The Education Ministry Key Lab of Resource Chemistry, Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University, Shanghai 200234, PR China.
The Education Ministry Key Lab of Resource Chemistry, Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University, Shanghai 200234, PR China.
J Colloid Interface Sci. 2021 Mar 15;586:563-575. doi: 10.1016/j.jcis.2020.10.121. Epub 2020 Nov 3.
Organic pollutants in electroplating wastewater can be removed by photodegradation, however the effect mechanism of heavy metal ions on photocatalytic activity still remains unknown. Herein, we firstly reported the self-assembly synthesis of titanium dioxide/reduced graphene oxide (TiO/rGO) composites for phenol-4-sulfonic acid (PSA) removal, and investigated the effects of Cu ions on photocatalytic efficiency. During the self-assemble process, rGO nanosheets were connected together to form network macropores, and simultaneously induced the deposition of hierarchically nanostructured TiO microspheres. The synergetic effects of TiO microspheres and rGO nanosheets improved the photocatalytic activity by enhancing light adsorption ability, stabilizing electron-hole separation and decreasing band gap energy. The Cu ions in wastewater showed positive and negative effects on PSA photodegradation. In the photocatalytic reaction, the electron-induced reduction reaction of Cu(II) into Cu(0) or Cu(I) took place, which inhibited electron-hole recombination and thus enhanced photocatalytic activity. However, the high chemical stability of PSA-Cu(II) complex compounds held back PSA photodegradation. The appropriate concentrations of Cu ions at around 25 mg/L accelerated PSA photodegradation over TiO/rGO composites. The PSA degradation into CO and HO was performed by using hydroquinone, benzoquinone and maleic acid as degradation intermediates. Hence, TiO/rGO composites are novel multifunctional photocatalysts to purify electroplating wastewater.
电镀废水中的有机污染物可以通过光降解去除，然而重金属离子对光催化活性的影响机制仍不清楚。本文首次报道了用于去除对苯二酚-4-磺酸（PSA）的二氧化钛/还原氧化石墨烯（TiO/rGO）复合材料的自组装合成，并研究了铜离子对光催化效率的影响。在自组装过程中，rGO 纳米片相互连接形成网络大孔，同时诱导分级纳米结构的 TiO 微球的沉积。TiO 微球和 rGO 纳米片的协同效应通过增强光吸收能力、稳定电子-空穴分离和降低带隙能来提高光催化活性。废水中的 Cu 离子对 PSA 光降解表现出正、负两方面的影响。在光催化反应中，Cu(II)发生电子诱导还原反应生成 Cu(0)或 Cu(I)，抑制了电子-空穴复合，从而增强了光催化活性。然而，PSA-Cu(II)配合物的高化学稳定性阻碍了 PSA 的光降解。在 25mg/L 左右的适当浓度的 Cu 离子加速了 TiO/rGO 复合材料对 PSA 的光降解。利用对苯二酚、苯醌和马来酸作为降解中间产物，将 PSA 降解为 CO 和 HO。因此，TiO/rGO 复合材料是一种新型的多功能光催化剂，可用于净化电镀废水。
