Resumo

VALENZUELA-PADILLA, Arturo Armando  e  TORRES-PEREZ, Jonatan. Azoic dyes (A5 and R40) removal by activated carbon from pecan nut shells. Ing. invest. y tecnol. [online]. 2020, vol.21, n.3, 00007.  Epub 02-Dez-2020. ISSN 2594-0732.  https://doi.org/10.22201/fi.25940732e.2020.21.3.027.

Commercial activated carbons have a high cost, are chemically activated and are effectively used to treat polluted water with azo dyes. The aim of this study was to activate a carbonaceous material from pecan nutshell by physical process and evaluate the sorption capacity of the material for Tartrazine (A5) and Allura Red (R40) in aqueous media. Through pyrolysis process, an activated carbon was obtained from pecan nutshell (CACN), which was activated with water steam. The pH of equilibrium (pHeq) and zero charge (pHPZC) were determined physicochemically. The equilibrium time and the maximum removal capacity of the CACN for the dyes A5 and R40 in distilled medium (MD), and the two-component system (A5-R40) in ionic (MI) and distilled medium (MD) were determined. The values obtained from pHeq and pHPZC were 9.8 and 8.2, respectively. The maximum removal of dyes in the CACN-MD / A5 and R40 systems was 95 % from a C0=10 mg L-1. The CACN-MD system for the dyes (A5 + R40) showed a 50 % removal. The CACN-MI had an 83 % removal and the sorption process data showed an acceptable fit to Freundlich kinetic model, indicating that the type of sorption was carried out on sorption sites with different energy. It was demonstrated that the CACN in ionic medium (MI) is an effective adsorbent material, since it removes high concentrations of dyes in short time, indicating that is a viable and alternative material for the treatment of polluted water with azo dyes.

Palavras-chave : Yellow No.5; agricultural wastes; sorption; red No. 40; water treatment.