School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao 266033, China E-mail:
Water Sci Technol. 2021 May;83(9):2135-2145. doi: 10.2166/wst.2021.116.
Titanium dioxide (TiO) photocatalyst was prepared with a sol-gel method and its characterizations were analyzed TiO photocatalytic reduction of Cr was investigated in visible light irradiation and reduction mechanisms were calculated. Prepared TiO is anatase with a bandgap of about 2.95 eV. Experimental results display that almost 100% of Cr is removed by visible light-driven TiO photocatalytic reduction after 120 min when CrO initial concentration is 1.0 mg·L, TiO dosage is 1.0 g·L, and pH value is 3. In acidic aqueous solution, HCrO is the dominant existing form of Cr and is adsorbed by TiO, forming a complex catalyst HCrO/TiO with an increase in wavelength to the visible light zone, demonstrated by UV-Vis diffuse reflection spectroscopy. Based on X-ray photoelectron spectroscopy data, it can be deduced that Cr is adsorbed on the surface of TiO and then reduced to Cr in situ by photoelectrons. Self-assembly of HCrO/TiO complex catalyst and self-reduction of Cr in situ are the key steps to start the visible light-driven TiO photocatalytic reduction. Furthermore, TiO photocatalytic reduction of Cr fits well with pseudo-first-order kinetics and has the potential application to treat chemical industrial wastewater.
二氧化钛（TiO）光催化剂采用溶胶-凝胶法制备，并对其进行了特性分析。研究了可见光照射下 TiO 的光催化还原 Cr 的作用，计算了还原机制。制备的 TiO 为锐钛矿，带隙约为 2.95eV。实验结果表明，当 CrO 初始浓度为 1.0mg·L、TiO 用量为 1.0g·L、pH 值为 3 时，CrO 在可见光驱动的 TiO 光催化还原下，经过 120min 后几乎 100%被去除。在酸性水溶液中，HCrO 是 Cr 的主要存在形式，被 TiO 吸附，形成一种复合催化剂 HCrO/TiO，随着波长向可见光区的增加，这一点通过紫外可见漫反射光谱得到了证明。根据 X 射线光电子能谱数据，可以推断 Cr 被吸附在 TiO 的表面，然后通过光电子原位还原为 Cr。HCrO/TiO 复合催化剂的自组装和 Cr 的原位自还原是启动可见光驱动的 TiO 光催化还原的关键步骤。此外，TiO 光催化还原 Cr 符合准一级动力学，具有处理化工废水的潜在应用价值。
