Analysis of monomeric and competitive adsorption mechanisms of nutrient ions on biochar surfaces based on molecular dynamics simulations.

This study explores the mechanisms of monomeric and competitive nutrient ion adsorption on biochar surfaces using molecular dynamics simulations and experimental data. CHO offers low-energy adsorption sites for ammoniacal nitrogen, while C-SH and C-NH facilitate adsorption for nitrate nitrogen and available phosphorus. Available potassium is primarily adsorbed near the benzene ring. Structures like CHO and CHNO contribute through physical and chemical adsorption mechanisms. The presence of mesopores enhances adsorption stability. In competitive systems, ammoniacal nitrogen adsorption remains largely unaffected by nitrate nitrogen and available phosphorus, although available potassium negatively impacts it. Nitrate nitrogen is influenced by electrostatic and intermolecular forces, and available phosphorus inhibits its adsorption, while available potassium aids nitrate nitrogen adsorption through ion reactions. This study elucidates the competitive adsorption mechanisms of biochar, providing theoretical support for industrial-scale preparation of nutrient-rich biochar.