Study On Reductive Dechlorination Of Chlorinated Organic Compound By Bimetal Under Microwave Irradiation

Chlorinated organic compounds are harmful and refractory. Besides, the industrial wastewater with high concentration of chlorinated organic compounds has seriously imperiled human health and zoology environment. It has been an obligatory duty to purify this kind of wastewater. Hence, new technology employed to purify the chlorinated organic wastewater is imperative. At present, the bimetal dechlorination for chlorinated organic wastewater shows good application potential. In order to provide new wastewater treatment methods and new ways, the bimetal system under microwave irradiation to reductive dechlorination from chlorinated organic wastewater was investigated.The two main work includes: (1) Dechlorination from 1,1,2,2-tetrachloroethane (1,1,2,2-TeCA) simulated wastewater was investigated under Fe/Mn bimetal system with microwave irradiation, moreover, the mechanism and reaction pathways for dechlorination from 1,1,2,2-TeCA simulated wastewater under Fe/Mn bimetal system with microwave irradiation were analyzed. (2) Reductive dechlorination from neoprene wastewater was also investigated.The technique of cooperation of Fe/Mn bimetal system and microwave irradiation is applied in the treatment of chlorinated organic wastewater. Factors governing the dechlorination rate of 1,1,2,2-TeCA were experimentally studied including microwave power, dosage of bimetal, molar ratio of Fe to Mn, reaction temperature, initial pH value. Results show that the dechlorination rate of 100 mg/L 1,1,2,2-TeCA simulated wastewater 100 mL was up to 74.8% under optimum conditions following: microwave power 800 W for 100 min at 25℃with initial pH value 7, dosage of Fe/Mn 50 g/L, and molar ratio of Fe to Mn 1:3.The mechanism of dechlorination from 1,1,2,2-TeCA simulated wastewater by Fe/Mn bimetal under microwave irradiation was discussed in this paper. Oxidative corrosion could happen to Fe in water solution, and then Fe2+ generated was released into the solution. At the same time, protons in water solution are reduced to atomic H which then forms to molecular hydrogen at the iron surface. The hydrogen is then transferred and adsorbed to the Mn where it partially dissociates back to atomic hydrogen. The cleavage of the C-Cl bonds takes place via hydrodechlorination.It is feasible to dechlorinate from neoprene wastewater in Fe/Mn bimetal under microwave irradiation. The dechlorination rate of neoprene wastewater was 77.3% for 100 mL neoprene wastewater under the operation conditions following pH 6~7, Fe/Mn 50 g/L, molar ratio of Fe to Mn 1:3, and microwave power 800 W for 70 min at 25℃.