Caracterização morfológica, cristalina e textural de bio-adsorventes produzidos via processamento hidrotérmico de resíduos de palha de milho com H2O sub-crítica: Aplicação na adsorção de ácido acético.

Abstract

This work aims to investigate the influence of temperature on the textural, morphological and crystalline characterization of bioabsorbents produced by hydrothermal processing of corn husk residues with hot compressed H2O. The experiments were carried out at 175, 200, 225 and 250 ºC, 240 minutes, heating rate of 2.0 ºC/min and biomass/H2O ratio of 1:10, using a pilot scale reactor of 18,927 L. The process is analyzed in terms of yields of reaction products as a function of temperature. The results showed yields of solids ranging from 62.92 to 35.82% (weight), gas yields ranging from 1.49 to 9.59% (weight) and liquid products ranging from 35.43 to 54.59% ( Weight). The yield of the solid phase decreases with temperature, presenting an inflection region between 200 and 225 °C, in which a drastic change occurs, while that of the liquid phase increases, presenting the same inflection region between 200 and 225 °C. The gas phase yield increases exponentially with temperature up to approximately 10% (weight) in the investigated temperature range. Elemental analysis of solid products shows that the carbon content increases, while the oxygen and hydrogen content decreases with temperature. The textural, morphological and crystalline characterization of solid phase products analyzed by TG/TDG, SEM/EDX, XRD and BET. The solid phase product (bio-adsorbent) obtained by hydrothermal processing of corn husk residues at 225 and 250 °C, 240 minutes, and biomass/H2O ratio of 1:10, were chemically activated with 2.0 NaOH solutions. M and 2.0 M HCl to investigate the adsorption of acetic acid solutions (1.0; 2.0; 3.0; and 4.0 mg/mL). The adsorption kinetics investigated at 30, 60, 120, 240, 480 and 960 seconds. The adsorption isotherm showed that chemically activated carbons were able to remove acetic acid from aqueous solutions.