Chemical Process Enhancement of Pyrolytic Carbon Black from Waste Tires

The pyrolysis of end-of-life tires presents a sustainable route for converting waste into valuable products, including pyrolytic carbon black (CBp). However, the high ash content in CBp (∼17-21%) limits its reinforcement performance compared with commercial carbon black (e.g., N330). This study investigates the enhancement of CBp through acid-base chemical treatment using hydrochloric acid (HCl) and sodium hydroxide (NaOH). Optimal duel treatment conditions (6 M HCl and 2 M NaOH, 70 °C, 60 min, 10 mL/g) reduced ash content from 17.15 to 2.25% and increased the Brunauer-Emmett-Teller (BET) surface area from 60.56 to 70.22 m²/g, surpassing that of N330 (39.08 m²/g). Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) revealed improved surface morphology and elemental purity, while Fourier-transform infrared (FTIR) and X-ray diffraction (XRD) confirmed enhanced functionalization and graphitic crystallinity. Although treated CBp exhibited only moderate improvements in mechanical properties within styrene-butadiene rubber (SBR) vulcanizates, it showed significantly better dispersion and elongation performance. A comparative Life Cycle Inventory (LCA) indicated that treated CBp (especially dCBp-duel) achieves superior purity and surface properties but at the cost of higher global warming potential (GWP) and water use. In contrast, raw CBp offers the lowest environmental burden and N330 has the highest energy demand. Trade-offs must be considered depending on application priority, performance, and sustainability.