Adsorption of methylene blue as a model for the use of Barro Branco as an alternative adsorbent for color removal

Abstract

The application of the solid–liquid adsorption technique with low-cost adsorbents has been offering promising results in the treatment of textile wastewaters. In this study, we used as an adsorbent Barro Branco (aluminum-silicate – Al 16.2%, Si 21.5% and O 44.77%), one of the main by-products of the extraction of mineral coal. The samples were obtained at the Esperança mine, Santa Catarina, Brazil. The experiments were carried out in an adsorber vessel with controlled temperature, pH and a mechanical stirrer. A 1.0 g sample of Barro Branco (210–297 μm) was added to each 50 cm³ of methylene blue dye solution. The results show that Barro Branco is a promising adsorbent for color removal, where the adsorption kinetics fit better to the pseudo-first-order rate law. The values of the rate constant of the adsorption decreased with the increase of the concentration. The isotherm constants agree well with the Langmuir equation and the Freundlich equation, with correlation coefficients close to 1.00 in both cases.

Acknowledgements: Carlos Alberto Policiano Almeida thanks Universidade Estadual do Centro–Oeste for the leave of absence during the PhD Course. He also thanks CAPES (PICDT) for a graduate fellowship.