期刊
CHEMOSPHERE
卷 41, 期 8, 页码 1173-1180出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/S0045-6535(00)00009-6
关键词
methylene blue; hydrogen peroxide; supported alumina; oxidation; catalyst
The catalyzed kinetics of the oxidative mineralization of the cationic dye methylene blue, phenothiazonium, 3,7-bis(dimethylamino)-chloride, with hydrogen peroxide were studied both in buffered and unbuffered solutions. The supported alumina catalysts used were in the form of copper(II), cobalt(II), manganese(II), and nickel(II)-ions. Also, some copper(II)-complexes were used, e.g. copper(II)-ammine ([Cu(amm)(4)](2+)), copper(II)-ethylenediamine ([Cu(en)(2)](2+)) and copper(II)-monoethanolamine ([Cu(mea)(2)](2+)). The reaction is first order with respect to methylene blue. On the other hand, the order with respect to hydrogen peroxide is concentration range dependent. This range depends strongly on the catalyst used. At lower [H2O2], the order was 1 which then decreases with increasing [H2O2] passing through 0 at the maximum rate and finally becomes negative. This phenomenon is parallel to the formation of a colored intermediate on the surface of the catalyst. This suggests that the intermediate has an inhibiting effect on the rate of color removal. Moreover, the rate of the reaction was found to be strongly dependent on the pH of the solution and its ionic strength. It increases with increasing both pH and the concentration of added potassium chloride. Also, the rate of reaction is inhibited in presence of sodium dodecylsulfate anionic surfactant. The repeated use of the different catalysts showed that their catalytic activities are almost unaffected. A reaction mechanism was proposed with the formation of free radicals as reactive intermediates. (C) 2000 Elsevier Science Ltd. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据