Negatively charged polyimide nanofiltration membranes with high selectivity and performance stability by optimization of synergistic imidization

作者：Wei, Chenjie; He, Zhifu; Lin, Ligang^*; Cheng, Qi; Huang, Kai; Ma, Sisi; Chen, Li^*

来源：Journal of Membrane Science, 2018, 563: 752-761.

DOI：10.1016/j.memsci.2018.06.046

• Polyimide
• Nanofiltration membrane
• Synergistic imidization
• Excellent stability

A simple strategy is proposed for high performance polyimide nanofiltration (PI-NF) membranes by optimization of a synergistic imidization reaction. Soluble poly(amic acid) polymers with partial imidization was successfully controlled and fabricated by chemical imidization. With the product as a matrix, NF membranes with an integrally skinned asymmetric architecture were obtained by phase inversion and subsequent thermal imidization. The brittle and ruptured defects caused by directly high temperature conversion for fabricating PI-NF membranes were effectively avoided. The prepared membrane showed high rejections for dye, PEG and typical salts. The fabricated PI-NF membranes were endowed with a high permeance of isopropyl alcohol [approximately 1 L/ (m(2) h bar)] and a high rejection of rose Bengal (greater than 92%). The molecular weight cut-off of PI-NF membrane is below 800 Da. The pure water flux of PI-NF membrane prepared under optimized conditions was approximately 20 L/(m(2) h) and the rejection for Na2SO4 was 93.91% at 5 bar. The rejection for different salts followed the order: Na2SO4 > MgSO4 > NaCl > MgCl2, revealed that Donnan exclusion theory and steric hindrance effect dominated the rejection mechanism. Furthermore, the NF membranes showed excellent stability over a long-term filtration process.

• 出版日期2018-10-1
• 单位天津工业大学