白云石与方沸石对Sr2+的吸附行为研究

Adsorption of Sr2+ on Dolomite and Analcime

  • 摘要: 采用静态实验法研究了黏土岩的组成矿物白云石和方沸石对Sr2+的吸附行为,考察了时间、初始pH值、初始浓度、离子强度以及腐殖酸对吸附的影响,并利用XRD、FT-IR和SEM对材料进行了表征。结果表明:两种材料均能有效吸附Sr2+,初始pH值升高会促进吸附,离子强度增大会抑制两种材料对Sr2+的吸附;吸附均在6 d时达到平衡,吸附过程均符合准二级动力学模型,说明吸附均以化学吸附为主;随着Sr2+初始浓度的增加,白云石吸附Sr2+的吸附分配比呈先增加后降低的趋势,方沸石吸附Sr2+的吸附分配比不断降低;腐殖酸会抑制白云石吸附Sr2+,对方沸石吸附Sr2+的过程略有促进;Langmuir和Freundlich模型拟合结果显示,白云石吸附Sr2+的吸附机理较为复杂,而Sr2+在方沸石上的吸附过程为单分子层吸附。上述结果可为高放废物地质处置的选址工作提供基础数据和参考。

     

    Abstract: The adsorption behavior and the effect of various experimental conditions on Sr2+ adsorption on dolomite and analcime were investigated respectively with batch sorption method, and XRD, FT-IR and SEM were carried out. The results show that dolomite and analcime can adsorb Sr2+ effectively, and the adsorption increases with the increase of initial pH and decreases with the increase of ionic strength. The adsorption equilibrium both are achieved after 6 d. The adsorption processes both are well described by pseudo-second-order kinetics model, which indicates that the adsorption processes may be chemical adsorption. As the increase of the initial concentration of Sr2+, the Kd of Sr2+ on dolomite increases first and then decreases, and the Kd of Sr2+ on analcime decreases. With the increase of humic acid, the Kd of Sr2+ on dolomite decreases, but the Kd of Sr2+ on analcime increases slightly. Langmuir and Freundlich isotherm model results show that the adsorption mechanism of Sr2+ on dolomite is relatively complex, and it is monolayer for analcime. The results can provide basic data and reference for the site selection of high level waste.

     

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