EFFECT OF NON-SOLVENT ADDITIVES TO THE CASTING SOLUTION ON THE STRUCTURE AND PROPERTIES OF POLYETHERSULFONE UF MEMBRANES

The obtained results allow us to propose a new approach to production of polyethersulfone (PES) ultrafiltration (UF) membranes with desired structure and performance. It was shown that UF membranes with a spongy structure are obtained from casting solutions located near the binodal line. However, with the increase of the precipitation value (PV) of non-solvent additives (NSA), the higher pure water flux (PWF) of membranes with the spongy structure is observed. UF membranes with maximum performance are obtained when degree of saturation (α* – the ratio of the NSA amount added to the polymer solution to the NSA amount which causes phase separation) α*= 0.52-0.81 (depending on PV of NSA). In this case, macrovoids will prevail in the structure of the supporting layer of membranes. The size and shape of macrovoids also depend on the PV of NSA. The higher the PV of NSA, the larger the size of macrovoids in the structure of supporting layer.