Green extraction of gold(III) and copper(II) from chloride media by palm kernel fatty acid distillate

Abstract

This work aimed to investigate the capability of palm kernel fatty acid distillate (PKFAD) as a green extractant for gold(III) and copper(II) from chloride media. The equilibrium pH (pHeq)-extraction isotherms of PKFAD for gold(III) and copper(II) from single-metal media (without and with an inert salt), extraction selectivity of PKFAD for gold(III) over copper(II) from binary-metal media, and the stripping of gold(III) and copper(II) from loaded PKFAD using different stripping agents were investigated. The existence of extracted species in loaded PKFAD and their extraction mechanisms were also verified and evaluated. The results revealed that PKFAD could extract both gold(III) (up to 99%) and copper(II) (up to 92%) at distinct pHeq without and with an inert salt, with the highest extraction selectivity for gold(III) over copper(II) achieved at pHeq 2. The highest stripping of gold(III) (76%) and copper(II) (95%) from loaded PKFAD was accomplished with 1 M thiourea-0.5 M hydrochloric acid solution and 2 M formic acid, respectively. Hence, PKFAD had shown great promise as a green extractant for gold(III) and copper(II) from chloride media.