In agricultural production, pesticides play an important role in increasing crop yields. However, pesticide residues are caused by improper handling by users during the production process. Chlorine dioxide and ozone, as strong oxidants with similarity in spatial structure, effectively degrade pesticide residues and are widely used in water treatment and the food industry. In order to better understand the mechanism of chlorine dioxide and ozone on pesticides, the properties of chlorine dioxide and ozone are introduced in this review. Herbicides, insecticides, and fungicides were selected for this study, and the influencing factors, kinetics, and degradation pathways of degraded pesticides are presented. The degradation of pesticides by chlorine dioxide follows the second-order kinetic model, reacting with functional groups with high electron density in pesticides by electron transfer. Ozone selectively undergoes electrophilic reactions with pesticides in solution. In addition, when the reaction system is alkaline, ozone accelerates the decomposition to form hydroxyl radicals ($·\mathrm{O}\mathrm{H}$), which react with pesticides. Ozone degradation of pesticides satisfies the pseudo-first-order kinetic model. By comparing the mechanism of pesticide degradation by chlorine dioxide and ozone, this paper provides a theoretical basis for solving the problem of pesticide residues in the food industry and water treatment in the future.

With the development of the chemical industry, benzene, toluene, ethylbenzene, and xylene (BTEX) have gradually become the major indoor air pollutants. Various gas treatment techniques are widely used to prevent the physical and mental health hazards of BTEX in semi-enclosed spaces. Chlorine dioxide (ClO₂) is an alternative to chlorine as a secondary disinfectant with a strong oxidation ability, a wide range of action, and no carcinogenic effects. In addition, ClO₂ has a unique permeability which allows it to eliminate volatile contaminants from the source. However, little attention has been paid to the removal of BTEX by ClO₂, due to the difficulty of removing BTEX in semi-enclosed areas and the lack of testing methods for the reaction intermediates. Therefore, this study explored the performance of ClO₂ advanced oxidation technology on both liquid and gaseous benzene, toluene, o-xylene, and m-xylene. The results showed that ClO₂ was efficient in the removal of BTEX. The byproducts were detected by gas chromatography-mass spectrometry (GC-MS) and the reaction mechanism was speculated using the ab initio molecular orbital calculations method. The results demonstrated that ClO₂ could remove the BTEX from the water and the air without causing secondary pollution.

The leachate generated from a landfill can cause significant harm to the environment and human health, so it must be treated before being discharged. A biochemical method is effective to treat the landfill leachate, but it requires a physicochemical pretreatment to help reduce the organic load and improve the biodegradability of the landfill leachate. In this work, hydrodynamic cavitation was used to pretreat the landfill leachate due to it being cost-effective, without additional chemicals, and environmentally friendly. The pretreatment experiments were conducted under an inlet pressure of 0.4 MPa and a basic pH. The influence of operating parameters such as the orifice opening rate, the arrangement of orifices, and the reaction time on the chemical oxygen demand, ammonium nitrogen, and biochemical oxygen demand removal in landfill leachate was studied, and the energy efficiency was evaluated. The results showed that under the above conditions, the removal rate for the chemical oxygen demand of the orifice plate with an annular orifice arrangement was better than that of the orifice plate with a radiation orifice arrangement, and the orifice plate with an orifice opening rate of 0.0417 had the best effectiveness. The energy efficiency under these two optimization conditions was also the highest. When the optimal operation time was 60 min, the removal rate of the chemical oxygen demand was 22.63%. The biodegradability of the landfill leachate was significantly improved with BOD₅/COD increasing by 57.27%. The study provides a theoretical basis and data support for the application of hydrodynamic cavitation as a low-cost and efficient treatment method in the pretreatment of landfill leachate.

2,2′,4,4′,6,6′-hexanitrostilbene (HNS) is a heat-resistant, low-sensitivity energetic material with widespread applications in pliable linear-shaped charges, high-temperature-resistant oil well perforating charges, and rocket propellants. However, the presence of highly toxic and mutagenic nitroaromatic compounds in HNS wastewater necessitates efficient and accurate detection methods. Unfortunately, the existing analytical methods for HNS detection are outdated and incompatible with modern equipment. This limits their application due to issues with detection range, accuracy, and cost. To address this gap, an improved method was developed using an Ultimate 3000 UHPLC system with methanol and water as the mobile phase and UV-Vis detection at 271 and 226 nm wavelengths. The results indicate that the optimal detection conditions are achieved with a methanol-to-water ratio of 70:30 and a flow rate of 0.5 mL/min, providing high accuracy and efficiency. Compared to traditional methods, this approach reduced the detection time by nearly 70%, with the shortest analysis time ranging from 6 to 6.5 min, significantly lowering the cost of HNS detection. The method demonstrated excellent linearity (R² > 0.9999) and high sensitivity within the concentration range of 0.50–150.00 mg/L, with precise and reliable results. This work provides both theoretical insights and experimental validation for the detection and analysis of HNS in wastewater.