Studies in Solvent Extraction and Supported Liquid Membrane for Platinum Recovery from Chloride Media by Tris(2-ethylhexyl) Phosphate

ABSTRACT

Extraction studies of platinum ions from chloride medium by solvent extraction (SX) and supported liquid membrane (SLM) using tris(2-ethylhexyl) phosphate (TEHP) were carried out. Platinum ions were extracted by TEHP in the presence of SnCl₂ during SX and stripped by an aqueous mixture of 2 M HCl + 0.05 M NaClO₃. The extraction was studied by varying Sn:Pt feed ratios and takes place through ion-pair association. Extraction studies with simulated spent catalyst dissolver solution containing Pt, Pd, Cr, Ni, Mn, and Fe showed high selectivity for Pt. The initial feed phase with platinum concentration of 5.1 × 10⁻⁴ M was effectively transported within 360 min using a polyvinylidene difluoride membrane with 0.45 µm pore size, dipped in 0.05 M TEHP/kerosene media. Permeability coefficient value of 1 × 10⁻³ cm/s was obtained at 3 M HCl (feed) across the membrane. Almost 96% of the platinum ions were recovered from a real spent autocatalyst solution.

KEYWORDS:

• Platinum
• Extraction
• SnCl₂
• Tris(2-ethylhexyl) Phosphate
• SLM

Additional information

Funding

The authors are grateful to University Grants Commission of India (Shweta Kumbhaj) and Pidilite Industries (Vandana Prabhu) for their financial assistance.