School of Engineering, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA, 6027, Australia.
School of Engineering, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA, 6027, Australia; School of Enviromental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang, 212003, China.
Water Res. 2019 Dec 15;167:115110. doi: 10.1016/j.watres.2019.115110. Epub 2019 Sep 24.
Membrane separation and advanced oxidation processes (AOPs) have been respectively demonstrated to be effective for a variety of water and/or wastewater treatments. Innovative integration of membrane with catalytic oxidation is thus expected to be more competing for more versatile applications. In this study, ceramic membranes (CMs) integrated with manganese oxide (MnO) were designed and fabricated via a simple one-step ball-milling method with a high temperature sintering. Functional membranes with different loadings of MnO (1.67%, 3.33% and 6.67% of the total membrane mass) were then fabricated. The micro-structures and compositions of the catalytic membranes were investigated by a number of advanced characterisations. It was found that the MnO nanocatalysts (10-20 nm) were distributed uniformly around the AlO particles (500 nm) of the membrane basal material, and can provide a large amount of active sites for the peroxymonosulfate (PMS) activation which can be facilitated within the pores of the catalytic membrane. The catalytic degradation of 4-hydroxylbenzoic acid (HBA), which is induced by the sulfate radicals via PMS activation, was investigated in a cross-flow membrane unit. The degradation efficiency slightly increased with a higher MnO loading. Moreover, even with the lowest loading of MnO (1.67%), the effectiveness of HBA degradation was still prominent, shown by that a 98.9% HBA degradation was achieved at the permeated side within 30 min when the initial HBA concentration was 80 ppm. The stability and leaching tests revealed a good stability of the catalytic membrane even after the 6th run. Electron paramagnetic resonance (EPR) and quenching tests were used to investigate the mechanism of PMS activation and HBA degradation. Both sulfate radicals (SO) and hydroxyl radicals (OH) were generated in the catalytic membrane process. Moreover, the contribution from non-radical process was also observed. This study provides a novel strategy for preparing a ceramic membrane with the function of catalytic degradation of organic pollutants, as well as outlining into future integration of separation and AOPs.
膜分离和高级氧化工艺（AOPs）已分别被证明对各种水和/或废水处理有效。因此，预计将膜与催化氧化进行创新性集成，将更具竞争力，适用于更多的应用。在这项研究中，通过高温烧结的简单一步球磨法设计并制备了负载氧化锰（MnO）的陶瓷膜（CM）。然后制备了不同 MnO 负载量（占总膜质量的 1.67%、3.33%和 6.67%）的功能膜。通过多种先进的表征方法研究了催化膜的微结构和组成。结果发现，MnO 纳米催化剂（10-20nm）均匀分布在膜基材料的 AlO 颗粒（500nm）周围，并且可以为过一硫酸盐（PMS）活化提供大量的活性位点，这可以在催化膜的孔内得到促进。通过 PMS 活化诱导硫酸盐自由基，研究了 4-羟基苯甲酸（HBA）在交叉流膜单元中的催化降解。降解效率随着 MnO 负载量的增加而略有提高。此外，即使 MnO 的负载量最低（1.67%），HBA 的降解效果仍然很显著，在初始 HBA 浓度为 80ppm 时，在渗透侧 30min 内即可实现 98.9%的 HBA 降解。稳定性和浸出试验表明，即使经过 6 次运行，催化膜仍具有良好的稳定性。电子顺磁共振（EPR）和猝灭试验用于研究 PMS 活化和 HBA 降解的机制。在催化膜过程中均生成了硫酸盐自由基（SO）和羟基自由基（OH）。此外，还观察到非自由基过程的贡献。本研究为制备具有有机污染物催化降解功能的陶瓷膜提供了一种新策略，并为分离与 AOPs 的未来集成勾勒了蓝图。
