There is general agreement that primary pyrolysis products of end-of-life tyres should be valorised to improve the economics of pyrolysis. In this work, tyre pyrolysis char (TPC) is produced in a pyrolysis pilot plant designed and built at our home university. The produced TPC was upgraded to tyre-derived activated carbon (TDAC) by activation with CO2, and then characterised using stereological analysis (SA) and nitrogen adsorption at 77 K. SA showed that the grains of TPC and TDAC were quasi- spherical and slightly elongated with a 25% increase in the mean particle cross-section surface area for TDAC. The textural properties of TDAC demonstrated the BET and micropore surface areas of 259 and 70 m2/g, respectively. Micropore volume and micropore surface area were 5.8 and 6.7 times higher for TDAC than TPC at  2 nm, respectively. The n-hexane adsorption was investigated using experiments and modelling. Eight adsorption isotherms along with three error functions were tested to model the adsorption equilibrium. The optimum sets of isotherm parameters were chosen by comparing sum of the normalized errors. The analysis indicated that the Freundlich isotherm gave the best agreement with the equilibrium experiments. In relation to different activated carbons, the adsorption capacity of TDAC for n-hexane is about 16.2 times higher than that of the worst reference material and 4.3 times lower than that of the best reference material. In addition, stereological analysis showed that activation with CO2 did not change the grain’s shape factors. However, a 25% increase in the mean particle cross-section surface area for TDAC was observed.

This work investigates adsorption of n-hexane on activated tyre pyrolysis char (ATPC) and granular activated carbon (GAC) as a reference material in a fixed-bed column. Microwave-assisted regeneration is also considered. The adsorbed amount of n-hexane on ATPC is in the range of 37–58 mg/g. Microwave-assisted desorption of ATPC samples enables the recovery of up to 95% of adsorbed n-hexane in this non-optimized microwave setup with the efficiency of microwave energy conversion into heat of only 5–6%. For the 50% breakthrough time, ATPC and GAC are able to purify the n-hexane gas volumes in the ranges of 20–90 and 935–1240 cm3/g, respectively. While adsorption kinetics is not satisfactorily described by pseudo-first and pseudo-second order kinetic models, it is very well reflected by a family of dynamic adsorption models, which are modelled with a single logistic function. Internal diffusion is likely the rate limiting step during adsorption on ATPC, while external and internal diffusion likely plays a role in adsorption to GAC. Although microwave-assisted regeneration is performed in a general purpose microwave reactor, both adsorbents show excellent performance and are very good candidates for the adsorption process. Preliminary results show that magnetite can further reduce microwave energy consumption.