Selective Separation and Determination of Copper and Gold in Gold Alloy Using Ion Exchange Polyurethane Foam

Abstract

A sensitive and selective determination of copper and gold in gold alloys was achieved using a strong anion exchange polyurethane foam (PUFIX) and polyurethane foam after hydrolysis (white‐PUF). The total sorption capacity of the resin was 4.22 and 0.85 mmol g⁻¹ for copper and gold, respectively. The maximum sorption of Cu (II) and Au (III) were in 0.02–0.2 and 0.06 M HCl, respectively. The half‐life values of sorption (t_1/2) was 2.2 and 0.5 min for Cu (II) and Au (III), respectively. The thermodynamic parameters were also determined. The red color formed on the surface of the white‐PUF is used for quantitative and/or semiquantitative determination of trace amounts of copper and gold ions spectrophotometrically or visually, respectively. As low as 4.8 ng cm⁻² of copper and gold is easily detected and Beer's law is obeyed in the concentration range of 0.025–0.21 µg mL⁻¹ with molar absorbtivity of 3.5×10⁴ L mol⁻¹ cm⁻¹. PUFIX and white‐PUF was verified as a good sorbent by Cu (II) and Au (III) determination in gold alloy.

Keywords:

• Copper (II)
• Gold (III)
• Ion exchanger
• Polyurethane foam
• Determination