Removal Of Methomyl Research Articles

Removal of methomyl in water by leaves-generated biochar: Effect of metallic coating, kinetics, and important role of hydroxyl radical

Methomyl (MET) can exist as fatal water pollutant due to its high leachability, and solubility, which is urgently to be efficiently removed. This work investigated its removal in water by cost-effective biochar; in which, the efficiencies of leaves-generated biochar (BC) as non-modified adsorbent, and copper oxide coated BC (COBC) and hematite (Fe2O3) coated BC (MBC) as modified adsorbents were compared. At initial concentration of 20.0 mg/L in purified water, the respective removals by BC, COBC, and MBC were 21.3 %, 16.4 %, and 18.9 % within 360 min at 0.5 g/L dosage, which were increased to 33.8 %, 18.9 %, and 26.1 % at an increased dosage of 1.0 g/L. However, the removal efficiencies of combined method with non-modified, and the modified adsorbents were increased less. The removal was increased from 33.8 % to 47.0 % by increasing BC dosage to 1.5 g/L, and removal was further increased to 54.0 % when MET concentration was decreased to 10.0 mg/L. The removal of MET by BC was pH-dependent as it could be increased up to 80.0 % at pH 11.0; while, the influence of temperature was slight. With analyses of the effect of dissolved oxygen, and free-radical quenching experiment, both the adsorption, and hydroxyl radical (•OH) induced degradation were found responsible for removal. Finally, removal in tap water (TW) was investigated, which indicated that the leaves-generated BC was suitable for MET removal in real water.

Electrochemical generation of ozone for application in environmental remediation

This work focuses on the production, in continuous mode, of ozone using a new electrochemical cell, specially designed and manufactured with 3-D printing to produce in a very efficient way high concentrations of this powerful oxidant. The gaseous ozone produced is tested in the degradation of a synthetic waste containing methomyl. The new cell has been characterized in terms of flow distribution, mass transfer, and production of ozone, being able to reach efficiencies as high as 9.5 g/kWh, which may be even competitive with those produced with the corona discharge technology. The prototype manufactured with an electrode area of 1.5 cm2 can produce a stream containing 30 mg/h of O3. This stream can be used to degrade methomyl. However, the direct bubbling was not found to be very efficient and activation of ozone with the simultaneous irradiation of UV light or the dosing of hydrogen peroxide was needed to improve performance, showing important synergism. The efficient removal of methomyl from wastewater opens the window for the development of alternative technologies to direct anodic oxidation based on the production and dosing of gaseous oxidants such as ozone. The operation of these new technologies does not depend on the salts contained in wastewater and prevents the deterioration in the quality of the waste because it does not leave any residue after application in the treated waste.

Uklanjanje metomila iz vodenih rastvora korišćenjem mikrosfera reaktiviranog aktivnog uglja

The removal of methomyl, one of the most frequent pesticides, from aqueous solutions has been studied by adsorption using the reactivated carbon microspheres separated from worn filtering protective suits. This study is significant in two aspects - the first is the in-situ adsorption of pesticides from aqueous solutions, and the second is recycling protective equipment as an effective material for water decontamination. Carbamate pesticide, methomyl is aimed to control foliage and soil-borne insect pests on various agricultural product. Also, due its toxicity, it has a great potential for usage in terroristic acts and tactical purposes during military operations. The reactivated carbon (RAC) microspheres were characterized by Scanning Electron Microscopes (SEM). The changes in relative concentration of methomyl during the adsorption onto the surface of the RAC microspheres was determinated using the UV-Visible spectrophotometer. The adsorption process is described by Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich adsorption isotherm models. The adsorption kinetics follows the second-order kinetics model, and the thermodynamics study confirms that the adsorption is exothermic and spontaneous. At optimal conditions, the adsorption capacity was qe = 8.631 mol g-1 × 10-8 and the adsorption rate was k = 0.749 g mmol-1 min-1. The Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich adsorption isotherm models were used to describe the adsorption process. The thermodynamic study of adsorption proves the process is spontaneous with exothermic nature.

Engineering ZIF-8 Hybridization by Extracted Lignin with Antibacterial Property for Uptake of Methomyl Residues from Wastewater

ABSTRACT The hybridization between lignin and ZIF-8 and the removal of methomyl insecticides from wastewater was studied. Fourier-Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Brunauer-Emmett-Teller (BET) were used to confirm the compounds. The effect of variables such as adsorbent dosage and contact time on the methomyl removal efficiency was investigated. The optimized condition dosage was 1 g L−1 at speed = 300 rpm, 300 min, and the pesticide concentration was 200 mg L−1 at room temperature (25°C) and pH = 7. The SEM and FTIR were used to thoroughly examine the reaction mechanism. Kinetic and isotherm parameters were precisely matched to the Langmuir and pseudo-second order models. The adsorption capacity in 60% ZIF-8@Lignin approached 324.6 mg g−1 which was significantly higher than that of lignin alone. Compared to other studies, the current study demonstrated superior adsorption capacity and cost-effectiveness. Antimicrobial testing confirmed that adding ZIF-8 to lignin enhanced the microbial activity and the minimum inhibitory concentration (MIC) value. The lowest values against all tested microbial strains were 19 mg mL−1.

Adsorption Isotherm of an Insecticide Methomyl onto Natural Clay

Adsorption isotherm of an insecticide methomyl onto natural clay has been investigated. The experimental data were fitted to isotherm models, Langmuir, Freundlich and Redlich Peterson. The Langmuir model fit the experimental data significantly better than Freundlich and Redlich Peterson models. A dimensionless separation factor, Ř, was used to judge the favorable adsorption. A chart based on material balance using single batch adsorber was constructed for different percentage of methomyl removal using the Langmuir model where the mass of natural clay required to treat a specified volume of solution is calculated. The effect of temperature showed the exothermic nature of the process. The enthalpy change, ΔH, of adsorption has been evaluated and it has a value of (-17.54 kJ/mol).

Methomyl removal from synthetic water using natural and modified bentonite clays

The removal of methomyl from synthetic aqueous solutions by using Ecuadorian bentonite clays was studied. A natural clay was purified (P-C) and modified by three methods: thermal activation at 200°C for 2 h, acid activation with a 3N sulfuric acid solution for 1 h, and saline activation with hexadecyltrimethyl ammonium bromide (HDTMA) for 12 h. Clays were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and the BET method. The removal was performed with the natural and modified bentonites considering three particle size ranges and three operating temperatures (20, 30 and 40°C). For this purpose, 0.5 g of clay were added to 50 mL of a 100 µg L−1 synthetic methomyl wastewater. Pesticide removal was quantified using ultraperformance liquid chromatography - tandem mass spectrometry. It was found that the adsorption process can be relatively efficient, particularly with thermally activated clays being used at 40°C. In this case, removal efficiencies between 66 and 76% were achieved. The highest efficiency was observed for a relatively large particle size (106-150 µm). The adsorption curves obtained were fitted to the Langmuir model. The analysis of variance for the removal of methomyl showed a significant effect for the temperature x clay x particle size interaction with a confidence level of 95% (p = 0.004).

Removal of the pesticide methomyl contained in simulated effluent from equipment washing by adsorption in residual orange bagasse

This work consists of the study of methomyl removal, an extremely toxic carbamate pesticide, contained in aqueous solutions synthesized, by adsorption in residual orange bagasse from industrial juices processing. The adsorption kinetics was studied by obtaining the best fit for the model of pseudo-second order (R2= 0.949). The Langmuir isotherm model adjusted better to the experimental data confirming the adsorption in monolayers, without interaction among the adsorbate molecules. The scanning electron microscopy (SEM) revealed that particulate adsorbents have rather irregular surface, but with rigid structure and virtually no internal pores. The characterization of the functional groups by infrared spectroscopy (FTIR) revealed the presence of hydroxyl, Carbonyl and carboxylic groups on the adsorbents particles surface. Central composite rotational design 2x2 (DCCR 2x2) was used for the statistical study of the effects of pH and solid/liquid ratio (R) on the methomyl adsorption capacity in orange bagasse particles. The obtained mathematical model adjusted well to the experimental data (R2= 95%). In the studied intervals the highest values of adsorption capacity (q) were 3.73 and 3.43 (mg.g-1), obtained under the conditions of pH 6.0 with R 0.017 g.mL-1 and pH 4.5 with R 0.015 g.mL-1, respectively. Thus, it was possible to conclude that there was a greater adsorption in assays containing greater adsorbent mass in pH slightly acid.

A case study of methomyl removal from aqueous solutions by four natural Albanian clays

AbstractThis study evaluated the adsorption properties of four Albanian natural clays from the regions of Brari, Currila, Dardha, and Prrenjasi for commercial methomyl from aqueous solutions. Three methomyl concentrations, 0.200, 0.400, and 0.600 mg/ml, were tested at 25°C to study the influence of the insecticide concentration on the adsorption process for each natural clay type. Within 48 hr of contact time, the adsorption pathways of methomyl on the selected clays are well described by a Langmuir‐like adsorption kinetic model and an intraparticle diffusion model. Hydrolysis and desorption inhibit the overall removal process. The increase of methomyl concentration in solution within the first 48 hr leads to linear adsorption increases well described by Langmuir and Freundlich adsorption isotherms and disfavors the desorption step for the Brari, Currila, and Dardha clays. For the methomyl concentration of 0.600 mg/ml, within 24 hr of contact time, the Dardha and Prrenjasi clays reveal 1.471 and 1.956 mg/g methomyl uptake, respectively. The Brari and Currila clays show longer saturation times followed by better methomyl retention. The Dardha and Prrenjasi clays exhibit fast and high adsorption combined with low retention times.

Synthesis of nanosized amorphous and nanocrystalline TiO2 for photochemical oxidation of methomyl insecticide in aqueous media

AbstractAqueous solution loaded with methomyl insecticide is photocatalytically treated upon UV radiation and TiO2 in a green sustainable oxidation technique. TiO2 is a highly promising photocatalytic oxidation method, whereas the main findings is increasing the surface area for maximizing the treatment efficiency. Herein, TiO2 was synthesized via sonochemical hydrolysis technique and amorphous TiO2 (TM100) was obtained. Further, annealing of amorphous TiO2 at 500 ºC resulting in anatase phase TiO2 (TN500). The phase structure of the both samples was confirmed by high‐resolution transmission electron microscope (HR‐TEM). The results revealed that the materials exhibited high methomyl removal efficiency due to its nanostructure nature. The optimum TM100 and TN500 for the treatment were 40 and 20 mg/L and resulted in 99.5 and 100% methomyl removal, respectively. Furthermore, pH and H2O2 effect were studied. Additionally, high correlation was attained between empirical and modelled values with a second‐order kinetic model for the two processes.

Microwave-assisted catalytic oxidation of methomyl pesticide by Cu/Cu2O/CuO hybrid nanoparticles as a Fenton-like source

Heterogeneous catalytic oxidation, Fenton-like (FL) hybrid nanoparticles (NPs) induced by microwave (MW) irradiation, was applied as a green technology pathway for methomyl pesticide oxidation. Three different hybrid nanostructured particles, C300, C400 and C500 containing various phase structures, i.e., Cu, Cu2O and CuO, were successfully synthesized by the thermal decomposition technique and used as a FL source in microwave-induced (MW/FL) system. The microstructure and morphology of the hybrid nanostructured particles were studied using an X-ray diffraction (XRD) field-emission scanning electron microscope (FE-SEM), respectively. Also, MW/FL system was compared to MW/H2O2 and (MW) alone. The influence of various operating parameters, i.e., microwave irradiation time and power, initial NPs concentration, H2O2 concentration and pH for the three MW/FL systems, was investigated, and the optimal operating conditions were compared. The results indicated that the MW/FL process outperformed the other systems, and around 91% of methomyl was removed after only 8 min of MW irradiation for the C300-based MW/FL system under optimal conditions. Notably, the results verified that the heterogeneous MW/FL oxidation system catalyzed over the synthesized NPs reacted with the wastewater at its initial pH without adjustment, which overcomes the weakness of the homogeneous Fenton catalyst. Hence, this advantage could expand the application of this oxidation technique and thus improves the system efficiency. Finally, the catalyst showed good reusability. The success of this technique explores the possibility of copper as a non-iron FL system in a MW-assisted system for the rapid removal of methomyl from wastewater.

Synthesis, Characterization and Evaluation of Peanut Shells-Derived Activated Carbons for Removal of Methomyl from Aqueous Solutions

Peanut shells-derived activated carbons (ACPNS) with different chemical characteristics, appropriate for the removal of methomyl pesticide in aqueous solutions are prepared. The steam activated carbon is obtained from the carbonized peanut shells in the presence of nitrogen in the temperature range from 973 to 1173K. The carbonized peanut shells are, further, chemically activated using NaOH and ZnCl2. The structure of the ACPNS was characterized by N2 adsorption at 77K, scan electron microscopy and FTIR. B.E.T methods are used to deduce the effective surface areas. The parameters (such as initial pH, temperature, etc) affecting the adsorption capacity of peanut shells-derived activated carbons toward methomyl removal from aqueous solutions are investigated using batch experiments. The study of kinetic models including pseudo first order and pseudo second-order are carried out. Adsorption isotherms are investigated. Equilibrium adsorption data fitted the Langmuir adsorption isotherm well with R2> 0.9980. The maximum adsorption capacities of peanut shells-derived activated carbons for the removal of methomyl, are calculated. The thermodynamic parameters including ΔG°, ΔH° and ΔS° for the adsorption processes of methomyl on the ACPNS were calculated, and the negative value of ΔG° indicated the spontaneous nature of adsorption. The prepared peanut shells derived activated carbons are successfully applied to the removal of methomyl pesticide from different water samples with a recovery % > 95 and a RSD< 3%. The mechanism of adsorption is proposed.

Characterisation of alginate-based nanocomposites prepared by radiation for removal of pesticides

Nanocomposites based on sodium alginate (NaAlg) and acrylic acid monomer (AAc) with different concentrations of calcite (C) or xonotlite (X) were prepared using gamma ray radiation. (NaAlg/AAc) hydrogel and its composites were characterised by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The introduction of calcite or xonotlite particles into (NaAlg/AAc) hydrogel increases the swelling capacity. The thermal stability improved by introducing calcite into (NaAlg/AAc) nanocomposite and decreased by introducing xonotlite. The prepared nanocomposites were used for removal of methomyl pesticide. It was found that the removal of methomyl by the nanocomposites is pH-dependent. The adsorption isotherm of various nanocomposites was fitted with Freundlich model. The maximum removal percent of methomyl is sequence in order of (NaAlg/AAc-X) > (NaAlg/AAc-C) > (NaAlg/AAc).

Structural characterization of natural organic matter and its impact on methomyl removal efficiency in Fenton process

This study aimed to characterize the NOM structural variation during Fenton process, in which the methomyl and humic acid were selected as the investigated compounds. The preliminary degradation experiments were conducted at various H2O2 and Fe2+ concentrations without the presence of NOM to determine the applied Fenton reagent dosages for subsequent NOM impact on Fenton degradation. The methomyl removal at 80% was observed at the Fenton reagent ratio ([H2O2]/[Fe2+]) of 1 while Fe2+ concentration was no less than 2mM. In the presence of NOM, the methomyl removal by Fenton process was further enhanced apparently. The NOM used in this study was found to be a macromolecule with tryptophan-like and tyrosine-like functional groups through fluorescence spectrometry analysis. The addition of ferrous ions in the NOM solution initiated the reactions between Fe2+/Fe3+ redox couples and NOM molecules, breaking the NOM into smaller organic fractions. These organic fractions were further oxidized into even smaller molecules by hydroxyl radicals after H2O2 addition. The NOM might compete with methomyl for hydroxyl radicals, and enhance the catalytical generation of hydroxyl radicals by reducing Fe3+ to Fe2+ at the same time. Apparently, the increase in OH generation was more than the OH consumption by NOM presence, resulting in the observed enhancement of methomyl removal.

Adsorption behavior of pesticide methomyl on activated carbon in a high gravity rotating packed bed reactor

High gravity rotating packed bed (HGRPB) reactor possesses the property of high mass transfer rate, which is expected to promote the adsorption rate for the process. In this study, HGRPB has been applied on adsorption removal of methomyl from solution, adopting the adsorbent of activated carbon F400. The influence of operating parameters of HGRPB on mass transfer such as the rotating speed (NR), the flow rate of solution (FL) and initial concentration of methomyl (Cb0) were examined. The traditionally internal mass transfer models combined with Freundlich isotherm were used to predict the surface and effective diffusion coefficients. In addition, the results have also been compared with those obtained from the traditional basket stirred batch reactor (BBR). The results showed that the larger values of NR and FL enhanced the effective intraparticle diffusion and provided more accessible adsorption sites so as to result in lower equilibrium concentration in HGRPB system when compared to SBR system. The results of adsorption kinetics demonstrated that surface and effective diffusions were both significantly greater in HGRPB system instead of BBR system. Furthermore, the values of BiS also manifested less internal mass transfer resistance in HGRPB system. The contribution ratio (RF) of the surface to pore diffusion mass transport showed that the larger contribution resulted from the surface diffusion in HGRPB system. Therefore, the results reasonably led to the conclusion that when the HGRPB system applied on the adsorption of methomyl on F400, the lower equilibrium concentration and faster internal mass transfer can be obtained so as to highly possess great potential to match the gradually stricter environmental standard.

Removal of an insecticide (methomyl) from aqueous solutions using natural clay

Adsorption of an insecticide (methomyl) onto natural clay have been investigated as a possible alternative method for its removal from aqueous solutions. The study was aimed to use low cost material as a step towards cleaner environment. The influence of system variables, such as particle size (dp) and temperature on the adsorption capacity have been studied. It was found that natural clay reached equilibrium with methomyl solution in time less than 3h. The experimental data were fitted to equilibrium isotherm models, Langmuir, Freundlich and Redlich–Peterson. A dimensionless separation factor, R^, was used to judge the favorable adsorption. The results indicated that percentage of insecticide removal ranged from 27.6 to 32.9 for initial concentration varied from 43.71 to 19.99mg/l. The effect of temperature showed the exothermic nature of the process. The enthalpy change (ΔH) of adsorption has been evaluated and it has a value of, −17.54kJ/mol. The Langmuir model fit the experimental data significantly better than Freundlich and Redlich–Peterson models. A chart based on material balance using single batch adsorber was constructed for different percentage of methomyl removal using the Langmuir isotherm where the mass of natural clay required to treat a specified volume of solution is calculated.

A Sustainable Water Purification Solution for Rural Communities

This study describes a method to decrease the incidence of diseases caused by pesticides, heavy metals, and bacteria through a simple, low-cost, and sustainable personal water purification solution for the citizens of Nagcarlan, Laguna in the Philippines. Activated carbon (AC) adsorption was the primary treatment used in the removal of methomyl, a carbamate pesticide, and hexavalent chromium (Cr(VI)), a heavy metal. Also, citricidal was used to disinfect water from coliforms. Surface hydroxyl with aliphatic and aromatic groups from the AC, were confirmed using Fourier transform infrared (FTIR) spectroscopy. The point of zero charge was determined to be 7.875 using pH drift tests. The optimal dosage from batch adsorption was found to be between 0.5 and 0.9 g/100 mL with a 28-30% Cr(VI) removal.. Results of Cr(VI) column adsorption through rapid small-scale column tests (RSSCT) showed that approximately 55% removal was attained for 1 hour using 2 L solution. It was also found out through RSSCT that 30 mg of citricidal and 0.3 g of AC resulted in 100% E.coli abrogation for at least 50 mL of contaminated water having a fecal coliform count of 2,000 colonies per 100 mL.

Comparison between Ozonation and Photo-Fenton Processes for Pesticide Methomyl Removal in Advanced Greenhouses

So-called “Advanced Greenhouses” are a new approach to the concept of protected agriculture. Among other technological and structural improvements, these facilities give the possibility of recycling the irrigation surplus water, rich in lixiviates, salts, pesticides and its metabolites. After many cycles, the current is so concentrated on those substances that it becomes necessary for the presence of a membrane separation stage which brine, highly concentrated on those named pollutants, has to be treated before being sent to the public sewage system. Advanced Oxidation Processes, among other chemical treatments, can be considered an alternative to process this current effluent. In this work, concentrated aqueous solutions of methomyl as model pesticide (200 mg·L−1) have been subjected to two of those processes: ozonation and photo-Fenton reaction. Analysis of the elimination of the pesticide itself and the grade of mineralization achieved have shown how, while the ozonation is the most effective process decomposing the pesticide (eliminating the total concentration in 60 minutes), the photo-Fenton reaction mineralizes successfully the 40% of the total organic load (the ozonation only can cope with 20%) but only decompose a 40% of the pesticide. Evolution of biodegradability and toxicity of the effluent along both processes was also analyzed. Intermediates generated both by ozonation and photo-Fenton did not increase the biodegradability of the treated effluents. Nevertheless, while acute toxicity just after 15 minutes of treatment with ozone is notably higher than for raw solution, and it is maintained till the end of the experiment (120 min), though, toxicity along photo-Fenton reaction has two growing and decreasing regions, always shows lower values than the provoked during ozonation. None of the two assayed processes has been proved to increase biocompatibility of highly concentrated methomyl solutions.

Photochemical Behavior of the Insecticide Methomyl Under Different Conditions

This article describes the photolytic and photocatalytic removal of the insecticide methomyl at low concentration from different types of water, upon UV, visible or natural solar light radiation, in the presence of TiO2 and ZnO, as well as using Fe-ZSM-5 zeolite and AlFe-pillared montmorillonite (photo-Fenton process). The rate of photodecomposition of methomyl was measured using UV spectrometry and HPLC, while its mineralization was investigated by ion chromatography (IC) and total organic carbon (TOC) analysis. The photochemical removal of methomyl is a natural and applicable model for the purification of water.

Adsorptive removal of the pesticide methomyl using hypercrosslinked polymers

The hypercrosslinked polymers Macronet MN-150 and MN-500 (denoted as MN-150 and MN-500) were investigated to remove the pesticide methomyl from aqueous solutions via adsorption. Furthermore, the effect of humid acid (used as background organic compound) on the adsorption capacity of methomyl for MN-150 was examined. The equilibria and kinetics of the adsorption of methomyl onto MN-150 and MN-500 can be well correlated with Langmuir and Freundlich isotherms, and conventional kinetic models (e.g., surface and pore diffusion models), respectively. The polymer MN-150 possesses a high potential to be applied as adsorbent for the removal of methomyl from aqueous solution when compared with MN-500. Furthermore, the competitive effect of humic acid on adsorption of methomyl on MN-150 can be ignored at low equilibrium concentrations. The transport of methomyl from solution into the polymer adsorbents is controlled by both, external and internal mass transfer mechanisms with film-surface diffusion model offering the better description. The surface mobility and flux of surface diffusion increase as the initial concentration increases.