Kinetics of Reactive Species in Water Produced by Ultraviolet Light Oxidation Processes

高级oxidation processes （AOPs）utilize reactive species produced by ultraviolet-light oxidationattracted much attention as创新技术for environmental conservation. The purposeof this study was to kinetically elucidate behavior of the reactive species in water for fundamentalinformation on photochemical reactor design.Model chemicals：ethanol (concentrations of 10ppm order) and its decomposition intermediates，acetic acid and oxalic acid in water，were decomposed in a batch-recycle photochemical-reaction system with (a) VUV(172nm) irradiation，(b) VUV+UVC(185+254nm) irradiationand (c) UVC(254nm) irradiation accompanied by H - D22 - D2O - D22 - D2. Concentrations of reactionintermediates （acetaldehyde, formaldehyde, acetic acid, oxalic acid）formic acid and TOC were sequentially determined；H - 22 D2O D22 - D2CO - D22 - D2 and pH changes were also traced. Experimental results were evaluated first by aconventional kinetic表达式，a new reaction model which took consideration of elementary processes incorporated inradiation chemistry.Regeneration rate of H - D22 - D2O - D22 - D2 was lower than those observed in theprevious decomposition experiments of methanol, formaldehyde, formic acidthe extent of regeneration solely depending on each reactant. Effect of organic concentration on TOCdecomposition rate was also low irrespective of组织species. Successful simulation of theoverall decomposition process was achieved by an analysis considering an extraordinarily longlife-time of hydroperoxy radicals与那些hydroxyl and organics-derived radicals. Part of the compared with those of hydroxyl and organics-derived radicals including ion radicals. Part of the研究工作presented at an international conference， APCRE99, in June 1999。

Advanced oxidation processes (AOPs), which utilize reactive species produced by ultraviolet-light oxidation, have attracted much attention as innovative technology for environmental conservation. The purpose of this study was to kinetically elucidate behavior of the reactive species in water for fundamental information on photochemical reactor design.Model chemicals: ethanol (concentrations of 10ppm order) and its decomposition intermediates, acetic acid and oxalic acid in water, were decomposed in a batch-recycle photochemical-reaction system with (a) VUV(172nm) irradiation, (b) VUV+UVC(185+254nm) irradiation, and (c) UVC(254nm) irradiation accompanied by HィイD22ィエD2OィイD22ィエD2. Concentrations of reaction intermediates (acetaldehyde, formaldehyde, acetic acid, oxalic acid, formic acid) and TOC were sequentially determined; HィイD22ィエD2OィイD22ィエD2, COィイD22ィエD2 and pH changes were also traced. Experimental results were evaluated first by a conventional kinetic expression, then by a new reaction model which took consideration of elementary processes incorporated in radiation chemistry.Regeneration rate of HィイD22ィエD2OィイD22ィエD2 was lower than those observed in the previous decomposition experiments of methanol, formaldehyde, and formic acid, the extent of regeneration solely depending on each reactant. Effect of organic concentration on TOC decomposition rate was also low irrespective of organic species. Successful simulation of the overall decomposition process was achieved by an analysis considering an extraordinarily long life-time of hydroperoxy radicals, compared with those of hydroxyl and organics-derived radicals including ion radicals. Part of the research work was presented at an international conference, APCRE99, in June 1999.