以硫脲和羟基磷酸钙复配体系为固定剂,结合SEM表征手段,研究其在水溶液中对重金属离子(Pb2+、Cd2+、Hg2+、Cu2+和Zn2+)的去除反应及其固定过程.结果表明,羟基磷酸钙对重金属离子具有良好的吸附性能,硫脲水解释放的硫离子与重金属离子反应生成稳定的硫化物.应用均匀设计实验方法探究了硫脲用量、羟基磷酸钙用量、氢氧化钠用量、土壤含水率及固定周期等因素对土壤中重金属固定效果的影响,并结合二次多项式逐步回归法确定了最优固定条件:硫脲、羟基磷酸钙和氢氧化钠的使用量与重金属总量摩尔比分别为5∶1,3.0442∶1和1.340 1∶1,土壤含水率33.26％,固定时间0.25 d.在该条件下,土壤中重金属固定率:铅99.57％、镉91.41％、汞93.01％、铜93.26％、锌91.37％.统计学分析表明该最大值可靠,该条件可以作为固定剂使用的最佳条件.%The removal and fixing process of heavy metal ions(Pb2+,Cd2+,Hg2+,Cu2+ and Zn2+ in aqueous solution were investigated by SEM with the combination system of thiourea and hydroxyapatite as fixatives.The result showed that hydroxyl calcium phosphate mainly displayed good adsorption capacity for heavy metal ions and the sulfur ion released by the hydrolysis of thiourea could cause the formation of stable sulfides by the reaction with heavy metal ions.The uniform design experiment was carried out to investigate the effects of reaction factors on the fixing rate,and the dosages of thiourea,hydroxyl apatite,NaOH,soil water content and fixed cycle are selected as the main reaction factors,and the best fix condition was demonstrated as follows:The molar ratio of the amount of thiourea,calcium hydroxide and sodium hydroxide to the total amount of heavy metals were 5∶ 1,3.044 2∶1 and 1.340 1 ∶ 1,the moisture content of soil was 33.26％,and the fixed time was 0.25 d.The optimal solidification conditions were established by the quadratic polynomial stepwise regression equation with the solidification of Pb 99.57％,Cd 91.41％,Hg 93.01％,Cu 93.26％ and Zn 91.37％ under above optimal solidification conditions.Statistic analysis showed that the maximum value was reliable and it could be used as the solidification conditions.
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