铝钙粉浸出渣制备沸石及其对锌冶炼废水的吸附性能

Preparation of zeolite from calcium aluminate leaching residues and its adsorption properties for zinc metallurgical wastewater

以聚合氯化铝(PAC)生产过程中铝钙粉浸出渣为原料,通过酸浸-焙烧-水热晶化工艺制备沸石,并研究其对锌冶炼废水中重金属的去除效果。结果表明:铝钙粉浸出渣通过酸浸-焙烧-水热晶化过程,当原料n(SiO2)/n(Al2O3)=2时,产物物相为结构完整的A型沸石;当原料n(SiO2)/n(Al2O3)=6时,产物物相为结构完整的P型沸石。拟二级动力学方程计算得到A型沸石对Zn^2+、Cd^2+的平衡吸附量分别为97.09、12.39 mg/g,P型沸石对Zn^2+、Cd^2+的平衡吸附量分别为57.84、10.82 mg/g。Freundlich吸附等温线拟合结果表明,A型沸石和P型沸石吸附Zn^2+、Cd^2+机理均为非均相表面的复杂吸附。当废水pH为8、吸附温度为25℃、吸附时间为150 min时,采用A型沸石处理锌冶炼废水,产渣量为1.1 g/L,废水中Cu^2+、Pb^2+、Zn^2+、Cd^2+、总砷(AsT)浓度分别由1.68、13.12、147.00、15.14、4.06 mg/L降至0.06、0.05、0.52、0.03、0.01 mg/L,达到《铅、锌污染物排放标准》(GB 25466—2010)。

Zeolites were prepared by the process of HCl leaching,roasting and hydrothermal crystallization using calcium aluminate leaching residues(CALR)which were generated from the production process of polyaluminum chloride,and raw their removal effect on heavy metals from zinc metallurgical wastewater were studied.The results show that,after CALR is treated through the process of HCl leaching,roasting and hydrothermal crystallization,when n(SiO2)/n(Al2O3)in raw material is 2,the product is a structurally intact Zeolite A,when n(SiO2)/n(Al2O3)in raw material is 6,the product is a structurally intact Zeolite P.According to the pseudo-second order kinetic model,the equilibrium adsorption capacities of Zeolite A and P for Zn^2+are 97.09 and 57.84 mg/g,respectively,and for Cd^2+are 12.39 and 10.82 mg/g,respectively.The fitting results of Freundlich adsorption isotherm show that the adsorption of Zn^2+and Cd^2+by Zeolite A and P is a complex adsorption on heterogeneous surface.When the wastewater pH is 8,adsorption temperature is 25℃,and adsorption time is 150 min,the amount of residue is 1.1 g/L,and the concentrations of Cu^2+,Pb^2+,Zn^2+,Cd^2+and AsT in wastewater decrease from 1.68,13.12,147.00,15.14 and 4.06 mg/L to 0.06,0.05,0.52,0.03 and 0.01 mg/L,respectively,by using zeolite A to treat the zinc metallurgical wastewater.The water qualities reach up to the《Emission standard of pollutants for lead and zinc industry》(GB 25466—2010).