Sodium Alginate Immobilized β-Cyclodextrin/Multi-walled Carbon Nanotubes as Hybrid Hydrogel Adsorbent for Perfluorinated Compounds Removal

Perfluorooctanesulfonic acid (PFOS) is classified as a chemically stable anthropogenic micropollutant has been found contaminating most of the water environment worldwide. Thus, this study focused on designing a new hybrid hydrogel adsorbent based on combination of biopolymers such as sodium alginate, beta-cyclodextrin and multi-walled carbon nanotubes to resolve the problem. The batch adsorption experiments were studied to investigate the adsorption efficacy for PFOS from the aqueous environment with several adsorption conditions such as adsorbent dosage, initial concentration, pH and contact time. The optimum operative variables that induced a delicate adsorption capacity of 91.6% for PFOS removal were 1000 mg of adsorbent dosage, 10 mg/L of PFOS solution, pH 3, and a contact time of 45 min. Kinetic and isotherm model were utilized to emphasized the equilibrium adsorption data and the perfectly fitted kinetic modelling is pseudo-second-order (R-2 = 0.976) while adsorption isotherm simulated by Langmuir model (R-2 = 0.918). Furthermore, the fabricated hybrid hydrogel bead could be reused multiple times without an obvious decrease in the removal efficiency. Hence, this work provides a feasible approach in developing a hybrid hydrogel adsorbent that could be used as high-performance adsorbent for PFOS remediation in the water treatment application.