Controlled synthesis of porous carbon materials from cow dung biomass and analysis of their adsorption properties: Modulation of lignocellulosic fractions and pore structure formation

Abstract

Globally, a large amount of agricultural waste is generated every year, and improper disposal can lead to serious environmental pollution. In particular, due to the expansion of large-scale cattle farming, the accumulation of large quantities of cattle manure can cause various environmental problems. Using agricultural waste, such as cattle manure, to produce porous carbon materials can enhance its resource utilization while mitigating its environmental impact. Accordingly, in this study, porous carbon materials were synthesized by partially degrading the lignocellulosic fractions in cow dung through a series of processes, including NaOH pretreatment under varying conditions (concentration, time, and temperature), pre‑carbonization, and KOH activation. Furthermore, the pore-formation mechanism of the porous carbon materials was analyzed in three stages: NaOH pretreatment, pre‑carbonization at 600 °C in an N₂ atmosphere, and KOH activation. Key factors influencing the structures of the materials were changes in the contents and linkages of cellulose, lignin, and hemicellulose. Among the tested samples, the pretreated CA-4-6-70 sample demonstrated the lowest lignin content and the highest cellulose content. Following pre‑carbonization and KOH activation, the specific surface area of this material reached 1402 m²/g, with a microporous area of 912 m²/g. Furthermore, the porous carbon materials synthesized in this study exhibited good CO₂ and methyl orange adsorption performance, demonstrating their potential for applications in environmental pollutant treatment.