Studies on the Preparation of Zanthoxylum bungeanum Branches Activated Carbon with Rich Mesopore and Toluene Adsorption Performances

Activated carbon adsorbents with rich mesopore were prepared by H₃PO₄ activation method using waste Zanthoxylum bungeanum branches as biomass raw materials and (NH₄)₂HPO₄ as additive. The physicochemical properties of the prepared activated carbon adsorbents were characterized by SEM, BET, FT-IR, and XRD. The prepared activated carbons were used to evaluate the toluene adsorption-desorption performances in air, and its renewable performance was also evaluated by toluene adsorption-desorption cycles. The addition of (NH₄)₂HPO₄ additive enhanced the pore-forming effects. The abundant gas products in process of the activation pore-forming can open the closed pores to promote pore expansion, and promote the mesoporous structure to be formed in the prepared activated carbon adsorbents. When the addition amount of (NH₄)₂HPO₄ is 1.0%, the specific surface area of the prepared AAC10 adsorbent was 1 082.2 m²·g^-1, the toluene adsorption amount reached 353.10 mg·g^-1, and the mesopore rate increased by 16.91%. The rich mesoporous structure effectively reduced the toluene desorption resistance, which allowed the corresponding activated carbon adsorbent to achieve the regeneration of toluene adsorption performances at 40 ℃ or even room temperature, and showed good renewable performance.