Fenton试剂协同TiO2光催化降解三氯乙酸及协同机理

为了研究Fenton试剂协同TiO2光催化降解三氯乙酸(TCAA)的反应及其协同机理,在自制的光催化反应装置中分别考察了Fenton、UV/TiO2及Fenton/ UV/TiO2 3个反应对TCAA的降解情况。研究结果表明,在TCAA初始浓度为2.0 mg/L,TiO2用量为1.0 g/L,紫外辐射光源为15 W(λmain=254 nm)的实验条件下,Fenton试剂协同TiO2光催化降解TCAA反应在pH 3~7范围内均有较高的降解率;TCAA 在Fenton、UV/TiO2及Fenton/ UV/TiO2 3个反应中的一级反应速率常数分别为0.0009、0.0131和0.0456 min-1;Fenton试剂与TiO2光催化反应间存在较明显的协同效应,其协同机理主要体现在两个方面:一是紫外光激发Fe(OH)2+和H2O2分解产生更多的·OH,二是Fenton试剂中部分被氧化成的Fe3+可与TiO2表面的光生电子结合被还原为Fe2+,抑制了光生电子与空穴的复合,从而提高了TiO2光催化降解TCAA的效率。

Synergetic degradation and mechanism of chloroacetic acid by TiO2 photocatalytic reaction cooperated with Fenton reagent

To investigate the synergetic effect between Fenton reagent and UV/TiO2, the degradation of trichloroacetic acid (TCAA) in Fenton reagent, UV/TiO2 and Fenton/UV/TiO2, respectively, was performed in a self-made photocatalytic reactor. Experimental results showed that TCAA was degraded greatly at pH 3~7 when the initial concentration of TCAA was 2.0 mg/L, the TiO2 dosage was 1.0 g/L, and UV light power was 15 W (λmain=254 nm). The first-order reaction constants for degrading TCAA were 0.0009 min-1, 0.0131 min-1 and 0.0456 min-1 in the Fenton reagent, UV/TiO2 and Fenton/UV/TiO2 reaction, respectively. The results also indicated that both Fenton reagent and UV/TiO2 reaction generated an obvious synergetic effect. The effect probably occurred because much ·OH radicals were produced in the Fe(OH)2+ and H2O2 decomposition reactions irradiated by UV light; and many photoinduced electrons voluntarily participated in the reduction from Fe3+ to Fe2+, resulting in improved TCAA degradation efficiency due to suppressed recombination of photogenereated electrons and holes.