Adsorption of perfluoroalkyl substances using chemically synthesized manganese-coated chitosan and activated carbon composite

Perfluoro octane sulfonate (PFOS) is part of the wide group of perfluoroalkyl substances (PFAS) and has become a major issue of environmental concern owing to its long-lasting quality, its ability to get accumulated in living organisms and further, the potential risks such as cancer development or reproductive system damage. This study aims to synthesize manganese (Mn2+) coated chitosan-activated carbon (MnAcC) composite for reducing PFOS contamination level in water. The experimental results determined that the maximum PFOS-removal efficiency for the MnAcC reached an 82.56 ± 2.56% (with error value of ±1.45) using adsorbent dose of 1.5 g/L at acidic pH 3. The composite was characterized through SEM, XRD and FTIR, which complemented morphological and crystalline structural and functional changes that made possible effective binding of PFOS. The well fitted Freundlich isotherm (R2 = 0.99) and pseudo-second-order kinetics (R2 ≈ 0.96) study exhibited multilayered and chemisorption adsorption mechanism, respectively. The Langmuir adsorption capacity exhibited maximum adsorption capacity of 34.25 mg/g. Through thermodynamic studies, the adsorption process was also confirmed to occur spontaneously and to be endothermic in nature. This research helps to elucidate the adsorption processes and mechanisms of bio-based materials, as well as to comprehend the biological remediation technologies. This work is leading the development of ecofriendly and cos-effective PFOS removal technologies and suggests a new market for the specialized study of the process and its scale-up of adsorbent based research.