不同添加物对UV-TiO_2体系降解水体中邻苯二甲酸二甲酯的影响

Effect of additive substances on UV-TiO_2 photodegradation of dimethyl phthalate in aqueous solution

利用光化学反应装置研究了在紫外光照射下,添加有机物、无机阴、阳离子和氧化性物质对TiO2光催化降解DMP的不同影响。结果表明,添加有机物甲醇、甲醛、丙酮使反应效率下降,阴离子Cl-,SO42-和CO32-对降解反应有抑制作用,其大小顺序为:Cl->SO42->CO32-,NO3-的作用不明显。阳离子Cu2+,Fe2+,Zn2+对TiO2的催化效果具有抑制作用,其作用大小顺序为:Fe2+>Zn2+>Cu2+,而Fe3+则具有促进作用。氧化性物质,如KBrO3,K2S2O8和H2O2等均可使反应效率提高,提高幅度S2O82->BrO3->H2O2。从光吸收、吸附作用以及对光生电子和空穴的捕获作用等方面讨论了上述物质影响TiO2光催化降解DMP效率的原因。最后通过各活性物种对降解反应贡献的定量对比,提出了能够进一步提高TiO2光催化降解效率的可行方向。

The depletion of dimethyl phthalate （DMP） was investigated in the presence of several co-existing organic and inorganic substances （ cations and anions）. The results indicate that the addition of organic substances （formaldehyde, methanol and acetone ） drastically suppress the decomposition of DMP. The addition of the examined anions, Cl-,SO4^2,CO3^2- and cations, Cu^2＋ ,Fe^2＋ ,Zn^2＋ has an adverse effect on the degradation rates to a varying degree of C1- 〉 SO4^2- 〉 CO3^2- and Fe^2＋ 〉 Zn^2＋ 〉 Cu^2＋ , except for NO3- nearly having no obvious action and ferric ion contributing to an enhancement effect. Oxidant substances, such as KBrO3, K2S208 and H202 all improve the photodegradation rate of DMP in order of S2082- 〉 BrO3 - 〉 H202. The effects of the above materials on DMP photocatalytie degradation were discussed from the optical absorption, adsorption, as well as photogenerated electrons and hole capture actions, etc. Finally, all kinds of reactive species contributing to photodegradation reaction were compared quantitatively and a feasible direction of further improving the efficiency of TiO2 photocatalytie degradation was proposed.