Preparation, characterization and performance studies of polyetherimide based membranes for water purification

Abstract

Membrane based separation has sustained its efficiency over other traditional techniques of water purification. Significant research has been carried out in this area, still the abundant scope of membrane technology has driven many scientists to further explore the field. The current research work is one such attempt to study the influence of organic and inorganic nanomaterials in the polymeric membranes. This research work is focused on modification of polyetherimide membrane by the addition of organic and inorganic additives to improve the physiochemical properties and its performance. The various additives employed in this work includes citric acid, ascorbic acid, activated bentonite, poly (4-styrenesulfonate) modified bentonite, polydopamine coated HNTs, amine functionalized HNTs, poly(m-aminophenol) coated HNTs and carboxylated Fe2O3 nanoparticles. The properties and performance of the membranes was analyzed by cross sectional morphology, surface hydrophilicity, water uptake capacity, porosity, surface topography studies, permeation properties and antifouling ability. The self-cleaning ability of the membranes was determined by evaluating the flux recovery ratio. The water purification ability of the membranes was assessed in terms of hazardous heavy metal ion rejection, humic acid removal and dye removal applications. The PEI membrane with 4 wt. % activated bentonite dosage showed maximum rejection of 69.3 %, 76.2 % and 82.5 % for 250 ppm of Cd (II), Ni (II) and Cu (II) ion solutions respectively. The 3 wt. % polydopamine modified HNTs in the membrane showed resistance to microbial growth with FRR of 74.5 % and reversible fouling ratio of 60.7 %. The membrane comprising of bentonite clay bearing the poly (4-styrenesulfonate) brushes showed 80.5 % (Pb2+) and 74.6 % (Cd2+) respectively, during PEUF. The hollow fiber membrane with 2 wt. % of poly (maminophenol) coated HNTs exhibited the water flux of 104.9 Lm-1h-1 and only 9.6 % of irreversible fouling with more than 90.3 % of flux recovery. These membranes also showed rejection of 97 % and 94 % for the hazardous reactive red 102 and reactive black 5 dyes respectively.