Purification of mining tire-derived carbon by chemical leaching: Toward the development of sustainable Li-ion battery anodes

End-of-life tires pose a significant environmental challenge due to their resistance to degradation and large-scale disposal issues. Pyrolysis offers a sustainable method to recover value-added products such as carbon black (CB); however, the recovered CB (rCB) typically contains high levels of impurities that limit its downstream commercial use. This study investigated the demineralization of rCB originating from the recycling of mining tires. Among the acids tested (HCl, H 2 SO 4 , HNO 3 ), HCl was the most effective, removing major metallic impurities (Zn, Ca, Fe), while NaOH was superior for the removal of silicates. The effect of process parameters including chemical concentration, rCB to chemical (slurry) ratio, and leaching time was systematically evaluated. Sequential HCl-NaOH treatment yielded purified CB with fixed carbon, volatile, ash, and moisture content of ~91 wt%, 6.7 wt%, 1.5 wt%, 1.1 wt%, respectively. SEM-EDS analysis confirmed effective impurity removal, with only traces of Si, Mg, and S remaining. When applied as an anode material in Li-ion cells, the leached CB exhibited a 74% increase in stable discharge capacity compared to raw carbon char, demonstrating its potential as a sustainable, value-added electrode material derived from waste mining tires.