摘要
[目的]研究土壤氧化锰对Cr(Ⅲ)的氧化反应.[方法]以γ-MnO2为研究对象,研究了pH、陪伴离子等溶液因素及陪伴矿物对Cr(Ⅲ)氧化的影响.[结果]在0.1~1.0 mmol/L Cr(Ⅲ)溶液中,Cr(Ⅵ)生成量随Cr(Ⅲ)浓度的升高而增大,未达到γ-MnO2最大氧化容量.Cr(Ⅲ)氧化过程分为快、慢2个阶段,初期较为迅速,而后期则较为缓慢.提高pH抑制了Cr(Ⅲ)氧化,其主要原因是羟基态Cr(Ⅲ)的活性较游离态低;Cu(II)存在同样不利于Cr(Ⅲ)氧化,这时因为前者亦可被γ-MnO2吸附,从而占据表面氧化位点;同时,Cr(Ⅲ)与EDTA和柠檬酸形成络合物后,也较难被氧化.当氧化铝与γ-MnO2共存时,由于二者存在竞争吸附Cr(Ⅲ),因而也不利于Cr(Ⅲ)向Cr(Ⅵ)转化.[结论]该研究可为全面了解Cr(Ⅵ)污染风险提供科学依据.
Abstract
[Objective]To study oxidation of Cr (Ⅲ) by manganese dioxide in soil.[Method]The capacity of γ-MnO2 with respect to Cr(Ⅲ) oxidation was examined as well as the influence of soil factors and accompanying minerals.[Result]The results showed that the Cr (Ⅵ) in the so-lution increased gradually with the increase of Cr (Ⅲ) concentration within the range of 0.1-1.0 mmol/L,indicating the maximum oxidation ca-pacity of γ-MnO2 was not reached.It was found in the kinetic experiments that the reaction proceeded very rapidly,followed by a slower stage as the time prolonged.Cr(Ⅲ) oxidation would be inhibited with the increase in pH as well as in the presence of Cu (Ⅱ).Additionally,the addition of EDTA,citric acid and aluminum oxide was also unfavorable for the Cr(Ⅲ) oxidation.[Conclusion]This study can proⅥde a scientific basis for understanding the risk of Cr (Ⅵ) pollution.
基金项目
2016年度广东大学生科技创新培育专项资金立项项目(pd-jh2016b0237)
国家科技期刊平台
NSTL
维普
万方数据