Li Baoqing, Zheng Zhiran, Fang Jianzhang, Gong Jiaxin, Fang Zhanqiang, Wang Wenxiang
Guangdong Engineering and Technology Research Center of Solid Waste Resource Recovery and Heavy Metal Pollution Control, Guangdong Polytechnic of Environmental Protection Engineering, Foshan, 528216, China.
School of Environment, South China Normal University, Guangzhou, 510006, China.
Environ Sci Pollut Res Int. 2021 Feb 24. doi: 10.1007/s11356-021-13057-8.
Although biochar (BC) has been widely used to adsorb pollutants in environment due to its natural and green characteristics, the structural defects of BC limit the ability to remove various environmental pollutants in aqueous solution. In this study, oxidized biochar (OBC) and sulfhydryl biochar (SBC) derived from pomelo peel (PP) were prepared through an oxidation and esterification reaction. BC and modified BC were used for the removal of methylene blue (MB), Cd, and phenanthrene (PHE) in aqueous solution. The adsorption behavior and efficiency toward different types of pollutants were studied by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), Raman, X-ray photoelectron spectroscopy (XPS), kinetics, and isotherm model fitting. The results showed that the change of pH had great effect on MB and Cd adsorption, but not on PHE. SBC not only possessed the newly formed sp-hybridized domains with easy access to aromatic pollutants but also had multiple functional groups (-COOH, -OH, -SH, -NH) that provided adsorption sites for positively charged pollutants. SBC was more flexible and efficient in purifying pollutants compared to BC and OBC, with the saturated adsorption capacities of MB (209.16 mg/g), Cd (786.19 mg/g), and PHE (521.58 mg/g). Moreover, the adsorption kinetic and isotherms fitting showed that the adsorption mechanisms were closely related to the structure of biochar and the properties of pollutants, including π-π interaction, surface charge, electrostatic interaction, surface functional groups, and Van der Waals force. In addition, the analysis of structure-function relationship demonstrated the enhanced hydrophilicity and the easy exposure of the binding sites on OBC and SBC. Hence, it was significantly effective to regulate microstructure and interfacial properties to promote its adsorption behaviors of biochar.
尽管生物炭（BC）因其天然绿色的特性已被广泛用于吸附环境中的污染物，但其结构缺陷限制了其去除水溶液中各种环境污染物的能力。在本研究中，通过氧化和酯化反应制备了源自柚子皮（PP）的氧化生物炭（OBC）和巯基生物炭（SBC）。将BC和改性BC用于去除水溶液中的亚甲基蓝（MB）、镉（Cd）和菲（PHE）。通过傅里叶变换红外光谱（FT-IR）、扫描电子显微镜（SEM）、拉曼光谱、X射线光电子能谱（XPS）、动力学和等温线模型拟合研究了对不同类型污染物的吸附行为和效率。结果表明，pH值的变化对MB和Cd的吸附有很大影响，但对PHE没有影响。SBC不仅具有易于接触芳香族污染物的新形成的sp杂化域，而且具有多个为带正电荷的污染物提供吸附位点的官能团（-COOH、-OH、-SH、-NH）。与BC和OBC相比，SBC在净化污染物方面更灵活高效，对MB（209.16 mg/g）、Cd（786.19 mg/g）和PHE（521.58 mg/g）的饱和吸附容量更高。此外，吸附动力学和等温线拟合表明，吸附机制与生物炭的结构和污染物的性质密切相关，包括π-π相互作用、表面电荷、静电相互作用、表面官能团和范德华力。此外，结构-功能关系分析表明OBC和SBC的亲水性增强且结合位点易于暴露。因此，调节微观结构和界面性质以促进生物炭的吸附行为具有显著效果。
