磺胺类药物光催化降解活性与分子电子结构相关性研究

以碳纳米管-二氧化钛为光催化剂,在可见光和紫外光照射条件下,研究磺胺、磺胺甲恶唑、磺胺噻唑及磺胺二甲嘧啶4种磺胺类药物在纯溶液和混合溶液中的光催化降解行为。采用量子化学理论中杂化密度泛函理论(DFT/B3LYP)对磺胺类分子构建几何模型,计算4种磺胺类药物的分子电子结构,研究它们光催化降解活性与分子电子结构的相关性。研究结果表明:4种磺胺类药物的可见光降解速率快慢为:磺胺>磺胺噻唑>磺胺甲恶唑>磺胺二甲嘧啶;纯溶液中磺胺类药物的光催化降解活性与分子电子结构存在密切的相关性,正辛醇-水分配系数越小、偶极矩越大、EHOMO越大、HOMO-LUMO能隙越小,降解速率越快;混合溶液中磺胺类药物的光催化降解速率不仅与其分子电子结构有关,也与其在光催化剂表面的吸附有关。

Correlativity between photocatalytic activity and molecular electronic structure for sulfonamides degradation

Photocatalytic degradation of sulfanilamide,sulfamethoxazole,sulfathiazole and sulfadimidine in aqueous suspension was investigated by using carbon nanotube modified TiO2 nanocomposite as the photocatalyst under visible-light and UV-light irradiation.The correlativity between molecule electronic structure and photocatalytic activity of sulfonamides was investigated by using quantum chemical method(density functional theory) DFT/B3LYP via calculating electronic structure changes.The results showed that the photocatalytic degradation rate of the four sulfonamides under visible-light irradiation was in the order of sulfanilamide>sulfathiazole>sulfamethoxazole>sulfadimidine.The photocatalytic activity of sulfonamides could be described better by their electronic structures:increasing the dipole moment and energy of HOMO and decreasing the n-octanol-water partition coefficient and the HOMO-LUMO gap lead to an increase in the photocatalytic degradation rate.The photocatalytic degradation rates of the sulfonamides in mixture relate to not only their molecule electronic structures but also the adsorption on the photocatalyst.