OPTIMIZATION OF GOLD SORPTION FROM AMMONIACAL THIOSULPHATE SOLUTION ON ANION EXCHANGE FIBER USING TAGUCHI EXPERIMENTAL DESIGN

Abstract

Taguchi experimental design was used to optimize the experimental parameters for Au sorption from ammoniacal thiosulfate solutions containing 2 mg/L Cu complexed as cuprous thiosulfate [Cu(S₂O₃)₃]⁵⁻ onto anion exchange fiber (METALICAPT® MFH11). An L₉ orthogonal array was chosen to study the effect of three parameters, namely Au initial concentration (10-30 mg/L), fiber quantity (0.05-0.55 g) and temperature (20-30°C). The sorption tests were carried out in batch mode at a stirring rate of 500 rpm and pH of 9.3. The experimental data were processed using signal-to-noise ratio and the analysis of variance was used to determine the most significant parameters. The optimal conditions for Au sorption were found to be 30 mg/L Au concentration, 0.05 g of fiber and temperature of 20°C. The obtained results indicated fiber quantity as the most influential parameter on Au sorption with a contribution of 66%, followed by Au initial concentration with a contribution of 33%. In the optimal conditions, the sorption capacity of the fiber was found to be 16.8 mg/g, in good agreement with the predicted result by Taguchi method (16.7 mg/g). Further investigations are necessary to examine the elution behavior of gold from the fiber.