Recovery of Au(III) and Ag(II) from e-waste solution using green organic solvent through solvent extraction system / Zarif Hannan Zulkafli

As the world undergoes rapid urbanization, the usage of natural sources growth has increased rapidly to a greater amount causing the rate of waste generation to increase align with it. On top of that, extracting gold and silver from wastes of electronic equipment (E-waste) is a sustainable strategy for the recovery of the previous metal, reducing environmental pollution, and addressing the growing demands for gold and silver resources. In this work, in order to recover precious metals such as Au(III) and Ag(II), solvent extraction system has been introduced as one of the technologies that can extract the precious metals from the E-waste solution. The past years, a serious environmental pollution and high energy consumption has been long-standing challenges in the gold and silver recovery industry because of using petroleum solvent as diluent and extractant that highly flammable and toxic. After considering this limitation, in this research using the application of green system solvent such as Palm Kernel Fatty Acid (PKFAD) and Jatropha Oil (JO) that used as a sole green organic solvent in the solvent extraction without addition of diluent and modifier. More than 90% of Au and 99% of Ag in PKFAD, whereas 97% of Au and 99% of Ag in JO was recovered through solvent extraction. Stripping can be performed using 0.5 M of thiourea and capable to strip 83 % of Au(III) and 70 % of Ag(II) in PKFAD, whereas in JO was obtained 71 % of Au(III) and 50 % of Ag(II) from loaded-organic phase. This research has also been conducted to identify the best pH equilibrium of aqueous solution on Au(III) and Ag(II) using different green organic solvent, and determine the effect of stripping agents towards the efficiency of the extraction. More importantly, this study has high values in recovery of Au(III) and Ag(II) while gives an environmental benefits.