optimize the COP variables, including LDH dose (0–1000 mg/L), initial diazinon concentration (50–200 mg/L), initial pH (3–10), and reaction time (10–90 min). Under the optimal conditions, COP effluent was introduced to the SBMBBR for further purification. The dispersive liquid–liquid microextraction (DLLME) method was employed to extract diazinon from aqueous samples. The GC-mass analysis was performed to determine by-products during diazinon degradation reactions. To evaluate system performance, the removal efficiency of chemical oxygen demand (COD), total organic carbon (TOC), and diazinon was compared in processes of aeration, single ozonation process (SOP), COP, SBMBBR, and COP/SBMBBR. The formation of the LDH nanoparticles was confirmed by XRD and EDS mapping analysis. In the COP reactor, under optimal conditions (initial diazinon concentration: 120 mg/L, pH: 8.25, LDH dose: 750 mg/L, and reaction time: 70 min), the removal efficiency of diazinon, COD, and TOC equaled 92, 80, and 74%, respectively. The effluent of COP reactor was treated further in the SBMBBR system with the pH of 6.5–7, hydraulic retention time (HRT) of 24 h, mixed liquor suspended solids attached to bio-carriers (MLSSatt.) of 4500 mg/L, mixed liquor volatile suspended solids attached to bio-carriers (MLVSSatt.) of 3600 mg/L, MLSS of 950 mg/L, and MLVSS of 830 mg/L. The use of COP/SBMBBR resulted in the complete degradation of diazinon pesticide and COD and TOC removal efficiency of 99.37 and 99%, respectively. Therefore, this method can be used for the purification of non-biodegradable industrial wastewater.

The catalytic ozonation of diazinon using nano-MgO@CNT@Gr as a new heterogenous catalyst: the optimization of effective factors by response surface methodology.

In this research, the degradation of the insecticide diazinon was studied using a new hybrid catalyst consisting of magnesium oxide nanoparticles (nano-MgO), carbon nanotubes (CNTs), and graphite (Gr), nano-MgO@CNT@Gr, under various experimental conditions. This study shows the optimization of the nano-MgO@CNT@Gr/O3 process for diazinon degradation in aqueous solutions. Box–Behnken experimental design (BBD) and response surface methodology (RSM) were used to assess and optimize the solo effects and interactions of four variables, pH, catalyst loading, reaction time, and initial diazinon concentration, during the nano-MgO@CNT@Gr/O3 process. Analysis of regression revealed an adequate fit of the experimental results with a quadratic model, with R2 > 0.91. Following the collection of analysis of variance (ANOVA) results, pH, catalyst loading, and reaction time were seen to have significant positive effects, whereas the concentration of diazinon had a considerable negative impact on diazinon removal via catalytic ozonation. The four variables for maximum diazinon removal were found to be optimum (82.43%) at the following levels: reaction time, 15 min; pH, 10; catalyst dosage, 1.5 g L−1; and diazinon concentration, 10 mg L−1. The degradation of diazinon gave six kinds of by-products. The mechanism of diazinon decomposition was considered on the basis of the identified by-products. According to these results, the nano-MgO@CNT@Gr/O3 process could be an applicable technique for the treatment of diazinon-containing wastewater.

Surfactant modified kaolinite (MK-BZK) as an adsorbent for the removal of diazinon from aqueous solutions

This paper presents the adsorption potential of natural kaolinite (NK) and kaolinite modified with benzalkonium chloride (MK-BZK) for the removal of the diazinon pesticide from contaminated water. Batch experiments were carried out with various experimental conditions such as pH (3, 7, and 11), adsorbent dosage (1, 5, and 10 g/L), initial diazinon concentration (5-100 g/L) and contact time (0-40 min). Based on the experimental data, the removal efficiency of MK-BZK was slightly higher (97) than that of NK (93) operating at pH 3 and optimum contact times of 10 and 15 min, respectively. The adsorption rate followed a pseudo-second-order kinetics model and the equilibrium adsorption fitted well the Freundlich adsorption isotherm model. The maximum adsorption capacity of diazinon on NK and MK-BZK was 0.86 and 2.25 mg/g, respectively. Overall, MK-BZK has potential as a local and cost-effective adsorbent to remove diazinon from aqueous solutions.

FIXED-BED COLUMN STUDY OF DIAZINON ADSORPTION ON THE CROSS-LINKED CHITOSAN/CARBON NANOTUBE

Adsorption of diazinon from aqueous solution was studied by using cross-linked Chitosan/Carbon Nanotube (CHN-CNT) in a fixed-bed column. The cross linked CHN-CNT with 2.5% of MWCNT was prepared with a protected crosslinking method. The effects of the initial concentration of diazinon, bed-height, and flow rate on the adsorption of diazinon onto the cross linked CHN-CNT were investigated. The highest bed capacity of 29.47 mg/g was obtained at the initial concentration of 50 mg/L, flow rate of 10.5 mL/min, and fixed bed-height of 4 cm. Three models, namely Bohart Adams, Thomas, and Yoon Nelson, were investigated to predict the breakthrough curves and to determine the characteristic parameters. The experimental data were well fitted with the Yoon Nelson model, indicating that it was suitable for continuous adsorption of diazinon onto cross-linked CHN-CNT in a fixed-bed column. The findings of this study revealed that the cross-linked CHN-CNT not only has a simple synthesis method and good strength but also adsorbs the diazinon well.