State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, PR China.
State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, PR China.
Water Res. 2019 Mar 1;150:310-320. doi: 10.1016/j.watres.2018.11.067. Epub 2018 Nov 27.
The photocatalytic decomposition of bromate (BrO), a possible human carcinogen, has attracted much attention because of its high efficiency and easier combination with ultraviolet (UV) disinfection in water treatment plants. In this study, the Fe(II)Ti(IV) layered double hydroxides (LDHs) have been made through a facile hydrothermal method and used as an alternative photocatalyst for reduction of BrO. LDHs prepared at a Fe/Ti molar ratio of ∼0.5 and pH 7.0, denoted as FeTi-0.5 (pH 7.0), exhibited the highest BrO removal efficiency (removal rate constant = 0.067 ± 0.002 min) compared to commercial TiO and the LDHs prepared at different pHs or different Fe/Ti ratios. The presence of alcohols in water enhanced the photocatalytic reduction of BrO due to the greater abundance of electrons caused by alcohols effectively reacting with holes. The neutral pH also favors the degradation of BrO. However, the presence of nitrate and nitrite can inhibit the degradation process, due to their reactions with hydrated electrons (e) and hydrogen atom radicals (H∙). Cyclic degradation runs and magnetic separation techniques demonstrated the superior reusability of the FeTi-0.5 (pH 7.0) LDH for BrO removal. The removal rate of BrO under UV was higher than that without UV, indicating that the decomposition proceeded primarily via a photo-reductive mechanism induced by e and H∙ and thus degradation pathways are proposed. Moreover, when tested in tap water, greater than 90% of BrO was removed after 60 min reaction in UV/FeTi-0.5 (pH 7.0) LDH systems in the presence of 5‰ (v/v) methanol. This demonstrates the high potential for such systems for removing BrO from disinfected drinking water. This work may shed lights on the design of effective photocatalysts for the enhanced degradation of BrO in water plants and the influence of constituents in raw water on the treatment.
溴酸盐（BrO）的光催化分解因其在水处理厂中具有高效率和更容易与紫外线（UV）消毒相结合而受到广泛关注。在这项研究中，通过简便的水热法制备了 Fe(II)Ti(IV) 层状双氢氧化物（LDHs），并将其用作替代光催化剂来还原 BrO。在 Fe/Ti 摩尔比约为 0.5 和 pH 7.0 下制备的 LDHs，记为 FeTi-0.5（pH 7.0），与商业 TiO 和在不同 pH 或不同 Fe/Ti 比下制备的 LDHs相比，具有最高的 BrO 去除效率（去除速率常数为 0.067 ± 0.002 min）。水中醇的存在由于醇与空穴有效反应而导致电子的丰度增加，从而增强了 BrO 的光催化还原。中性 pH 也有利于 BrO 的降解。然而，硝酸盐和亚硝酸盐的存在会抑制降解过程，因为它们与水合电子（e）和氢原子自由基（H·）反应。循环降解运行和磁性分离技术证明了 FeTi-0.5（pH 7.0）LDH 用于 BrO 去除的优越可重复使用性。在 UV 下的 BrO 去除率高于无 UV 下的去除率，这表明分解主要通过 e 和 H·诱导的光还原机制进行，因此提出了降解途径。此外，在自来水中进行测试时，在存在 5‰（v/v）甲醇的情况下，在 UV/FeTi-0.5（pH 7.0）LDH 系统中反应 60 分钟后，超过 90%的 BrO 被去除。这表明该系统在去除消毒饮用水中的 BrO 方面具有很高的潜力。这项工作可能为设计用于增强水中 BrO 降解的有效光催化剂以及原水中成分对处理的影响提供了一些启示。
