Effective treatment of dye polluted wastewater using nanoporous CaCl₂ modified polyethersulfone membrane

High molecular weight polyethersulfone (PES) nanoporous membranes modified with different loading of calcium chloride (0.5, 1, 2 and 3 wt.%) were prepared by dry-wet phase inversion method. Low molecular weight polyethylene glycol (PEG200) was used as pore constrictor and pore former for the blend membrane series. Fabricated membranes were characterized with various analytical and experimental techniques. Results showed that the CaCl₂ blend PES/PEG200 membranes were nanoporous in nature with improved porosity and permeability. Addition of CaCl₂ improved the mechanical stability and water permeability of the composite membranes. Performance of CaCl₂ incorporated PES/PEG 200 membranes was investigated using selected dyes (congo red, orange II, crystal violet and methylene blue) and salts (Na₂SO₄ and MgSO₄) separation from its aqueous solution. CaCl₂ doped membrane showed better dye rejection behaviour with a permeate flux sequence as congo red < crystal violet < orange II < methylene blue. Size and charge based exclusions along with adsorption were identified as the separating principles. Fouling analysis clearly showed that CaCl₂ incorporated membranes possessed better antifouling effect than membrane without CaCl₂. Studies indicated that 1 wt.% CaCl₂ loaded PES/PEG 200 membrane showed better performance than other fabricated CaCl₂ blend membranes. Thus the CaCl₂ blended PES/PEG200 membranes are promising for the treatment of dye polluted wastewater.