Hybrid chemical and physical activation techniques for engineering hierarchical pore structures in activated carbon for enhanced adsorption performance.

This study explores the synergistic impact of hybrid chemical activation (CA) and physical activation (PA) on creating hierarchical pore structures in activated carbons (ACs) derived from various biomass precursors, aiming to improve adsorption performance of radioactive, non-radioactive and organic pollutants that have harmful effects on the environment and living organisms. The Physicochemical properties were systematically determined for the hybrid activated carbon product by using different techniques. CA using H3PO4 and NaOH synergistic with PA via steam pyrolysis above 900 °C promotes pore development through dehydration, cross-linking, and etching, resulting in carbons with an ultra-high Brunauer-Emmett-Teller (BET) specific surface area SBET ~ 2000 m2/g. This exceptional surface area provides an extreme density of exposed active sites and an optimized open micro/mesoporous network. Mathematical modeling, including vector analysis of localized stress fields and kinetic/geometrical pore formation equations, elucidates the distinct yet interconnected pathways influencing pore evolution during each activation phase. A very important matter, the model demonstrates that the chemical pre-treatment acts as a structural scaffold, successfully mitigating pore wall collapse and preventing sintering during the high-temperature steam etching. The micro/mesoporous carbons showed high phenol removal efficiency, achieving a maximum adsorption capacity of 110 mg/g at pH ~ 9.5 and up to 90% removal efficiency, highlighting the importance of pore structure preservation for sustainable performance. The study provides insights into optimizing activation parameters for high-performance, sustainable activated carbons in environmental remediation applications.