Concentration of whey protein from cheese whey effluent using ultrafiltration by combination of hydrophilic metal oxides and hydrophobic polymer

BACKGROUND: In this study, hydrophilic metal oxides such as TiO₂, ZrO₂ and ZnO were used as modifier for the preparation of polyethersulfone (PES) mixed matrix membranes (MMMs) for the filtration of cheese whey effluent. Nano metal oxide loading concentration was varied from 0.5 to 2.5 wt%. RESULTS: Characterization of metal oxide studies show that the particles are hydrophilic and nanoscaled. ZnO nanoparticles are in the form of nanocluster and of size 14.28–20.10 nm. Physio-chemical characterization of PES MMMs indicated that the nano metal oxides dispersed well in the PES matrix. Contact angle decreased up to 59.88° for 1.5 wt% TiO₂ embedded PES (TiO₂ePES) MMMs. Also, 1.5 wt% TiO₂ePES MMMs gives a higher water permeability of 4.62 × 10^–7 m s^–1 kPa^–1. Among membranes, 1.5 wt% TiO₂ePES, 2.0 wt% ZrO₂ePES and 1.5 wt% ZnOePES MMMs showed better flux, lower percentage fouling and better rejection for individual whey proteins. CONCLUSION: The whey protein from cheese whey effluent was concentrated up to maximum of 43.9 mg L^–1 using 2.0 wt% ZrO₂ePES MMMs. It was found that 1.5 wt% TiO₂ePES MMMs gives a higher average flux of 25.09 L m^–2 h^–1 and a lower flux reduction percentage of 39%.