Synthesis of carbon based hybrid material for extraction of hazardous metals (Pb, Cr) from E-waste

In the rapidly evolving landscape of electronic devices, the operational lifespan of electronics and electrical equipment has markedly decreased. This obsolescence contributes to a significant increase in electronic waste (e- waste), which, if mishandled, poses environmental hazards due to the release of toxic elements such as Pb, Cr, and Hg. In pursuit of sustainable e-waste management strategies, this study investigates the utilization of activated carbon (AC) based hydrogel beads for the selective extraction of hazardous elements, particularly Pb and Cr. To enhance the efficacy of the separation process, a physical pre-processing step is introduced before subjecting the waste printed circuit boards (PCBs) to acid treatment. AC is synthesized and impregnated into Calcium Alginate matrices to form AC-Ca-Alg beads. The optimized composition of the beads was determined to be 4 % AC, 4 % Ca-Alg, and 92 % water. The synthesized AC is subjected to comprehensive characterization employing XRD, FTIR, and SEM-EDS techniques. Furthermore, the interaction mechanisms between Lead, Chromium, and the AC-Ca-Alg beads are elucidated through sorption and isotherm studies. It was observed that the maximum uptake of lead achieved at pH 6 and for chromium within the pH range of 4-6. The sorption of Pb onto the AC-Ca-Alg beads conforms to the Langmuir isotherm model, with maximum sorption capacity calculated as 29.66 mg g-1. For Cr maximum sorption capacity is calculated as 26.93 mg g-1. Notably, the AC-Ca-Alg beads demonstrate high efficiency in the recovery of heavy metals, including Pb, Cr, and Fe, from actual acid leached solutions of e-waste.