| As for pollution of printing and dyeing wastewater, this thesis summarizes the sort feature of printing and dyeing wastewater and their harms to environment, introduces the treatment methods of printing and dyeing wastewater and their evolvements, and analyzes advantages and disadvantages of different methods respectively. Subsequently jar test on decolorization of simulated wastewater of Reactive Red K-2BP (RR24) by sponge iron was carried, based which the decolorization kinetics was studied, the surface chemistry of sponge iron in reaction system was analyzed systematically, and bench-scale decolorization experiment was investigated.The jar test showed that the the decolorization rate of RR 24 at 60 min was up to 93.89% when particle diameter of sponge iron was 1~3mm, influent concentration was 30mg/L, and pH=7.5; High decolorization efficiency appeared when initial pH=6 and particle diameter of sponge iron was small; Decreasing influent concentration, increasing reaction temperature and dosage of sponge iron has been found to enhance the decolorization rate; Certain manganese mineral could catalyze the decolorization reaction, and the optimal mass ratio of manganese mineral to sponge iron was 1:18 through the experiment.Study on the decolorization kinetics showed that reaction order of decolorization of RR24 by sponge iron was 1.6; The model of decolorization kinetics including surface attenuation rate of sponge iron was expressed, which could well describe the process of the decolorization reaction; Based on the analysis of jar test data, the effects on the reaction velocity constant K and surface attenuation rate Ka were investigated by some factors, such as initial concentration, pH, temperature, particle diameter and dosage of sponge iron as well as the catalysis of manganese mineral.The mechanism of sponge iron corrosion cell has been further proved through the study on the surface chemistry of sponge iron, meanwhile certain manganese mineral... |
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