Abstract:

The graphitized biochar WSC600K-B was prepared using waste walnut shell as raw material and KOH as modifier. The material was characterized by SEM, TEM, BET, XRD and Raman spectrum. The adsorption performance and mechanism of sulfamethoxazole (SMX) by WSC600K-B were investigated. The results showed that after activated by KOH, the surface of WSC600K-B presented orderly graphite lattice articles, the corresponding I_D/I_G was 1.037,and the degree of graphitization was high. The pore structure of WSC600K-B with honeycomb briquette shape was greatly improved, the pore was uniformly distributed, and the specific surface area increased to 733.64m²/g. At room temperature and pH=5, the removal rate of 50mg/L SMX by 0.25g/L WSC600K-B could reach 94.28%, and the adsorption capacity was 203.64mg/g. The adsorption process was significantly affected by pH and coexisting ions. The higher the pH value, the lower the adsorption efficiency. Coexisting ions inhibited the adsorption process. The adsorption process was in accordance with the second-order kinetic model and the Freundlich isothermal model, which was a multi-molecular layer chemical adsorption. Pore filling, π-π stacking, hydrogen bonding, hydrophobic interaction, and electrostatic interaction occurred during the reaction and the adsorption behavior was a spontaneous exothermic reaction.

Key words: graphitization, walnut shell, biochar, sulfamethoxazole, adsorption

摘要：

以废弃生物质核桃壳为原料，KOH为改性剂，制备了石墨化生物质炭WSC600K-B，并通过SEM、TEM、BET、XRD、拉曼光谱等对材料进行了表征，考察了其吸附磺胺甲唑（SMX）的性能和机理。研究结果表明，经KOH活化后，WSC600K-B表面呈现排列整齐的石墨晶格条纹，对应I_D/I_G为1.037，石墨化程度较高；孔隙结构大大提高，呈蜂窝煤状，孔隙均匀分布，比表面积增大为733.64m²/g。室温下，pH=5时，0.25g/L WSC600K-B对50mg/L SMX的去除率可达94.28%，吸附容量为203.64mg/g。WSC600K-B对SMX的吸附过程受pH和共存离子影响，pH越高去除率越低，共存离子会抑制吸附过程。吸附过程符合二级动力学模型以及Freundlich等温模型，为多分子层化学吸附，反应存在孔径填充、π-π堆积、氢键作用、疏水作用和静电作用，吸附行为是自发进行的放热反应。

关键词: 石墨化, 核桃壳, 生物质炭, 磺胺甲唑, 吸附