Adsorption of direct yellow 12 from aqueous solutions by an iron oxide-gelatin nanoadsorbent; kinetic, isotherm and mechanism analysis

Fe3O4–gelatin was synthesized via a controlled co–precipitation method to obtain uniform and high efficient nanocomposite for direct yellow 12 (DY12) removal. The effect of dose of adsorbent, pH, contact time and initial dye concentration on the removal of DY12 was examined. The adsorbent morphology and chemical composition were evaluated using FE–SEM, VSM, FT–IR, XRD and BET. The analyses for characterization indicated that Fe3O4–gelatin was successfully obtained with crystallite size and average particle diameter about 82 nm and 81 nm, respectively. Langmuir, Freundlich, Temkin and Elovich isotherm models were checked by adsorption equilibrium data and Langmuir model indicated the best consistency with the experimental results and the maximum adsorption capacity was 1250 mg g−1. In addition, kinetic studies were investigated using pseudo–first–order, pseudo–second–order, Elovich and the intra–particle diffusion models. It was revealed that the adsorption behavior of DY12 on Fe3O4–gelatin was closer demonstrated by the pseudo–second–order kinetic model. The equation of Weber and Morris and Boyd plot were also studied to evaluate the adsorption mechanism. According to the results, Fe3O4–gelatin nanoadsorbent has high ability to remove DY12 from aqueous solution.