湿法制磷酸废水中的有毒砷的消减

Degradation of Arsenic in Wastewater of Wet-process Phosphoric Acid

采用物理吸附、光催化及化学絮凝三种方法对宜昌一化工有限公司湿法制磷酸中含As废水(砷含量为13.56mg/L)进行了消减研究,三种方法中:物理吸附法活性炭的饱和吸附含量是1.0 g/50mL,此时废水84.4%的As被吸附除去,黏土的吸附试验中未发现吸附饱和现象;化学氧化法中,Fenton试剂最佳浓度比为[H2O2]∶[Fe3+]=200∶1,此时可以将82.2%的As3+氧化为低毒的As5+;化学絮凝法中,絮凝剂-96、絮凝剂-98及硅藻土三种絮凝剂作用的最佳pH分别为12.6、12.6、11.8,絮凝剂的最佳用量分别为10、9、13.0 mg/mL对废水中As3+转化率分别为65.7%、73.2%、76.3%.设计了含As废水处理装置,经处理后废水中As的含量达到国家工业废水排放标准.

Physical absorption, photocatalysis and chemical flocculation methods were used to investigate the degradation of arsenic （ about 13.56 mg/L） in wastewater of wet-process phosphoric acid from a Chemical Co., Ltd in Yichang, China.The results showed that the absorption capacity of activated carbon was 1g/50mL and 84.4%arsenic could be absorbed efficiently,while the clay could not reach the saturat-ed adsorption in the physical absorption.As3＋was oxidized to lower poisonous As5＋by Fenton reagent and the removal rate reached 82.2%at the optimum parameter [ H2 O2 ] ∶[ Fe3＋]=200 ∶1 using the photoca-talysis method.As to the method of chemical flocculation, the optimum conditions of flocculant-96, floc-culant-98, flocculant-diatomite were as follows： the optimum pH was 12.6, 12.6, 11.8, the optimum quantity of flocculant was 10,9,13 mg/mL and the removal rate of As3＋was 65.7%,73.2%,76.3%,re-spectively.At last, an experimental device was designed to degradate arsenic in wastewater from Wet-process phosphoric acid and the concentration of As3＋in the treated wastewater could meet the state stand-ard for discharging of industry wastewater.