二氧化钛悬浆体系中过硫酸盐对苯酚光催化降解的影响

研究了二氧化钛悬浮溶液中过硫酸盐对苯酚的吸附和光催化降解动力学的影响.在过硫酸盐浓度较低的条件下,S2 O2 - 8的加入能有效提高苯酚的光催化降解速率和表观量子产率,UV TiO2 K2 S2 O8体系下的表观量子产率大于UV TiO2 与UV K2 S2 O8两体系下表观量子产率之和;但是,当过硫酸盐浓度较高时,随着S2 O2 - 8浓度的增加,竞争性吸附加剧,二氧化钛表面的苯酚吸附量急剧减少,导致苯酚的降解速率和表观量子产率不升反降,苯酚平衡吸附量与光催化降解速率呈高度一致性.在本实验条件下,当K2 S2 O8浓度为5 0 0mg·L- 1 时表观量子产率达到最大,协同因子达0 3 9.在不同强度的入射光条件下,也能得到相似的结果.此外,讨论了pH值对不同体系TOC去除率的影响,并对在K2 S2 O8存在时TiO2 的光催化机理进行了探讨

Effect of persulphate on photocatalysis of phenol in aqueous TiO2 suspensions

The effect of persulphate on the photocatalytic degradation kinetics and adsorption behavior of phenol in TiO2 aqueous dispersions was investigated. The addition of persulphate, as an electron accepter, could not automatically increase the rate of photocatalytic degradation and quantum yield. When the concentration of persulphate was low, the addition of persulphate could increase the photocatalytic degradation rate and apparent quantum yield effectively. The apparent quantum yield in the system of UV/ TiO2/ K2S2O8 was much higher than the sum of those in the systems of UV/ TiO2 and UV/ K2S2O8, respectively. When the concentration of persulphate was much higher, however, the competitive adsorption of persulphate increased so fast that the adsorption quantity of phenol decreased rapidly with the increase of persulphate addition. In other words, both adsorption quantity and photocatalytic degradation rate of phenol appeared to be coherent. The results obtained from the apparent quantum yields showed that the optimal concentration of K2S2O8 was 500 mg?L-1 in the condition of this study. The synergy factor at the incident irradiation intensity of 0.025 Wcm-2 was 0.39. And the similar results were obtained at various incident irradiation intensities. In addition, the effect of pH value on TOC removal and a plausible mechanism of photocatalytic degradation in the presence of persulphate were discussed.