富磷水系中方解石吸附铀的探究

Adsorption of Uranium on Calcite of the Phosphorus-rich System

运用静态实验方法,探讨了不同p H、离子强度、磷酸盐浓度、固液比、铀初始质量浓度以及接触时长等条件下富磷水系中方解石吸附铀的机制.通过对平衡浓度、吸附量、吸附时长等的分析,实验结果表明富磷水系中方解石吸附铀受p H、磷酸盐浓度、固液比、铀初始质量浓度、离子强度及接触时长等多因素影响.平衡条件下,在7<p H<11之间,铀在方解石上的吸附量随p H增加而增大,p H=8时吸附量达到最高,p H>11时,随p H的升高方解石吸附铀的量呈下降趋势;当其他条件一定时,吸附率随固液比增加而减小;随着铀初始浓度的增加,方解石吸附铀量增加;随着离子强度、吸附时长的增加,方解石吸附铀的量增加,在反应10 h时达到最大吸附量,反应基本达到平衡.实验还对富磷水系方解石吸附铀的等温吸附和不同接触时长的吸附数据进行了拟合,结果表明,Freundlich型等温吸附模型和Ho准二级反应动力学方程能较好地描述富磷水系方解石吸附铀的过程.

In this paper, the mechanism of uranium adsorption on calcite of phosphate-rich system under different pH, ionic strength, phosphate concentration, solid liquid ratio, initial concentration of uranium and different adsorption time was investigated by static experimental method. Through the analysis of the equilibrium concentration, adsorption rate, adsorption effect, adsorption time and other factors, it showed that the uranium adsorption on calcite in phosphaterich system by pH, phosphate concentration, solid-liquid ratio, adsorption effect time, ionic strength and other factors. Under the equilibrium conditions, at pH7-11, the uranium adsorption on calcite increased with the increase of pH. At pH 8, the adsorption capacity reached the maximum. With the increase of pH 〉 11, the amount of uranium adsorbed on sediment decreased with the increase of pH. Under the same conditions, the adsorption capacity increased with the increase of solid liquid ratio. As the initial concentration of uranium increased, the adsorption capacity increased. With the increased of time and ionic strength, the adsorption rate increased. The adsorption rate reached highest level at the reaction of 10 h, and the reaction reached equilibrium basically. The experimental results showed that the Freundlich isotherm model and the Ho kinetic equation could describe the uranium sorption process in the calcite of phosphate-rich system better.