Potential of unprocessed residue from obtaining silicon metal as an adsorbent of methyl red dye

ABSTRACT

Industrial effluents containing organic contaminants and inorganics are discharged into water sources, causing damage to aquatic organisms and, consequently, serious diseases to humans. In this research we investigated the adsorption capacity against methyl red dye nitrogen (adsorbent) by the industrial residue (adsorbent) from the manufacture of silicon metal, the results were adjusted to the adsorption isotherm models. The granulometric, morphological and chemical characterization of the material was performed. Techniques such as SEM-EDS and ICP-OES were used. For the residue, the zero load point (pHPCZ), influence of pH and agitation velocity on the adsorption capacity were measured. The characteristics of the adsorption equilibrium were determined by applying the Freundlich, Tempkin and Dubinin-Radushkevich linear adsorption isotherms, while the kinetic processes were availed using the linear models of pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion. The pseudo-second order model, with R² equal to 1,0000 and Q² of 0,9999, was the best fit to the adsorption kinetic condition and Temkin model, whose R² and Q² values were 0,9008 and 0,7929, respectively, was the one that best represented the equilibrium observed. The adsorption process was characterized as being favorable and the results indicated that the residue has potential to be used as an absorbent for methyl red dye.

Keywords
Adsorption mechanism; Methyl red; Kinetic; Isotherms