Statistical Analysis of Synthesis Parameters to Fabricate PVDF/PVP/TiO2 Membranes via Phase-Inversion with Enhanced Filtration Performance and Photocatalytic Properties

Abstract

Non-solvent induced phase-inversion is one of the most used methods to fabricate membranes. However, there are only a few studies supported by statistical analysis on how the different fabrication conditions affect the formation and performance of membranes. In this paper, a central composite design was employed to analyze how different fabrication conditions affect the pure water flux, pore size, and photocatalytic activity of polyvinylidene fluoride (PVDF) membranes. Polyvinylpyrrolidone (PVP) was used to form pores, and titanium dioxide (TiO2) to ensure the photocatalytic activity of the membranes. The studied bath temperatures (15 to 25 °C) and evaporation times (0 to 60 s) did not significantly affect the pore size and pure water flux of the membranes. The concentration of PVDF (12.5 to 17.5%) affected the viscosity, formation capability, and pore sizes. PVDF at high concentrations resulted in membranes with small pore sizes. PVP affected the pore size and should be used to a limited extent to avoid possible hole formation. TiO2 contents were responsible for the decolorization of a methyl orange solution (10−5 M) up to 90% over the period studied (30 h). A higher content of TiO2 did not increase the decolorization rate. Acidic conditions increased the photocatalytic activity of the TiO2-membranes.

Effects of Different TiO2/CNT Coatings of PVDF Membranes on the Filtration of Oil-Contaminated Wastewaters

“…Various in situ and ex situ techniques for developing membrane materials have been explored to improve the filtration performance of membranes. In the former case, additives can be loaded into dope or coagulation solutions to incorporate them into membrane matrices [10][11][12]. In the latter case, chemical or physical surface coatings can be considered [13][14][15][16].…”

“…Among other materials (like graphene oxide [17], sodium alginate hydrogel [18], calcium carbonate [19], etc. ), metal and metal-oxide nanoparticles (such as Ag, Cu, Al 2 O 3 , MgO, ZnO, SiO 2 , ZrO 2 , Fe 2 O 3 , and TiO 2 [20,21]) are also widely used as additives in the field of membrane modification to improve the filtration performance by altering the structural and physicochemical properties of the membranes, such as hydrophilicity [17,18,[20][21][22][23], porosity [12], electrical charge [15], and chemical, thermal, and mechanical stability [10].…”