PEI改性生物炭的制备及对CO2吸附性能的评价

Preparation of PEI-modified biochar and evaluation of its CO adsorption performance

采用超声辅助-水热法将聚乙烯亚胺(PEI)成功接枝到玉米芯生物炭表面,制备了PEI改性生物炭材料(PBC),并通过X射线衍射(XRD)、扫描电子显微镜(SEM)、比表面积分析仪和傅里叶红外光谱仪(FTIR)等方法对其表征.结果表明,虽然PEI通过C=N、C—N和离子键与生物炭表面的活性基团链接,但制备的PBC材料仍保持原生炭的无定型结构和形貌,且比表面积高达928.1 m2·g^(-1).同时,还研究了PBC的吸附性能和热力学行为,结果表明,吸附过程符合Langmuir等温吸附机制,属于微孔单层吸附过程,而且随温度的降低,吸附量增大,在10、20和30℃时,饱和吸附量(Qm)分别为6.47、4.75和2.64 mmol·g^(-1).此外,PBC重复利用性能良好,容易实现热再生,即使循环利用10次,吸附性能也无显著变化(p>0.05),且穿透吸附量(QB)保持在2.6~2.7 mmol·g^(-1).

Polyethyleneimine(PEI) was successfully grafted onto the surface of corn cob biochar by ultrasonic-assisted-hydrothermal method, and PEI modified biochar material(PBC) was prepared. It was characterized by XRD, SEM, BET, and FT-IR. The results exhibited that PEI was linked to the active groups on the surface of biochar through C=N,C-N and ionic bonds. The PBC materials with a specific surface area of 928.1 m2·g^(-1), still remained the amorphous structure and morphology the same as the original biochar. In addition, the adsorption performance and thermodynamic behavior of PBC were also studied. The results concluded that the adsorption process was consistent with the Langmuir isothermal adsorption model, which was a uniform adsorption process of microporous monolayers, and the adsorption capacities enhanced with decreasing temperature at 10, 20, and 30 ℃, with the Qm were 6.47, 4.75, and 2.64 mmol·g^(-1), respectively. Finally, PBC has good recyclability and easy to achieve thermal regeneration. Even if it was reused 10 cycles, there were no significant changes in adsorption performance(p>0.05), and QB remained between 2.6 mmol·g^(-1) and 2.7 mmol·g^(-1).