Environmental remediation of antibiotics and herbicides using artificial humic substances

The sustainable mitigation of antibiotic and herbicide residues requires materials that integrate effective contaminant sequestration with soil quality improvement. Here, we present a novel, scalable strategy for synthesizing artificial humic substances (AHS) from poplar bark via alkaline hydrothermal humification, which accelerates natural humification pathways and generates a supramolecular structure rich in carboxyl, pHenolic, and quinone functional groups. The engineered AHS was assessed for selective removal of tetracycline (TC), sulfamethoxazole (SMX), and atrazine (ATZ). Under optimized neutral conditions (pH 7.0, ambient temperature), AHS achieved adsorption capacities of 65.8, 10.7, and 10.8 mg/g for TC, SMX, and ATZ, respectively, driven primarily by hydrogen bonding, π–π stacking, and electrostatic forces. Kinetic analysis followed a pseudo-second-order model, and equilibrium data were consistent with the Langmuir isotherm (R 2 ≥ 0.985), indicating monolayer adsorption on a mesoporous surface. Competitive adsorption experiments demonstrated strong selectivity toward TC (K TC/SMX = 5.21; K TC/ATZ = 2.56). Soil amendment with AHS significantly enhanced pollutant immobilization, achieving >95% removal of TC and SMX after four weeks of aging. Dynamic leaching experiments demonstrated that a layered AHS-soil configuration functions as a superior reactive barrier compared to homogeneous mixing. Collectively, these results demonstrate that poplar bark-derived AHS offers a robust, bifunctional platform for integrated water purification and soil remediation, providing a practical and environmentally sustainable approach to mitigate organic pollutants. • Artificial humic substance synthesized from poplar bark via hydrothermal treatment. • AHS effectively adsorbed antibiotics and herbicides from aqueous and soil systems. • Adsorption followed the pseudo-second-order kinetics and Langmuir isotherm model. • AHS-amended soils demonstrated contaminant removal after four weeks of incubation. • Layered AHS configuration exhibited superior leaching control and pollutant retention.