Biosorption of Cr(VI) using coconut fibers from agro-industrial waste magnetized using magnetite nanoparticles

• Published in: Environmental technology 2021-10, Vol.42 (23), p.3595-3606
• Main Authors: Carvalho Costa, Antonio Wilson Macedo, Guerhardt, Flavio, Ribeiro Júnior, Silvestre Eduardo Rocha, Cânovas, Geovana, Vanale, Rosangela Maria, de Freitas Coelho, Diego, Ehrhardt, Daniela Diniz, Rosa, Jorge Marcos, BasileTambourgi, Elias, Curvelo Santana, José Carlos, de Souza, Roberto Rodrigues
• Format: Article
• Language: English
• Subjects: Adsorbates; Adsorptivity; agricultural waste; Agricultural wastes; Biosorption; Chromium; coconut shell; Emission spectroscopy; Experiments; Fibers; Fluorescence; Fourier transforms; hexavalent chromium; Inductively coupled plasma; Industrial wastes; Infrared spectroscopy; Magnetite; magnetite nanoparticles; Magnetization; Nanoparticles; Optimization; pH effects; Potassium dichromate; Scanning electron microscopy; Spectrum analysis; X ray powder diffraction; X-ray fluorescence
• ISSN: 0959-3330; 1479-487X
• DOI: 10.1080/09593330.2020.1752812

Herein, the biosorption of Cr(VI) by magnetized coconut fibres obtained from agricultural waste has been described. Magnetization was achieved by incorporating magnetite nanoparticles into the fibres by a coprecipitation reaction in alkaline media. The biosorption capacity of the fibres was evaluated by two series of experiments. In the first series, 500 mg L −1 of the biosorbent was added to a 50 mg L −1 K 2 Cr 2 O 7 solution at 28 °C and stirred at 200 rpm and the pH was varied from 1 to 13 to determine the optimum pH value. The second series of experiments evaluated the sorption capacity of the fibres at the optimum pH, under the same agitation speed and temperature but with an adsorbate concentration of 100 mg L −1 . The biosorbents were characterized using Fourier transform-infrared spectroscopy, inductively coupled plasma-atomic emission spectroscopy, scanning electron microscopy, dispersive X-ray fluorescence, and X-ray powder diffraction. The biosorption experiments demonstrated that the magnetization process increased the biosorption capacity of the material. Optimum biosorption occurred at pH 2, and at optimal conditions, the best adsorptive efficiency exceeded 90%, reaching a biosorption capacity of 87.38 mg g −1 for the magnetized fibre and 23.87 mg g −1 for the natural fibre, with an equilibrium time of less than 20 min.