Application of synthesized bovine serum albumin-magnetic iron oxide for phosphate recovery

Abstract

Phosphorous is an essential nutrient that is widely used as a fertilizer in agriculture. However, its increased discharge from agricultural runoff contributes to eutrophication, necessitating its removal from wastewater. Adsorption is one of several treatment processes for this purpose. In this study, bovine serum albumin-magnetic iron oxide (BSA-MIO) was successfully synthesized using the co-precipitation method. Its morphology was characterized by field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy. Different parameters that affect adsorption, such as initial phosphate concentration, reaction time, adsorbent dosage, pH, coexisting anions, and temperature, were investigated. The results showed that phosphate adsorption increased with reaction time and temperature while it decreased with an increase in solution pH. The phosphate adsorption equilibrium time using BSA-MIO was 1 h. The estimated maximum adsorption capacity of BSA-MIO was 20.7 mg P.g(1). Moreover, the pseudo-second-order model (R-2 > 0.99) and Langmuir model (R-2 > 0.99) elucidated the better description of the adsorption kinetics and isotherm, respectively, thereby suggesting the chemisorption nature of adsorption. The coexisting anions (NO3, Cl, SO42, and CO32) showed no significant effect on phosphate adsorption. Moreover, the adsorbed phosphate was successfully desorbed using different concentrations and combinations of NaOH and NaCl.