Rate analysis of sorption of Ce3+, Sm3+, and Yb3+ ions from aqueous solution using Dowex 50W-X8 as a sorbent in a continuous flow reactor

Kinetic analysis of removal of three rare earth elements metals, Ce³⁺, Sm³⁺, and Yb³⁺ ions from aqueous solutions in a continuous flow fixed bed reactor using Dowex 50W-X8 ion-exchange resin was conducted. The performance of the fixed bed sorption was evaluated using the concept of the sorption breakthrough process. Parameters characteristic of a fixed bed sorption such as breakthrough times, saturation times, critical reactor lengths, and lengths of mass transfer zone were inferred from the metal ion concentration breakthrough curves. The sorption capacity of Dowex 50W-X8 ion-exchange resin for Ce³⁺, Sm³⁺, and Yb³⁺ are 191, 252, and 294 mg/g, respectively. The sorption kinetics were evaluated using a zero-order, first-order and second-order reaction models. The kinetics of the sorption process follows a zero-order model which has not been reported before. The rate constants of sorption using the zero-order kinetic model are obtained. Two different analysis were conducted to identify whether the diffusion is intraparticle or film diffusion. Both analysis confirms that the film diffusion is the controlling mechanism in reactor bed.