(1. 中南大学 冶金与环境学院，长沙 410083；
2. 青海省环境科学研究设计院，西宁 810000)
摘 要: 详细研究氯化铅在碳酸氢铵溶液中的物相转化机理，对比分析同一条件下不同转化剂的转化脱氯效果，转化脱氯效果由大到小依次为NH4HCO3、Na2CO3、(NH4)2CO3、K2CO3；得出NH4HCO3作为转化剂时的最佳转化条件：溶液初始pH=10.0、NH4HCO3浓度1.68 mol/L、反应温度50 ℃、反应时间120 min；PbCl2在转化过程中会经历PbCl2 Pb2Cl2(CO3) PbCO3的转化过程，在最佳工艺条件下转化率可达99%以上，转化产物为纯净的PbCO3。通过不同转化阶段得到的产物的物相分析，确定PbCl2在NH4HCO3溶液中转化为PbCO3的机理、途径及影响机制。转化体系的pH值是影响转化率、转化途径及最终产物物相组成的最显著因素，而转化剂浓度、转化时间和温度，只会对PbCl2脱氯速率造成影响，并不会影响PbCl2的转化途径和最终产物组成。
关键字: 氯化铅；碳酸氢铵；物相转化机理；脱氯率；转化产物
（1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
2. Qinghai Provincial Research and Design Academy of Environmental Sciences, Xining, 810000, China）
Abstract:The phase transformation mechanism of PbCl2 in ammonium bicarbonate solution was investigated. The dechlorination efficiencies of different conversion agent in the same condition were determined as follow from big to little: NH4HCO3, Na2CO3, (NH4)2CO3, K2CO3. The optimum transforming conditions of PbCl2 using NH4HCO3 as transforming agent were also detected and determined as follow: initial pH=10.0, cNH4HCO3=1.68 mol/L, reacting temperature 50 ℃, reaction time 120 min. 99% PbCl2 transforms into PbCO3 through PbCl2 Pb2Cl2(CO3) PbCO3 process. The final resultant is pure PbCO3. The phase analysis of conversion products at different conversion stages were carried out to investigate the transformation and influencing mechanism. The results indicate that pH value of the solution is the most significant influencing factor on PbCl2 conversion rate, transformation path and final resultant compositions. While, the NH4HCO3 concentration, reaction time and temperature only affect the dechlorination rate, and don’t affect the transformation path of PbCl2 and the compositions of the conversion products.
Key words: lead chloride; ammonium bicarbonate; phase transformation mechanism; dechlorination rate; transformation product
