含锌离子模拟废水沉淀研究及污泥表征

采用氢氧化钙、碳酸钠和硫化钠处理含锌废水,在溶液pH、锌离子浓度、颗粒粒径、颗粒Zeta电位、上清液浊度和污泥体积等指标测定的基础上,结合沉淀产物表征,探讨了沉淀剂用量对锌离子去除率的影响及沉淀机理。研究结果表明,n(Ca(OH)2∶n(Zn)=1.5,去除率达到最大值99.65%,n(Na2CO3)∶n(Zn)=1.5,去除率达到最大值99.89%,n(Na2S)∶n(Zn)=2.5,去除率达到最大值99.95%。X-射线衍射和热重分析表明,氢氧化钙与废水生成的沉淀物为碳酸钙和氧化锌,碳酸钠与废水生成的沉淀物为氧化锌和碱式碳酸锌,硫化钠与废水生成的沉淀物为硫化锌,这对污泥处理处置以及回收利用有指导意义。

Precipitation of simulated wastewater containing zinc ions and characterization of sludge

Calcium hydroxide, sodium carbonate and sodium sulfide were used as precipitants to remove zinc ions from simulated wastewater. Based on measurements of pH, Zeta-potential, supernatant turbidity, sludge volume, particle size and characterization of precipitation products, the influence of precipitant dosage on the zinc ions removal and the reaction mechanisms were examined. The results showed that sodium sulfide performed the highest zinc removal, 99.95% at 2.5-folds of the stoichiometric dosage, compared with calcium hydroxide and sodium carbonate. When calcium hydroxide was added to simulated wastewater at 1.5-folds of the stoichiometric dosage, the removal of zinc can reach 99.65%, whereas sodium carbonate was added to simulated wastewater at 1.5-folds of the stoichiometric dosage, the removal of zinc can reach 99.89%. According to the X-ray diffraction and thermogravimetric analysis, the products resulted from calcium hydroxide precipitation were calcium carbonate and zinc oxide, and the products resulted from sodium carbonate precipitation was Zn₅(CO₃)₂(OH)₆ and zinc oxide, and the products resulted from sodium sulfide were ZnS, which is invaluable to the disposal and utilization of the sludge.