Preparation of sucrose-derived activated carbon in one pot with desirable hierarchically porous structure for efficient dyes removal

Sugar is an excellent raw material for activated carbon preparation because of its wide availability, sustainability, and low mineral content. Herein, we developed an easy method for preparing sucrose-derived activated carbon (SAC) with desirable hierarchically porous structures by combining the foaming of molten sucrose, dual-templating (K₂C₂O₄·H₂O and CaCO₃), and sequential etching by dual-templating activators at elevated temperatures. As an adsorbent, SAC–800 has a high specific surface (1594 m²/g), with rich both micro- and mesopores (microsurface vs external surface area is 812 and 782 m²/g). As a result of its desirable hierarchically porous structures, it adsorbs dyes fast and efficiently, attributed to the rich specific surface area that favors adsorption capability and pore size distribution that affects mass transport and adsorption speed. The adsorption for Rhodamine B and Congo Red is spontaneous and endothermic process. The adsorption capacities reach 357 and 780 mg/g for Rhodamine B and Congo Red, respectively, while the rate constants for adsorption (k_a) and desorption (k_d) for Rhodamine B are 4.23 × 10^–3 L/(mg·min) and 0.12 L/min, and 1.02 × 10^–3 L/(mg·min) and 5.6 × 10^–3 L/min for Congo Red. With the easy preparation procedure and the desirable hierarchically porous structures, sucrose-derived activated carbons are promising candidates for potential practical applications.