Producción y evaluación de materiales adsorbentes a partir de tusa de maíz por procesos de pirólisis para la remoción sostenible de contaminación por cromo en soluciones acuosas

Abstract

The growing problem of water pollution from industrial activities, especially tanneries and mining, has prompted a search for friendly and economical solutions to remove pollutants such as chromium. In this study, adsorption is employed as a treatment method, using agricultural residues such as corn stover, for the production of carbonaceous adsorbents. Three materials derived from corn stover were evaluated: untreated corn stover (TM), biochar (BC600) and activated biochar (BCA600). The biochar and activated biochar were produced with a pyrolysis process at 600 °C, in the case of BCA600 phosphoric acid was used as activating agent and the materials were subjected to particle size analysis, BET and zero loading point. The measurement of chromium concentration in aqueous medium was performed by UV-Vis spectrophotometry using diphenylcarbazide as colorimetric agent at pH 2 and 3. The results of the batch adsorption tests determined a removal of 78.16% after 1 hour at optimum pH of 2 for BC600 and an adsorption capacity of 10.12 mg/g, being the best adsorbent of the three. The kinetic tests showed a correlation of 0.951 and 0.998 for the Pseudo First Order and Pseudo Second Order models, while in the equilibrium analysis 0.979 and 0.957 were obtained for the Langmuir and Freundlich model respectively, indicating a composite adsorption process. Finally, an acid regeneration was applied to the BC600 adsorbent using HCl in two adsorption cycles, achieving a regeneration of 79.64% and 57.80%.