Optimization of a high performance 3-aminopropyltriethoxysilane-silica impregnated polyethersulfone membrane using response surface methodology for ultrafiltration of synthetic oil-water emulsion

This work aims at determining the desired membrane preparation conditions for polyethersulfone (PES) composite membrane for the ultrafiltration of synthetic oil in water emulsion. 3-aminopropyltriethoxysilane modified silica (APTES-SiO₂) nanoparticles were prepared via one-pot stober method and blended in PES dope solutions which significantly influenced membrane properties. The effects of PES, polyethylene glycol (PEG), APTES-SiO₂ and coagulation bath temperature (CBT) on the oil permeate flux (OPF), oil rejection (OR) and pure water flux (PWF), as well as their interactions were investigated. Response surface methodology based on the central composite design were used for statistical analysis, optimization and modeling of the PES membrane. The significant terms that affects PWF was observed to be PES, PEG and the interacting effects between PES and APTES-SiO₂ whereas, PES and PEG were observed for OPF. In the case of OR, the significant terms were observed to be the quadratic effects of PES, APTES-SiO₂, coagulation bath temperature as well as the interactions between PES and PEG. The optimum conditions for PES, CBT, APTES-SiO₂ and PEG were found to be 17.25 wt.%, 15 °C, 3.6 wt.% and 3.72 wt.%, respectively with PWF, OPF and OR maintained at 235.2 kg/m² h, 159.8 kg/m² h and 99.2%, respectively.