Optimized Ginkgo leaf biochar: An efficient adsorbent for 2,4-D herbicide removal from wastewater

This research exploited biochar, sourced from Ginkgo leaves (GLs), to facilitate the adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D) in aqueous environments. The results reveal that GL biochar, activated with ZnCl₂ at a temperature of 500°C (500-ZGBC), demonstrated the greatest specific surface area (S_BET) of 536.0 m² g^-1 for 2,4-D adsorption. The biochar's properties, including specific surface area, morphology, structure, thermal stability, and functional groups, were analyzed. Additionally, studies of kinetic and isotherm profiles were conducted, yielding the highest recorded adsorption capacity of 281.8 mg g^-1. Pore filling, hydrogen bonding, π-π interactions, surface complexation with Zn groups, and electrostatic interactions contribute significantly to the adsorption performance of 500-ZGBC for 2,4-D. Optimal adsorption was determined to occur at pH 2.117, with a dose of 0.4230 g L^-1 of 500-ZGBC, and an initial concentration of 2,4-D at 294.7 mg L^-1, as evidenced by the application of the response surface method (RSM). PRACTITIONER POINTS: Premium pharmaceutical-grade biochar, derived from Ginkgo leaves, boasting a S_BET of 536.0 m² g^-1 was produced. An absorption capacity reaching 281.8 mg g^-1 was observed in Ginkgo leaf biochar for 2,4-dichlorophenoxyacetic acid (2,4-D) adsorption. The adsorption procedure was refined through the employment of response surface methodology.