黏土质白云岩去除水中铅离子作用及机理

黏土质白云岩是新生代形成的弱固结沉积白云岩,具有丰富且开放的孔隙率及高化学反应活性,其作为环境工程材料的应用值得探讨。本文研究了黏土质白云岩去除溶液中铅的效果和作用机理,考察了黏土质白云岩除铅动力学以及初始浓度、固液比对除铅效果的影响。结果表明,黏土质白云岩与不同浓度的铅溶液反应达到平衡所需的时间不同,初始铅浓度越高反应平衡时间越长,与铅浓度100 mg/L溶液反应70 h才基本达到平衡;黏土质白云岩除铅效果主要受反应平衡后溶液的p H值控制,固液比也可影响溶液p H值;固液比越高,平衡p H值越高,铅去除越完全;黏土质白云岩去除溶液中铅离子的作用机制是其中的白云石诱导的铅沉淀,白云石溶解同时形成了碱式碳酸铅。

The function and mechanism of the removal of lead ions from aqueous solutions by clayey dolomite

Clayey dolomite is a kind of weakly consolidated sedimentary rock with rich and open holes and high chemical activity from Cenozoic. As a useful environmental engineering material, it deserves further study. This paper discusses the effect and mechanism of the removal of lead ions from aqueous solutions by clayey dolomite. A series of experiments were designed for studying kinetic parameters (time impact), the rate of solid and aqueous concentration, and initial concentration in solutions which may influence and change the effect of removing lead ions. The results show that the equilibrium time of removing lead ions depends on the initial concentration of lead solutions. The equilibrium time is longer when the initial concentration is higher. 100 mg/L lead solution basically demands 70 hours to reach the equilibrium position. In addition, the effect of removal is controlled by final pH. A higher pH value gives rise to a more thorough removal during the process. A higher solid-aqueous rate and higher pH value can improve the removal efficiency. The main mechanism of removal is that lead ions are induced to deposition by clayey dolomite, and meanwhile hydrocerussite is produced after dolomite dissolution.