Chlorite alteration in aqueous solutions and uranium removal by altered chlorite

Abstract

Chlorite alteration and the U removal capacity of altered chlorite were investigated. Batch kinetic dissolution tests using clinochlore CCa-2 were conducted for 60 days in aqueous solutions of various pHs and ionic strengths. Batch sorption tests using these altered chlorite samples were conducted for 48 h with natural groundwater containing 3.06 x 10(-6) M U. Chlorite dissolution was influenced more by pH(o) than by the ionic strength of the solution. TEM analysis revealed Fe(oxy)hydroxide aggregates in the solid residue from the batch dissolution test with 0.1 M NaClO4 solution at pH(o) = 10. The U removal capacity of the reacted chlorite samples at pH(o) = 6-10 was higher than that of the reacted chlorite samples at pH(o) = 3. The degree of dissolution of chlorite samples reacted at pH(o) =3-8 was inversely proportional to the U removal capacity, but that of chlorite samples reacted at pH(o) =10 was proportional to the U removal capacity. The positive correlation between the U removal capacity and degree of chlorite dissolution at pH(o) =10 might be due to the formation of Fe-containing secondary minerals and changes in the reactive sites. (C) 2016 Elsevier B.V. All rights reserved.