Facile synthesis of magnetic activated carbon/<i>β</i>-cyclodextrin polymers composite and application for the adsorption of methylene blue from wastewater

Dye wastewater pollutes aquatic ecosystems, has toxic effects on aquatic organisms and can enter the human body through the food chain, causing potential health hazards. Magnetic ferrite-based adsorbents have attracted a lot of attention because they combine the advantages of magnetic materials and adsorbent materials. In this study, the activated carbon (AC) was crosslinked with Fe₃O₄ nanoparticles and β-cyclodextrin polymer (β-CDP) by a simple method to obtain MAC/β-CDP biosorbent, which can effectively remove methylene blue (MB). The specific surface area of MAC/β-CDP was 434 m² g⁻¹ by nitrogen adsorption desorption method. The MAC/β-CDP composite shown good adsorption capacity. The optimal adsorption conditions were determined as follows: initial pH = 8, MAC/β-CDP dosage (0.2 g/50 mL), contact time (180 min) and the removal rate of cationic dye reached more than 97.14%. In addition, the maximum adsorption capacity of MAC/β-CDP composite for MB (50 mL) was 1.21 mg g⁻¹, and the adsorption isotherm curve followed Langmuir (R² = 0.9621) and Freundlich (R² = 0.9982) models. In addition, after three cycles of regeneration, the regeneration rate of MAC/β-CDP was 96.76%. These results demonstrate the potential of MAC/β-CDP in the practical removal of MB pollutants in wastewater.