摘要
[目的]研究土壤氧化锰对Cr(Ⅲ)的氧化反应。[方法]以γ-MnO_2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-MnO_2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-MnO_2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-MnO_2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。
[ 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.
出处
《安徽农业科学》
CAS
2017年第30期75-77,共3页
Journal of Anhui Agricultural Sciences
基金
2016年度广东大学生科技创新培育专项资金立项项目(pdjh2016b0237)
