阿拉尔河悬浮物对铀的吸附影响研究

为了解阿拉尔河悬浮物对铀的吸附特性,通过静态吸附实验,研究了吸附时间、pH值、温度和铀初始浓度等因素对模拟含铀水中U(VI)去除率的影响,并从热力学和动力学方面对吸附过程进行了分析。结果表明,在T=25℃,溶液初始pH=7,接触时间为16 h时,悬浮物对铀的平衡吸附率最佳,为95.48%。随着铀初始浓度的增加,吸附量增加,但吸附率随之下降,升高温度有利于铀的吸附。铀在悬浮物上的吸附过程符合Langmuir等温吸附方程,说明悬浮物对铀为单分子层吸附,且化学吸附占主导地位。吸附动力学过程可用准二级吸附动力学模型描述,表明吸附主要受动力学控制,由两个以上步骤共同控制。FTIR和EDS分析结果表明,吸附过程中铀主要与悬浮物表面活性基团螯合并以表面络合吸附为主。吸附前后的能谱对比分析表明,吸附过程中存在离子交换行为。因此,悬浮物对铀的吸附机理是以表面络合吸附和离子交换为主、物理吸附为辅的混合吸附过程。

Adsorption of Uranium on Suspended Solids from Alar River

In order to understand the Alar river suspended solids influence on the adsorption characteristics of uranium,using static adsorption experiments to study the adsorption time,pH,temperature and initial concentration as the contributory factors of the removal rate of uranium U(VI)in the simulation water,thermodynamics and kinetics of adsorption process are analyzed.The results show that :at room temperature,initial solution pH=7,the most balance adsorption rate reachs 95.48% after 16 h.With the increase of initial concentration of uranium,adsorption quantity increases while the adsorption rate drops,higher temperature makes for the adsorption of uranium.The adsorption process conforms to Langmuir isothermal adsorption equation,which indicates that the adsorption is between monolayers and multilayers,and the chemical adsorption plays a dominant role in the adsorption process.The adsorption process can be described by an equation of pseudo 2nd-order model,it means that the adsorption is mainly controlled by the kinetics of more than two steps.The FTIR and EDS analysis results show that the uranium is mainly combined with the active groups on the suspended solids surface,it is given priority to the surface complexing adsorption.The EDS results before and after adsorption show that exit iron changes in the process.So,the adsorption is based on surface complexing adsorption and take the ion exchange as a supplement.