Fe3O4/AC nanocomposite as a novel nano adsorbent for effective removal of cationic dye: Process optimization based on Taguchi design method, kinetics, equilibrium and thermodynamics

In this study, we have synthesized a new Fe3O4/AC nanocomposite using low-cost adsorbent by microwave assisted in situ co-precipitation technique that was used as an effective adsorbent for the removal of methylene blue (MB) using the Taguchi design method as an optimization strategy. The optimum parameters are pH 7, Fe3O4/AC nanocomposite dose 0.03 g, contact time 30 min, initial concentration of MB 25 mg/L and temperature 298 K. The obtained results of ANOVA show that their percent contribution in descending order is pH (66.81%) adsorbent dose (25.54%) temperature (4.83%) initial MB concentration (1.23%) contact time (0.32%). The kinetic data were fitted to the pseudo-first-order, pseudo-second-order and intra-particle diffusion models and adsorption of MB dye followed pseudosecond- order kinetics. The obtained values of regression coefficient for Langmuir (0.98), Freundlich (0.93) and Dubinin–Radushkevich (0.94) showed that adsorption process fits to the Langmuir isotherm and the maximum adsorption capacity is 384.6 mg/g. Moreover, the thermodynamics studies suggested the spontaneous nature of the adsorption process.