Kinetics of the adsorption of strontium(II) by a novel silica-based 4,4′,(5′)-di(tert-butylcyclohexano)-18-crown-6 extraction resin in nitric acid medium

A new type of silica-based chelating extraction resin, DtBuCH18C6/SiO2-P, was prepared by impregnating a crown ether derivative, 4,4′,(5′)-di(tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6), into the porous silica/polymer composite particles (SiO2-P). The adsorption of Sr(II) and some other fission product elements was investigated by a batch adsorption experiment in HNO3 medium. It was found that Sr(II) exhibits a strong adsorption onto the extraction resin, while the other fission product elements show almost no or only weak adsorption. The adsorption kinetics of Sr(II) was explained by assuming as the rate-controlling step the complex-formation reaction between Sr(II) and DtBuCH18C6 contained in the extraction resin. The rate equation of Sr(II) adsorption was determined as:-d[Sr(II)]/dt = k[Sr(II)][DtBuCH18C6][NO3−]0.5.