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Boron Removal by Adsorption on Cobalt(II) Doped Chitosan Bio-composite

Kluczka, Joanna, Tórz, Artur, Łącka, Dorota, Kazek-Kęsik, Alicja, Adamek, Jakub
Journal of polymers and the environment 2018 v.26 no.5 pp. 2039-2048
Fourier transform infrared spectroscopy, X-ray diffraction, adsorption, ambient temperature, aqueous solutions, batch systems, biocomposites, boric acid, boron, chitosan, cobalt, coprecipitation, desorption, heat production, hydrogels, hydrogen bonding, models, moieties, pH, sorption isotherms
Cobalt(II) doped chitosan bio-composite was prepared, characterized and used to oxoborate separation from aqueous solutions. The adsorption process was carried out in a batch system. The effect of pH, temperature, time and initial boron concentration on the boron adsorption were tested. The maximum boron adsorption was reached at pH range 8.0–8.5 at room temperature and within 60 min. Calculations based on Langmuir and Freundlich models showed the heterogeneous nature of boron adsorption on Co-CTS bio-composite. On the base of research on optimization of pH and results from XRD and FTIR analysis it was found that boron adsorption by Co-CTS occurred through the co-precipitation and adsorption of B on cobalt hydroxide following the Coulomb attraction of B(OH)₄⁻ species on positively charged sites and molecular attraction of H₃BO₃ through hydrogen bond with amine or hydroxyl groups of chitosan. The modelling of the thermodynamic data indicated the nonspontaneous and exothermic nature of the adsorption process. The pseudo-second-order model adequately described the boron adsorption on Co-CTS hydrogel. Desorption by means of alkaline solution at pH 12 was carried out successfully. Adsorption–desorption efficiencies in 3 cycles were almost 100%.