中文摘要：

25℃和pH3．0～5．0条件下，研究了Mn（Ⅱ）和Fe（Ⅲ）对草酸还原Cr（Ⅵ）的催化作用。结果表明：避光条件下，Mn（Ⅱ）对草酸还原Cr（Ⅵ）有显著的催化作用，光照下其催化作用进一步得到提高。然而，避光条件下Fe（Ⅲ）对草酸还原Cr（Ⅵ）的影响甚微，但在光照条件下，Fe（Ⅲ）表现出极优越的催化作用。溶液pH值和照射光波长对反应有显著影响，Mn（Ⅱ）和Fe（Ⅲ）的催化作用随pH值提高而减弱；紫外光照射下两金属离子的催化作用大于模拟日光照射的。因此，本研究结果对由Cr（Ⅵ）引起的土壤和水的污染治理具有理论和实践指导意义。

英文摘要：

The catalytic role of Mn（ Ⅱ ） and Fe（ Ⅲ ） in the reduction of Cr（ Ⅵ ） by oxalic acid was investigated at 25 ℃ and in a pH range from 3.0 to 5.0. The results demonstrated that Mn（ Ⅱ ） greatly catalyzed the reduction of Cr（ Ⅵ ） by oxalic acid without light and the reaction rate was increased further in the presence of Mn（ Ⅱ ） with light. Without light, the effect of Fe（ Ⅲ ） on the reduction of Cr（ Ⅵ ） by oxalic acid was neglected. However, the reaction rate was markedly accelerated with light. Solution acidic degree and light wavelength exerted an important influence on the reduction of Cr（Ⅵ）. The catalysis of Mn（Ⅱ） and Fe（Ⅲ） was reduced with pH rising. Under UV irradiation, the catalysis of Mn（Ⅱ） and Fe（Ⅲ） was much stronger than that of mimicking solar light. So, the results are helpful for treating the soil and water contaminated by Cr（Ⅵ）.