ION-EXCHANGE PROPERTIES OF CRYSTALLINE BISMUTH MOLYBDENUM HYDROUS OXIDE AND ITS INTERCALATES - EQUILIBRIUM AND KINETICS OF UO22+ IONS ON THE CRYSTALS

The sorption of uranyl ions on crystalline bismuth molybdenum hydrous oxide and its intercalates were investigated from point of view of bot h equilibrium and kinetics. Ion exchange isotherms of uranyl ions on t he crystals were obtained, and ionic sieve effect was employed to desc ribe the characteristics of ion exchange isotherms. The best fitting f or sorption of uranyl ions on BMHO was achieved by means of the Langmu ir isotherm, while the Freundlich isotherm appeared to best fit for it s intercalates. The slightly negative free-energy change indicates tha t, thermodynamically, the crystals behave less favourable for uranyl i ons. The equation derived from S(N)2 chemical reactions was proved to fit the rate cut-yes, and the rare constants were determined The compa rison between the calculated and observed pH values as a function of t ime further verified the chemical reaction mechanism.