| The dye and printing wastewater is one of the main origins of the industry wastewater in our country. Because of the large chromaticity, toxicity, alkalinity, complex composition and so on, it can not be treated thoroughly via the traditional technologies. The wastewater does great harm to the environment and human health, therefore the innocuous treatment of dyeing wastewater has become an important problem in printing and dyeing industry and the environment protection. The residual dye molecules in the wastewater are the main reason to cause the high COD and the large chromaticity, so the removal of dye molecules has a very practical significance.In the research, the simulated dye wastewater was prepared by directly violet D-BL dye. Reduction product of siderite as the supporter, the carbon from three various carbon sources respectively was loaded. A novel iron-carbon composite material used for micro-electrolysis was prepared and the removal to the dye by it was studied. The factors to the removal rate like calcination conditions, the Fe/C ratio in the preparation process were investigated. The surface appearance and the elements composition of the prepared material ware characterized. Then, the material applied pulverized coal as the carbon source (F/C composites) was selected to research the dye removal property of the novel iron-carbon composite materials. And a comparative study between the F/C material prepared under optimal condition and the traditional micro-electrolysis material of the separation of iron and carbon was developed. Besides, the influence factors to the micro-electrolysis process of directly violet D-BL were studied, such as the salt concentration in the solution, the pH of the original wastewater, the reaction temperature and reaction time. Furthermore, a simulative experiment of filter column with the material was finished. The main experimental conclusions are as follows:(1) Via high-temperature solid-state method or impregnation/calcination method, the carbon was loaded into the surface of the reduction products of siderite. The experiment of the dye removal by it in the micro-electrolysis technology shows:The modified micro-electrolytic material F/C, applying of pulverized coal as carbon source and being calcinated at a high temperature, had a better dye removal ability than the materials prepared applied sucrose and starch as carbon source.(2) The key influence factors of the preparation process of The F/C composites via high-temperature solid-state method were the calcination temperature and the iron-carbon ratio. And the optimum preparation conditions of the material are an iron/carbon ratio of1:1and a calcination temperature of1200℃under nitrogen atmosphere. The F/C materials got a good removal to direct violet D-BL wastewater with90.27%.(3) The comparative study between the F/C material prepared under optimal condition and the traditional micro-electrolysis material of the separation of iron and carbon showed the F/C composites material was better and the decolorization rate of91.92%and78.66%respectively with processing time of24h.(4) The optimal treatment condition:materials particle size of60～80mesh, the influent pH7, a reaction temperature of25℃, and the reaction time of8h. The decolorization rate was up to95%. Besides, the concentration of inorganic anions in the original wastewater would promote the decolorization process.(5) The filter column filled with F/C composites material had a good running result. The running condition was flow rate of30ml/h, original dye concentration of100mg/L, Cl-concentration of20g/L and filled amount of5g. After running of35h, the dye removal rate still maintained at70%. By calculation, the treatment capacity to directly violet to D-BL of the prepared F/C composites is15.7mg/g.(6)The analysis of the reaction mechanism of new iron-carbon composite micro-electrolysis method showed that the entire reaction process is an electrochemical redox reaction and the comprehensive effect of the adsorption, oxidation and reduction, condensation, precipitation leaded to it. |
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