Resumo

TEJADA TOVAR, Candelaria; VILLABONA ORTIZ, Ángel  e  JIMENEZ VILLADIEGO, María. REMOVING OF HEXAVALENT CHROMIUM ON CHEMICALLY PRETREATED CACAO WASTE. rev.udcaactual.divulg.cient. [online]. 2017, vol.20, n.1, pp.139-147. ISSN 0123-4226.

The availability of quality water resources is a factor of great scientific interest because of the high burden of anthropic contaminants in water sources, with particular attention to metals due to their bioaccumulation and toxicity. In this research the adsorption of hexavalent chromium using cocoa shell as adsorbent material, as well as two chemical treatments with sodium hydroxide and hydrochloric acid was studied. The effect of removing this metal-ion was evaluated. Measurement of this metal in aqueous solution was realized by UV-Vis spectroscopy using diphenylcarbazide reagent. The effect of particle size in the process was studied and the adjustment of the kinetics was done with models of first order, second order, Elovich and diffusion It was found that the model with the best fit to the experimental data was Elovich, while Freundlich´s isotherm describes the adsorption process in a better way. Thereby it was established that the catalytic surface of this bioadsorbent is heterogeneous, exhibiting different energies of activation. Furthermore it was observed that the modification with hydrochloric acid improved the adsorption capacity of this material.

Palavras-chave : Adsorption; biomaterial; Chromium (VI); chemical treatment.

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