Chitosan/maghemite composite: A magsorbent for the adsorption of methyl orange

• Synthesis of a magsorbent based on chitosan.
• Encapsulation of maghemite nanoparticles does not alter their magnetic properties.
• Magnetic chitosan beads are efficient for the removal of methyl orange (750 mg/g).
• Adsorption of methyl orange by the magsorbent is pH-dependent.
• The magsorbent could be reused after regeneration with NaOH.

In this study, magnetic beads were prepared by encapsulation of magnetic nanoparticles in epichlorohydrin cross-linked chitosan beads. Their adsorption characteristics were assessed by using methyl orange (MO) as an adsorbate. MO adsorption onto chitosan beads was found to be optimal in the pH range of 3–5. The adsorption isotherm was well described by the Langmuir model and showed high MO adsorption capacity (2.38 mmol/g, i.e. 779 mg/g). MO adsorption kinetics followed a pseudo-second-order kinetic model, indicating that adsorption was the rate-limiting step. At 0.305 mmol/L, only 19 min was required to reach 90% adsorption and 50% of the MO was adsorbed in 2 min. Desorption studies of MO using NaOH showed the reusability of the magsorbent. No release of iron species was observed at pH > 2.4.

Figure optionsDownload high-quality image (94 K)Download as PowerPoint slide