In order to develop a low-cost, fast, and efficient adsorbent, the fish bone charcoal B600 prepared at 600 °C was modified by chitosan (Cs) and Fe3O4 to produce the material Cs-Fe3O4-B600. Results showed that Cs-Fe3O4-B600 had magnetic responsiveness and can achieve solid-liquid separation, macropores disappeared, pore volume and specific surface area are increased, and amino functional groups appear on the surface. The adsorption process of Cd(II) by Cs-Fe3O4-B600 conformed best to the pseudo-second order kinetics model and the Langmuir model, respectively. The behavior over a whole range of adsorption was consistent with chemical adsorption being the rate-controlling step, which is a very fast adsorption process, and the isothermal adsorption is mainly monolayer adsorption, which belongs to favorable adsorption. In addition, the saturated adsorption capacity obtained for the Cs-Fe3O4-B600 to Cd(II) was 64.31 mg·g-1, which was 1.7 times than B600. The structure and morphology of Cs-Fe3O4-B600 were characterized through SEM-EDS, TEM, FTIR, and XRD, indicating that the main mechanism of Cs-Fe3O4-B600 and Cd(II) is mainly the complexation of amino groups, and it also includes part of the ion exchange between Cd(II) and Fe3O4. Therefore, Cs-Fe3O4-B600 can be employed as an effective agent for remediation of Cd contaminated water.
Keywords: Cd; Fe3O4; adsorption mechanism; chitosan; fish bone char; modification.