Removal of Hexavalent and Total Chromium from Aqueous Solution
Removal of Hexavalent and Total Chromium from Aqueous Solution by Avocado Shell
Eliseo Cristiani-Urbina1,*, Alma Rosa Netzahuatl-Muñoz1,2, María del Carmen Cristiani-Urbina3
1
Escuela Nacional de Ciencias Biológicas, IPN. Prolongación de Carpio y Plan de Ayala s/n. Colonia Santo Tomás. México, D.F., 11340, México. ecristia@encb.ipn.mx 2 Universidad Politécnica de Tlaxcala. Av. Universidad Politécnica No. 1. Colonia San Pedro Xalcaltzinco. Tepeyanco, Tlaxcala, 90180, México. 3 Universidad Autónoma de Chiapas, Campus I. Boulevard Belisario Domínguez km 1081 s/n. Tuxtla Gutiérrez, Chiapas, 29000, México The main aim of this work was to evaluate the potential of Hass avocado (Persea americana Mill var. ‘Hass’) shell to remove hexavalent chromium [Cr(VI)] and total chromium from aqueous solutions. Results showed that avocado shell removed Cr(VI) by two different mechanisms: chromium biosorption and bioreduction of Cr(VI) to Cr(III). The capacity for removing Cr(VI) and total chromium gradually increased as the contact time proceeded, reaching values of 101.81 and 61.67 mg g-1 respectively, after 120 h. The opposite behavior was observed concerning the volumetric rates of Cr(VI) and total chromium removal. The pseudo-second order model adequately described the kinetic process of chromium biosorption by avocado shell, which suggests that this process chiefly occurs as a result of chemisorption.
1. Introduction
Chromium compounds are environmental pollutants occurring in soil, water and industrial effluents because they are widely used in many industrial activities. Although chromium has several oxidation states, chromium compounds mainly occur in the environment as trivalent [Cr(III)] and hexavalent [Cr(VI)] chromium. Cr(VI) is highly toxic, mutagenic, carcinogenic and teratogenic. Cr(III) is much less toxic and mutagenic than Cr(VI), but long-term exposure to high Cr(III) concentrations may cause allergic skin reactions, cancer and DNA damage. The World Health
Eliseo Cristiani-Urbina1,*, Alma Rosa Netzahuatl-Muñoz1,2, María del Carmen Cristiani-Urbina3
1
Escuela Nacional de Ciencias Biológicas, IPN. Prolongación de Carpio y Plan de Ayala s/n. Colonia Santo Tomás. México, D.F., 11340, México. ecristia@encb.ipn.mx 2 Universidad Politécnica de Tlaxcala. Av. Universidad Politécnica No. 1. Colonia San Pedro Xalcaltzinco. Tepeyanco, Tlaxcala, 90180, México. 3 Universidad Autónoma de Chiapas, Campus I. Boulevard Belisario Domínguez km 1081 s/n. Tuxtla Gutiérrez, Chiapas, 29000, México The main aim of this work was to evaluate the potential of Hass avocado (Persea americana Mill var. ‘Hass’) shell to remove hexavalent chromium [Cr(VI)] and total chromium from aqueous solutions. Results showed that avocado shell removed Cr(VI) by two different mechanisms: chromium biosorption and bioreduction of Cr(VI) to Cr(III). The capacity for removing Cr(VI) and total chromium gradually increased as the contact time proceeded, reaching values of 101.81 and 61.67 mg g-1 respectively, after 120 h. The opposite behavior was observed concerning the volumetric rates of Cr(VI) and total chromium removal. The pseudo-second order model adequately described the kinetic process of chromium biosorption by avocado shell, which suggests that this process chiefly occurs as a result of chemisorption.
1. Introduction
Chromium compounds are environmental pollutants occurring in soil, water and industrial effluents because they are widely used in many industrial activities. Although chromium has several oxidation states, chromium compounds mainly occur in the environment as trivalent [Cr(III)] and hexavalent [Cr(VI)] chromium. Cr(VI) is highly toxic, mutagenic, carcinogenic and teratogenic. Cr(III) is much less toxic and mutagenic than Cr(VI), but long-term exposure to high Cr(III) concentrations may cause allergic skin reactions, cancer and DNA damage. The World Health
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