Studying the effect of different pore‐formers on characteristics and separation performance of PCTFE MF membrane

Abstract

When fabricating polymeric membranes using the non‐solvent induced phase separation (NIPS) technique, the characteristics and performance of the resulting membranes are significantly influenced by the additives incorporated into the casting solution. In this study, polychlorotrifluoroethylene (PCTFE) microfiltration (MF) membranes were fabricated using different pore‐formers including organic solvents, inorganic salts, and polymers. PCTFE was used as an attractive polymer for the first time in the liquid filtration process. This is due to its favorable properties for MF membranes such as ease of processing, high mechanical robustness, and fouling‐resistance. Dimethylformamide (DMF), ethanol, NaCl, ammonium bicarbonate, and polyethylene glycol (PEG) were incorporated at 1–4 wt% concentration as pore‐forming agents into the PCTFE solution. The prepared membranes were characterized by scanning electron microscopy (SEM), water contact angle measurement, and their filtration performance was assessed by pure water permeability (PWP) measurement and separation of milk fat in a cross‐flow membrane module. From the results, the overall porosity, surface porosity, mean pore size, hydrophilicity, PWP, steady flux, and fat rejection were in the following order for the modified membranes: PCTFE/DMF > PCTFE/PEG > PCTFE/ethanol > PCTFE/ammonium bicarbonate > PCTFE/NaCl. Among modified membranes, the highest fat rejection (95.8%) was obtained for the 1 wt% DMF‐containing casting solution. The fat rejection of this membrane was slightly less than the neat PCTFE membrane (97.5%), but its steady permeate flux was more than twice that of the pure sample. Additionally, the anti‐fouling and mechanical characteristics of the membranes were also investigated to assess the suitability of PCTFE polymers for the MF process.Highlights MF process was conducted using novel PCTFE flat‐sheet membranes. The PCTFE membrane was prepared with different pore‐formers. Using different concentrations of pore‐formers affected the membrane structure. Using pore‐formers affected the PCTFE membrane performance.