A Case Study of Waste Scrap Tyre-Derived Carbon Black Tested for Nitrogen, Carbon Dioxide, and Cyclohexane Adsorption

Waste scrap tyres were thermally decomposed at the temperature of 600 °C and heating rate of 10 °C·min(−1). Decomposition was followed by the TG analysis. The resulting pyrolytic carbon black was chemically activated by a KOH solution at 800 °C. Activated and non-activated carbon black were investigated using high pressure thermogravimetry, where adsorption isotherms of N(2), CO(2), and cyclohexane were determined. Isotherms were determined over a wide range of pressure, 0.03–4.5 MPa for N(2) and 0.03–2 MPa for CO(2). In non-activated carbon black, for the same pressure and temperature, a five times greater gas uptake of CO(2) than N(2) was determined. Contrary to non-activated carbon black, activated carbon black showed improved textural properties with a well-developed irregular mesoporous-macroporous structure with a significant amount of micropores. The sorption capacity of pyrolytic carbon black was also increased by activation. The uptake of CO(2) was three times and for cyclohexane ten times higher in activated carbon black than in the non-activated one. Specific surface areas evaluated from linearized forms of Langmuir isotherm and the BET isotherm revealed that for both methods, the values are comparable for non-activated carbon black measured by CO(2) and for activated carbon black measured by cyclohexane. It was found out that the N(2) sorption capacity of carbon black depends only on its specific surface area size, contrary to CO(2) sorption capacity, which is affected by both the size of specific surface area and the nature of carbon black.