石墨烯量子点纳滤膜的仿生修饰及稳定性研究

Biomimetic modification and stability of graphene quantum dots nanofiltration membranes

亲水修饰是提高纳滤膜抗污染性能的重要方法。采用氯化胆碱(ChC)对石墨烯量子点(GQDs-TMC)纳滤膜进行后处理仿生修饰,模拟细胞膜上磷酰胆碱的两性离子抗污染表面。红外光谱(FTIR)和表面元素分析(EDS)表明ChC以共价键结合在纳滤膜分离层上。提高反应温度和氯化胆碱溶液浓度,可以增加纳滤膜的仿生修饰程度。ChC的季铵基团与GQDs-TMC纳滤膜分离层羧基基团形成两性离子结构,提高了仿生修饰(GQDs/ChC-TMC)纳滤膜的亲水性,降低了表面电势,提高了对染料分子和二价盐离子的截留率,并且显著增强了抗污染性能。经过酸、碱和氧化剂溶液浸泡处理及高温纳滤膜分离实验,GQDs/ChC-TMC纳滤膜的渗透率和截留率均未发生较大改变,表明仿生纳滤膜具有优异的化学稳定性和耐热稳定性。

Biomimetic modification is an important method to improve the antifouling performance of nanofiltration membranes.Choline chloride(ChC)was used to post-process the graphene quantum dots(GQDs-TMC)nanofiltration membrane to mimic the zwitterionic anti-pollution surface of phosphorylcholine on the cell membrane.Fourier transform infrared spectrometer(FTIR)and energy dispersive spectrometer(EDS)measurement showed that choline chloride molecules were covalently bonded to the separation layer of nanofiltration membrane.The degree of biomimetic modification would be enhanced by increasing the reaction temperature and the concentration of choline chloride solution.The quaternary ammonium groups of ChC forms zwitterionic structure with carboxyl groups in the separation layer of nanofiltration membranes,which improved the hydrophilicity of the biomimetic nanofiltration(GQDs/ChC-TMC)membranes,reduced the surface potential,improved the rejection ratios of dye molecules and divalent salt ions,and significantly enhanced the antifouling performance.After soaking in acid,alkali and oxidant solutions and high temperature separation experiments of nanofiltration membrane,the permeability and rejection ratio of GQDs/ChC-TMC nanofiltration membranes have not changed significantly.It indicated that the biomimetic nanofiltration membrane has excellent chemical stability and thermal stability.