Gold sorption model studies. The two candidate sorbents, poly-1 and poly-2, were tested for gold uptake from the TCCA/NaBr leach solution (Fig. ). Gold powder was first leached into solution by reaction with TCCA (40 equiv.) and NaBr (20 equiv.) and filtered to remove any solids. The resulting solution (pH = 1.35) was analyzed by AAS, indicating a gold concentration of 967 ppm. These relatively high concentrations of gold and leaching reagents were tested first so that both quenching and gold recovery could be assessed using poly-1 and poly-2. First, a portion of poly-1 (1.0 g, milled to particles < 1 mm in size) was added to a 40 mL sample of the leach solution and mixed at room temperature for 18.5 hours. Over this time, the solution changed from yellow to red in color. The polymer was recovered by filtration and the leach solution was analyzed by AAS, revealing negligible gold uptake. This result was attributed to the first portion of poly-1 quenching active oxidant in the leach solution. A second portion of poly-1 (1.0 g) was added to the filtered leach solution and mixed at room temperature for 5 hours, after which time the leach solution was cloudy and white in appearance. AAS analysis of the leach solution indicated 42 ppm gold remained in solution, which corresponds to 96% uptake by poly-1 and that approximately 37 mg of gold was bound to 1.0 g of sorbent. A similar experiment then was carried out by adding poly-2 (1.00 g) to a new sample of the leach solution (40 mL, 967 ppm in gold). After 18.5 hours of mixing, the solution was clear. The polymer was recovered by filtration. The leach solution had a final gold concentration of 45 ppm, indicating 95% gold uptake by the polymer sorbent. It was thought that the higher surface area of poly-2 (a powder) accounts for its ability to quench the leach solution and bind gold with a single 1.0 gram portion. In a control experiment where elemental sulfur was used as the gold sorbent (< 150 µm particle size), only 9% of the gold was removed from solution when 1.0 g of sulfur was added to the leach solution and the leach solution did not become clear in color (Fig. ). This important result highlights the ability of the polysulfides in poly-1 and poly-2 to both quench active oxidants and bind to gold more effectively than elemental sulfur.