On the extraction of gold(III) with dibutyl carbitol

Extraction of HAuCl4 with diethylene glycol dibutyl ether (dibutyl carbitol) was studied in the gold(III) concentration range 10(-6)-1.5 mol/L at c (HCl) = 1 mol/L and T = 25A degrees C, distribution ratios were determined. Experiments were made at other c (HCl). A unified extraction isotherm was obtained with the use of activity coefficients of HAuCl4. The main extraction equilibrium is H (aq) (+) + AuCl (4aq) (-) = HAuCl4 org, K (0) (extractant and water molecules are omitted). For low c (Au)logK (0) = 1.89 +/- 0.06. Dimerization equilibrium 2HAuCl(4 org) = (HAuCl4)(2 org) has logK (2) = 2.1. Extracts are electrically conducting, the share of ionic subsystem increases with C (Au) and reaches about 10% at c (Au org) = 0.1 mol/L. Alteration of phase volumes on extraction was studied: Delta V (aq) a parts per thousand -0.20n (Au), Delta V (org) = -0.8 Delta V (aq), where n (Au) is the number of moles of gold(III) that transfer from aqueous into organic phase. It was shown that 6 +/- 1 water molecules are co-extracted with each HAuCl4 molecule.