Rhodium cementation from spent plating solution using Taguchi's method

The Taguchi method was used as the experimental design to determine the optimum conditions of cementation behaviour of the spent rhodium sulphate plating solution. Cementation was carried out using metallic zinc powder. The experimental conditions were studied in the range of 25-45°C for reaction temperature (A), 0·5-1·5 for pH of solution (B), 30-50 mg for zinc powder (C) and 30-60 min for reaction time (D). Experimental parameters and their levels were determined in the light of preliminary tests. An orthogonal array (OA) L₉3⁴ consisting of four parameters each with three levels, was chosen. The optimal conditions found for cementation of rhodium, such as: reaction temperature, pH of the solution, mass of zinc and reaction time are respectively: 45°C, 1·5, 50 mg and 60 min. A verification experiment was conducted under optimum conditions and it was found that theoretically calculated and experimentally obtained results were in good agreement at 99?98 and 99·95% respectively.