Synergistic modification of forward osmosis membrane with UiO-66-NH2 and quaternary ammonium salt and its separation performance for dye wastewater

In order to improve dye separation and antifouling performance of forward osmosis (FO) membranes, polychloromethylstyrene (PCMS) was introduced into polyvinylidene fluoride (PVDF) porous supported membranes by a blending phase inversion method, and UiO-66-NH2 was evenly fixed onto the membrane surface by nucleophilic substitution reaction between UiO-66-NH2 and chloromethyl of PCMS. Moreover, an improved interfacial polymerization process to fabricate FO composite membranes with high permeability and separation performance was performed by adding trimethylammonium chloride (TMPAC) to its aqueous solution. The structure and property of the supported membrane and FO membrane were analyzed, and the permeability separation and antifouling properties of the FO membrane were tested using a forward osmosis device. The results show that the introduction of UiO-66-NH2 effectively improves hydrophilic, charge and permeation properties of FO membranes. Meanwhile, the introduction of quaternary ammonium salt in the interfacial polymerization process greatly improves the separation and antifouling performance of the FO membrane. The pure water flux of the modified FO membrane (M2-T) was 22.4 L‧m-2‧h-1, and its rejection to Rhodamine 6G and Orange G in dye wastewater were 97.82% and 99.84%, respectively. The normalized flux decay rate was only 10.18% after 6 hours of Rhodamine 6G separation, and the pure water flux recovery rate still remained 95.66%. © 2023 Zhejiang University. All rights reserved.