One-step synthesis of Si-containing biochar from wheat dust for oxytetracycline hydrochloride removal: Mechanisms and life cycle assessment

Wheat dust (WD) is a mixed organic dust produced during the storage, transportation and processing of wheat, and its components include cellulose and ash, etc. To achieve its resource utilization, a “one-step” alkali-activated pyrolysis method was developed to prepare a Si-containing biochar (Si-WDB). Response surface methodology (RSM) was employed to optimize adsorption conditions for oxytetracycline hydrochloride (OTC). The specific surface area of Si-WDB increased to 241.75 m 2 /g, approximately 331 times that of the pristine WD (0.73 m 2 /g). Semi-quantitative pore-structure analysis suggested that mesopore-associated surface accommodation could account for approximately 72.47% of the measured adsorption capacity. Multi-scale characterizations and DFT calculations suggested that endogenous silicon was redistributed into or associated with the carbonaceous matrix during pyrolysis, providing Si-containing sites that might contribute to OTC adsorption through localized Si-involved interactions, together with π–π EDA interactions and hydrogen bonding. Life cycle assessment (LCA) confirmed a lower carbon footprint (7.06 kg CO₂ eq/kg Si-WDB), highlighting the environmental sustainability of the waste-to-resource strategy. This study established a sustainable pathway for upgrading silicon-rich agricultural waste into biochar adsorbent for antibiotic contaminated water remediation.