Influence of Zeolite-A Doping and Solvent Mixing Ratio for Electrospun PVDF-Based Membranes

The current study evaluates the characteristics of electrospun PVDF-based membranes doped with zeolite-A in terms of their structural, morphological, thermal, mechanical, hydrophobic, optoelectrical, and adsorption properties. The effects of the DMF-acetone ratio on solvent and zeolite-doping concentration have been evaluated using SEM-EDX, BET, Raman, XRD, DSC-TGA, UV-VIS spectroscopy, contact angle measurements, and mechanical testing. The membranes prepared with solvents low in acetone and increased zeolite content exhibited a higher crystallinity degree exceeding 50%. Zeolite-enriched membranes have a slightly higher content in the α crystalline phase of PVDF when compared to zeolite-free membranes. Electrospinning processing decreased the sample's subcooling, improving its thermal stability. Zeolite-doping reduced the band gap energy to 1.3 eV from a maximum of 2.7 eV in PVDF membranes. Membranes doped with 3 or 4 wt.% zeolite exhibit improved load-elongation values at break, reaching up to 4.2 N and 47 mm, respectively, and increased flexibility due to their porous structures and the ratio of crystalline to amorphous phases. The membranes adsorbed an MB equilibrium quantity up to 18.5 mg/g and obeyed the pseudo-second-order (PSO) kinetic model within the first 24 h. Thus, the synergistic effect of zeolite content and solvent ratio can effectively adjust the sample's structure, texture, and properties.