Saeed Laki - Membrane Processes Research Laboratory (MPRL),Department of Petrochemical Eng., Amirkabir University of Technology, Mahshahr Campus, Mahshahr, Iran
Ali Kargari - Corresponding Author Address: Membrane Processes Research Laboratory (MPRL),Department of Petrochemical Eng., Amirkabir University of Technology, Mahshahr Campus, Mahshahr, Iran
Ahmad Arabi Shamsabadi - Membrane Processes Research Laboratory (MPRL),Department of Petrochemical Eng., Amirkabir University of Technology, Mahshahr Campus, Mahshahr, Iran

Solvent extraction has been a very effective unit operation in hydrometallurgy.In this paper,experimentqal study of solvent extraction is presented for extraction of silver from nitrate solution using mono/di 2-ethylhexyl phosphoric acid ester (MDEHPA) in an industrial organic solvent (mainly paraffinic and naphthenic hydrocarbon in C10- C14 range). Effect of operation parameters such as pH, contact time and extractant concentration were investigated. Stoichiometry equation ofthe silver extraction process with MDEHPA has been proposed too. Because of aciditic property of MDEHPA, the extraction increased with pH to 100%. The formation of precipitate was occurred at pH 9, due to hydrolysis phenomena of silver. The extraction of silver at lowequilibrium pH is low, due to the protonation effect of H+ on MDEHPA. Results indicate the extraction of Ag(I) ( 74.8 %) was quite rapid and attained the equilibrium within one minute. Also long contact time had no adverse effect on extraction The MDEHPA has a good extraction performance at pH 7.5 - 8 , also silver extraction will increase by increasing concentration of MDEHPA.

Solvent extraction, silver, MDEHPA, pH,contact time, extractant concentration