高锰酸钾凝胶缓释剂的制备及其缓释去除水中三氯乙烯

Preparation and characterization of slow-release potassium permanganate gel for the removal of chlorinated hydrocarbons in groundwater

本研究开发一种结合原位化学氧化和二氧化硅溶胶-凝胶的可控氧化剂释放技术,制备出一种高锰酸钾(KMnO_(4))凝胶缓释剂(SRPG).优化SPRG的制备条件和探究影响其在水中缓释效率的因素,并考察其对不同氯代烃的降解效果.结果表明:二氧化硅溶胶的质量分数、KMnO_(4)的含量及pH对SRPG凝胶化过程有显著的影响;提高缓释剂中KMnO_(4)的含量和降低二氧化硅溶胶质量分数,可有效提高SRPG中KMnO_(4)的释放速率,当KMnO_(4)质量分数为6.51‰,二氧化硅溶胶质量分数为40%,KMnO_(4)的释放符合拟一阶动力学,释放速率k_(obs)=0.83 h-1(R2=0.9750),且12 h后KMnO_(4)释放率为82.7%;SRPG可有效降解水中氯代烃污染物,其中对三氯乙烯(TCE)的去除效果最佳,反应24 h可去除水中98%的TCE.因此,SRPG在原位化学氧化修复土壤和地下水中氯代烃的实际工程中具有良好的应用前景.

An in-situ chemical oxidation technique combining controlled oxidant release and silica sol-gel was developed to prepare a slow-release potassium permanganate(KMnO_(4))gel(SRPG).The effects of preparation conditions on the slow-release process of SPRG and the degradation of different chlorinated hydrocarbons were investigated and optimized.The results showed that the mass fraction of silica sol,the KMnO_(4) content,and the pH condition significantly influenced the gelation process of SRPG.When the mass fraction of KMnO_(4) and silica sol was 6.51‰and 40%,respectively,the release rate of KMnO_(4) could be fit by the pseudo first-order kinetic model.The rate constant of KMnO_(4) release was kobs=0.83 h-1(R2=0.9750),and the release ratio of KMnO_(4) was 82.7%after 12 h.The SRPG could effectively degrade different chlorinated hydrocarbon pollutants in water,with the best performance for trichloroethylene(TCE)degradation.It was shown that 98%of TCE was removed by SRPG after 24 h.Therefore,SRPG has a promising technique for the in-situ chemical oxidation of chlorinated hydrocarbons for the soil and groundwater remediation.