Equilibrium studies of yttrium adsorption from aqueous solutions by titanium dioxide

Abstract

This research evaluates the adsorption of yttrium from aqueous solutions by titanium dioxide with surface arsenate groups (4As–TiO2) and titanium dioxide with surface arsenate groups doped by neodymium (Nd/4As–TiO2). The impacts of various adsorption parameters such as contact time, pH and initial metal concentrations were investigated in batch adsorption experiments. Experimental data for yttrium ions adsorption onto Nd/4As–TiO2 fits well with the Elovich kinetic model (R2 = 0.99) and the Lagergen kinetic model based on pseudo-first order equation (R2 = 0.97). Yttrium ions adsorption onto 4As–TiO2 fits well with the Lagergen kinetic model based on pseudo-second order equation (R2 = 0.999). The process of yttrium adsorption in equilibrium conditions was adequately described by Langmuir adsorption theory. The assumption is that possible mechanisms for yttrium adsorption onto investigated adsorbents is surface complexation in the form of Y(OH)2+ or Y(OH)2+ in neutral medium and surface precipitation in alkali medium. It was shown that modification of the TiO2 surface by arsenate groups promotes the adsorption of yttrium ions. The introduction of neodymium into the TiO2 structure with surface arsenate groups increases the difference in adsorption of yttrium and strontium ions, therefore Nd/4As–TiO2 can be useful to separate 90Sr and 90Y in nuclear forensics.