Department of Environmental Engineering, China Jiliang University, Hangzhou, 310018, Zhejiang, China.
College of Environment Science and Resources, Xiangtan University, Xiangtan, 411105, China.
Environ Pollut. 2023 Jun 15;327:121454. doi: 10.1016/j.envpol.2023.121454. Epub 2023 Mar 28.
The heterogeneous photo-Fenton process is an effective technology for degrading organic contaminants in wastewater, and Fe-based catalysts are recently preferred due to their low biotoxicity and geological abundance. Herein, we synthesized a Fe-containing red mud biochar (RMBC) via one-step co-pyrolysis of red mud and shaddock peel as a photo-Fenton catalyst to activate HO and degrade an azo dye (acid orange 7, AO7). RMBC showed excellent AO7 removal capability with a decolorization efficiency of nearly 100% and a mineralization efficiency of 87% in the heterogeneous photo-Fenton process with visible light irradiation, which were kept stable in five successive reuses. RMBC provided Fe for HO activation, and the light irradiation facilitated the redox cycle of Fe/Fe in the system to produce more reactive oxygen species (ROS, i.e., •OH) for AO7 degradation. Further investigation revealed that •OH was the predominant ROS responsible for AO7 degradation in the light-free condition, while more ROS were produced in the system with light irradiation, and O was the primary ROS in the photo-Fenton process for AO7 removal, followed by •OH and O. This study provides insight into the interfacial mechanisms of RMBC as a photo-Fenton catalyst for treating non-degradable organic contaminants in water through advanced oxidation processes under visible light irradiation.
非均相类芬顿工艺是一种有效降解废水中有机污染物的技术，而近年来由于铁基催化剂具有低生物毒性和丰富的地质资源而受到青睐。在此，我们通过一步共热解赤泥和柚子皮合成了一种含铁赤泥生物炭（RMBC），作为类芬顿催化剂来激活 HO 并降解偶氮染料（酸性橙 7，AO7）。在可见光照射下的非均相类芬顿工艺中，RMBC 表现出优异的 AO7 去除能力，脱色效率接近 100%，矿化效率为 87%，在五次连续重复使用中保持稳定。RMBC 为 HO 激活提供了 Fe，光照促进了系统中 Fe/Fe 的氧化还原循环，从而产生更多的活性氧物种（ROS，即 •OH）用于 AO7 的降解。进一步的研究表明，在无光照条件下，•OH 是降解 AO7 的主要 ROS，而在有光照的系统中会产生更多的 ROS，O 是光芬顿工艺去除 AO7 的主要 ROS，其次是 •OH 和 O。本研究通过可见光照射下的高级氧化工艺，深入了解 RMBC 作为光芬顿催化剂处理水中不可降解有机污染物的界面机制。
