A MODEL TO DESCRIBE THE ADSORPTION AND REDUCTION OF Cr (VI) FROM AN AQUEOUS SOLUTION BY AGAVE LECHUGUILLA BIOMASS
The biosorption and reduction of Cr (VI) onto packed columns of Agave lechuguilla were analyzed using an advection-dispersion with a first order reaction (ADR) model and its analytical solution. Design parameters, such as an axial dispersion coefficient, a retardation factor, a distribution coefficient, and a general first-order decay constant, were estimated as functions of inlet metal ion concentration, pH, operation time, flow rate, cross-sectional column area, the density and length of the bed. The RMSE values (0.096, 0170 and 0.180) with the corresponding flow rates of 1, 2, 3 (10-3) dm3 min-1, respectively, indicated that the ADR model applied to the experimental data adequately explains the adsorption and reduction of Cr (VI) by lechuguilla biomass. The experimental results at different pH values along with the calculated parameters suggest that the adsorption of Cr (VI) took place in the internal pores and the reduction reaction occurred in the external surface of the biomass.
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