Evaluating molecular weight of PVP on characteristics of CTA membrane dialysis

Abstract

The polymer inclusion membranes used for the selective transport and separation of metal species have emerged in recent years. Their development depends on the method of preparation and the study of their intimate structure.In this work, we have developed a novel class of cellulose triacetate (CTA) membranes modified by poly-electrolytes incorporation that are selectively permeable to metallic ions.The effect of molecular weight of Polyvinylpyrrolidone (PVP) as additive on morphology and transport performance of (CTA) membrane was studied in this work. Diverse CTA membranes have been developed. PVP at different molecular weight (10,000, 24,000 and 40,000) was noted, respectively, (PVPk10, PVPk25 and PVPk30) and Polyethylene glycol (PEG (2000)) were used to modify the morphology and performance of membranes based CTA. The membranes have been prepared by dissolving amounts of CTA, PVP and PEG in Chloroform. The films obtained after solvent evaporation were characterized by thermogravimetric analysis (TGA), Fourier Transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). It was found that the degradation of the membranes is done in two steps. The first one starts at 250°C due to thermal degradation of the polymeric chains. The SEM image shows that the porosity decreases with increasing of molecular weight of PVP. The influence of the molecular weight of PVP in performance of membranes was examined by application of dialysis process using cations solution containing Cd2+, Cu2+, Ni2+ and Zn2+. The membrane containing PVPk10 showed better efficiency compared to the other ones.