Radiochemical studies on the extraction of trace amounts of mercury (II) from aqueous iodide solutions using 4-(5-nonyl) pyridine as a solvent

Results are reported for the liquid-liquid extraction of trace amounts (approx. 10-8M) of mercury(II) from aqueous iodide solutions by 4-(5-nonyl) pyridine (NPy) in benzene. The data indicate that mercury(II) can be extracted with extremely high partition values from water and a wide range of hydrochloric, nitric, and sulfuric acid concentrations with only 0.01 to 0.1 M NPy. The optimal conditions for the extraction have been carefully selected from a critical study of the various factors involved such as the effects of the concentration of the mineral acids, iodide ions, salting and complexing agents, and the solvent concentration. Common salts have little effect on extraction in concentrations up to 1 M. Regeneration of the solvent is achieved by stripping mercury with moderately concentrated nitric acid. The effects of various complexing agents on the extraction of the metal are described. Distribution coefficients and separation factors of several metal ions relative to mercury(II) are also reported for the optimal concentrations of the mineral acid solutions containing 0.2 M potassium iodide. Ferric iron does not interfere with extraction