Eco-friendly synthesis of magnetic activated carbon from used water filter cartridges for efficient methylene blue adsorption

Using activated carbon (AC) derived from used water filter cartridges (UWFC), we developed a waste-to-resource method to remove dyes from water. Mild reactivation at 400 ° C for 1 h produced AC-UWFC, which was subsequently transformed into magnetic activated carbon (MAC-UWFC) for efficient adsorption of methylene blue (MB). Characterization confirmed a mesoporous structure (BET: 404.78 m 2 g − 1 ) with high stability. Optimal adsorption occurred at a pH of 8, using 0.2 g of MAC-UWFC over 1 h. Adsorption followed the Langmuir isotherm (227.27 mg g − 1 ) and pseudo-second-order kinetics. MAC-UWFC maintained an efficiency of 92.32% after eight cycles, demonstrating its effectiveness in wastewater treatment. Preparation & applications of MAC-UWFC