An Inorganic Microsphere Composite for the Selective Removal of137Cesium from Acidic Nuclear Waste Solutions. 1: Equilibrium Capacity and Kinetic Properties of the Sorbent

Abstract

A new inorganic ion exchange composite consisting of ammonium molybdophosphate, (NH₄)₃P(Mo₃O₁₀)₄·3H₂O (AMP), synthesized within hollow aluminosilicate microspheres (AMP‐C) has been developed. Two different batches of the sorbent were produced resulting in 20% and 25% AMP loading for two and three loading cycles, respectively. The selective cesium exchange capacity of this inorganic composite was evaluated using simulated sodium bearing waste solution as a surrogate for the acidic tank waste currently stored at the Idaho National Laboratory (INL). Equilibrium isotherms obtained from these experiments were very favorable for cesium uptake and indicated maximum cesium loading of approximately 9% by weight of dry AMP. Batch kinetic experiments were also performed to obtain the necessary data to estimate the effective diffusion coefficient for cesium in the sorbent particle. These experiments resulted in effective intraparticle cesium diffusivity coefficients of 4.99 × 10⁻⁸ cm²/min and 4.72 × 10⁻⁸ cm²/min for the 20% and 25% AMP‐C material, respectively.