Impact of hydrothermal treatment and activation atmosphere on the porosity development of activated carbon from date pits

This study explores the production activated carbon from date pits without the use of chemical additives, employing steam and CO₂ as activating agents in accordance with green chemistry principles. A novel activation approach is introduced, integrating both agents to enhance porosity development. The study systematically examines the differences in microporosity formation between CO₂ and steam activation, as well as the influence of hydrothermal pretreatment on the final material properties. Activated carbons with high BET surface areas and distinct pore size distributions were synthesized, including predominantly microporous, materials with both micropores and substantial mesopores, and samples exhibiting a pore network comprising micro-, meso- and macropores. The results demonstrate that hydrothermal pretreatment enhances biochar yield increasing it by approximately 25 %. The evolution of the burn-off was found to be dependent on the pretreatment conditions, carbonization temperature, and the activating agent. Notably, the findings suggest that hydrothermal pretreatment influences biochar reactivity in different ways. Despite the similar surface functional group compositions observed in treated and untreated carbons, hydrothermally treated samples unexpectedly exhibited greater hydrophobicity. Additionally, the combined use of CO₂ and steam agents led to a higher burn-off compared to their individual, highlighting a synergistic effect in the activation process.