Sponge Iron Reduction Coupled With Microwave Strengthen The Heterogeneous Fenton Technology For The Leather Wastewater Treatment

With the Discharge standard of water pollutants for leather and fur making industry(GB30486-2013) promulgated, traditional leather wastewater treatment process has been difficult to meet the increasing requirements of wastewater discharge standards. According to the characteristics of leather wastewater and the harm to environment, This paper introduce the research progress at home and abroad for leather wastewater treatment. Deal with the problems, carry out the sponge iron pre-treatment coupled with microwave strengthen the heterogeneous Fenton technology for the leather wastewater treatment process. Studys mainly in the following aspects.(1) Sponge iron degradate of six common leather dyes. Select Acid Brown 98(AB), Eriochrome Black T(EB), Bismarck Brown R(BB), Acid Blue 9(AB), Reactive Brilliant Red X-3B(RR) and Direct Yellow(BY) leather dyes as the object. Study the sponge iron dosage, particle size, shaking speed, the initial concentration, initial pH, activation or not and other factors affecting the efficiency of leather decolorization.The results shows: under optimum conditions, the six decolorization efficiency reached 95.2%, 98.9%, 94.2%, 92.6%, 97.0% and 87.8%, respectively, and obtian good results of decolorization and degradation.(2) Sponge iron degradation and adsorption Cr(â…¥) in leather wastewater. Study the factors of sponge iron dosage, particle size, shaking speed, initial pH, initial concentration, temperature, the reaction system and other zero-valent iron affect the efficiency of removal Cr(â…¥) in leather wastewater. Under optimization parameters, the efficiency of removal Cr(â…¥) up to 95%. Using of sodium humic acid and tannins simulation humic acid, common inorganic ions in water simulation anion and cation ions to explore the impact on Cr(â…¥) removal efficiency.(3) Study the physical and chemical properties of the sponge iron surface before and after reaction by SEM, TEM, XRD, XPS, Mapping characterizations to explore the reaction mechanism. The results showed that, Cr(â…¥) reduction reactions generate Cr-Fe floc and iron oxide deposited on its surface, so the sponge iron gradually inactivated; with 2% hydrochloric acid in an ultrasonic system after regeneration 5min, it can be restore to original activity, and sponge iron BET, pore volume and pore diameter increased to varying degrees, so the sponge iron is a water treatment material can be recycled.(4) Microwave strengthen heterogeneous Fenton removal leather wastewater COD. Using response surface methodology based central composite design establish mathematical model, optimize the reaction conditions, predict test results.Sponge iron pretreatment can effectively removal the chromacity and Cr(â…¥)in leather wastewater, through microwave strengthen Fenton can quickly and efficiently reduce wastewater nonbiodegradable COD. This technology is a potential applications for leather wastewater treatment in future.