| Budget Amount *help |
¥7,100,000 (Direct Cost: ¥7,100,000)
Fiscal Year 1999: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1998: ¥5,700,000 (Direct Cost: ¥5,700,000)
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| Research Abstract |
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.
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