Preparation and characterization of novel magnetic nano-adsorbent based on chitosan for removal of methylene blue

Dyes are scientifically and generally a new type of environmental pollutions, which has caused worldwide concern. Many research has been done in this field to remove dyes from wastewater based on the adsorption process via nano-adsorbents. This study described the synthesis of a new magnetic nano-adsorbent based on chitosan hydrogel beads to remove methylene blue as the cationic dye from aqueous solutions. Chitosan hydrogel beads were cross-linked with cellulose and synthesized in the presence of magnetic bentonite nanoparticles (Fe3O4\Bent). Fe3O4\Bent nanoparticles were obtained from the synthesis of Fe3O4 magnetic nanoparticles in the presence of bentonite nanoclay by co-precipitation and in situ method. The structure of nano-adsorbents were investigated by FT-IR, XRD, FE-SEM, TEM, and VSM techniques. The adsorption capacities of hydrogel beads for Methylene blue dye were studied via different important parameters including the effect of pH, contact time, the effect of initial dye concentration and the effect of temperature. The results showed that the kinetic data and adsorption isotherm were best-correlated to the pseudo-second-order model and Langmuir model, respectively. The thermodynamic data (ΔG, ΔS, and ΔH) indicated that the adsorption process was spontaneous, favorable and endothermic.