Demineralization strategies of carbon black derived from pyrolysis of waste tires

Abstract

The pyrolysis of waste tires offers an environmentally friendly solution to the global tire waste problem. Pyrolytic carbon black (PCB) is an important by-product that can be reintroduced into industrial processes. This study aimed to improve the commercial viability of PCB by reducing its ash content. Pyrolysis was optimized at 420 °C for 4 h with a nitrogen flow rate of 1 L min^-1. Demineralization, crucial for minimizing ash, was carried out using acid and alkali treatments (H₂SO₄, HNO₃, HCl, NaOH). Two demineralization strategies were tested, one using fresh acid for three cycles and the other reusing the solution. The most effective method used 1 M HNO₃ at 80 °C for 1 h, reducing the ash content to 1.7%. The demineralized PCB (PCBd) had improved properties, including a BET surface area of 74 m²  g^-1, an iodine number of 57 mg g^-1, and a particle size distribution up to 140 nm, comparable to commercial carbon blacks. These results highlight the potential of PCBd as a sustainable alternative for tire management and material production.