Department of Environmental Science, Zhejiang University, Hangzhou, Zhejiang 310058, China; Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou 310058, China.
Sci Total Environ. 2020 Jul 1;724:138278. doi: 10.1016/j.scitotenv.2020.138278. Epub 2020 Mar 27.
A novel magnetic catalytic composite (MBM) was developed by compositing α-MnO with a magnetic biochar containing FeO. XRD and EDS confirmed the crystalline structure and the chemical composition of MBM, while the one-dimensional α-MnO nanorods were observed on MBM by SEM. 4-chlorophenol as a typical toxic chlorinated organic compound was selected as the model pollutant. Even the MBM composite (MnO content: 0.2 g/L) needed the same time (120 min) as the pure α-MnO nanorods (0.2 g/L) to completely remove the 4-chlorophenol (10 mg/L) with overdosed peroxydisulfate (PDS), MBM indicated faster pollutant removal rate than the pure α-MnO nanorods in the first 100 min. It is possible that the adsorption of 4-chlorophenol by biochar might shorten the migration pathway of the generated active species to the pollutants, resulting the boosted removal rate. MBM was stable in the neutral environment which was desirable for the efficient pollutant removal. Both the radical quenching tests and the EPR spectra identified the main active specie generated by activation of PDS through MBM was singlet oxygen possibly generated by recombination of superoxide ions from the metastable manganese intermediates at neutral pH. TOC data of the effluent ensured 63.5% of the pollutant molecules were completely mineralized after the degradation. The applied magnetic field could recover MBM easily for reuse. This work shed lights on the preparation of highly efficient and environmentally friendly catalytic composites for PDS activation in persistent pollutant removal.
一种新型磁性催化复合材料（MBM）由含 FeO 的磁性生物炭与α-MnO 复合而成。XRD 和 EDS 证实了 MBM 的晶体结构和化学成分，而 SEM 则观察到 MBM 上存在一维的α-MnO 纳米棒。以典型的有毒含氯有机化合物 4-氯苯酚为模型污染物。即使 MBM 复合材料（MnO 含量：0.2 g/L）与纯α-MnO 纳米棒（0.2 g/L）需要相同的时间（120 min）才能完全去除过剂量过硫酸钠（PDS）中的 10 mg/L 的 4-氯苯酚，但在最初的 100 min 内，MBM 表现出比纯α-MnO 纳米棒更快的污染物去除率。这可能是因为生物炭对 4-氯苯酚的吸附缩短了生成的活性物质向污染物迁移的途径，从而提高了去除率。MBM 在中性环境中稳定，这有利于高效去除污染物。自由基猝灭试验和 EPR 图谱均表明，通过 MBM 激活 PDS 生成的主要活性物质可能是单线态氧，其可能是由中性 pH 下亚稳锰中间体的超氧离子复合产生的。出水的 TOC 数据确保了 63.5%的污染物分子在降解后完全矿化。施加的磁场可以很容易地回收 MBM 以重复使用。这项工作为高效、环保的催化复合材料在持久性污染物去除中用于 PDS 活化提供了思路。
