Functionalization of Biomass-derived Activated Carbon and Electrochemical Reduction for the Recovery of Gold from Mobile Phone Leachate

In this age of cutting-edge technology, electronic equipment consumption, such as mobile phones, has increased tremendously. This was followed by a staggering increase in electronic waste (e-waste). However, it has been known that e-wastes contain higher amounts of precious metals than pristine sources, such as Au, which is valuable as an alternative precious metal source. Due to its various advantages, adsorption has emerged as one of the most common metal removal or recovery methods. A crucial aspect of adsorption is developing a cost-effective adsorbent for selective recovery of Au from the e-wastes. Thus, functionalized biomass-based adsorbent was developed to recover precious metals from e-waste. Functionalized activated carbon (ACIL900) has an appealing high adsorption capacity (116.2 mg g-1) performance and follows the chemisorption route, which fits with the monolayer model. The presence of IL boosts the adsorption efficiency due to its compatible interaction with the metal complexes. Remarkably, ACIL900 could quantitatively adsorb precious metals and several base metals from mobile phone leachate. The selective recovery of Au from the adsorbent was performed by sequential desorption using various solutions. Finally, Au was successfully recovered from the desorption solution using an electrochemical reduction process. ACIL900 was also found to maintain its performance for three adsorption-desorption cycles. This work reported the full recovery of Au from e-waste to its final pure product through the combination of adsorption, sequential desorption, and electrochemical reduction.