Coconut shell activated carbon engineered for triphasic adsorption and multimechanistic removal of emerging contaminant F-53B

Abstract

Abstract A novel substitute for perfluorooctane sulfonate (PFOS), 6:2 Chlorinated polyfluoroalkyl ether acid (6:2 Cl-PFAES, F-53B), has been widely used in the electroplating and firefighting industries, raising concerns due to increasing environmental prevalence. This study systematically investigated the adsorption characteristics of F-53B by coconut shell activated carbon (CSAC) and elucidated the underlying mechanisms through adsorption kinetics, isotherm modeling, and multi-scale characterization. Results show that the maximum adsorption capacity of CSAC for F-53B reached 261.64 mg/g, with the process best described by the pseudo-second-order kinetic model (R2 > 0.97) and the Langmuir isotherm (R2 > 0.94). Intraparticle diffusion modeling revealed a three-stage adsorption sequence: surface adsorption (0–2 h), pore diffusion (2–8 h), and dynamic equilibrium (8–48 h). Solution pH influenced adsorption efficiency by regulating surface charge. Under acidic conditions (pH 7) led to a 70% reduction in adsorption efficiency (p 85% removal efficiency under wide pH conditions and tolerates coexisting ions (e.g., Cl−, SO4 2−, Ca2+).This study highlights the multi-mechanistic synergy of CSAC in theremoval of F-53B, providing theoretical foundations and technical insights for biochar-based remediation of emerging contaminants.

Keywords

• F-53B
• Coconut shell activated carbon (CSAC)
• Influencing factors
• Multi-mechanistic synergy
• Adsorption properties
• Characterization analysis