Seyed Abdollatif Hashemifard

This study focuses on the effect of two normal alkanes as additive on the structural parameters and pure water permeate of ultrafiltration (UF) flat sheet polyethersulfone (PES) membranes. Asymmetric PES membrane was fabricated by phase inversion method and n-hexane and n-decane was used as additive and water as the coagulation bath. The effects of different concentration of these additives on the structural parameters were investigated and the prepared membranes were characterized in terms of gas permeation test, pure water permeation (PWP) and bulk porosity measurement. It was expected that two distinct phase inversions to be observed since both the polymer and the additives were insoluble in the coagulation bath and act in different ways. Experimental results revealed that by adding these additives the casting solution was still thermodynamically stable and by influencing the rate of the polymer precipitation resultant membrane were more porous compared to the neat membrane. The results demonstrated that with increasing concentration of additives in dope solution, pure water permeation, gas permeation, pore size and porosity simultaneously increased. However in the case of n-hexane, there was a maximum point at the concentration of 0.4%. In conclusion, the finding of this work showed the high influence of the n-alkanes on the structural parameters of the PES UF membranes.