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 N₂, CO₂, and cyclohexane were determined. Isotherms were determined over a wide range of pressure, 0.03-4.5 MPa for N₂ and 0.03-2 MPa for CO₂. In non-activated carbon black, for the same pressure and temperature, a five times greater gas uptake of CO₂ than N₂ 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 CO₂ 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 CO₂ and for activated carbon black measured by cyclohexane. It was found out that the N₂ sorption capacity of carbon black depends only on its specific surface area size, contrary to CO₂ sorption capacity, which is affected by both the size of specific surface area and the nature of carbon black.