Fast removal of samarium ions in water on highly efficient nanocomposite based graphene oxide modified with polyhydroquinone: Isotherms, kinetics, thermodynamics and desorption

Abstract

Nowadays, the removal of the rare-earth elements in water and hydrogeosystems is an urgent issue. Therefore, graphene oxide / polyhydroquinone nanocomposite was used to remove samarium ions (Sm3+) in aqueous solutions. The sorption and desorption of Sm3+ ions on the graphene oxide / polyhydroquinone nanocomposite from aqueous solutions are studied with contact time (15.0 min.), initial concentration (100.0 mg/L), the weight of sorbent (0.3 g/L), pH of a solution (6.0) and temp. (25C°). The rate constants of sorption, equilibrium sorption capacity, percentage sorption and desorption, entropy and enthalpy of Sm3+ extraction process are discussed. The analysis of the proceed mechanisms is conducted with the kinetic dependences and sorption isotherms, for which reason the empirical equations of pseudo-first and pseudo-second-order, Elovich and intraparticle diffusion, as well as the equations of Langmuir, Freundlich, Temkin, Dubinin-Radushkevich were used. It should be noted that the absorption of Sm3+ proceeded according to the mixed diffusion mechanism and is controlled by the interactions among the sorbent and the functional groups of the sorbent. According to Langmuir's model, the maximum sorption capacity of the developed sorbent was 357.14 mg g−1. Thus, the high efficiency of the developed sorbent for the purification and remediation of hydrogeosystems for samarium ions is useful. The reported method may be used for the removal of 360 million tons of wastewater with rare earth elements including samarium ions.