A Study Of Treatment Of Waste Water With Sulfate Radical In Heterogeneous Conditions

In this study, we choose Rhodamine B as the target pollutants because of according to data display, among the discharge of industrial waste water in China, textile waste water emissions up to 23 billion tons per year,which occupied the total emissions of waste water at the rate of 10.6%,ranked the third. Among the large number of textile waste water,dyeing waste water occupied the total emissions of waste water at the rate of 80%, so the study on dye waste water treatment methods is very meaningful.Advanced oxidation technology can be roughly divided into two categories:homogeneous reaction and heterogeneous reactions. In this study, we used heterogeneous, in the catalyst preparation process, used activated carbon as carrier, by the aging calcination method of transition metal iron supported on activated carbon, and characterized by XRD.The results showed that iron is loaded on activated carbon in the form of oxides. In this study,we used the Fe/AC catalyze persulfate(K2S2O8), which can make sulfate radical free radical with strong oxidizing property(·SO4-)to degradation RhB solution. The optimum conditions for the preparation of the catalyst were determined, and then catalyst dosage, oxidant dosage,initial concentration of reaction solution, initial pH and temperature of reaction solution were confirmed, the best experimental conditions for degradation of RhB was obtained. Due to the microwave, ultrasound, UV light can be coordinated to promote the production of sulfate radical,the effects of different variables on the experiment were investigated in the microwave system, the ultrasonic system and the ultraviolet irradiation system, then the best experimental conditions for degradation of RhB was obtained. In the above four reaction systems, the free radicals generated during the reaction were verified, and the UV-Vis absorption spectra were analyzed.The results following:(1)At room temperature, the dosage of Fe/AC was 1.5g/L, K2S2O8 dosage was 0.6g/L,under the conditions of initial pH of solution, the decolorization rate could reach over 80%for RhB solution of 100mg/L 2.5h later; higher temperature is favorable for the decolorizationof RhB, the decolorization of RhB may reach 99% when the temperature is 65℃.(2)Under microwave assisted conditions, the dosage of Fe/AC was 0.6g/L, K2S2O8 dosage was 0.4g/L, under the conditions of initial pH of solution, the decolorization rate could reach over 76% for RhB solution of 100mg/L 50 min later. Compared with room temperature condition, microwave assisted greatly shorten the time required for the decolorization of RhB.(3)Under ultrasound assisted condition, the dosage of Fe/AC was 1.2g/L, K2S2O8 dosage was 0.8g/L, under the conditions of initial pH of solution, the decolorization rate could reach over 70% for RhB solution of 100mg/L 40 min later. RhB decolorization rate increased by27% compared with that without ultrasound.(4)Under UV irradiation, the dosage of Fe/AC was 1.5g/L, K2S2O8 dosage was 0.4g/L,under the conditions of initial pH of solution, the decolorization rate could reach over 73%for RhB solution of 100mg/L 2.5h later. Compared with Fe/AC-K2S2O8, the decolorization of RhB increased 15%.In the above four systems, according to the verification experiment of free radical, ·SO4-and ·OH decolorization of RhB solution together.