Selective separation of dye/salt mixtures via a tannic acid-polyethyleneimine-modified hollow fiber membrane with high flux†

In this study, a loose nanofiltration (NF) membrane with excellent perm-selectivity was fabricated via co-depositing tannic acid (TA) and polyethyleneimine (PEI) on a PVDF hollow fiber substrate. The performance of the TA-PEI-modified hollow fiber membrane (HFM) was optimized by tuning certain parameters (e.g., TA concentration and co-deposition time). The tailored membrane TA-PEI/PVDF exhibited competitive water permeability (32 L m⁻² h⁻¹ per bar) while maintaining an excellent dye rejection performance (i.e., 99% for CR). Furthermore, it presented low retention for inorganic salts (i.e., 2.3% for NaCl and 6.4% Na₂SO₄). The as-fabricated TA-PEI/PVDF loose NF HFM was proved to have good stability and antifouling performance for treating simulated textile wastewater. In summary, we believe that the as-prepared loose NF HFM has great application prospects for practical wastewater treatment.