Publications by authors named "Zexiu An"

The design and synthesis of new herbicidal active compounds based on a new target are of great significance for the development of new herbicides. Transketolase (TK) plays a key role in the Calvin cycle of plant photosynthesis and has been confirmed as a potential candidate target to develop and discover new herbicides. To obtain compounds with ultraefficient targeting of TK, a series of pyrazole amide derivatives were designed and synthesized through structural optimization for lead compound based on TK as the new target.

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  • Dicamba is an effective herbicide used in combination with genetically modified crops, but its volatility can lead to drift damage to nearby sensitive plants.
  • The study developed a sensitive detection method for dicamba using nanobodies obtained from immunizing camels, leading to the creation of an indirect competitive immunoassay called Nb-242.
  • Nb-242 demonstrated strong specificity for dicamba and good correlation with standard detection methods, providing a reliable tool for environmental monitoring of this herbicide.
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Fomesafen belongs to the diphenyl ether herbicide, and is widely used in the control of broadleaf weeds in crop fields due to its high efficiency and good selectivity. The residual of fomesafen in soil has a toxic effect on subsequent sensitive crops and the microbial community structure because of its long residual period. Therefore, an efficient method for detecting fomesafen is critical to guide the correct and reasonable use of this herbicide.

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  • Mineral aerosol particles influence environmental risks related to liquid crystal monomers (LCMs) by affecting their chemical reactions with ozone (O).
  • The study examined the reaction mechanisms of three LCMs with O using density functional theory, revealing that O mostly attaches to the benzene ring, producing various aromatic compounds.
  • Titanium dioxide (TiO) interacts with LCMs by adsorbing them but slightly reduces their reactivity, allowing LCMs to persist and travel further, thus increasing contamination spread.
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Adjusting pH values in aqueous environments can significantly improve the efficiency by which parabens and halo-parabens are removed. In this study, 20 neutral and deprotonated species were selected as models to investigate their pH-dependent removal mechanisms and kinetics by a UV/HO process using density functional theory (DFT). Compared to neutral species, deprotonated species exhibit higher reactivity to HO due to their high electron cloud density.

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Halogenated α, β-unsaturated C-dicarbonyl (X-BDA), a novel family of high-toxicity ring cleavage products, is produced during the disinfection of phenolic compounds. The technique of electrocatalytic hydrodehalogenation (ECH) is efficient in rupturing carbon-halogen bonds and generating useful chemicals. This study used first principles to examine the ECH reaction mechanism of X-BDA and the subsequent hydrogenation reaction of the toxic derivative BDA over the 1 T'-MoS/TiCT (T = O, OH, F) catalysts.

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In this work, the hydroxylation mechanisms and kinetics of some emerging disinfection byproducts (DBPs) have been systematically investigated through theoretical calculation methods. Five chlorophenols and eleven halogenated pyridinols were chosen as the model compounds to study their pH-dependent reaction laws in UV/HO system. For the reactions of HO with 37 different dissociation forms, radical adduct formation (RAF) was the main reaction pathway, and the reactivity decreased with the increase of halogenation degree.

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Residues in surface water of ribavirin, which used extensively during the COVID-19 pandemic, have become an emerging issue due to its adverse impact on the environment and human health. UV/HO and UV/peroxydisulfate (PDS) have different degradation effects on ribavirin, and the same operational parameter have different effects on the two processes. In this study, the reaction mechanism and degradation efficiency for ribavirin were studied to compare the differences under UV/HO and UV/PDS processes.

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Aromatic disinfection by-products (DBPs), which are generally more toxic than aliphatic DBPs, have attracted increasing attention. The toxicity of 13 typical halophenols on Scenedesmus obliquus was experimentally investigated, and the ozonation mechanism and kinetics of representative halophenols were further studied by quantum chemical calculations. The results showed that the EC values of halophenols ranged from 2.

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Herbicide residues in the environment threaten high-quality agriculture and human health. Consequently, in situ remediation of herbicide contamination is vital. We synthesized a novel self-catalyzed nanozyme, ultrasmall (2-3 nm) copper peroxide nanodots modified by citric acid (CP@CA) for this purpose, which can break down into HO and Cu in water or soil.

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Metal-free photocatalysts for high efficient photocatalytic degradation of pollutants have attracted growing concern in recent years. Herein, relying on density functional theory (DFT) calculations, boron and phosphorus doped CN layers were explored for the potential of utilization as photocatalysts for 4, 5-dichloroguaiacol (4, 5-DCG) removal. Our computations revealed that the adsorption energy of 4, 5-DCG on B@N-doped CN layers were 26.

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Catechol pollutants (CATPs) serving as chelating agents could coordinate with many metal ions to form various CATPs-metal complexes. Little information is available on the effects of complexation of metal ions on CATPs degradation. This work presents a systematical study of •OH-mediated degradation of catechol and catechol-metal complexes over the whole pH range in advanced oxidation processes (AOPs).

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Low-molecular-weight (LMW) phthalate acid esters (PAEs) tend to enter the atmosphere, flying for several kilometers, so it is easy to endanger human health. This work is the first to use quantum chemistry calculations (Gaussian 16 program) and computational toxicology (ECOSAR, TEST, and Toxtree software) to comprehensively study the ozonolysis mechanism of six LMW PAEs (dimethyl phthalate (DMP), diethyl phthalate (DEP), dipropyl phthalate (DPP), diisopropyl phthalate (DIP), dibutyl phthalate (DBP), and diisobutyl phthalate (DIBP)) in the atmosphere and the toxicity of DMP (take DMP as an example) in the conversion process. The results show that the electron-donating effect of the ortho position of the LMW PAEs has the most obvious influence on the ozonolysis.

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Chlorine-based advanced oxidation processes (AOPs) have been extensively studied to remove contaminants through generating HO and reactive chlorine species, including ClO and Cl. In this work, 2,4,6-tribromoanisole (246TBA) and 2,4,6-tribromophenol (246TBP) were selected as model to investigate the reaction mechanisms and micro-kinetics of brominated contaminants with HO, ClO and Cl in chlorine-based AOPs. Also, the apparent degradation kinetics of two compounds were simulated at pH 3.

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As an excellent conductive herbicide, swep is widely used in weed removal. Its remaining in atmosphere and water can not only contaminate the environment but also pose a threat to human health. This work presented a systematic theoretical study of HO-mediated degradation mechanisms and kinetics of swep in atmosphere and water environment.

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Article Synopsis
  • Research on radical oxidation processes using peracetic acid is limited, focusing on the reactions of acetaminophen (ACT) with hydroxyl and organic radicals.
  • The study calculated the reactivities of key organic radicals and found that CHCOO and HO are the most effective in degrading ACT, with CHCOO also playing a significant role in hydroxylating aromatic compounds.
  • CHCOOO demonstrated high reactivity, particularly with phenolate and aniline, and the hydroxylation by CHCOO may produce more toxic hydroxylated products.
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Pyrethroid, a pesticide widely used worldwide, could mimic, block, or synergize the effects of endogenous hormones in humans or mammals after entering into the atmosphere and after being sprayed and applied in large quantities. This research aims to study the mechanism, kinetics, and eco-toxicity evaluation of the ozonolysis of permethrin (PER)-one of the typical pyrethroid (type I) pesticides. Existing experimental studies only predicted that ozonolysis of PER could generate a cycloperoxy analogue of PER (IM13-1-11), and the reaction mechanism has not yet been completed.

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As one of the main components of combustion of tobacco products occurs (CARB), crotonaldehyde has an acute toxicity and widely exists in the atmosphere, which is harmful to human health. The removal efficiency of VOCs by ozonation can reach 80-90%. Based on the theory of quantum chemistry, the degradation mechanism, kinetics and toxicity of crotonaldehyde by ozonation in gas phase and heterogeneous phase were studied.

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  • ClO and BrO are newly identified reactive radicals that help break down micropollutants, but more research is needed on their effectiveness in this area.
  • A study on caffeine's degradation revealed that the dominant reaction for HO, ClO, and BrO involves radical adduct formation, with specific reaction sites varying for each radical.
  • The research found that while ClO has a significant role in caffeine degradation, it and BrO do not produce stable harmful intermediates, though caffeine and its breakdown products can be toxic to both humans and aquatic life.
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Parabens are widely employed in toothpaste, cosmetics, textiles, beverages, and preservatives, causing a serious environmental concern because they are endocrine-disrupting compounds (EDCs). As one of the highly reactive oxidants, ozone has a great effect on EDC removal. To understand the degradation and transformation of parabens in the aquatic environment and their toxicity to aquatic organisms, the degradation reaction of parabens initiated by O was studied meticulously using quantum chemical calculations.

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Advanced oxidation processes (AOPs) based on hydroxyl radicals (•OH) are the most important technologies for the removal of bio-recalcitrant organic pollutants in industrial wastewater. The pH is one of the crucial environmental parameters that affect the removal efficiency of pollutants in AOPs. In this work, the mechanistic and kinetic insights into the roles of pH on the hydroxylation of five aromatic acids and bases in UV/HO process have been investigated using theoretical calculation methods.

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