Thiamethoxam Removal Research Articles

Comprehensive effects of thiamethoxam from contaminated soil on lettuce growth and metabolism

The second-generation neonicotinoid thiamethoxam, is prevalent in soils because of its extensive application and persistence. However, the comprehensive effects of thiamethoxam residue in soils on cultivated plants are still poorly understood. This study examined variations of growth state, physiological parameters, antioxidant activity, and metabolites in lettuce after thiamethoxam exposure; the removal effects of different washing procedures were also investigated. The results indicated that thiamethoxam in soils significantly increased the fresh weight, seedling height and chlorophyll content in lettuce, and also altered its lipid, carbohydrate, nucleotide and amino acids composition based on untargeted metabolomics. KEGG pathway analysis uncovered a disruption of lipid pathways in lettuce exposed to both low and high concentrations of thiamethoxam treatments. In addition, the terminal residues of thiamethoxam in lettuce were below the corresponding maximum residue limits stipulated for China. The thiamethoxam removal rates achieved by common washing procedures in lettuce ranged from 26.9% to 42.6%. This study thus promotes the understanding of the potential food safety risk caused by residual thiamethoxam in soils.

Synthesizes of graphene oxide grafted with chitosan and copper oxide nanoparticles for the removal of lambda-cyhalothrin and thiamethoxam insecticides from wastewater

Abstract The residue of lambda-cyhalothrin (LCT) and thiamethoxam (TMX) insecticides are toxic systemic pyrethroid and neonicotinoid insecticides and their entrance into water bodies can have a toxic impact on aquatic and terrestrial life. Therefore, producing of economical, sustainable and effective adsorbents is immediately required for the removal of these insecticides from polluted water. In this study, the nanocomposite of graphene oxide (GO) grafted with chitosan (CS) and copper oxide nanoparticles (Cu-NPs) was synthesized, characterized and assessed, for the first time, for LCT and TMX removal from wastewater using sorption and mechanism studies. The removal of LCT and TMX was assessed by varying the adsorbent dose, initial concentrations of insecticides, pH, exposure time and temperature to achieve optimum sorption conditions. The nanocomposite provides more than 80% removal rate for 1400 mg/L of insecticides in an aqueous solution using only 100 mg of nanocomposite at 318 K in 120 min due to large surface area and pore volume. The adsorption equilibrium data best followed the Langmuir model, with an adsorption capacity of 153 and 193 mg/g for the LCT and TMX, respectively. The pseudo-second-order explained the kinetics best, and the thermodynamic study indicated that the process was spontaneous, and endothermic and proceeded with the increase in randomness. The suggested mechanisms of LCT and TMX sorption by GO-CS-Cu nanocomposite are hydrogen bonding and electrostatic attraction. The reusability study of GO-CS-Cu was executed up to five cycles and maintains its efficiency even after the considered cycles. In conclusion, the study proves the promising use of GO-CS-Cu as a stable, reusable and promising adsorbent for LCT and TMX removal from wastewater at the industrial level.

ZIF-8 and humic acid modified magnetic corn stalk biochar: An efficient, magnetically stable, and eco-friendly adsorbent for imidacloprid and thiamethoxam removal

Neonicotinoids, ones of the most used pesticides extensively present in water environment, are hazardous to environment and human. Herein, a novel magnetic adsorbent ZIF-8-HA@MCSB is designed by modifying ZIF-8 and humic acid (HA) onto the surface of magnetic corn stalk biochar (MCSB) for removing imidacloprid (IMI) and thiamethoxam (THI) from water. MCSB has a superior adsorption performance among magnetic biochars (MBCs); the modification of ZIF-8 creating hierarchically porous structure and HA promoting the crystal growth of ZIF-8 can enhance its adsorption performance. Hence, ZIF-8-HA@MCSB exhibits the high maximum adsorption capacities for IMI (163.9 mg g−1) and THI (123.5 mg g−1). Meanwhile, the HA modification offers a protective shell for magnetic Fe3O4, which endows ZIF-8-HA@MCSB with distinguished magnetic stability. Even in pH = 2 solution, ZIF-8-HA@MCSB still possesses a saturation magnetization value of 13.07 emu g−1, which is beneficial for its separation and reuse. Especially, ZIF-8-HA@MCSB can be repeatedly used 5 times with high removal efficiencies (over 90%). Furthermore, the low Fe (less than 0.3 mg L−1 at pH ≥ 2) and Zn (less than 1.0 mg L−1 at pH ≥ 3) leaching concentrations in a wide pH range guarantee the environmental security of ZIF-8-HA@MCSB. And a promoting effect on wheat growth enables waste ZIF-8-HA@MCSB potentially to be fertilizer for crop production, which agrees with the sustainable concept. Therefore, the advantages of having high adsorption capacities for IMI and THI, resistant to acid, and friendliness to environment indicate that ZIF-8-HA@MCSB has a significant potential for real neonicotinoids removal. Novelty StatementIn this work, a novel magnetic adsorbent (ZIF-8-HA@MCSB) with the high adsorption capacities of IMI and THI is obtained by simply modifying ZIF-8 and humic acid (HA) onto the magnetic corn stalk biochar (MCSB) surface. Such a magnetic adsorbent has never been reported before. More importantly, compared with various modification methods to increase the adsorption capacity, there are few reports on concerning the acid resistance and environmental friendliness of magnetic adsorbents, especially the corresponding adsorption capacity also increases.

Sustainable alternative for removing pesticides in water: Nanomodified activated carbon produced from yeast residue biomass

The systemic insecticide thiamethoxam (TMX) has been frequently used with the need to intensify agricultural activities and food production. Given the pollution concern, biosorption emerges as an efficient and low-cost treatment. Thus, this work proposes to use the environmentally friendly activated carbon magnetic nanocomposite (YAC-NP) produced with yeast residues from the sugar-alcohol industry for the sorption of TMX in water. YAC-NP and its precursors (NP and YAC) were characterized by X-ray (XRD) and Fourier Transform Infrared (FTIR) spectroscopies to investigate their morphology and interaction with TMX. The Boehm titration informed the predominance of acidic character to YAC by the presence of carboxylic, lactone, and phenolic groups. The YAC-NP pH at the point of zero charge (pHPZC) was 6.05, and the best conditions for TMX sorption by YAC-NP occurred at the 2–7 pH range and 30 min of contact time. Sorption tests were performed using batch procedures at increasing concentrations of TMX (5–100 mg/L) and 1 g/L adsorbent dose. The experimental adsorption capacities (Qexp) for YAC, NP, and YAC-NP were 31.52 ± 1.69, 2.42 ± 0.54, and 12.50 ± 0.33 mg/g, respectively. TMX contents were determined by Ultraviolet–visible Spectroscopy (UV/Vis). The pseudo-2nd-order kinetic equation best fit the experimental data (r2 = 0.9996). Among the eight isotherm models applied to the experimental data, Hill, D-R, Temkin, Toth, and R–P were the models that best described the sorption process. YAC-NP reusability in TMX removal was assessed, and a decrease from 71.87 to 0.69% was observed after 10 adsorption cycles.

Adsorptive capacity of a g-C3N4 matrix for thiamethoxam removal: A DFT study

In this study, the adsorptive capacity of the insecticide thiamethoxam (TMX) on a graphitic carbon nitride matrix (g-C3N4) was studied theoretically. Two adsorbent-adsorbate complexes, g-C3N4-TMX1 and g-C3N4-TMX2 was formed through hydrogen bonds (HB) and the the hydrogen bonds lengths ranging from 2.610 Å to 3.538 Å. Topological analyses based on the quantum theory of atoms in molecules confirmed the bond critical points of hydrogen bonds. Further, it allowed for the classification of the HBs as weak, with hydrogen bond energy values ranging from −0.98 to −6.58 kJ mol−1. Calculations of the energies involved in the processes proved that the interaction of TMX with the g-C3N4 matrix occurs in two sites with values of ΔEBind = −71.65 kJ mol−1 and ΔEBind = −70.44 kJ mol−1, sites 1 and 2, respectively. The results showed that the interaction is is spontaneous and exothermic, as indicated by the negative values of ΔG and ΔH.

Visible light excited graphitic carbon nitride for efficient degradation of thiamethoxam: Removal efficiency, factors effect and reaction mechanism study

In this decade, photocatalytic degradation of organic contaminants has attracted great attentions. In this study, we used graphic carbon nitride (g-C3N4) nanosheets as the photocatalyst for the degradation of thiamethoxam (THM). The properties of g-C3N4 nanosheets have been fully characterized by the analysis techniques. The experiments results shown that under the optimum condition, 91.3% of THM degradation efficiency can be reached in the presence of g-C3N4 nanosheets within 60 min under visible light irradiation. Take the realistic application into consideration and to fully investigate the reaction process, the influence of reaction parameters, including the dosage of g-C3N4 nanosheets, initial THM concentration, and initial solution pH value, co-existence ions, humic acid (HA) and fulvic acid (FA) have been systematically studied and discussed. Results demonstrated that weak acidity and neutral condition is benefit for THM decomposition, and Ca2+ and Mg2+ present enhanced inhibition effect than Na+ for THM removal. Meanwhile, PO43- and CO32- show strong inhibition effect, but HA and FA performed weak inhibitory effect. The trapping experiments and electron spin resonance (ESR) measurement demonstrated that superoxide radical (•O2-), hydroxyl radical (•OH) and holes (h+) are all generated during the reaction process. There are all participated in the THM decomposition process and •O2- plays the major role on it. The results obtained in this study indicated that metal free g-C3N4 present great photocatalytic activity and stability for THM removal and owns great potential in the application of actual agricultural environment.

Biochar Generated from Agro-Industry Sugarcane Residue by Low Temperature Pyrolysis Utilized as an Adsorption Agent for the Removal of Thiamethoxam Pesticide in Wastewater

Biochar produced from different raw materials by pyrolysis have been utilized as an alternative material for organic compound adsorption. This study aims to evaluate the use of biochar generated from sugar cane filter cake, after pyrolysis treatment at 380 °C, in the adsorption process of thiamethoxam pesticide in wastewater. The biochar was studied based on moisture, volatile matter, ash content, surface area and porosity, using elemental analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy. The results showed that the use of biochar as an adsorbent for organic compounds is promising, due to its surface area (19.8 m2 g−1), mesoporosity, and functional groups, such as hydroxyl, present on the biochar surface. The Langmuir and Freundlich isothermal models were used for the adsorption study. The pseudo-first- and pseudo-second-order models were used in the kinetic study of the adsorption process. The results indicated that the adsorption process was well described by the Langmuir isotherm and pseudo-second-order models. Finally, the rate of thiamethoxam removal by biochar was approximately 70% over a period of 60 min, and biochar is, therefore, suitable for the decontamination of wastewater with thiamethoxam.

Montmorillonite-supported nanoscale zero-valent iron for thiamethoxam removal: response surface optimization and degradation pathway.

As a highly efficient insecticide, thiamethoxam was widely used in the world. However, it was bioaccumulative and toxic to aquatic organisms that must be removed from water. In this work, nanoscale zero-valent iron particles loaded on montmorillonite (nZVI/Mt) were successfully synthesized for effective removal of thiamethoxam. The properties of nZVI/Mt for the removal of thiamethoxam were investigated, and the reaction conditions were optimized through response surface methodology. Furthermore, the degradation products were analyzed by liquid chromatography-mass spectrometry (LC/MS). The results demonstrated that the reaction activity of nZVI was enhanced because the agglomeration and oxidation of nZVI particles were effectively inhibited by using montmorillonite as a support. The significance of the effects of each factor on the removal of thiamethoxam was determined to be in the order of pH˃temperature˃reaction time˃nZVI/Mt dosage. The optimal conditions were as follows: a dosage of nZVI/Mt of 2g/L, a reaction time of 2h, a reaction temperature of 35°C, and a solution pH of 3. The removal efficiency of thiamethoxam (C0 = 20mg/L) was observed to be as high as 94.29% under the optimal conditions, which was close to the value of 94.47% that was predicted using the mathematical model, indicating that the model could accurately predict the removal efficiency of thiamethoxam. The degradation mechanism involved the -NO2 group on the thiamethoxam molecule was reduced and eliminated by nZVI/Mt.

Bioremediation potential of select bacterial species for the neonicotinoid insecticides, thiamethoxam and imidacloprid

Thiamethoxam (THM) and imidacloprid (IMI), are environmentally persistent neonicotinoid insecticides which have become increasingly favored in the past decade due to their specificity as insect neurotoxicants. However, neonicotinoids have been implicated as a potential contributing factor in Colony Collapse Disorder (CCD) which affects produce production on a global scale. The present study characterizes the bioremediation potential of six bacterial species: Pseudomonas fluorescens, Pseudomonas putida, Pseudomonas aeruginosa, Alcaligenes faecalis, Escherichia coli, and Streptococcus lactis. In Phase I, we evaluated the utilization of IMI or THM as the sole carbon or nitrogen source by P. fluorescens, P. putida, and P. aeruginosa. All three species were better able to utilize THM over IMI as their sole carbon or nitrogen source. Thus, further studies proceeded with THM only. In Phase II, we assessed the kinetics of THM removal from aqueous media by the six species. Significant (p < 0.0001) reductions in 70 mg/L THM concentration were observed for P. fluorescens (67%), P. putida (65%), P. aeruginosa (52%), and A. faecalis (39%) over the 24-day study period, and for E. coli (60%) and S. lactis (12%) over the 14-day study period. The THM removal by all species followed a first-order kinetic reaction. HPLC chromatograms of P. fluorescens, P. putida, and E. coli cultures revealed that as the area of the THM peak decreased over time, the area of an unidentified metabolite peak increased. In Phase III, we examined the effect of temperature on the transformation capacity of the bacterial species which was observed at 2 ℃, 22 ℃, and 30 ℃. Maximal THM removal occurred at 30 °C for all bacterial species assessed. Identification of the metabolite is currently underway. If the metabolite is found to be less hazardous than THM, further testing will follow to evaluate the use of this bioremediation technique in the field.

Thiamethoxam removal by Fenton and biological oxidation

AbstractBACKGROUNDThiamethoxam (TMX) is a potential insecticide pollutant of hydric resources that must be removed. Advanced oxidation processes (AOPs) are usually effective, but expensive to implement. Combining Fenton's reagent with biological oxidation circumvents the shortcomings of Fenton technology, facilitating the biodegradation of the resulting effluents in a sequencing batch reactor (SBR).RESULTSFenton‐like oxidation of TMX with variable hydrogen peroxide (H2O2) doses afforded total organic carbon (TOC) conversion and chemical oxygen demand (COD) removal by (respectively) 40% and 80% from pure TMX, and 40% and 60% from commercial TMX. The effluents from Fenton oxidation using substoichiometric H2O2 doses were less ecotoxic and more biodegradable than the initial solution and, therefore, susceptible to a biological treatment. Biological oxidation of effluents obtained from 50% and 75% H2O2 doses was accomplished for different organic loads in 6‐h cycles. Coupling Fenton and biological oxidation of TMX afforded TOC conversion and COD removal of 80% for the effluent obtained with a 75% H2O2 dose.CONCLUSIONSCoupling Fenton–biological oxidation efficiently reduces the amounts of H2O2 needed and produces biodegradable effluents. In addition, the biological treatment increases COD and TOC removal by ≤80% for the overall treatment. © 2019 Society of Chemical Industry

Electrochemical removal of thiamethoxam using three-dimensional porous PbO2-CeO2 composite electrode: Electrode characterization, operational parameters optimization and degradation pathways

Highly performed electrode is one of the key factors affecting the efficiency of electrochemical oxidation toward organic pollutants. In the present work, three-dimensional porous PbO2-CeO2 composite electrodes (3D/PbO2-CeO2) were fabricated by composite electrodeposition method using oxygen bubbles as template, to eliminate neonicotinoid thiamethoxam in aqueous solution. The surface morphology, structure, and composition of the 3D/PbO2-CeO2 electrodes were well characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). Then the influence of the applied current density, the initial concentration of thiamethoxam, the concentration of supporting electrolyte, and initial pH value on the thiamethoxam removal ratio were also optimized. Amount to twenty deductive intermediates of thiamethoxam degradation were identified by HPLC-MS analysis, and dechlorination, hydrogen abstraction, denitration, and hydroxylation were observed in electrochemical oxidation process of thiamethoxam. Based on these identified byproducts, a hypothetical degradation mechanism has been proposed, which was divided into two parallel pathways according to the different initial oxidation position on thiamethoxam, such as chlorine atom on thiazole ring and nitro group on 1,3,5-oxadiazinane ring. All the intermediates were ultimately mineralized into H2O and CO2. The electrochemical oxidation based on 3D/PbO2-CeO2 electrodes in this work is a promising approach to effective removal of thiamethoxam.

Occurrence of Neonicotinoid Insecticides in Finished Drinking Water and Fate during Drinking Water Treatment

Neonicotinoid insecticides are widespread in surface waters across the agriculturally intensive Midwestern United States. We report for the first time the presence of three neonicotinoids in finished drinking water and demonstrate their general persistence during conventional water treatment. Periodic tap water grab samples were collected at the University of Iowa over 7 weeks in 2016 (May–July) after maize/soy planting. Clothianidin, imidacloprid, and thiamethoxam were ubiquitously detected in finished water samples at concentrations ranging from 0.24 to 57.3 ng/L. Samples collected along the University of Iowa treatment train indicate no apparent removal of clothianidin or imidacloprid, with modest thiamethoxam removal (∼50%). In contrast, the concentrations of all neonicotinoids were substantially lower in the Iowa City treatment facility finished water using granular activated carbon (GAC) filtration. Batch experiments investigated potential losses. Thiamethoxam losses are due to base-catalyzed hydrol...

Optimization of thiamethoxam adsorption parameters using multi-walled carbon nanotubes by means of fractional factorial design

The aim of this work was to evaluate significant factors affecting the thiamethoxam adsorption efficiency using oxidized multi-walled carbon nanotubes (MWCNTs) as adsorbents. Five factors (initial solution concentration of thiamethoxam in water, temperature, solution pH, MWCNTs weight and contact time) were investigated using 2V5-1 fractional factorial design. The obtained linear model was statistically tested using analysis of variance (ANOVA) and the analysis of residuals was used to investigate the model validity. It was observed that the factors and their second-order interactions affecting the thiamethoxam removal can be divided into three groups: very important, moderately important and insignificant ones. The initial solution concentration was found to be the most influencing parameter on thiamethoxam adsorption from water. Optimization of the factors levels was carried out by minimizing those parameters which are usually critical in real life: the temperature (energy), contact time (money) and weight of MWCNTs (potential health hazard), in order to maximize the adsorbed amount of the pollutant. The results of maximal adsorbed thiamethoxam amount in both real and optimized experiments indicate that among minimized parameters the adsorption time is one that makes the largest difference. The results of this study indicate that fractional factorial design is very useful tool for screening the higher number of parameters and reducing the number of adsorption experiments.

Degradation of thiamethoxam in water by the synergy effect between the plasma discharge and the TiO2 photocatalysis

TiO2 loaded on the honeycomb ceramic was tentatively introduced into dielectric barrier discharge (DBD) in a radial-flow configuration, for plasma-induced photocatalytic degradation of a model organic pollutant thiamethoxam in water. The solution was made to flow as a film over the surface of the honeycomb ceramic, whose hydrophilic force kept the water surface undisturbed by the electrical discharge. This characteristic enabled a reduction of the discharge gap. The results indicated that rate constant of thiamethoxam degradation, energy utilization efficiency of thiamethoxam removal and TOC removal were significantly enhanced due to the synergy effect between the plasma discharge and the TiO2 photocatalysis. The system could adapt to a wide range of liquid conductivity. The TiO2 film was calcined at 500°C and the crystal structure of the TiO2 showed no change after use. Higher concentration of H2O2 and ·OH were obtained.