Abstract

BEJARANO, María et al. Study of the adsorption of Drimaren Yellow CL-2R and Basic Navy Blue 2 RN dyes on activated clays. Novasinergia [online]. 2020, vol.3, n.2, pp.93-107.  Epub Dec 01, 2020. ISSN 2631-2654.  https://doi.org/10.37135/ns.01.06.08.

Clays have become highly engaging non-conventional adsorbents due to their availability, low cost, and high effectiveness adsorbing dye. The objective of this research was to study the adsorption of a cationic dye Drimaren Yellow CL-2R and an anionic dye Basic Navy Blue 2 RN on three clays from Cochancay, Santa Clara, and Shirahuan natural Ecuadorian deposits. Clays were characterized by x-ray fluorescence spectroscopy and x-ray diffraction. The ultraviolet-visible spectroscopy allowed the quantification of the dyes remaining in the solution. We studied the pH, the absorbate's contact time with the adsorbent, initial dye concentration, and clay amount effects. The effectiveness of three clays removing the cationic dye was 95-99%, and the anionic dye was 70%. The Langmuir's isothermal model fits the cationic (R2=0.998), and anionic (R2=0.977) dyes adsorption mechanism. The Shirahuan clay shows a higher cationic dye adsorption capacity (27.53 mg/g). The Cochancay clay shows a higher anionic dye adsorption capacity (5.81 mg/g). The dye adsorption kinetic follows the "pseudo-second-order" model for both dyes and suggests that the adsorption rate is proportional to the available adsorption sites' square. The results suggest that intraparticle diffusion is a major controlling adsorption step. Activated clays show six times greater adsorption capacity removing cationic dye than anionic dye from synthetic water samples.

Keywords : isotherms; adsorption kinetics; Basic Navy 2 RN; clays; Drimaren Yellow CL-2R.

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