Removal of methylene blue and congo red by magnetic chitosan nanocomposite: Characterization and adsorption studies

Dyes are stable organic pollutants that have been used in many industries and become one of the toxic contaminants for the environment. This research aimed at preparing a magnetic chitosan nanocomposite (MCN) as an effective adsorbent for cationic and anionic dye removal from aqueous solution. The MCN was synthesized using a coprecipitation method. The physical properties of MCN were characterized using elemental analysis (CHNO), vibrating sample magnetometry (VSM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and X-ray diffractometry (XRD). The results confirm that chitosan has been embedded on the surface of magnetic material and shows superparamagnetic properties behavior. A series of adsorption were conducted to investigate dosage of adsorbent, contact time and initial dye concentration to obtain the optimum condition of adsorption for both methylene blue (MB) and congo red (CR) dyes. The experimental equilibrium adsorption were then analyzed by the Langmuir and Freundlich isotherm models. Based on the correlation coefficient (R²) values, the equilibrium adsorption data were fitted to the Langmuir isotherm model. The maximum adsorption capacity (q_m) obtained from the Langmuir isotherm model for MB and CR onto MCN was 0.1308 and 1.8257 mg/g, respectively. Results highlight the potential of MCN application as an adsorbent for water contaminated by dyes.