Energy Materials & Physics Group, Department of Physics, Shanghai University, Shanghai 200444, China; Institute of Low-Dimensional Carbon and Device Physics, Shanghai University, Shanghai 200444, China.
College of Physics and Electronic Information & Henan Key Laboratory of Electromagnetic Transformation and Detection, Luoyang Normal University, Luoyang 471934, China.
Sci Total Environ. 2021 Nov 15;795:148786. doi: 10.1016/j.scitotenv.2021.148786. Epub 2021 Jul 2.
Bromate, a toxic by-product of bromide-containing drinking water after disinfecting with ozone, has attracted much attention in the past two decades. Traditional methods to activate zero-valent metals for reducing bromate are to eliminate their surface oxide layer by acid washing. In this work, for the first time, zero-valent Al (ZVAl) was surface treated by the following procedures including soaking, soaking and freeze-drying, soaking and heat-treating, and γ-AlO covering Al particle surfaces (GCAP). It was found that all of above surface treated ZVAls have an obvious high efficiency for bromate reduction relative to pristine ZVAl. The bromate reduction rate is GCAP > soaking Al > freeze-drying Al > soaking and heat-treating Al > pristine Al, and using GCAP just 30 min is taken to completely reduce bromate to bromide in neutral solution. Mechanism analyses revealed that Al surface treating or covered by fine γ-AlO phase can promote the hydration and breakage of Al surface passive oxide layer, resulting in a fast contact of inner Al with outside ions, leading to a high reduction rate of bromate in neutral solution. XPS analyses indicated that there are no bromate or bromide ions adsorbed on Al particle surfaces, implying that there is a high direct donating efficiency of electrons from inner Al to bromate ions in solution. Furthermore, GCAP has a good reusability and >90% bromate can be reduced even it was reused up to 4 cycles.
溴酸盐是臭氧消毒含溴饮用水后产生的有毒副产物，在过去二十年中引起了广泛关注。传统的用零价金属激活来还原溴酸盐的方法是通过酸洗来消除其表面氧化层。在这项工作中，首次通过以下程序对零价铝（ZVAl）进行表面处理，包括浸泡、浸泡和冻干、浸泡和热处理以及 γ-AlO 覆盖铝颗粒表面（GCAP）。结果发现，所有经过表面处理的 ZVAls 相对于原始 ZVAl 对溴酸盐还原都具有明显的高效率。溴酸盐还原速率为 GCAP > 浸泡 Al > 冻干 Al > 浸泡和热处理 Al > 原始 Al，使用 GCAP 仅 30 分钟即可在中性溶液中完全将溴酸盐还原为溴化物。机理分析表明，Al 表面的细 γ-AlO 相的处理或覆盖可以促进 Al 表面的水合和钝化氧化物层的破裂，导致内层 Al 与外部离子快速接触，从而在中性溶液中实现高的溴酸盐还原速率。XPS 分析表明，Al 颗粒表面没有吸附溴酸盐或溴化物离子，这意味着溶液中内层 Al 向溴酸盐离子具有高的直接电子供体效率。此外，GCAP 具有良好的可重复使用性，即使重复使用 4 次，仍能将超过 90%的溴酸盐还原。
