Lithium perchlorate modified nanoporous polyethersulfone membranefor improved dye rejection

Nanoporous polyethersulfone (PES) membranes were synthesized using lithium perchlorate (LiClO₄) as an additive in the casting dope. Membranes were prepared through phase inversion method from PES/polyethylene glycol (PEG)/LiClO₄ system using dimethylformamide (DMF) as the primary solvent and water as secondary solvent. Effect of LiClO₄ on the membrane performance was studied by varying its composition from 0 wt% to 5 wt%. SEM studies indicated that the LiClO₄ blended PES membranes possessed dense top surface and finger-like sub-layer. Atomic force microscopy analysis clearly showed that the addition of LiClO₄ resulted in nano-structure membranes with small surface pore size and low surface roughness. Contact angle measurements confirmed the enhanced hydrophilicity of the composite membranes due to LiClO₄ inclusion. Pure water flux measurements demonstrated high flux capabilities of LiClO₄ blended PES membranes as compared with pristine PES membrane. Dye rejection performance studies using Congo red, Crystal violet and Methylene blue as probe molecules, indicated a better dye removal efficiency of the LiClO₄ incorporated PES membrane. Fouling analysis in terms of fouling recovery ratio exhibited the better anti-fouling ability of the PES membranes due to LiClO₄ incorporation. Analysis on the obtained result showed that the 3 wt% LiClO₄ blended PES membrane possessed desirable characteristics among the synthesized PES/PEG/LiClO₄ membrane series.