Title: Adsorption of hazardous dye Rhodamine B onto Brazilian natural bentonite

Authors: Bárbara Machado Zimmermann; Guilherme Luiz Dotto; Raquel Cristine Kuhn; Marcio Antonio Mazutti; Helen Treichel; Edson Luiz Foletto

Addresses: Department of Sanitary and Environmental Engineering, Federal University of Santa Maria, 97105–900, Santa Maria, Brazil ' Chemical Engineering Department, Federal University of Santa Maria, 97105–900, Santa Maria, Brazil ' Chemical Engineering Department, Federal University of Santa Maria, 97105–900, Santa Maria, Brazil ' Chemical Engineering Department, Federal University of Santa Maria, 97105–900, Santa Maria, Brazil ' Environmental Science and Technology, Federal University of Fronteira Sul, 99700–000, Erechim, Brazil ' Chemical Engineering Department, Federal University of Santa Maria, 97105–900, Santa Maria, Brazil

Abstract: The potential of a Brazilian natural bentonite to remove Rhodamine B (RhB) dye from aqueous solutions was evaluated. The bentonite was characterised by X-ray diffraction, thermogravimetric analysis, particle size distribution and N2-adsorption isotherms. The adsorption of RhB onto bentonite was evaluated in batch system. The pH effect (2.5-10.5), kinetic curves and equilibrium isotherms (initial dye concentrations from 100 to 600 mg L⁻¹) were studied at 25°C and 250 rpm. It was found that the Brazilian bentonite presented a mesoporous structure with surface area of 14.35 m² g⁻¹ and average pore size of 28 nm. The adsorption capacity remained practically constant from pH 2.5 to pH 10.5. The Elovich model was adequate to represent the adsorption kinetic curves. Langmuir and Freundlich models were suitable to represent the adsorption isotherm. The maximum adsorption capacity was 77.3 mg g⁻¹, obtained at 25°C, pH of 4.5 and adsorbent dosage of 500 mg L⁻¹. It was demonstrated that the Brazilian bentonite can be utilised as a promising adsorbent to remove RhB from aqueous solutions.

Keywords: adsorption capacity; Brazil; natural bentonite; effluent; Elovich models; Freundlich models; isotherms; kinetics; Langmuir models; Rhodamine B; RhB removal; hazardous dyes; adsorbents; wastewater treatment.

DOI: 10.1504/IJETM.2016.074798

International Journal of Environmental Technology and Management, 2016 Vol.19 No.1, pp.1 - 15

Received: 25 Jun 2015
Accepted: 27 Sep 2015
Published online: 19 Feb 2016 *

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