Preparation and characterization of PVDF/TiO2 mixed matrix membrane via in situ colloidal precipitation method Original Research Article

In this study, titanium dioxide (TiO2) nanoparticles (NPs) were incorporated into polyvinylidene fluoride (PVDF) membrane to produce a mixed matrix membrane via phase inversion and colloidal precipitation method. In order to avoid agglomeration and to maintain the stability of NPs in the coagulation bath, NPs were dispersed in the bath via sonication and peptization. The membrane surface morphology and distribution pattern of NPs on the membrane surface were observed by field emission scanning electron microscopy. It was found that the NP size and distribution of NPs on the membrane surface were affected to a very great extent by the type of solvent used in the dope formulation and concentration of TiO2 in the coagulation bath. Membrane prepared using N-methyl-2-pyrrolidone (NMP) as solvent has smaller surface particles and narrower particle size distribution compared to N-N-dimethylacetamide (DMAc) and N,N-dimethyl formamide (DMF) due to the hydrophobic/hydrophilic interactions between NPs and polymer solution. However, the pore size of membrane prepared using NMP was relatively big, thus resulted in poorer humic acid (HA) rejection. PVDF/TiO2 mixed matrix membrane using DMAc as solvent with 0.01 g/L of TiO2 in the coagulation bath exhibited extraordinary permeability (43.21 L/m2 h) with superior retention properties (98.28%) of humic acid.