生物炭孔径结构-氮缺陷与四环素降解的相关性

制备了具有不同孔径结构和氮缺陷的生物炭材料,通过吸附、过硫酸盐高级氧化(催化)两种反应体系获得的动力学数据,结合氮气吸脱附测试、X射线光电子能谱、拉曼光谱、电子顺磁共振测试等表征手段,系统并深入分析了孔径结构-氮缺陷与典型抗生素污染物(盐酸四环素)降解的相关性.结果表明,孔径结构中与降解过程线性相关性最大的是介孔面积,相关系数(R²)高达0.9804,其次是总比表面积.而元素中与降解过程线性相关性最大的为氮元素,特别是石墨氮(R²为0.9766)及吡啶氮(R²为0.9596).此外,吸附、催化两个反应体系中孔径结构的相关性规律基本一致,但氮元素,尤其是石墨氮和吡啶氮,在催化体系中的R²大于吸附.通过淬灭实验、电子顺磁共振测试、线性扫描伏安法及拉曼测试等分析发现,该催化过程主要是以单线态氧为主的非自由路径.本研究为过硫酸盐高级氧化系统中生物炭基催化材料的制备明确了思路:对于盐酸四环素这类抗生素的降解可制备具有高介孔面积、高比表面积及富氮元素,特别是石墨氮及吡啶氮的生物炭材料.

Correlation between biochar pore structure-nitrogen defects and tetracycline hydrochloride degradation

Different pore structure and nitrogen defects of biochar materials were prepared in this work. The dynamic data of adsorption and persulfate-based advanced oxidation process (catalysis) systems were combined with the nitrogen adsorption -desorption test, X-ray photoelectron spectroscopy, Raman test and other characterization methods. They were used to analysis the correlation of pore structure-nitrogen defects and typical antibiotics (tetracycline hydrochloride) degradation systematically and deeply. The results showed that mesoporous surface area and specific surface area were most correlated with persulfate reaction. Nitrogen, especially graphite nitrogen (R²=0.9766) and pyridine nitrogen (R²=0.9596), was the most relevant elements to the reaction process of the system. In addition, the correlation between pore structure and the results was basically same in adsorption and catalysis processes. But nitrogen showed greater correlation in catalysis system than adsorption. Through quenching experiment, linear sweep voltammetry and Raman test, it was found that the catalysis was mainly dominated by singlet oxygen, which meant it was nonradical pathway. Finally, a better preparation direction for biochar materials to be used as activators in the persulfate-based advanced oxidation process of tetracycline hydrochloride was provided. Biochar materials with larger mesoporous surface area, larger specific surface area and more nitrogen, especially graphite nitrogen and pyridine nitrogen should be prepared for the catalysis of tetracycline hydrochloride.