The adsorption of bovine serum albumin (BSA) and human hemoglobin (Hb) on naturally occurring adsorbents was studied to evaluate the potential recovery of proteins from meat industry wastewaters. Spent peppermint tea (PM), powdered purple corn cob (PC), natural clay (NC) and chemically modified clay (MC) were investigated to elucidate the effects of pH, adsorbent dose, initial protein concentration, presence of Hofmeister salts and heavy metals on the adsorption. Equilibrium data was fitted according to isotherm models, obtaining a maximum adsorption capacity of 318 and 344 mg BSA/g for PM and NC, respectively at pH 8. Moreover, Hb displayed maximum adsorption capacity of 125 and 143 mg/g for PM and PC, respectively at pH 5. Hofmeister salt effect was only observed for the PM/Hb system. Salts tend to decrease, and the presence of Cu(II) ions had negligible impacts on the adsorption with NC and PC. Desorption experiments confirmed that more than 85% of both proteins can be recovered with diluted acids and bases. Scanning electron microscopy (SEM) and Fourier-transformed infrared (FTIR) spectroscopy analyses demonstrated that the adsorbents have favorable morphological and chemical properties for the adsorption of proteins. Future studies should include kinetics experiment to provide further insight into the potential use of these eco-friendly materials for the treatment and recover of proteins from solutions.
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