Li Ying, Li Hui, Zhong Ning, Quan Guixiang, Lan Yeqing
Water Environ Res. 2015 May;87(5):450-60. doi: 10.2175/106143015x14212658614351.
The catalytic roles of manganese(II) [Mn(II)] and iron(III) [Fe(III)] in the reduction of hexavalent chromium [Cr(VI)] by mandelic acid, both with and without the presence of light, was investigated through a series of batch experiments. The results demonstrated that both Mn(II) and Fe(III) could markedly accelerate the photoreduction of Cr(VI) by mandelic acid; additionally, the catalysis of Fe(III) was superior to that of Mn(II). Without the presence of light, Mn(II) still enhanced the reduction of Cr(VI) by mandelic acid, but Fe(III) did not exert any impact on the reaction. When compared with the activities of phenylacetic acid, it was concluded that the catalytic roles of both Mn(II) and Fe(III) in the reduction of Cr(VI) were directly related to the α-OH group and not to the carboxyl group. The photoreduction of Cr(VI) by mandelic acid, assisted by Mn(II), followed pseudo-first-order kinetics at the initial stage of the reaction, but in the presence of Fe(III) it followed a pseudo-zero-order model.
通过一系列批量实验，研究了锰（II）[Mn（II）]和铁（III）[Fe（III）]在有光和无光条件下对扁桃酸还原六价铬[Cr（VI）]的催化作用。结果表明，Mn（II）和Fe（III）均能显著加速扁桃酸对Cr（VI）的光还原；此外，Fe（III）的催化作用优于Mn（II）。在无光条件下，Mn（II）仍能增强扁桃酸对Cr（VI）的还原作用，但Fe（III）对该反应没有任何影响。与苯乙酸的活性相比，得出结论：Mn（II）和Fe（III）在还原Cr（VI）中的催化作用均与α-OH基团直接相关，而与羧基无关。在Mn（II）辅助下，扁桃酸对Cr（VI）的光还原在反应初期遵循准一级动力学，但在Fe（III）存在下遵循准零级模型。
