Investigation of effective parameters of Lanthanum and Cerium Adsorption from Aqueous solutions using Amberlit XAD-7 resin impregnated With DEHPA

Abstract

In This study, an absorbent consisting of DEHPA impregnated onto Amberlite XAD-7 resin was prepared and used for the adsorption of Ce (ΙΙΙ) and La(ΙΙΙ) ions from aqueous solution. The absorbent (XAD-7 + DEHPA) was charaterized by SEM and FTIR analysis Techniques. Several influential variables such as, contact time, pH and temperature were studied in batch mode of operation. Th results showed that the optimum adsorption condition were acjieved at pH=6, optimum amount of absorbent and the equilibrium time equal to 0.6 gr and 180 min, respectively. According to the results the adsorption percentage of cerium and lanthanum ions onto the aforementioned resin were 99.99%, 78.76% respectively. Various isotherms models such as Langmuir, Freundlich, Temkin and Dubinin-Radushkevich were used in 25°C to analyze the equilibrium isotherm data and results showed that Langmuir model had a better agreement with the experimental data. The maximum adsorption capacity of the resin for cerium and Lanthanum ions were 8.28 mg.g-1, 5.52 mg.g-1 respectively. The kinetic data were fitted to pesudo- frist- order, pesudo-second-order and Intra particle diffusion models. Based on the results, the pesudo- frist- order model and Intra particle diffusion model described the experimental data as well. Thermodynamic parameters of adsorption such as ΔHº, ΔS°, ΔG° were calcutated. Positive ΔHº and negative ΔG° were indicative of the endothermic and spontaneous nature of the adsorption. The aforementioned resin shows the stability during the five cycles of adsorption-desorption and it’s degradation was less than 3%

Keywords

• adsorption
• rare earth elements
• cerium and lanthanum
• solvent impregnated resins
• extractor