Sorption of strontium on hydrous zirconium oxide

Surface characteristics of hydrous zirconium oxide (HZO) and its sorption b ehavior toward strontium were investigated. In sodium nitrate solution, the point of zero charge (PZC) of HZO was found to be 2.88 by the pH-titration technique. The sorption edge, however, occurs at pH = 8. The lack of sorpt ion of Sr2+ in the pH range 2.88 < pH < 8, seems to be due to the low diele ctric constant of HZO. The beginning of sorption at pH = 8 was attributed t o the hydrolysis of Sr2+ to a lower charged SrOH+. An estimate of enthalpy and entropy changes accompanying H+/Sr2+ exchange were determined by the te mperarure-variation method. The increase in the entropy of the overall syst em seems to favor the exchange of H+ with Sr2+.