Liquid – liquid Extraction of Palladium by Dibenzo-18-Crown-6 from Salt’s Media.

Abstract

Liquid-Liquid extraction of palladium by using Dibenzo-18-Crown-6 (DB18C6)
dissolved in 1,2-dichloroethane (1,2-DCE) has been investigated. The distribution ratio
(DPd) and percent of extraction (EPd %) were determined as a function of crown ether and
palladium concentration, pH value, shaking time ,presence of salt media ( NH4Cl ,KCl,
NaCl ) and solvent polarity. Depending on the mole ratio analysis method, it was suggested
that the most tolerable categories were [(M+DB18C6)2 (PdCl4)-2] where M+ are ( NH4+
,K+ ,Na+ )
The thermodynamic extraction data indicated that the extraction was dependent on the
temperature and the Vant Hoff plot was linear over the temperature range studied (283-313
K). The result is ΔHex. has a positive value (endothermic) due to the extend of bonding
between cation and the donor atoms of crown ether cavity and solvation energy changes,
ΔSex. has a positive value, and ΔGex. has a negative value (spontaneous process) and the
complex was stable at higher temperature.