Recovery of Au, Ag and Cu from printed circuit board leachate using activated carbon derived from foxtail fruit

Abstract

Printed circuit boards (PCBs) are the e-waste generated from the end-of-life electronic equipment such as laptops and mobile phone. PCBs contain various metals including precious metals (gold, silver, copper) and detrimental heavy metals as well (arsenic, mercury) [9]. Recycling of e-waste is potentially to be one of the best mechanisms to overcome the human and environmental health threat hence, the valuable metals can be recovered and could avoid the depletion of our ore resources. In this paper, hydrometallurgical process on PCBs was carrying out to recover the precious metals. The PCBs were immersed into aqua regia leaching solution and later the targeted metals were leached out and extracted using activated carbon through adsorption process. The precious metals were then recovered by desorbing the spent activated carbon using hydrochloric acid (HCl) as desorbing agent. In this study, foxtail palm fruit was used to produce activated carbon for metals recovery process. Therefore, the objective of this study was to evaluate the efficiency of the prepared activated carbon derived from foxtail fruit for the recovery of Au, Ag and Cu contain in the PCB leachate. The effect of adsorbent dosage (1, 2, 3, 4, 5g), contact time (20, 40, 60, 80, 100 min) and desorption process of spent activated were investigated. The characterization of the prepared activated carbon was determined using field emission scanning electron microscope (FESEM) whereas the PCBs leachate solution before and after metal recovery process were quantified using flame atomic absorption spectrophotometer (FAAS). The obtained result showed that, the adsorption percentage of Au, Ag and Cu at high adsorbent dosage (5g) with longer contact time (100 min) were 65.51%, 30.30% and 62.51% respectively. However, the attained result for desorption percentage of the metals recovery for Au, Ag and Cu were recorded to be higher at shorter contact time (20 min) as the spent activated carbon could deteriorate at longer contact time with concentrated HCl. The percentage recovery values for 20 minutes desorption process were 99.77% (Au) when 5g of activated carbon was used, whilst 97.41% (Ag) and 98.83% (Cu) were obtained when 2g of activated carbon were applied, respectively. Thus, it can be concluded that the adsorption of Au, Ag and Cu were greater when higher dosage of activated carbon and longer contact time were applied. Meanwhile, shorter contact time were needed to recover the metals. Therefore, this study could be one of the finding in safeguarding our environment by minimizing the e-waste pollution as well as practicing metal recycling in community.