Preparation of activated carbon from bamboo shoot shell by pyrolysis self-activation method and its arsenic adsorption performance

Objective This paper aims to explore an efficient arsenic removal activated carbon material using bamboo shoot shell residue from bamboo processing.

Method Bamboo shoot shell was used as the raw material, while microwave heating was employed as the heat source. Activated carbon from bamboo shoot shell was prepared through catalytic pyrolysis self-activation technique at different activation temperatures and times. The microstructure, specific surface area, pore structure, graphitization degree, surface elements, and functional groups of the activated carbon were characterized to reveal the influence of activation time and temperature on its microstructure. The arsenic adsorption performance of the activated carbon was investigated, and the differences in specific surface area and arsenic adsorption capacity were compared among different preparation methods.

Result At an activation temperature of 1 050 ℃ and activation time of 30 min, the activated carbon exhibited an orderly and dense pore structure. The specific surface area reached 1 251.7 m²/g, with a pore volume of 0.697 cm³/g. The ratio of micropore specific surface area and the ratio of pore volume were 60.9% and 64.0%, respectively. The average pore diameter was 0.448 nm, primarily composed of micropores and a small amount of mesopores. The pore size was much larger than the spatial configuration dimensions of arsenate ions (AsO₄ ³⁻) and arsenous acid molecules (H₃AsO₃), which facilitated the adsorption of As(Ⅲ) and As(V). The graphitization degree (R) was 1.340, and the surface contained abundant oxygen-containing functional groups. The maximum adsorption capacity for As(Ⅲ) was 3.87 mg/g, while for As(V), it was 3.17 mg/g. Compared with the specific surface area and arsenic adsorption capacity of activated carbon in previous literature, the bamboo strip activated carbon demonstrated certain advantages.

Conclusion Properly increasing the activation temperature and extending the activation time are beneficial for the formation of surface micropores, thereby enhancing the arsenic adsorption capacity. However, excessively high activation temperature and prolonged activation time can cause the collapse of pore structure, resulting in reduced specific surface area, micropore ratio, and reduce arsenic adsorption capacity. This research provides a simple and environmentally friendly method for the preparation of efficient arsenic removal activated carbon materials, offering promising arsenic treatment performance in water bodies.