Selective binding of mercury to thiourea-based coordinating resins

The selective binding of mercury from hydrochloric acid by thiourea-based coordinating resins, ITU, BTUO-1, BTUL-1 and BTUL-2, synthesized in our laboratory, has been studied with batch and column operations. The resins have been shown to have a high capacity for the adsorption of mercury(II) from acidic chloride solutions and good selectivity for the extraction of mercury over cadmium and zinc. Both the capacity and selectivity of the resins decrease with increasing HCl concentration in the feed solution. The extraction of mercury by these resins can be explained by 1:1 species formation. BTU resins show faster adsorption and elution kinetics in column operation. The adsorption rate is enhanced by the HCl concentration in the feed solution. The mercury-loaded resins can be quantitatively eluted by a solution containing 5% thiourea in 1% HCl. The resins were tested for removing soluble mercury from neutral chloride solution (dental waste effluents) to a level lower than 10 ppb by fixed bed column operation.