In the recent years, several studies from developing economies have reported the presence of per- and polyfluoroalkyl substances (PFAS) in water bodies, with perfluorooctanoic acid (PFOA) predominating, a potential endocrine disruptor. In this study, an engineered sugarcane bagasse biochar–chitosan composite (SBCT) was designed, synthesized, and evaluated as a novel adsorbent for the removal of PFOA from aqueous systems at concentrations up to 500 ppb. Batch adsorption experiments were conducted to investigate the effects of initial PFOA concentration, contact time, pH, adsorbent dosage, and temperature. Scanning electron microscopy (SEM) showed that SBCT has a significant porous structure. The composite showed over 90% of PFOA removal from water. Further, peaks corresponding to C–F bonds observed after adsorption by Fourier transform infrared (FTIR) spectroscopy confirms the adsorption of PFOA on SBCT. The protonated amine groups (NH3+) in chitosan enhanced the adsorption of anionic PFOA through electrostatic attraction with carboxyl groups (COO−). The kinetic study revealed that pseudo-first-order best described the adsorption process, with an equilibrium adsorption capacity (qeq) of 2.78 mg/g, suggesting that physisorption is the predominant mechanism. The Langmuir Isotherm model gave the best fit, establishing a maximum adsorption capacity (qmax) of 9.08 mg/g. Thermodynamic analysis revealed that the adsorption process was spontaneous and exothermic, consistent with physisorption. The regeneration capacity of the SBCT composite demonstrated exceptional reusability over five methanol adsorption–desorption cycles. The adsorption kinetics, equilibrium behavior, and regeneration efficiency suggest that SBCT is a viable low-cost adsorbent for batch adsorption-based treatment systems targeting PFOA removal, particularly in decentralized and resource-constrained water treatment applications.
Pavithra et al. (Wed,) studied this question.