Lin Yi-Li, Zheng Nai-Yun, Gan Hao-Yu, Chang An-Xian, Luo Huai-Xuan, Mao Yao-Jie
Department of Safety, Health and Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung 824, Taiwan.
Membranes (Basel). 2021 Nov 22;11(11):904. doi: 10.3390/membranes11110904.
This study in-situ modified a commercial nanofiltration membrane, NF90, through the concentration-polymerization-enhanced radical graft polarization method by applying two agents of 3-sulfopropyl methacrylate potassium salt (SPM) and 2-hydroxyethyl methacrylate (HEMA) with different dosages. Surface characterization revealed that the modified membranes became rougher and more hydrophilic compared with the pristine membrane. The modified membranes exhibited considerably enhanced separation performance with 5.8-19.6% higher NaCl rejection and 17.2-19.9% higher pharmaceuticals and personal care products (PPCPs) rejection than the pristine membrane. When treating the feedwater with high silica concentration, the modified membranes exhibited relatively less flux decline with high percentage of reversible fouling, especially the ones modified using a lower monomer concentration (0.01 M SPM and 0.01 M HEMA). Moreover, membrane modification enhanced the PPCP rejection (1.3-5.4%) after silica fouling by mitigating foulant deposition on the membrane surface. The fouling mechanism was confirmed to be intermediate blocking of membrane pores. Therefore, the in-situ modification technique with a low monomer concentration proved to be effective for mitigating silica fouling and improving PPCP rejection, which can be easily performed and cost-effective in practical application.
本研究通过浓度聚合增强自由基接枝极化法，使用不同剂量的3-磺丙基甲基丙烯酸酯钾盐（SPM）和甲基丙烯酸2-羟乙酯（HEMA）两种试剂对商用纳滤膜NF90进行原位改性。表面表征显示，与原始膜相比，改性膜变得更粗糙且更具亲水性。改性膜的分离性能显著提高，对氯化钠的截留率比原始膜高5.8 - 19.6%，对药物和个人护理产品（PPCPs）的截留率比原始膜高17.2 - 19.9%。在处理高硅浓度的进水时，改性膜表现出相对较小的通量下降，且可逆污染比例较高，特别是使用较低单体浓度（0.01 M SPM和0.01 M HEMA）改性的膜。此外，膜改性通过减轻污染物在膜表面的沉积，提高了二氧化硅污染后对PPCP的截留率（提高了1.3 - 5.4%）。污垢形成机制被确认为膜孔的中间堵塞。因此，低单体浓度的原位改性技术被证明对减轻二氧化硅污染和提高PPCP截留率有效，在实际应用中操作简便且成本效益高。
