Preparation of an adsorbent derived from canola hull by slow pyrolysis for effective carbon dioxide adsorption

Canola hull was proposed as a valuable precursor for activated carbon production, due to its abundance, low cost, and economic viability. This study aimed to develop a waste-based biosorbent from canola hulls by slow pyrolysis for effective CO 2 capture. The biochar was synthesized from the canola hull using a fixed-bed tubular reactor through slow pyrolysis at various temperatures. The optimum biochar was activated using KOH as a chemical activating agent at different impregnation ratios. The biochar and activated carbon were characterized by elemental analysis, thermogravimetric analysis, surface textural analysis and FT-IR analysis. All the activated carbon samples with impregnation ratios of 0, 0.2, and 0.4 were screened at a total inlet mass flow rate of 100 mL/min (15% CO 2 + 85% N 2 ). Activated carbon prepared with an impregnation ratio of 0.4 (0.4AC) with a specific surface area of 1112 m 2 /g exhibited the highest adsorption capacity of CO 2 (2.9 mmol/g) at 25 °C under ambient pressure when the feed gas was 15% CO 2 ). 0.4AC was chosen for further study at different feed compositions. The breakthrough curves were analyzed for the compositions 5%, 15%, and 25% CO 2 in feed, and the effects of adsorption parameters were discussed. The maximum CO 2 uptake of the canola hull-based activated carbon (0.4AC) is 13.0 mmol/g at ambient pressure and 25 °C, with 100% CO 2 inlet. Adsorption isotherm and kinetic were studied on the 0.4AC adsorbent. The canola hull-based adsorbent with desirable physiochemical and surface textural properties can work as an effective adsorbent for CO 2 capture.