Fabrication of multi-functional imprinted composite membrane for selective tetracycline and oil-in-water emulsion separation

In this work, we present a new multi-functional imprinted composite membrane to be used for selective tetracycline (TC) and oil-in-water emulsion separation. In order to improve the hydrophilicity of the PVDF base membrane, delayed phase inversion method was utilized to introduce the hydrophilic UiO-66-NH2, while polydopamine (pDA) coating provides a secondary reaction platform. The imprinted composite membranes were prepared by a simple sol-gel process where TC was used as the template and 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS) were the functional monomer and crosslinker, respectively. The PUIM has superhydrophilicity/underwater superoleophobicity with water contact angle (WCA) of 0° and underwater oil contact angle (UOCA) of 162°. The prepared membrane can not only selectively separate TC from surfactant-stabilized emulsion with separation efficiency of 89.1%, but also separate various oil-in-water emulsions with separation efficiency of above 99%. Moreover, the imprinted composite membranes (PUIM) showed excellent antifouling performance, indicating that it could maintain stable separation performance after repeatedly used in separation process. Combining all these results, the multi-functional imprinted composite membranes demonstrate high potential to be employed in wastewater treatment processes, containing organic and oil.