Analytical Sciences

Development of an Analytical Method for Trace Gold in Aqueous Solution Using Polyurethane Foam Sorbents: Kinetic and Thermodynamic Characteristic of Gold(III) Sorption

A. S. BASHAMMAKH, S. O. BAHAFFI, F. M. AL-SHAREEF, and M. S. EL-SHAHAWI

Department of Chemistry, Faculty of Science, King Abdulaziz University, P. O. Box 80203, Jeddah 21589, Saudi Arabia

The kinetic parameters of gold(III) sorption by unloaded polyurethane foams (PUFs) and PUFs impregnated with some onium cations e.g. tetramethylammonium perchlorate (TMA⁺ClO₄^-), tetrabutylammonium iodide (TBA⁺I^-), and tetraheptylammonium bromide (THA⁺Br^-), have been determined. The retention steps were found to be fast, reached equilibrium in a few minutes and followed a first-order rate equation with an overall rate constant, k, of 0.0076 and 0.007 min^-1, respectively. The thermodynamic characteristics of gold(III) retention by the unloaded PUFs and THA⁺Br^- immobilized PUFs have been critically studied. The negative values of ΔH and ΔS are interpreted as the exothermic and spontaneous reaction of gold(III) sorption onto unloaded PUFs and foams impregnated with THA⁺Br^-. The cellular structure of the PUFs sorbent offer unique advantages over conventional bulk-type sorbents in the rapid, versatile effective separation and/or preconcentration of gold ions.

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