Sustainable bioremediation of glufosinate pesticide from agricultural runoff using Schiff base functionalized chitosan-activated carbon nanocomposite: Characterization, adsorption, kinetics, and real conditions evaluation

• Decreased chitosan crystallinity confirmed successful chemical modification. • The composite showed superior glufosinate adsorption efficiency over 95 %. • Adsorption kinetics were described by a pseudo-second-order model. • Isotherm analysis suggested mono- and multilayer adsorption on the surface. • The synergistic effect between the components enhanced the performance. Chemical modification of the chitosan biopolymer is a common route to enhance its accessibility in various applications, particularly in the remediation of pesticides from agricultural runoff in wastewater treatment plants. Chitosan was chemically modified via coupling with 3,4-diaminobutan-2-one to increase the amino group content. The modified biopolymer was then composited with activated carbon through co-precipitation to form a chitosan-3,4-diaminobutan-2-one-activated carbon composite. The structures of the composite and its intermediates were confirmed using various spectroscopic analyses. The chemical modification and compositing impact on the chitosan during the removal process was followed and discussed. The composite demonstrated outstanding efficiency in removing glufosinate from agricultural wastewater, achieving a removal efficiency of 95%. Activated carbon alone reached 97 mg·g⁻¹, and modified chitosan reached 120.48 mg·g⁻¹. However, the final composite achieved a high capacity of 166.67 mg·g⁻¹ under optimal conditions (200 ppm glufosinate, pH=5.6, 25 °C, 180 min). Modeling: Adsorption and kinetic isotherms followed the Freundlich model and Pseudo-second-order trends. The process consisted of three stages, governed by the diffusion of glufosinate into various composite pores. The adsorption mechanism was discussed in depth.