Study On The Modified Fly Ash And Its Decolorizing Performance To The Azo Dye Wastewater

The dyeing wastewater presents the features of complicated component, deep chromes, anti-degradation and high toxicity. The environmental pollution is becoming increasingly serious. Therefore, the search for economic and effective approach has become an urgent need to be addressed. Fly ash, the industrial waste, has porous structure and special component. These properties have attracted extensive attention of the domestic and foreign scholars for its application in the dyeing wastewater treatment. But its low activity results in low decolorizing effect of the dyeing wastewater and restricts its practical application.In present paper, azo dyes acid black 10B and acid red B were selected as treating objects according to their characteristics of stability and anti-biodegradation. Fly ash was treated by acid and coated by special photocatalytical materials in order to improve its decolorizing performance. Moreover, the decolorization rules and mechanism was explored and the technological conditions were optimized. The main contents are as follows:(1) First, the characteristics and treatment ways of dyeing wastewater were introduced. Then source, composition, characteristics, applications and research progress were reviewed. In the end, main problems to be solved in this paper were presented.(2) The optimum technological conditions of fly ash's modification were determined.First, the fly ash was activated with sulfuric acid and the technological conditions of modification were discussed using the acid black 10B and acid red B solution as treating objects. Then, the modified fly ash was coated with ZnO, CeO2 or TiO2 respectively and the technological conditions of coating were studied.(3) The technological conditions of dyeing wastewater treatment were optimized.The optimum technological conditions of decoloration with fly ash were investigated by single factor experiments of calcination temperature, coating amount, the ratio of fly ash to water, reaction time, pH value, optical source and waste water concentration. The results provide a base for the practical application of fly ash. (4) The modified fly ash-H2O2 decolorizing system was established.The fly ash modified by acid can catalyzed the generation of free radical·OH from H2O2, which can degrade the acid red B effectively because of its strong oxidizing. So the modified fly ash-H2O2 decolorizing system has double functions of the adsorption and degradation.(5) The mechanism and kinetics of the decolorizing reaction was studied.