New Regeneration Process of Heavy-Metal-Loaded Chelating Resins

Abstract

An alternative to the classical acid‐base regeneration of chelating resins loaded with heavy metals is investigated. The new process consists in recovering the heavy metals with recyclable soluble complexing agents. The semiclosed reactor includes a fixed bed and a stirred tank. A three‐parameter model, which implies a double equilibrium in series, is introduced. When less than 10 % of the metal is still fixed on the resin at the end of the desorption, a simplified form of the model with two parameters, which describes a quick equilibrium followed by a first‐order kinetics reaction, is proposed. Both forms of the model can simulate results for different experimental conditions (polymer and metal types, polymer initial concentration). It was observed for both cases that the first equilibrium constant depends on the polymer type and that the rate constant of desorption depends on the metal type. The scale‐up of desorption is then conducted at mini‐pilot scale. Scale‐up criteria tend to minimize the desorption time and the soluble polymer quantity used.

Model for the determination of diffusion coefficients of heterovalent ions in macroporous ion exchange resins by the zero-length column method

“…It is known the effect of the pH on the ion exchange capacity of weak acid resins (Menoud et al, 2000). All the experiments were carried out without any modification of metallic solution pH or buffer.…”