Highly efficient removal of perfluorooctanesulfonic acid (PFOS) from aqueous solutions at neutral pH using a novel and reusable porous Aluminum-Carbon composite (PACC)

Perfluorooctanesulfonic acid (PFOS) is a persistent organic contaminant that requires effective removal from water. In this study, a porous Aluminum–Carbon composite (PACC) was synthesized through pyrolysis of an Aluminum chloride–terephthalic acid precursor (3:1 molar ratio) at 550 °C. The resulting adsorbent exhibited a high surface area (140.67 m 2 g -1 ) and a mesoporous α-Al 2 O 3 –carbon framework (6.95 nm), as confirmed by BET and XRD analyses. FTIR spectra verified the presence of surface functional groups (–OH, C=O, and –COOH) responsible for electrostatic and hydrophobic interactions with PFOS molecules. Optimization using Box–Behnken design and response surface methodology achieved a 94.23% removal efficiency for an initial PFOS concentration of 5 mg L -1 at natural pH of 8, contact time of 56 min, and adsorbent dosage of 0.87 g L -1 . Equilibrium data fitted best to the Langmuir model, revealing a high monolayer adsorption capacity (q max = 634 mg g -1 ), confirming strong and uniform binding of PFOS molecules to the PACC surface. Kinetic analysis followed a pseudo-second-order model, indicating chemisorption as the rate-controlling mechanism. The PACC demonstrated excellent reusability, maintaining high adsorption efficiency over five regeneration cycles with minimal capacity loss. Its high performance under near-neutral conditions, rapid adsorption rate, and structural stability highlight its superiority over conventional adsorbents. Overall, the synergistic combination of electrostatic and hydrophobic interactions within the α-Al 2 O 3 –carbon framework establishes PACC as a high-capacity, reusable, and environmentally sustainable adsorbent for PFOS removal from contaminated water. • Novel porous Aluminum-Carbon composite (PACC) synthesized for efficient PFOS removal. • Achieved 94.23% PFOS removal efficiency at neutral pH. • Demonstrated high PFOS adsorption capacity of 634 mg g -1 . • PACC showed excellent reusability (100%) over five regeneration cycles. • Adsorption process optimized using Box-Behnken Design and RSM.