Impregnation of task-specific ionic liquid into a solid support for removal of neodymium and gadolinium ions from aqueous solution

Impregnation of trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate, as an ionic liquid, into silica was carried out for removal of neodymium and gadolinium ions from aqueous solution. Silica and the impregnated silica (Cyphos@silica) were characterized using FT-IR, SEM, XRD and TGA. Comparative sorption behavior of silica and Cyphos@silica for sorption of neodymium and gadolinium ions was investigated. The experimental outcome revealed that the impregnation process enhanced the sorption behavior of silica, from 18 to 67% for neodymium ion and from 20 to 89.45% for gadolinium ion. From the kinetic studies, the sorption could be described well by pseudo-second-order model. Langmuir and Freundlich isotherms were performed to determine the best fit equation for the sorption process; the results indicated that the latter surpasses the former. Comparison of the sorption capacity of Cyphos@silica with other materials reported in the literature shows that the former has a comparatively high sorption capacity. Desorption percent of gadolinium and neodymium ions from Cyphos@silica using 1.0 mol/L of HNO3 was found to be 97.74 and 86.33%, respectively. The desorption studies revealed the reusability of Cyphos@silica for further sorption. (C) 2017 Elsevier B.V. All rights reserved.