Extraction mechanism study of manganese(II) from sulfate and acetate mediaby bis(2-ethylhexyl)phosphinic acid (PIA-8)

Liquid-liquid extraction of manganese(II) from sulfate and acetate media us ing bis(2-ethylhexyl)phosphinic acid (PIA-8, IIR) in toluene has been studi ed. The extraction was quantitative with 0.02 mol l(-1)PIA-8 in toluene in the pH range 4.5-6.0 for sulfate media and 6.0-6.8 for acetate media. The s toichiometry of the extracted species of manganese(II) was determined on th e basis of the slope analysis method. The extraction reactions proceed with cation exchange mechanism and extracted species were MnR2. 2HR in sulfate medium and Mn(Ac-)(2)R-2. 2HR in acetate medium. Effect of various paramete rs such as equilibrium period, effect of various diluents and stripping age nts for extraction of Mn(II) from sulfate media were studied. This method w as applied for separation of manganese(II) from binary and ternary mixtures and extended for the determination of Mn(II) in real samples. Temperature dependence of the extraction equilibrium constants was examined to find the apparent thermodynamic functions (DeltaH, DeltaS and DeltaG) for extractio n reaction in sulfate media.