Ca2+ Dependent Flocculation Efficiency of Avian Egg protein Revealed Unique surface Specific Interaction with Kaolin Particles: A new Perception in Bioflocculant Research

Abstract In this study, the flocculation efficiency (FE) of avian egg-white was investigated as a protein rich natural bioflocculant to flocculate kaolin dispersion. The FE was optimized under various conditions. Its cation dependent interaction with kaolin basal planes was also investigated through FT-IR, EEM, Zeta Potential and SEM-EDX techniques. The maximum flocculation rate (91%) was observed at the CaCl2 dosage of 100 ppm and at pH 6.0 due to the electrostatic interaction of Ca2+ ions with the gibbsite basal planes of kaolin at this condition. Among several monovalent, divalent and trivalent cations, Ca2+ alone showed higher FE than other cations. It showed the unique interaction of Ca2+ ions with Avian Egg-white Flocculant (AVGF) functional groups. EEM study was used to reveal the involvement of such functional groups. The results revealed that the carboxylate groups instead of aromatic amino acid side chains are involving in such interaction. This hypothesis was further confirmed in wastewater flocculation experiments in which the Ca2+ and AVGF complex showed weak interaction with suspended particles of domestic wastewater.