Physicochemical properties of synthetic nano-birnessite and its enhanced scavenging of Co2+ and Sr2+ ions from aqueous solutions

Abstract Nano-birnessite was prepared, characterized and used for removal of cobalt and strontium ions from aqueous solutions. Scanning electron microscope and atomic force microscope images indicated that the particles of the prepared material are presented in the nano-scale form, the grain size was found in a range of 58–95 nm. Specific surface area of the prepared nano-birnessite was determined and found to be 200.54 m 2 /g. The Capacities of nano-birnessite for cobalt and strontium are 2.97 and 3.04 meq/g, respectively. The kinetic studies indicated that the sorption of the two ions obeys pseudo-second-order model and controlled by an intra-particle diffusion mechanism. The diffusivity of Co 2+ and Sr 2+ ions onto nano-birnessite was determined and indicated that the sorption is chemisorption process. Hence, nano-birnessite material is an efficient sorbent and can be used to decrease the influx of pollutants, such as; Co 2+ and Sr 2+ ions to the environment or their removal from contaminated media.