Removal of Hexavalent and Total Chromium from Aqueous Solution by Avocado Shell

摘要

The main aim of this work was to evaluate the potential of Hass avocado (Persearnamericana Mill var. ‘Hass') shell to remove hexavalent chromium [Cr(VI)] and totalrnchromium from aqueous solutions. Results showed that avocado shell removed Cr(VI)rnby two different mechanisms: chromium biosorption and bioreduction of Cr(VI) tornCr(III). The capacity for removing Cr(VI) and total chromium gradually increased asrnthe contact time proceeded, reaching values of 101.81 and 61.67 mg g-1 respectively,rnafter 120 h. The opposite behavior was observed concerning the volumetric rates ofrnCr(VI) and total chromium removal. The pseudo-second order model adequatelyrndescribed the kinetic process of chromium biosorption by avocado shell, which suggestsrnthat this process chiefly occurs as a result of chemisorption.