Preparation and Characterization of Magnetic Chitosan/-Carrageenan Nanocomposite and its Application for Removal of Eriochrome black-T from Aqueous Solutions

Due to the non-biodegradability of some dyes especially water soluble dyes, dye can pollute surface and groundwaters. Subsequently, discharging dye-contaminated wastewaters in the environment can endanger the human and aquatic life. In this work, a chitosan-based magnetic adsorbent was used for removal of anionic eriochrome black T. Magnetic nanoparticles were synthesized in situ in the presence of chitosan. The obtained magnetic chitosan was then crosslinked with kappa-carrageenan in order to overcome the solubility of chitosan under acidic conditions. The structure of magnetic adsorbent was investigated by XRD, SEM, TEM, FT-IR, and VSM techniques. The removal of eriochrome black T by magnetic adsorbent was studied regarding dye concentration, pH, temperature, ionic strength, and contact time. The experimental adsorption isotherms were in good accordance with the Langmuir model. According to the Langmuir constants, the maximum adsorption capacity of magnetic adsorbent was acquired 150 mg/g. The adsorption kinetic data were properly described according to the pseudo-second-order kinetic model. A decrease in dye adsorption capacity of the adsorbent was observed as the pH of dye solution was increased. The ease of preparation for magnetic adsorbent and its high adsorption capacity for eriochrome black T makes it a good candidate for removal of pollutants.