不同温度和pH条件下,通过批式试验研究了苦杏仁酸、苹果酸、乳酸还原Cr(Ⅵ)的反应速率.结果表明,这3种α-OH酸还原Cr(Ⅵ)的能力表现为:苦杏仁酸>苹果酸>乳酸.苦杏仁酸对Cr(Ⅵ)的还原作用受pH变化的影响较大,而乳酸受温度变化的影响较大.同时研究了Mn(Ⅱ)对3种α-OH酸还原Cr(Ⅵ)反应速率的影响.结果表明,Mn(Ⅱ)对3种α-OH酸还原Cr(Ⅵ)均有催化作用,其中对苦杏仁酸表现更为明显.
The reduction of Cr(Ⅵ) by mandelic, malic and lactic acids was studied in batch experimental systems at different temperatures and pH values. The results showed that the ability to reduce Cr(Ⅵ) by the organic acids with α-OH was in the order:mandelic acid 〉 malic acid 〉 lactic acid. The influence of pH on the reduction of Cr (Ⅵ) by mandelic acid was strongest among the three organic acids, and temperature exerted the greatest effect on the reaction between lactic acid and Cr(Ⅵ). The influence of Mn(Ⅱ) on the reduction of Cr(Ⅵ) by the three organic acids was also studied. Mn(Ⅱ) catalysed the reduction of Cr(Ⅵ) by α-OH acids, especially mandelic acid.