TiO2光催化氧化降解乳酸的工艺及机理研究

以TiO2为催化剂、紫外灯为光源对乳酸进行光催化降解实验,考察了乳酸初始浓度、TiO2用量、反应时间、曝气方式等因素对乳酸降解率的影响,并在此基础上应用正交实验对降解条件进行优化,同时对乳酸的降解机理进行了探索研究。实验结果表明：以300 W紫外汞灯为光源,在乳酸初始浓度为0.5 g/L、TiO2量为0.20 g/L、反应时间120 min、持续通入空气鼓泡的条件下,乳酸降解效果最佳,乳酸降解率为99.9%;降解12 h总有机碳去除率达91.2%。乳酸光催化降解的反应途径为：乳酸脱羧生成乙醇,乙醇被氧化生成乙醛,进而氧化为乙酸,所有的中间产物被继续降解,最终矿化为CO2和H2O等小分子物质。

Study on photocatalytic oxidation degradation technology and mechanism of lactic acid with TiO_2

The photocatalytic degradation of lactic acid using TiO2 as catalyst was investigated under ultraviolet lamp.The influences of lactic acid initial concentration,dosages of TiO2,reaction time and aeration modes on degradation ratio of lactic acid were investigated.After that the titanium dioxide photocatalysis conditions of lactic acid were optimized by the orthogonal test,and the photocatalytic degradation mechanism of lactic acid was discussed.The experimental results showed that the optimal photocatalysis conditions are as following： lactic acid initial concentration 0.5 g/L,TiO2 0.20 g/L,under 300 W ultraviolet mercury lamp for 120 min with continuous aerating,the degradation rate of lactic acid were 99.9% under the optimal conditions.The total organic carbon（TOC） was removed by 91.2% in 12 h.The photocatalytic degradation pathway for lactic acid was identified.Ethanol was obtained from lactic acid by decarboxylation,acetaldehyde was obtained from the product of ethanol oxidation reaction,and acetic acid was obtained from acetaldehyde oxidation reaction.Eventually,the intermediates from lactic acid were photodegraded into CO2 and H2O.