Ultrasonication Assisted Urea Treated Biochar: An Eco‐Friendly Adsorbent for CO2 Capture

Abstract Cheap, efficient and eco‐friendly adsorbents have received great attention for CO 2 capture. Nowadays, biochars are promising CO 2 adsorbents with the advantages of their low‐cost, tunable porous structural characteristics, facile surface treatment and easy regeneration. In this work, biochar synthesized from wheat straw, an agricultural waste, by pyrolysis was used as a CO 2 adsorbent. CO 2 capture studies were conducted by thermogravimetric analyses (TGA) at 25 °C under 100 mL min −1 CO 2 for 2 h. The CO 2 adsorption capacity of the biochar was determined as 23.33 mg g −1 . To enhance CO 2 adsorption capacity, ultrasonication and urea treatment were applied to the biochar. With the combination of these treatment methods, CO 2 adsorption capacity of the biochar increased to 73.56 mg g −1 due to an increase in its micro‐pore volume and presence of functional amine groups. Possible CO 2 capture mechanisms were stated as pore filling with CO 2 molecules, van der Waals forces, weak hydrogen bond, and Lewis acid‐base interactions in addition to reactions of amine groups with CO 2 molecules. After five CO 2 adsorption‐desorption cycles, ultrasonication assisted urea treated biochar was still used with over 90 % performance. The results show that the low‐cost and eco‐friendly physicochemical treated biochar is a favorable adsorbent for CO 2 capture.