College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, Hunan, China.
College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, Hunan, China.
Chemosphere. 2020 Dec;261:127747. doi: 10.1016/j.chemosphere.2020.127747. Epub 2020 Jul 22.
To develop a metal-free biochar with high and inherent catalytic activity towards refractory and highly toxic contaminants in advanced oxidation processes, it is necessary to explore its reaction pathways and responsible catalytic sites. Herein, a metal-free biochar derived from corn cob (CCBC) was prepared and used for reaction pathway analysis during peroxydisulfate (PDS) activation. The pyrolysis temperature played an important role for regulating the biochar structure and properties, and CCBC obtained at 800 °C showed the best adsorption capacity and catalytic activity towards five typical organic pollutants, including 2, 4-dichlorophenol, Tetracycline hydrochloride, Ciprofloxacin, Methyl orange and Rhodamine B, due to its richer pore and defect structure. Further treatment of pharmaceutical wastewater demonstrated the good efficiency and potential of this metal-free catalyst for practical application. Radical (58% contribution) and non-radical (42% contribution) pathways were both found in CCBC/PDS system. More importantly, further redox experiments manifested that the carbon framework (defects, sp-hybrid carbon, etc.) only made a contribution to the free radical pathway, while the ketone group (CO) of CCBC was proved to be mainly responsible for the non-radical pathway, namely the generation of singlet oxygen (O).
为了在高级氧化过程中开发出对难处理和高毒性污染物具有高固有催化活性的无金属生物炭，有必要探索其反应途径和负责的催化位点。本文以玉米芯为原料制备了一种无金属生物炭（CCBC），并用于过一硫酸盐（PDS）活化过程中的反应途径分析。热解温度对调节生物炭的结构和性能起着重要作用，在 800°C 下获得的 CCBC 由于具有更丰富的孔和缺陷结构，对 5 种典型的有机污染物（包括 2,4-二氯苯酚、盐酸四环素、环丙沙星、甲基橙和罗丹明 B）表现出最好的吸附能力和催化活性。进一步处理医药废水证明了这种无金属催化剂在实际应用中的良好效率和潜力。在 CCBC/PDS 体系中发现了自由基（贡献 58%）和非自由基（贡献 42%）途径。更重要的是，进一步的氧化还原实验表明，碳骨架（缺陷、sp 杂化碳等）仅对自由基途径有贡献，而 CCBC 的酮基（CO）被证明主要负责非自由基途径，即单线态氧（O）的生成。
