Modification of PVDF hollow fiber membrane by co-deposition of PDA/MPC-co-AEMA for membrane distillation application with anti-fouling and anti-scaling properties

In this study, a self-prepared polyvinylidene fluoride (PVDF) hollow fiber membrane with a hierarchical structure was used for facile modification by co-deposition of polydopamine (PDA) and poly(MPC-co-2-aminoethyl methacrylate hydrochloride) (MPC-co-AEMA) for application in direct contact membrane distillation (DCMD). The facile formation of the PDA/MPC-co-AEMA layer on the membrane outer surface drastically changed the chemical and physical properties of the membrane surface. Although the membrane became hydrophilic and smooth with a low porosity and small pore size, the bulk structure of the membrane remained almost intact. For a saline solution including protein and Ca2+ as organic fouling and scaling agents, the deposition of the hydrophilic PDA/MPC-co-AEMA layer on hydrophobic PVDF led to the alleviation of the membrane fouling and scaling during long-term DCMD application. Whereas the formation of a hydrated layer on the membrane surface avoided BSA fouling by avoiding hydrophobic–hydrophobic interactions, a combination of several chemo-physical properties of the modified membrane surface resulted in anti-scaling properties.