Sorption of La(III) and Er(III) Ions on Silica Gel with Implemented Monoethanolamine

The results of studying the process of lanthanum(III) and erbium(III) ions sorption from model solutions on ASK silica gel modified with monoethanolamine are presented. The influence of the solutions composition (pH and salt background) on sorption equilibria was studied. The rate constants of La(III) and Er(III) ions sorption were calculated for pseudo-first and pseudo-second order equations at 296, 303, and 313 K. The adsorption isotherms of the selected ions were processed in the coordinates of the Langmuir, Freundlich, Dubinin–Radushkevich and Temkin equations. Using the sorption equilibrium constants of the Langmuir model, the thermodynamic parameters of sorption were calculated for different temperatures. According to the obtained values of the thermal effects of the process, the sorption of lanthanum(III) and erbium(III) ions on the studied sorbent is caused mainly by physical forces. As the temperature increases, the equilibrium for both ions shifts towards desorption. The kinetics of sorption of La(III) and Er(III) ions in their combined presence was studied.