放射性核素钍污染土壤有机酸化学淋洗工艺

The process of organic acid chemical leaching of radionuclide thorium polluted soil

选用草酸、柠檬酸和酒石酸对不同粒径典型放射性钍污染土壤进行淋洗试验,考察淋洗后淋洗液各指标参数变化,以土壤可提取形态分析淋洗后流动性和稳定性的变化,结合淋洗动力学和XRD手段来表征土壤修复机理及土壤晶相破坏程度.结果表明:草酸、柠檬酸和酒石酸振荡淋洗最优参数为0.5mol/L条件下振荡8h,淋洗效果依次为:草酸>柠檬酸>酒石酸>苹果酸>乙酸.达到修复目的前提下,淋洗后土壤整体晶相破坏程度较小,二氧化硅衍射峰明显增强,各土样中残渣态的占比提高19.39%~27.20%、0.63%~8.45%,流动性降低6.81%~11.33%,稳定性得到增强,为放射性污染土壤化学淋洗修复提供参考.

Oxalic acid,citric acid and tartaric acid were selected to study the leaching effect on typical radioactive thorium contaminated soil with different particle sizes.The changes of fluidity and stability of leaching solution after leaching were analyzed in terms of soil extractable forms,and the soil remediation mechanism and the destruction degree of soil crystalline phase were characterized with leaching kinetics and X-ray diffraction analysis(XRD).The experimental results showed that for oscillating leaching of oxalic acid,citric acid and tartaric acid,the optimal parameter was oscillating for 8hours with concentration of 0.5mol/L,and the leaching effect was in the descending order of oxalic acid>citric acid>tartaric acid>malic acid>acetic acid.On the premise of achieving the purpose of remediation,the whole crystalline phase of the soil after leaching was less damaged,the diffraction peaks of silica was obviously enhanced,the proportions of residual state in each soil sample were increased by 19.39%~27.20%and 0.63%~8.45%,the fluidity was obviously lowered by approximately 10%,and the stability was slightly enhanced.The results provided guiding references for chemical leaching remediation of radioactive contaminated soil.