| Summary: | 碩士 === 國立交通大學 === 環境工程所 === 90 === GAC, a good adsorption, is often used of disposing polluted materials, or used of acting as the catalyst of heterogeneous reaction, owing to its enormous surface area, porous structure and characteristic flexibility. Recently, some researches put iron oxides or granular size solid catalysts (for example, graphite and activated carbon) to use in oxidation process, and they even consider to put this way practically using in the process of environmental disposal. This research is order to understand the influence of the surface treatment processes on the catalytic activity of supported iron oxide.
From the experiment of the disposal process, it shows that it doesn’t cause any effects on its surface by using H2O2 to wash GAC, but it does by using nitric acid; this may sharply reduce its specific surface area, make the average pore size increase, and the micropore volume decrease. Although GAC is washed by nitric acid which decreases the capability of absorbing organics, it highly increases the percentage of the rate of ER and ED in heterogeneous reaction. The stoichiometric efficiency, ER and ED, is defined individually as the ratio of the reduction and degradation amount of 4-CP to the decomposition amount of H2O2.
From the outcome of different iron oxide coated ways, it shows that the raising reactive rate of catalyzing H2O2 decomposition after silica sand is coated by iron oxide, and the reactive is similar to iron oxide, implying the role of the silica sand is only as a support. So silica sand is a good carrier for coated, but it is helpless to affect on the decomposition rate of H2O2.
However, after GAC is coated by iron oxide, the reaction is different from normal iron oxide; the rate of catalyst on certain modified base is faster than normal iron oxide apparently. Unlike the silica sand, GAC is not merely a carrier, and it does contribute to the catalytic activity on H2O2 decomposition. C-GAC has a better effect on decomposing H2O2, reducing and dechloring organics than uncoated GAC. The best coated way of GAC is to add drugs gradually and dip it in on multiple impregnation method. C-GAC gets its best removing effect at low pH condition; moreover, it doesn’t have any absolute relation between the iron quantity contained and the effects.
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