高通量荷正电碳量子点杂化纳滤膜的制备及应用

Preparation and application of high-flux positively charged nanofiltration membrane filled with carbon quantum dots

为了提高纳滤膜的分离性能,以表面带有氨基基团碳量子点(Amino-functionalized carbon quantum dots, N-CQD)为填充粒子,采用界面聚合方法制备高通量荷正电杂化聚酰胺纳滤膜,并对N-CQD和杂化纳滤膜结构、形貌和性能进行表征分析。结果表明:良好的亲水性和表面带有可参与界面聚合反应的氨基基团,使N-CQD通过化学键均匀、稳定地分布在聚酰胺基体中,因此可同时提高纳滤膜通量和截留率。在最佳制膜条件下,所制备的纳滤膜的水通量为58.22 L/(m^(2)·h),与未添加N-CQD纳滤膜相比,通量提高了约2.6倍;同时截留的无机盐按截留率从大到小依次为MgCl_(2)(95.4%)、CaCl_(2)(92.1%)、MgSO_(4)(85.2%)、NaCl(64.8%)、Na_(2)SO_(4)(48.6%)。制备得到的纳滤膜对二价阳离子有较高的截留率,在硬水软化领域具有实际应用价值。

To improve the separation performance of nanofiltration membrane, we employed carbon quantum dots with amino groups on their surface(N-CQD) as nanofiller to prepare high-flux positively charged polyamide nanofiltration membranes via interfacial polymerization. The structure, morphology, and performance of N-CQD and corresponding nanofiltration membrane were fully characterized. The results show that N-CQD can disperse uniformly and stably in polyamide matrix through chemically bond, benefiting from their good hydrophilicity and amino groups on their surface that can participate in the interface polymerization. All these merits led to improved water permeability without the sacrifice of salt rejections. At the optimized conditions, the water flux of prepared nanofiltration membrane was 58.22 L/(m^(2)·h), which was 2.6 times higher than that of pristine nanofiltration membrane. Meanwhile, the sequence of salt rejection was MgCl_(2)(95.4%), CaCl_(2)(92.1%), MgSO_(4)(85.2%), NaCl(64.8%), Na_(2)SO_(4)(48.6%) from high to low. The high rejection to divalent cation makes the prepared nanofiltration membrane suitable for water softening.