The effect of humic acid and bovine serum albumin on the adsorption and stability of ZnO nanoparticles on powdered activated carbon

Natural organic matter (NOM) can influence the properties and behavior of metal nanoparticles (MNPs) in aquatic environments. Thus, understanding the effect of NOM on MNPs' physiochemical properties is critical for identifying an effective water treatment processes, and controlling the potential risk they pose to ecological and human health. In this study, adsorption and leaching experiments were performed with powder activated carbon (PAC), to investigate the effect of humic acid (HA) and bovine serum albumin (BSA) on the removal of ZnO nanoparticles (ZnONPs) from an aqueous environment and their stability on the adsorbed PAC. The different ZnONPs forms- particulate, colloidal, and dissolved Zn fractions, were respectively considered. The adsorption experiments demonstrated that both colloidal and dissolved Zn fractions can adsorb on the PAC's surface. As the HA concentration increased from 0 to 20 mg/L, the colloidal Zn fraction's adsorption efficiency decreased from 74.49% to 61.24%. However, BSA did not significantly influence the colloidal Zn fraction's adsorption. The leaching experiments showed that the colloidal Zn fraction would release from the PAC's surface, and most of them transferred to the dissolved Zn fraction. As the HA concentration increased from 0 to 20 mg/L, the Zn concentration leached from the PAC adsorbed ZnONPs reduced from 0.956 to 0.694 mg/g. Comparatively, the leached Zn concentration varied only slightly with an equal increase in BSA concentration. (C) 2019 Published by Elsevier Ltd.