木质素基重捕剂处理含砷酸性废水研究

Study on treatment of arsenic-containing acidic wastewater with lignin-based recapture agent

以碱木质素为基体通过Mannich反应、二硫化碳加成合成新型重金属捕集剂(重捕剂)N-亚甲基碱木质素-N′-二硫代氨基甲酸己二胺钠盐(Lig-DTC),用于螯合含砷酸性废水中的重金属,经絮凝以沉淀形式析出,处理后的酸性水可以回用。以酸性废水重金属离子剩余质量浓度为评价标准,通过正交实验和单因素实验对重捕剂加入量、反应时间、溶液pH、絮凝剂投加量等因素进行考察。得到最佳工艺条件(以100 mL废水计):在不调节废水酸性情况下,Lig-DTC用量为60 mg,反应时间为15 min,聚丙烯酰胺(阴离子型PAM,质量分数为0.1%)用量为1.1 mL,静置时间为30 min。在此条件下,残余重金属离子质量浓度达到处理要求,酸性废水可以进入系统循环回用。

Synthesis of a new heavy metal collector(or heavy trap)N-methylene base lignin-N′-dithiocarbamic acid hexamethylene diamine salt(Lig-DTC)with alkali lignin as matrix by Mannich reaction and carbon disulfide addition,used to chelate heavy metals in arsenic-containing acidic wastewater,precipitated by flocculation,and the treated acidic water can be reused.Taking the residual mass concentration of heavy metal ions in acid wastewater as the evaluation standard,the factors such as dosage of the heavy trap,reaction time,pH of the solution and the dosage of the flocculant were investigated by orthogonal experiment and single factor experiment.The best process conditions(based on 100 mL wastewater)were obtained as follows:the dosage of Lig-DTC was 60 mg,the reaction time was 15 min,the dosage of polyacrylamide(anionic PAM,mass fraction of 0.1%)was 1.1 mL and the rest time was 30 min without adjusting the acidity of wastewater.Under this conditions,the residual heavy metal ion mass concentration met the processing requirements,and the acidic wastewater can enter the system cycle.