Simultaneous Removals of Cr(VI) and Organic Pollutants using Photocatalyst with Ion Exchange Membranes

• Main Authors: Din-Lit Ho, 何頂立
• Other Authors: 陳孝行
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/4am9ge

碩士 === 國立臺北科技大學 === 環境工程與管理研究所 === 96 === In this research using Photocatalysis theory is that photocatalistic utilizes UV light to excite electric-hole pairs accordingly e- and h+. TiO2 can not only be oxidized by electric-hole, but also can reduce the contaminant by electric. In other words, the oxidant contaminant is degraded when the electric exists in water; witch is according to Le Chatelier''s principle that consumption of the e- can increase h+. Therefore, the result shows the treatment rate of using TiO2 simultaneous treatment oxidant and reductant contaminants is better than single rate, and this is the first step of this research. According to photocatalysis theory, TiO2 not only can not only be oxidized, but also can reduce the contaminants. When simultaneous treatment Cr(VI) and EDTA are 50mg/L by 1.00g/L TiO2, simultaneous treatment Cr(VI) removal efficiency is more than single 27.9%. If the adding of TiO2 is more than 1.00 g/L, it can cause block effect that decreases the removal rate. Because simultaneous treatment efficiency is more than single, EDTA concentration can be enhanced to 400 mg/L. Therefore, it is the best result found to deal with Cr(VI) for 50 mg/ L and organic pollution in 400 mg/L in the water, and Cr(VI) is over 99% of the efficiency rate during 120 minutes; moreover, the efficiency of EDTA at one minute can also be over 96%.. According to the mass balance, it can be found that chromate has loss mass. Analysis results of XRD and EDS show that photocatalistic absorbs some chromate on its surface about 41~48% by adding TiO2 1.00 g/L. The best is under the acid condition with the response condition of dealing with these two kinds of contaminants. When the pH value is adjusted to neutral or base, their response decreases. When we combine ion exchange membrane and deal with two kinds of contaminants, we can discuss the inside reaction. Because electric hole reacts with organic pollution using ion exchange membrane, it shows that electric-hole pairs surface strength can be reduced. According to radius of ion and electric neutralization of two side of membrane, Cr(III) could not pass through the caion exchange membrane, Cr(III) could be oxidized back Cr(VI), and it shows that photocatalistic has simutanious oxidant and reduction contaminants. When single removal or organic pollution is not enough, Cr(VI) is reduced into Cr(III), according to Le Chatelier''s principle.