The adsorption-exchange equilibrium time and the adsorption isotherms of UO 2+, 137Cs, 169yb and HPO42-on modified peat have been investigated by batch experiments. The effect of pH on the adsorption-exchange percentage (E) and the distribution coefficients (Ka) was also examined. It was found that the adsorption-exchange of UO22 § and 169yb on the modified peat was described well by Freundlich isotherm, whereas the adsorption-exchange of 137Cs and HPO42-on modified peat corresponded to a Langmuir isotherm and the maximum adsorption capacities of the modified peat for ~37Cs and HPO 2-ions were 4.4 and 4.1 I.tg/g, respectively. The optimum pH for the adsorption-exchange of UO22+, 137Cs, 169yb and HPO2-on the modified peat was 7.0 at 25 ~

Our previous paper reported the effect of acidity and temperature on uranous-uranil isotope exchange reaction in sulphuric acid solutionJ It was found that the half-life of the isotope reaction tu2 is around 10 seconds, when the acidity and the temperature of the reaction system are reasonably selected. However, when the uranium isotopes are enriched by ion exchange the single separation factor could be 1.00l. Thus, the half-life, tu2 is less than one second for potential industrial application.

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