Recovered carbon black: A comprehensive review of activation, demineralization, and incorporation in rubber matrices
Clara M.C. Silva, Clara M.C. Silva, Cristiana Maganinho, Adélio Mendes, João Rocha, Inês Portugal
Abstract
The rapid growth of the automobile industry has substantially increased end-of-life tires (ELT) production with over 2 300 million units manufactured in 2022. Despite known processes to recover materials and energy from ELT, a significant number of tires still end up in landfills, posing environmental problems. Pyrolysis offers a promising alternative to produce energy and marketable products like recovered carbon black (rCB). Incorporating rCB into rubber matrices shows potential for partially replacing commercial carbon black, but more research is required to understand its reinforcing effects and recyclability through repeated pyrolysis cycles. Furthermore, tire composition variability affects rCB quality, challenging consistent production for market applications. Post-treatments like activation and demineralization enhance rCB properties but pose challenges, with higher activation degrees improving pore structure but reducing carbon content while demineralization removes impurities but raises concerns about chemical use and equipment wear. Further research is needed to develop scalable and economically viable post-treatments along with their life cycle assessment. Here, a comprehensive literature review on rCB activation and demineralization is presented and, since the ultimate goal is to reuse rCB in the production of new tires, the rCB incorporation into rubber matrices is also reviewed.