Introducing gel-based UiO-66-NH2 into polyamide matrix for preparation of new super hydrophilic membrane with superior performance in dyeing wastewater treatment

Gel-based ultra-small size UiO-66-NH2, a zirconium metal-organic framework (Zr-MOF), was synthesized through a new energy efficient method. Then, this inherent hydrophilic nanomaterial with a 20 nm average size was incorporated into polyamide (PA) layer to form a thin film nanocomposite (TFN) membrane. Characterization results revealed that the TFN membranes had a continuous striped Turing structure and a super hydrophilic surface, with contact angle below 11 degrees. The membranes were found to have a good performance in dye/ salt fractionation. For instance, when the gel-based UiO-66-NH2 loading amount was 0.1 wt% in the organic solution during interfacial polymerization (TFN-0.1), the permeance and rejection were 31.6 L/m(2).h.bar and 92.2%, 29.7 L/m(2).h.bar and 95.9%, and 27.2 L/m(2).h.bar and 99.6% for methyl orange (MO, 327 Da), sunset yellow (SY, 452 Da), and Congo red (CR, 696 Da), respectively. A remarkable result was obtained for the challenging separation between NaCl and a small size dye, i.e., MO: 91.8% MO rejection along with 9.7% NaCl rejection. Moreover, the TFN-0.1 membrane was found to have a high stability in a 3 days continuous test to separate NaCl from CR/NaCl solution. Furthermore, the membrane has a good antifouling performance with 88% flux recovery. Thus, the prepared membrane has potential for dyeing wastewater treatment.

Automated summary

A gel-based ultra-small size UiO-66-NH2, a zirconium metal-organic framework, was synthesized through a new method and incorporated into a polyamide layer to form a thin film nanocomposite membrane. The membrane exhibited excellent performance in dye/salt fractionation, with high permeance and rejection rates for various dyes. Additionally, the membrane showed stability in continuous testing and good antifouling performance, indicating potential for dyeing wastewater treatment.