Preparation of bead-type biosorbent from water-soluble Spirulina platensis extracts for chromium (VI) removal

A bead-shaped biosorbent for removal of Cr(VI) from industrial waste waters/aqueous media was fabricated using water soluble Spirulina platensis extract (SPE). The addition of LiCl to DMSO affected the solubility of SPE, and 1 M LiCl/DMSO was the optimal solvent system for the preparation of SPE beads. The shape of the SPE bead was determined by the concentration of SPE, and the type of coagulant affected the mechanical properties of the bead. The optimum pH for the Cr(VI) adsorption was 2.0. The maximum adsorption capacity of the SPE beads was 41.12 mg/g at pH 2.0, and the adsorption behavior of Cr(VI) on the SPE beads followed the Brunauer-Emmett-Teller (BET) isotherm. The results indicated that 0.1 M NaOH was the most effective desorption agent. The successive recycling of the adsorption-desorption process was stable for more than five cycles, and the recycling efficiency was 70%. (C) 2014 Elsevier B.V. All rights reserved.