Dimethoate degradation by VUV/UV process: Kinetics, mechanism and economic feasibility
| Autor: | Yubin Tang, Zhengdi Wu, Laxiang Yang, Mengkai Li, Zhimin Qiang |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Environmental Engineering
Vacuum Ultraviolet Rays Health Toxicology and Mutagenesis Radical 0208 environmental biotechnology Quantum yield 02 engineering and technology 010501 environmental sciences medicine.disease_cause Photochemistry 01 natural sciences Water Purification Chemical kinetics medicine Environmental Chemistry Dimethoate 0105 earth and related environmental sciences Photolysis Chemistry Photodissociation Public Health Environmental and Occupational Health General Medicine General Chemistry Pollution 020801 environmental engineering Kinetics Pesticide degradation Degradation (geology) Feasibility Studies Water treatment Oxidation-Reduction Ultraviolet Water Pollutants Chemical |
| Zdroj: | Chemosphere. 273 |
| ISSN: | 1879-1298 |
| Popis: | Vacuum ultraviolet/ultraviolet (VUV/UV) process has been applied to water treatment recently, but little is known about its efficacy and mechanism for pesticide degradation. This study investigated the degradation kinetics and mechanism of a typical organophosphorus pesticide, dimethoate (DMT) by VUV/UV, and then the economic feasibility was assessed. DMT degradation followed well the pseudo-first-order reaction kinetics at an initial concentration of ≤5.0 mg L−1. DMT was degraded by 97.8% after 10 min of VUV/UV exposure (VUV fluence = 12 mJ cm−2), whereas by only 5.2% after 10 min of UV exposure (UV fluence = 156 mJ cm−2). The apparent quantum yield of DMT degradation by VUV/UV was determined to be 0.19, and at most 50.7% of hydroxyl radicals (HO•) generated from VUV photolysis of water could be utilized for DMT degradation. As the pH increased from 5.0 to 9.0, the DMT degradation rate decreased from 0.43 to 0.23 min−1. DMT degradation pathways in the VUV/UV process were proposed based on identified organic intermediates and inorganic ions. SO42− was first released due to HO• attack on the S P bond of DMT, which governed the DMT degradation efficiency; while the release of PO43− was pertinent to the DMT mineralization efficiency. DMT solution toxicity was significantly reduced after VUV/UV treatment. An electrical energy-per-order (EEO) value of 0.57 kWh m−3 Order−1 demonstrated the economic feasibility of the VUV/UV process for DMT removal in small-scale drinking water treatment. |
| Databáze: | OpenAIRE |
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