Photocatalytic self-cleaning EVAL membrane by incorporating bio-inspired functionalized MIL-101(Fe) for dye/salt separation

This work was expected to develop a new loose NF membrane with facile materials to conduct dye/salt sepa-ration and endow it with versatile capacities to offer an applicable solution to treat textile wastewater. Ethylene vinyl alcohol (EVAL) was first chosen to fabricate loose nanofiltration (NF) membrane through non-solvent induced phase separation (NIPS) method. Besides, MIL-101(Fe) showed outstanding photocatalytic capacity in degrading organic molecules while a low-cost bio-inspired coating, catechol, was utilized to modify MIL-101(Fe). A combination of modified MIL-101(Fe) and EVAL could have a high water permeability (43.2 L.m(-2).h(-1).bar(-1)) with superior rejection to small molecule negative charged dyes (Chlorazol black T: 99.8%, Congo Red: 99.7%, Eriochrome black T: 98.4%) and low rejection to various salts (Na2SO4: 4.8 %, NaCl: 2.1 %, MgCl2: 2.9%, MgSO4: 4.9% and CaCl2: 3.3%). Meanwhile, the EVAL loose NF membrane with the best performance had excellent antifouling capacity and long-term stability in EBT/Na2SO4 separation. Moreover, the membrane could degrade dyes to self-clean the membrane surface through photocatalytic process, which originated from the Fe-O clusters in MIL-101(Fe).

Automated summary

This study developed a new loose nanofiltration (NF) membrane for treating textile wastewater. The membrane, made of ethylene vinyl alcohol (EVAL) and modified MIL-101(Fe), exhibited high water permeability and superior rejection of dyes. It also demonstrated excellent antifouling capacity and long-term stability.