The multiple roles of phenols in the degradation of aniline contaminants by sulfate radicals: A combined study of DFT calculations and experiments.

Recent research revealed inhibition or enhancement of dissolved organic matter (DOM) to the degradation of trace organic contaminants (TrOC) in natural and engineered water systems. Phenols containing acetyl, carboxyl, formyl, hydroxy, and methoxy groups were selected as the model DOM to quantitatively study their roles in the degradation of simple anilines, sulfonamide antibiotics, phenylurea pesticides by sulfate radicals (SO). Experimental results found that p-methoxyphenol inhibited aniline and sulfamethoxazole degradation by thermally activated peroxydisulfate (TAP), while p-acetylphenol slightly promoted aniline degradation.

Unravelling the effects of complexation of transition metal ions on the hydroxylation of catechol over the whole pH region.

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).

Theoretical insights into the degradation of swep by hydroxyl radicals in atmosphere and water environment: Mechanisms, kinetics and toxicity.

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.

Ozonolysis of Permethrin in the Atmosphere: Mechanism, Kinetics, and Evaluation of Toxicity.

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.

Atmospheric ozonolysis of crotonaldehyde in the absence and presence of hydroxylated silica oligomer cluster adsorption.

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.

Theoretical Study of Ozonation of Methylparaben and Ethylparaben in Aqueous Solution.

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.

Full insights into the roles of pH on hydroxylation of aromatic acids/bases and toxicity evaluation.

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.

Reactivity of aromatic contaminants towards nitrate radical in tropospheric gas and aqueous phase.

Aromatic compounds (ACs) give a substantial contribution to the anthropogenic emissions of volatile organic compounds. Nitrate radicals (NO) are significant oxidants in the lower troposphere during nighttime, with concentrations of (2-20) × 10 molecules cm. In this study, the tropospheric gas and liquid phase reactions of ACs with nitrate radical are investigated using theoretical computational methods, which can give a deep insight into the reaction mechanisms and kinetics.

Theoretical investigation on the contribution of HO, SO and CO radicals to the degradation of phenacetin in water: Mechanisms, kinetics, and toxicity evaluation.

Indirect oxidation induced by reactive free radicals, such as hydroxyl radical (HO), sulfate radical (SO) and carbonate radical (CO), plays an important or even crucial role in the degradation of micropollutants. Thus, the coadjutant degradation of phenacetin (PNT) by HO, SO and CO, as well as the synergistic effect of O on HO and HO were studied through mechanism, kinetics and toxicity evaluation. The results showed that the degradation of PNT was mainly caused by radical adduct formation (RAF) reaction (69% for Г, the same as below) and H atom transfer (HAT) reaction (31%) of HO.

Ozonation of diclofenac in the aqueous solution: Mechanism, kinetics and ecotoxicity assessment.

The pharmaceutical and personal care products (PPCPs) in aquatic environment have aroused more interest recently. Many of them are hard to degrade by the typical biological treatments. Diclofenac (DCF), as a significant anti-inflammatory drug, is a typical PPCP and widely existed in water environment.

Effect of pH on ·OH-induced degradation progress of syringol/syringaldehyde and health effect.

Syringol and syringaldehyde are widely present pollutants in atmosphere and wastewater due to lignin pyrolysis and draining of pulp mill effluents. The hydroxylation degradation mechanisms and kinetics and health effect assessment of them under high and low-NO regimes in atmosphere and wastewater have been studied theoretically. The effect of pH on reaction mechanisms and rate constants in their ·OH-initiated degradation processes has been fully investigated.

Degradation of prosulfocarb by hydroxyl radicals in gas and aqueous phase: Mechanisms, kinetics and toxicity.

Prosulfocarb (PSC) is a thiocarbamate herbicide mainly used in winter cereals and a relevant aerosol precursor under OH radicals (OH) photooxidation conditions. We investigated the environmental risks, mechanisms, kinetics and products for the PSC withOH by employing theoretical chemical calculations. Two reaction types of H-abstraction andOH-addition reactions were taken into account.

Mechanisms and Kinetic Parameters for the Gas-Phase Reactions of 3-Methyl-3-buten-2-one and 3-Methyl-3-penten-2-one with Ozone.

Ozonolysis of unsaturated ketones is a common atmospheric chemical process that plays a significant role in controlling the atmospheric budget of OH and O, organic acids, and secondary organic aerosols (SOA). In this work, the detailed reaction mechanism and rate coefficients for the reactions of O with two unsaturated ketones, 3-methyl-3-buten-2-one (MBO332) and 3-methyl-3-penten-2-one (MPO332), were investigated by using density functional theory (DFT) and Rice-Ramsperger-Kassel-Marcus (RRKM) theory. The results indicate that the major products are butanedione and formaldehyde for MBO332, and butanedione and acetaldehyde for MPO332.