Abstract
Sulfonated homo and co- polyimide (sPI) were synthesized with new compositional ratios, and used as additives (0.5 wt%, 0.75 wt%, and 1.0 wt%) to prepare blend membranes with polysulfone (PSf). Flat sheet membranes for ultrafiltration (UF) were casted using the phase inversion technique. Surface morphology of the prepared UF membranes were characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Surface charge of the membranes were determined by zeta potential, and hydrophilicity was studied by contact angle measurement. The contact angle of the membrane decreased with increasing sPI additive indicates increasing the hydrophilicity of the blend membranes. Filtration studies were conducted for rejection of heavy metals (Pb2+ and Cd2+) and proteins (pepsin and BSA). Blend membranes showed better rejection than pure PSf membrane. Among the blend membranes it was observed that with increasing amount of sPIs enhance the membrane properties and finally, PSf-sPI5 membrane with 1 wt% of sPI5 showed the improved permeability (72.1 L m−2 h−1 bar−1), and the best rejection properties were found for both metal ions (≈98% of Pb2+; ≈92% of Cd2+) and proteins (>98% of BSA; > 86% of Pepsin). Over all, this membrane was having better hydrophilicity, porosity and higher number of sites to attach the metal ions. Its performance was even better than several-reported sulfonic acid based UF membranes. All these intriguing properties directed this new UF membrane for its potential application in wastewater treatment.
Highlights
Sulfonated homo and co- polyimide were synthesized with new compositional ratios, and used as additives (0.5 wt%, 0.75 wt%, and 1.0 wt%) to prepare blend membranes with polysulfone (PSf)
When the membranes were subjected to heavy metals rejection study for the Cu2+ and Zn2+ in a polymer enhanced UF (PEUF) technique, in presence of polyethyleneimine (PEI) as complexing agent, the blend membrane showed better rejection capacity the membrane with pure PSf
Size exclusion chromatography (SEC) was performed using a MCX column connected with a Viscotek SEC system, and was calibrated against narrow molecular weight polyethylene glycol standards
Summary
Sulfonated homo and co- polyimide (sPI) were synthesized with new compositional ratios, and used as additives (0.5 wt%, 0.75 wt%, and 1.0 wt%) to prepare blend membranes with polysulfone (PSf). Polymeric membrane is the core of the UF separation technology Since this process is effective and already gains much interest in academic and industrial research, in the this article, the primary effort has been made to develop new blend membrane with better properties to remove non-biodegradable and toxic heavy metal ions[3,6] and at the same time protein based organic pollutants[7,8,9]. Jacob et al.[10], dissolved sulfonated polyethersulfone (sPES)/polysulfone (PSf) in N-methyl-2-pyrrolidone (NMP) and prepared flat sheet membranes by dry–wet phase inversion technique They used PEG-200 as a non-solvent additive in the casting solution to control the porosity, and studied the effect of sPES/PSf blending weight ratio on the morphology, hydrophilicity, water content, porosity, hydraulic resistance, pure water flux, compaction, and molecular weight cut-off (MWCO) of the prepared membranes. Several other researchers prepared sulfonated polymer based membranes[14,19], and studied their properties for UF process
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