Facile synthesis of sludge-derived MnOx-N-biochar as an efficient catalyst for peroxymonosulfate activation
Facile synthesis of sludge-derived MnOx-N-biochar as an efficient catalyst for peroxymonosulfate activation
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DOI：
10.1016/j.apcatb.2019.117765
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发表时间：
2019-10-15
影响因子：
22.1
通讯作者：
Song, Yu
中科院分区：
文献类型：
--
作者：
Mian, Md Manik;Liu, Guijian;Song, Yu
污水污泥（SS）是废水处理厂不可避免的副产品，正面临着环境安全和具有成本效益的处置的众多挑战。因此，非常需要探索有效的 SS 增值技术。在这项研究中，通过NH4OH活化和热解（800摄氏度）合成了污泥衍生的碳载MnOx作为催化剂（ASMn-Nb），以增强过一硫酸盐（PMS）分解以及随后酸性橙7和罗丹明B的降解。样品表征表明，MnCl2调节在ASMn-Nb上产生混合价Mn氧化物，而NH4OH活化显着增强了N-杂原子、表面积、和微孔率。合成的混合催化剂在较宽的pH范围内表现出优异的PMS分解能力，与原污泥生物炭处理相比，40分钟内AO7去除效率提高16%-100%。此外，该催化剂可回收、化学稳定，并且在催化过程中产生的金属浸出可以忽略不计。对催化机制的进一步研究表明，自由基和非自由基过程控制 PMS 分解，而介导的电子转移作为主要自由基和 O-1(2)、SO4 中心点-和 (OH)-O-中心点自由基诱导催化作为 PMS 活化和随后 AO7 降解的次要机制。最后，提出了 ASMn-Nb 和 AO7 降解路径上 PMS 分解的可能机制。这项研究同时提供了一种提高污泥衍生生物炭催化性能的简便途径和一种可能的 SS 增值技术。
Sewage sludge (SS), the inevitable byproduct of wastewater treatment plants, is facing numerous challenges of environmentally safe and cost-effective disposal. Thus, exploration of efficient SS valorization technique is highly desired. In this study, a sludge derived carbon-supported MnOx as a catalyst (ASMn-Nb) was synthesized through NH4OH activation and pyrolysis (800 degrees C) to enhance peroxymonosulfate (PMS) decomposition and subsequent degradation of acid orange 7 and rhodamine B. The sample characterization indicated that MnCl2 conditioning produces mixed valent Mn oxides on ASMn-Nb, while NH4OH activation significantly enhances N-heteroatoms, surface area, and microporosity. The as-synthesized hybrid catalyst exhibited excellent PMS decomposition ability in a wide range of pH, which enhances AO7 removal efficiency 16%-100% in 40 min compared with that treated with raw sludge biochar. Moreover, the catalyst is recyclable, chemically stable, and produce negligible metal leaching during catalysis. Further investigation of catalytic mechanisms revealed that both radicle and non-radicle processes governing PMS decomposition, whereas mediated electron transfer as the primary and O-1(2), SO4 center dot-, and (OH)-O-center dot radicals induced catalysis as the secondary mechanisms of PMS activation and subsequent AO7 degradation. Finally, a probable mechanism of PMS decomposition over ASMn-Nb and AO7 degradation path is proposed. This study concurrently provides a facile route of improving the catalytic performance of sludge derived-biochar and a probable SS valorization technique.