Al(OH)_3胶体的制备及其对铀的吸附机理

Preparation of aluminum hydroxide colloid and its adsorption mechanism for uranium(Ⅵ)

为了研究在地浸采铀中胶体对矿层的阻塞及对铀酰离子吸附迁移影响,采用硝酸铝与氨水为原料制备Al(OH)3,并用在pH=6条件下制备所得的Al(OH)3对铀进行吸附实验研究,考察了吸附的pH值、初始浓度及吸附时间等对Al(OH)3吸附铀的影响。对实验数据使用准一级、复合二级与Elovich动力学模型进行计算与分析,得出Elovich动力学方程更适合描述Al(OH)3对铀吸附,吸附主要是表面吸附;使用Freundlich与Langmuir等温吸附方程对实验数据进行拟合,结果表明Langmuir模型更适合描述Al(OH)3对铀酰离子的吸附;对吸附前、后的Al(OH)3进行SEM与激光粒度分析。

In order to study the effect of colloidal seam blocking and adsorption and migration of uranyl ions/n situ leaching of uranium, aluminum nitrate and ammonia hydrate were used as the starting materials for preparation of Al（OH）3, and that prepared at pH = 6 was used to adsorb U（Ⅵ） from the solution. The effects of pH value, initial uranium concentration, and contact time on the adsorption were investigated. The pseudo-first-order, composite-second-order and Elovich dynamic models were used to analyze the adsorption data. Freundlich and Langmuir adsorption isotherm models were applied to experimental equilibrium data. The properties of Al（OH）3 were determined by SEM and laser particle size analyzer. The adsorption kinetic parameters obtained shows that the Elovich dynamic model describes the adsorption of uranium on Al（OH）3 colloids well, so the adsorption appears on external surface. The equilibrium data agree well with the Langmuir model.