Functionalized palm biomass-derived activated carbon for the removal of Pt(IV) from a simulated leachate

Over the years, demand for Platinum Group Metals (PGMs) has grown steadily due to increased production of various advanced technologies, such as automotive and electronic products. PGMs are predominantly used in automotive catalysts in the automotive industry. Along with the increase in automotive production, deactivated automotive catalysts pose environmental and health hazards. These wastes are excellent alternative sources of PGMs, which can be exploited to bridge the gap between the demand and supply of PGMs. Adsorption is one of the most popular metal removal/recovery methods due to its various advantages, such as ease of use and cost-effectiveness. In consideration of this method, developing an inexpensive and efficient adsorbent is a crucial point. Thus, activated carbon (AC), derived from a palm kernel shell that is abundantly available in Indonesia, was functionalized using ionic liquid (ACIL) and used for Pt(IV) removal from a simulated automotive catalyst waste leachate. The functionalized AC showed a high adsorption capacity (178.6 mg g⁻¹), in which the adsorption of Pt(IV) followed a chemisorption route, fitting with the monolayer model. The functionalized adsorbent also showed excellent performance during continuous Pt(IV) adsorption from simulated leachate. Recovery of precious metals, such as Pt(IV) and Pd(II), from the simulated leachate containing other metals was possible by maintaining the high hydrochloric acid concentration. Furthermore, targeted separation of Pt(IV) was achieved through sequential desorption using NaClO₄. In addition, ACIL showed remarkable reusability after being used for three cycles without showing a noticeable decrease in performance. Thus, this study highlights the capability of a functionalized adsorbent from palm oil industry biomass to recover precious metals from simulated leachate of automotive waste.