Amino-functionalized magnetic cellulose nanocomposite as adsorbent for removal of Cr(VI): Synthesis and adsorption studies

Abstract

A novel amino-functionalized magnetic cellulose composite was prepared by a process involving: (1) synthesis of magnetic silica nanoparticles using the co-precipitation method followed by the hydrolysis of sodium silicate, (2) coating with cellulose through the regeneration of cellulose dissolved in 7wt% NaOH/12wt% urea aqueous solvent, (3) grafting of glycidyl methacrylate using cerium initiated polymerization and (4) ring-opening reaction of epoxy groups with ethylenediamine to yield amino groups. Once generated, the resulting composite was tested for its ability to remove Cr(VI) from an aqueous solution in batch experiments. The results demonstrated that Cr(VI) adsorption was highly pH dependent. The optimized pH value was 2.0. The adsorption isotherms of the adsorbent fit the Langmuir model, with the maximum adsorption capacity of 171.5mg/g at 25°C. The adsorption rate was considerably fast, and the adsorption reached equilibrium within 10min. The obtained thermodynamic parameters showed that the adsorption of Cr(VI) onto the adsorbent was an exothermic and spontaneous process. In addition, the Cr(VI) ions could be effectively desorbed using a 0.1mol/L NaOH solution and the adsorbent exhibited a good reusability. The composite material should be a promising adsorbent for Cr(VI) removal, with the advantages of high adsorption capacity, rapid adsorption rate and convenient recovery under magnetic field.