Degradation Of Insecticides Research Articles

Hydrophilic magnetic COFs: The Answer to photocatalytic degradation and removal of imidacloprid insecticide

The widespread use of imidacloprid (IMI) in pest control presents significant environmental challenges due to its persistence and low removal efficiency. This study introduces magnetic Covalent Organic Frameworks (COFs) functionalized with Fe₃O₄ nanoparticles (Fe₃O₄@HMN-COF, Fe₃O₄@MAN-COF, and Fe₃O₄@SIN-COF) as efficient adsorbents for IMI removal from water. These COFs, engineered with nitrogen-rich structures and extensive π-electron systems, achieve superior adsorption through π-π interactions, hydrophobic interactions, and hydrogen bonding. Characterization via FT-IR, XRD, and nitrogen sorption isotherms confirmed their high hydrophilicity, stability, and large surface areas. The magnetic properties of the COFs facilitated easy separation from water, enhancing practicality. Kinetic studies for all COFs indicated a pseudo-second-order model, suggesting chemisorption, with adsorption capacities of 600 mg/g for Fe₃O₄@HMN-COF, 480 mg/g for Fe₃O₄@MAN-COF, and 375 mg/g for Fe₃O₄@SIN-COF. Thermodynamic analyses revealed spontaneous and endothermic adsorption processes. Reusability tests showed minimal capacity loss over multiple cycles, underscoring their practical applicability. Practical tests in honey and fruit samples confirmed high efficacy, demonstrating the COFs' versatility. The study also optimized the photocatalytic degradation of imidacloprid using these COFs, with Fe₃O₄@HMN-COF achieving 98.5 % efficiency under optimal conditions (10 mg L−1 IMI, 0.01 g catalyst dose, pH 11, 30 °C, UV light). These findings highlight the potential of magnetic COFs for sustainable environmental remediation of pesticide-contaminated water.

Exploring the Green Power Unleashed by ZnO-Immobilized Aspergillus oryzae Cutinase for the Degradation of Insecticide and Polyester Waste

Exploring the Green Power Unleashed by ZnO-Immobilized Aspergillus oryzae Cutinase for the Degradation of Insecticide and Polyester Waste

A novel photocatalyst of Y2O3-BaO-ZnO ternary system for enhanced photocatalytic degradation of carbofuran insecticide

A novel Y2O3-BaO-ZnO ternary system was synthesized via precipitation of a mixture of Y(NO3)3.6 H2O:Ba(NO3)2:Zn(NO3)2.6 H2O using some Fibonacci sequences. The Y2O3-BaO-ZnO was applied to the photocatalyst to investigate the degradation of carbofuran insecticide. The Y2O3-BaO-ZnO prepared at the sequence ratio of 5:8:13 (YBZ5) exhibited the highest photocatalytic performance. Morphological characterization showed that the particle size of the YBZ5 sample was significantly smaller than that of ZnO by over half, possibly providing high surface areas. The crystalline structure, functional group, and surface chemical composition investigations confirmed the presence of Y2O3, BaO, and ZnO. The fluorescence study exhibited no difference. Based on band gap energy and energy band alignment analysis, the Y2O3-BaO-ZnO ternary system demonstrated a well-aligned valence band. The energy band alignment analysis revealed a good alignment of the valence band for continuous hole transport in the Y2O3-BaO-ZnO ternary system. The alignment induces charge separation which reduces recombination and provides efficient active carriers at the surfaces of the photocatalyst, allowing reactions with toxic molecules. Therefore, the synergistic function of high surface areas and appropriate energy band alignments of the novel Y2O3-BaO-ZnO ternary system is considered the crucial factor in the enhancement of photocatalytic performance.

Evaluation of a hybrid advanced oxidation process for removal of pirimicarb insecticide in aqueous media: Statistical optimization and estimation of electrical energy consumption

AbstractIn this paper, the role of periodate and persulfate as inorganic oxidants were studied in presence of ultraviolet radiation and titanium dioxide nanoparticles as a hybrid advanced oxidation photocatalytic processes for degradation and mineralization of the pirimicarb insecticide in aqueous media. The effects of several factors such as the ultraviolet irradiation, initial oxidant concentration, titanium dioxide nanoparticles dosage, and pH on the process performance were investigated. The process optimization was performed by the central composite design as a tools of response surface methodology for 30 mg L−1 of the insecticide initial concentration at 25°C and 10 min of degradation process. A degradation efficiency of about 86% and 85% have been obtained for the persulfate and periodate processes, respectively, in the optimum conditions. The mineralization efficiency of the process using persulfate and periodate were about 35% and 46% after 60 min, respectively. The kinetic studies show that both processes follow a pseudo‐first‐order kinetic model and the rate constants were 0.1483 min−1 for the persulfate and 0.1152 min−1 for the periodate process. Generally, it can be concluded that this method is suitable for the degradation and mineralization of toxic aromatic compounds.

Activation of peroxymonosulfate and peroxydisulfate by nitrogen-doped carbon nanotubes for effective degradation of neonicotinoid insecticides

Nitrogen-doped carbon nanotubes (N-CNTs) have been considered as an excellent metal-free activator for persulfate-based advanced oxidation processes. However, the critical role of N-doping in the activation of peroxymonosulfate (PMS) and peroxydisulfate (PDS) remains a significant difference even opposed in scientific understanding. Herein, the CNTs and N-CNTs were used to active PMS and PDS for degradation of neonicotinoid insecticides (NNIs), one of the emerging refractory organic pollutants. The N-CNTs achieve 92.6% of nitenpyram (Nit) degradation within only 10 min under PMS system, much higher than that of CNTs/PMS system (∼10%). Moreover, the N-CNTs can active PMS to conduct degradation through a combined 1O2 and electron transfer process with k of 4.94 × 10−2 L·mg−1·min−1, which was quite different from N-CNTs/PDS system (single electron transfer process, k = 1.84 × 10−3 L·mg−1·min−1). A positive correlation between degradation rates of five NNIs and their electron-donating ability is established, further verifying the importance of electron transfer in NNIs degradation. This study proves the superiority of N-CNTs/PMS over N-CNTs/PDS in Nit degradation and the underlying mechanisms, and reveals the importance of electron-donating ability of NNIs in their degradation by N-CNTs/PMS. These findings are of great significance for their removal from the environment.

Behavior of Thiamethoxam and Clothianidin in Young Oilseed Rape Plants before Flowering, Monitored by QuEChERS/LC–MS/MS Protocol

Behavior of Thiamethoxam and Clothianidin in Young Oilseed Rape Plants before Flowering, Monitored by QuEChERS/LC–MS/MS Protocol

Diversity of culturable gut bacteria in natural aphid populations and their contribution to insecticide degradation

Microorganisms in insects play pivotal roles in various aspects, including nutrition, development, protection, physiology, and behavior. Aphids, a distinct group of insects that feed on plant sap, have been the focus of research exploring the intricate relationships between microbes and insects. While extensive investigations have delved into the obligate endosymbionts in aphids, there remains a gap in understanding the diversity of gut microbes and other associated microorganisms. This study employed culture-dependent methods to isolate microorganisms from diverse aphid species (Aphis gossypii, A. nerii, A. craccivora, Hysteroneura setariae, and Myzus persicae). The results identified three bacterial phyla (Firmicutes, Proteobacteria, Actinobacteria), belonging to families such as Bacillaceae, Corynebacteriaceae, Micrococcaceae, Morganellaceae, Staphylococcaceae, and Xanthomonadaceae. Bacillus emerged as the predominant taxon, with Aphis craccivora exhibiting both high abundance and an even distribution of bacteria. Both A. craccivora and A. gossypii displayed a diverse array of bacterial species, with A. gossypii exhibiting the highest dominance index. Hysteroneura setariae showcased a diverse dominance of bacteria among aphids. Notably, the microorganisms Exiguobacterium indicum MPB-2 and Pseudomonas hibiscicola CCF 2-2 demonstrated the ability to degrade imidacloprid at a rate of 18–22%. This finding emphasizes their capacity to utilize insecticides as sole sources of carbon and nitrogen, ultimately benefiting the fitness of the insects. This study contributes to our understanding of the microorganisms presented in aphids. Highlighting the efficacy of culture-dependent methods in unveiling the diversity of these microscopic organisms.

The role of insect gut microbiota in host fitness, detoxification and nutrient supplementation.

Insects are incredibly diverse, ubiquitous and have successfully flourished out of the dynamic and often unpredictable nature of evolutionary processes. The resident microbiome has accompanied the physical and biological adaptations that enable their continued survival and proliferation in a wide array of environments. The host insect and microbiome's bidirectional relationship exhibits their capability to influence each other's physiology, behavior and characteristics. Insects are reported to rely directly on the microbial community to break down complex food, adapt to nutrient-deficit environments, protect themselves from natural adversaries and control the expression of social behavior. High-throughput metagenomic approaches have enhanced the potential for determining the abundance, composition, diversity and functional activities of microbial fauna associated with insect hosts, enabling in-depth investigation into insect-microbe interactions. We undertook a review of some of the major advances in the field of metagenomics, focusing on insect-microbe interaction, diversity and composition of resident microbiota, the functional capability of endosymbionts and discussions on different symbiotic relationships. The review aims to be a valuable resource on insect gut symbiotic microbiota by providing a comprehensive understanding of how insect gut symbionts systematically perform a range of functions, viz., insecticide degradation, nutritional support and immune fitness. A thorough understanding of manipulating specific gut symbionts may aid in developing advanced insect-associated research to attain health and design strategies for pest management.

Comparative assessment of the gut bacterial diversity associated with field population of three rice stem borers and their in vitro insecticide degradation ability

Insects harbour diverse range of microbes in the digestive tract. An investigation was carried out to isolate and characterize the culturable gut bacterial fauna of three stem borers attacking rice (Scirpophaga incertulus, Sesamia inferens and Chilo suppressalis) morphologically, biochemically and genetically (based on 16S rDNA sequences). Their ability to degrade two commonly used insecticides, i.e., chlorpyrifos and chlorantraniliprole was quantified in vitro through minimal media study using GC–MS and HPLC, respectively. There was a great variation in the gut bacterial composition of these three borers in spite of belonging to same guild and being collected from the same host (Varshadhan: CRLC-899) at the same time from ICAR-NRRI farm, Cuttack, India. Bacillus was prominent in S. incertulus and C. suppressalis whereas Stenotrophomonas was dominant in S. inferens. It is the first report of encountering B. pumilus, B. cereus and Acinetobacter calcoaceticus from the gut of S. incertulus and Paraclostridium from the gut of S. inferens. Chlorpyrifos and chlorantraniliprole was degraded to the tune of 44.87–92.02 % and 10.52 to 74.38 %, respectively. B. subtilis most efficiently degraded chlorpyrifos, while Klebsiella sp. and A. calcoaceticus were superior in degrading Chlorantraniliprole. The gut bacterial consortium of S. inferens was the most efficient in degrading the insecticides. The differential abilities of the gut bacterial isolates to degrade the insecticides provide insights for their possible involvement in xenobiotic detoxification in their host and further study on this aspect may improve management strategies of these pests. These insects can also serve as novel sources for profiling insecticide-degrading microbes for bioremediation programmes.

Pt/MWCNT/ZnTiO3 nanocomposite: An efficient, reusable visible-light responsive photocatalyst for degradation of Thiamethoxam insecticide and methylene blue in aqueous phase

Surface modification and bandgap manipulation of ZnTiO3 are proposed to significantly enhance its photocatalytic activity by reducing charge carrier recombination. In this study, we developed a novel ternary photocatalyst by incorporating Pt nanoparticles (Pt NPs), multiwall carbon nanotubes (MWCNT) and ZnTiO3 nanostructures. The synthesis of ZnTiO3 was carried out using the sol-gel methodology, while the Pt@MWCNT/ZnTiO3 photocatalyst was fabricated through ultrasonication and photo-reduction routes. X-ray diffraction (XRD) analysis confirmed the formation of rhombohedral ZnTiO3, and transmission electron microscopy (TEM) examination revealed a well-dispersed arrangement of Pt NPs on the MWCNT/ZnTiO3 nanocomposite. The successful development of the Pt@MWCNT/ZnTiO3 photocatalyst was affirmed through Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectroscopy (EDS) examinations. A reduction in the bandgap energy was observed with the modification of ZnTiO3 to the ternary Pt@MWCNT/ZnTiO3. The newly developed Pt@MWCNT/ZnTiO3 photocatalyst demonstrated exceptional effectiveness, achieving a remarkable 92.62 % removal of the insecticide derivative thiamethoxam (TXM) in just 40 min under visible light. This represents 2.12 times greater efficiency than pure ZnTiO3. Moreover, the Pt@MWCNT/ZnTiO3 nanostructure exhibited remarkable efficacy in the degradation of methylene blue (MB) dye, eliminating its complex structure in just 12 min, with excellent reusability. The outstanding photodegradation capabilities of Pt@MWCNT/ZnTiO3 can be attributed to the presence of highly ordered mesoporous ZnTiO3, an increase in surface area, a favorable bandgap, and improved visible light absorption. Additionally, this Pt@MWCNT/ZnTiO3 photocatalyst demonstrated effective mitigation of charge carrier recombination. The highly efficient nature of the developed ternary Pt@MWCNT/ZnTiO3 photocatalyst holds substantial promise for widespread applications in environmental remediation activities.

New insights into chlorantraniliprole metabolic resistance mechanisms mediated by the striped rice borer cytochrome P450 monooxygenases: A case study of metabolic differences

The anthranilic diamide insecticide chlorantraniliprole has been extensively applied to control Lepidoptera pests. However, its overuse leads to the development of resistance and accumulation of residue in the environment. Four P450s (CYP6CV5, CYP9A68, CYP321F3, and CYP324A12) were first found to be constitutively overexpressed in an SSB CAP-resistant strain. It is imperative to further elucidate the molecular mechanisms underlying P450s-mediated CAP resistance for mitigating its environmental contamination. Here, we heterologously expressed these four P450s in insect cells and evaluated their abilities to metabolize CAP. Western blotting and reduced CO difference spectrum tests showed that these four P450 proteins had been successfully expressed in Sf9 cells, which are indicative of active functional enzymes. The recombinant proteins CYP6CV5, CYP9A68, CYP321F3, and CYP324A12 exhibited a preference for metabolizing the fluorescent P450 model probe substrates EC, BFC, EFC, and EC with enzyme activities of 0.54, 0.67, 0.57, and 0.46 pmol/min/pmol P450, respectively. In vitro metabolism revealed distinct CAP metabolic rates (0.97, 0.86, 0.75, and 0.55 pmol/min/pmol P450) and efficiencies (0.45, 0.37, 0.30, and 0.17) of the four recombinant P450 enzymes, thereby elucidating different protein catalytic activities. Furthermore, molecular model docking confirmed metabolic differences and efficiencies of these P450s and unveiled the hydroxylation reaction in generating N-demethylation and methylphenyl hydroxylation during CAP metabolism. Our findings not only first provide new insights into the mechanisms of P450s-mediated metabolic resistance to CAP at the protein level in SSB but also demonstrate significant differences in the capacities of multiple P450s for insecticide degradation and facilitate the evaluation and mitigation of toxic risks associated with CAP application in the environment.

Novel derivative compound produced from carbofuran insecticide degradation and transformation promoted by Pseudomonasfluorescens

Carbofuran insecticide is one of the insecticides most often used by Indonesian farmers. The United Nations Environment Program (UNEP) 2011 in the decision of UNEP/FAO/RC/CRC.11/6, agreed that the active ingredient Carbofuran is dangerous to human health and the environment. P. fluorescens bacteria are known to be able to remediate carbofuran-contaminated soil. This study examines more deeply the biodegradation and biotransformation processes of Carbofuran in P. fluorescens bacteria. The research was carried out at the Laboratory of Plant Diseases, Faculty of Agriculture, Brawijaya University; Analytical Chemistry Laboratory, State Polytechnic of Malang; and Analytical Chemistry Laboratory, Udayana University from February to August 2020. The results showed that P. fluorescens was able to degrade the insecticide Carbofuran in liquid media up to 82 % and the growth of P. fluorescens bacteria reached 2.9 x 1012 CFU/mL, bacteria P. fluorescens is able to degrade the insecticide Carbofuran in a mixture of soil and compost up to 85 % and the growth of P. fluorescens bacteria reaches 7.5 x 1013 CFU/mL, resulting in Carbofuran insecticide derivatives from the biotransformation process, there are 3-hydroxy-7-phenol; 2,3-dihydro-1-benzofuran-2,2,7-triol; (2Z)-2-[(2Z)-pent-2-en-1-ylidene]butane-1,4,4-trio; 7-phenol; 2,2,3-trihydroxy-2,3-dihydro-1-benzofuran-7-yl hydrogen carbonate; 2,2-dimethyl-2,3-dihydro-1-benzofuran-7-yl acetate; 7-(hydroxymethoxy)-2,3-dihydro-1-benzofuran-2,2,3,5-tetrol; 3-hidroksi-2-fenilpropil Carbamat; 2-(3-hydroperoxy-2-hydroxyphenyl)ethane-1,1-diol, 3-keto-7-fenol; 4-hydroxy-2,2-dimethyl-2,3-dihydro-1H-inden-1-one; 3-hydroxy-carbofuran; and 7-methoxy-2,2-dimethyl-2,3-dihydro-1-benzofuran-3,5-diol. Carbofuran derivative compounds from the biodegradation of P. fluorescens bacteria are less toxic than the active ingredient Carbofuran.

Co-Mn-Fe spinel-carbon composite catalysts enhanced persulfate activation for degradation of neonicotinoid insecticides: (Non) radical path identification, degradation pathway and toxicity analysis

The extensive utilization of neonicotinoid insecticides (NNIs) in agricultural practices ultimately poses a significant threat to both the environment and human health. This work focuses on the efficient degradation and detoxification of the representative NNI, thiamethoxam (THX), and explores the underlying mechanism using a Co-Fe-Mn mixed spinel doped carbon composite catalyst activated persulfate. The findings demonstrate that the composite effectively degrades THX, achieving a degradation rate of 95% in 30 mins, while requiring only a fraction (one-sixteenth) of the oxidant dosage compared to pure carbon. The study aimed to examine the negative impact of reactive halogens on reactive oxygen species within a saline environment. The degradation byproducts were linked to the presence of two common electron-withdrawing groups, namely halogens and nitro in the THX molecule. It was hypothesized that the degradation process was primarily influenced by C-N bond breaking and hydroxylation occurring between the diazine oxide and 2-chlorothiazole rings. Consequently, dehalogenation and carbonylation processes facilitated the elimination of halogenated components and pharmacophores from the THX, leading to detoxification. In addition to the identified free radical pathway including SO4•−, •OH and O2•− contributed to THX degradation, the participation of non-radical pathways (1O2 and electron transfer) were also confirmed. The efficacy of detoxification was further validated through toxicity assessment, employing quantitative conformation relationship prediction and microbial culture utilizing Bacillus subtilis.

Photocatalytic Degradation of Neonicotinoid Insecticides over Perlite-Supported TiO2

The aim of this study was to investigate the photocatalytic degradation of the neonicotinoid insecticide acetamiprid in aqueous solution. Experiments were carried out in a 250 mL batch reactor with recirculation of the reaction mixture and using a UVA-LED radiation source with a heterogeneous UVC-modified perlite-based TiO2 photocatalyst. The photocatalytic degradation of acetamiprid was optimized using a Box–Behnken design (BBD) of the response surface methodology (RSM). The variables in the process optimization were catalyst type, volume of the reaction mixture, and light radiation intensity. From the experimental data obtained, the conversions of the photocatalytic reactions, the reaction rate constants, and the mean square deviations were calculated. The experimental results have shown that the conversion of the reaction is significantly affected by the type of catalyst, i.e., the method used to immobilise the photocatalytic layer on the perlite granules. The highest conversions of 48.49% were reached with catalysts obtained by impregnation methods, while the conversions were quite low (8.68%) for catalysts obtained by sol-gel methods. It was also found that the highest conversions were achieved with the highest radiation intensity and the smallest volume of reaction mixture.

Comparative analyses of the effects of sublethal doses of emamectin benzoate and tetrachlorantraniliprole on the gut microbiota of Spodoptera frugiperda (Lepidoptera: Noctuidae).

Spodoptera frugiperda (J. E. Smith) is an important invasive pest that poses a serious threat to global crop production. Both emamectin benzoate (EB) and diamide insecticides are effective insecticides used to protect against S. frugiperda. Here, 16S rRNA sequencing was used to characterize the gut microbiota in S. frugiperda larvae exposed to EB or tetrachlorantraniliprole (TE). Firmicutes and Proteobacteria were found to be the dominant bacterial phyla present in the intestines of S. frugiperda. Following insecticide treatment, larvae were enriched for species involved in the process of insecticide degradation. High-level alpha and beta diversity indices suggested that exposure to TE and EB significantly altered the composition and diversity of the gastrointestinal microbiota in S. frugiperda. At 24 h post-EB treatment, Burkholderia-Caballeronia-Paraburkholderia abundance was significantly increased relative to the control group, with significant increases in Stenotrophobacter, Nitrospira, Blastocatella, Sulfurifustis, and Flavobacterium also being evident in these larvae. These microbes may play a role in the degradation or detoxification of EB and TE, although further work will be needed to explore the mechanisms underlying such activity. Overall, these findings will serve as a theoretical foundation for subsequent studies of the relationship between the gut microbiota and insecticide resistance in S. frugiperda (J. E. Smith) (Lepidoptera: Noctuidae).

Efficient Knocking Out of the Organophosphorus Insecticides Degradation Gene opdB in Cupriavidus nantongensis X1T via CRISPR/Cas9 with Red System.

Cupriavidus nantongensis X1T is a type strain of the genus Cupriavidus, that can degrade eight kinds of organophosphorus insecticides (OPs). Conventional genetic manipulations in Cupriavidus species are time-consuming, difficult, and hard to control. The clustered regularly interspaced short palindromic repeat (CRISPR)/associated protein 9 (Cas9) system has emerged as a powerful tool for genome editing applied in prokaryotes and eukaryotes due to its simplicity, efficiency, and accuracy. Here, we combined CRISPR/Cas9 with the Red system to perform seamless genetic manipulation in the X1T strain. Two plasmids, pACasN and pDCRH were constructed. The pACasN plasmid contained Cas9 nuclease and Red recombinase, and the pDCRH plasmid contained the dual single-guide RNA (sgRNA) of organophosphorus hydrolase (OpdB) in the X1T strain. For gene editing, two plasmids were transferred to the X1T strain and a mutant strain in which genetic recombination had taken place, resulting in the targeted deletion of opdB. The incidence of homologous recombination was over 30%. Biodegradation experiments suggested that the opdB gene was responsible for the catabolism of organophosphorus insecticides. This study was the first to use the CRISPR/Cas9 system for gene targeting in the genus Cupriavidus, and it furthered our understanding of the process of degradation of organophosphorus insecticides in the X1T strain.

Effect of pH, Dissolved Organic Carbon, and Sodium Dodecyl Sulfate to Degradation of Fenobucarb Insecticide in Paddy Soil-Water System

ABSTRACT In paddy rice farming systems, the degradation of insecticides from the soil reduces their occurrence as well as their levels in surface and groundwater. Degradation of insecticide fenobucarb in the paddy soil-water system was carried out by surface soil collected from paddy rice in the Hue province of Vietnam. Experiments were conducted using a batch technique, the fenobucarb-spiked paddy soils were shaken end-over-end with solutions of pH 7, pH 9, 25 mg L−1 DOC, and 1 critical micelle (cmc) sodium dodecyl sulfate (SDS). After each period (24, 48, 72, … 144 hours), the soil solutions were separated into the aliquot and the solid phase to analyze fenobucarb and intermediate metabolic products 2-sec-butyl phenol. The decrease of fenobucarb and the appearance of (2-sec-butyl-phenol) were the result of hydrolysis and biodegradation by fenobucarb-acclimatized microorganisms that were capable of degrading fenobucarb in the paddy soil. The degradation of fenobucarb in both the soil and water phases in the paddy soil-water system was enhanced in the experiment with pH 7, followed by those with pH 9, 25 mg L−1 DOC, and 1 cmc SDS. With pH 9, in addition to decomposition by bacteria present in the soil, fenobucarb was hydrolyzed under basic conditions. The presence of 25 mg L−1 DOC and 1 cmc SDS in the aqueous solution increased desorption and microbial activity in the soil and increased the biodegradation efficiency of fenobucarb in the paddy soil-water system. However, the degradation of fenobucarb in the 1 cmc SDS solution was inhibited because SDS solution may be preferentially utilized by microorganisms, and fenobucarb would have a competitive effect with SDS. Irrigation water for paddy fields often receives untreated domestic and industrial wastewater that may contain multiple compounds such as DOC and SDS. Therefore, it contributes to the elimination of fenobucarb insecticide in the paddy soil-water system.

In situ growth of CuFeS2/CuS bridged heterojunction catalyst with mixed redox-couple cations for excellent photocatalytic degradation of organophosphate insecticide: CFD and DFT modeling

The coupling of interfacial electron transfer engineering and mass transfer booster photoreactors has merged as a promising strategy for facilitating photogenerated charge carriers' consumption capability and maximizing photocatalytic efficiency. Herein, a type II visible-light-driven CuFeS2/CuS (CFC) p-n heterojunction was synthesized for photocatalytic degradation of the Malathion (MA) in a compact static mixer photoreactor (SMPR). Physicochemical, photoelectrochemical and density functional theory (DFT) analyses verify the characteristics of type II p-n homojunction and interfacial charge transfer that exists between the interlayer in n-type CuFeS2 and p-type CuS and create an ultrahigh electron transfer tunnel. This system accelerates the separation of photoinduced electrons as well as increases the yields of reactive species (•O2−, h+ and •OH). The CuFeS2/CuS heterojunction revealed high photocatalytic activity, which can completely degrade malathion (25 mg/L) in an aqueous solution within 80 min. Additionally, the computational fluid dynamics (CFD) technique was applied to study the hydrodynamics studies of the photoreactor. The magnitude of solution velocity, photocatalyst particles’ trajectory, and malathion concentration profile was analyzed according to the CFD results and further validated based on the experimental data. The total degradation efficiency of malathion was achieved at 80 min. This study enables deep insights into the risk assessment of intermediates and their toxicity as well as promotes new avenues in the photocatalytic process for the effective degradation of organic pollutants in wastewater.

Biodegradation of the nitrile-containing insecticides sulfoxaflor, flonicamid, thiacloprid, and acetamiprid by immobilized Escherichia coli harboring genes of nitrile hydratase and a cobalt transporter

The nitrile-containing insecticides sulfoxaflor, flonicamid, thiacloprid, and acetamiprid are used widely in agriculture, polluting the environment and harming animals. The Co2+-dependent enzyme nitrile hydratase (NHase) is a powerful tool for the degradation of nitrile-containing insecticides. Here, the NHase activities of Escherichia coli pET28a-PsNHase, harboring Pseudomonas stutzeri CGMCC 22915 (Ps) NHase gene, and E. coli pET28a-PsNHase-PsCbiM, harboring genes of PsNHase and a cobalt transporter PsCbiM, were compared. The presence of PsCbiM promoted PsNHase activity. E. coli pET28a-PsNHase-PsCbiM was immobilized using calcium alginate, which increased the tolerance of its NHase to acidic, alkaline, and high-temperature environments. Immobilized E. coli pET28a-PsNHase-PsCbiM was applied to degrade sulfoxaflor, flonicamid, thiacloprid, and acetamiprid. These insecticides were both substrates and inhibitors of immobilized E. coli pET28a-PsNHase-PsCbiM. Substrate inhibition model assays showed that the optimum initial concentrations of sulfoxaflor, flonicamid, thiacloprid, and acetamiprid for degradation by immobilized cells were 455.01, 195.50, 139.20, and 410.26 μmol/L, respectively. Degradation of nitrile-containing insecticides by immobilized engineered E. coli cells was reported here for the first time. This study provides a novel and excellent bioremediation agent for treatment of wastewater contaminated with nitrile-containing insecticides.

Adsorption and degradation of neonicotinoid insecticides in agricultural soils.

The adsorption and degradation of seven commercially available neonicotinoid insecticides in four types of agricultural soils from three states (Mississippi, Arkansas, and Tennessee) in the USA were studied. The adsorptions of all the neonicotinoids fit a linear isotherm. The adsorption distribution coefficients (Kd) were found to be below 2.0 L/kg for all the neonicotinoids in all the soils from Mississippi and Arkansas. Only in the Tennessee soilsamples, the Kd ranged from 0.96 to 4.21 L/kg. These low values indicate a low affinity and high mobility of these insecticides in the soils. The soil organic carbon-water partitioning coefficient Koc ranged from 349 to 2569 L/kg. These Kd values showed strong positive correlations with organic carbon content of the soils. The calculated Gibbs energy change (ΔG) of these insecticides in all the soils ranged from - 14.6 to - 19.5kJ/mol, indicating that physical process was dominant in the adsorptions. The degradations of all these neonicotinoids in the soils followed a first-order kinetics with half-lives ranging from 33 to 305days. The order of the insecticides with decreasing degradation rate is as follows: clothianidin > thiamethoxam > imidacloprid > acetamiprid > dinotefuran > thiacloprid > nitenpyram. The moisture content, clay content, and cation exchange capacity showed positive effects on the degradation rate of all the neonicotinoids. The Groundwater Ubiquity Score (GUS) calculated from the adsorption distribution coefficient, organic content, and half-life indicates that, except for thiacloprid, all the neonicotinoids in all the soils are possible leachers, having potentials to permeate into and through groundwater zones.