Adsorption kinetics and thermodynamics studies of gold(III) ions using thioctic acid functionalized silica coated magnetite nanoparticles

Abstract Thioctic acid functionalized silica coated magnetite nanoparticles, RS-SR-NH-SiO 2 -Fe 3 O 4 , has been synthesized and its ability for the recovery of Au(III) in aqueous solutions was assessed. The results of the adsorption thermodynamics and kinetics showed that this magnetic adsorbent has good adsorption capacity for Au(III) and the best interpretation for the experimental data was given by the Langmuir isotherm model. The adsorption kinetics of RS-SR-NH-SiO 2 -Fe 3 O 4 was well fitted with the pseudo-second-order rate equation. The thermodynamic parameters Δ G , Δ H and Δ S were also evaluated and the overall adsorption process was exothermic and spontaneous in nature.