Development of a new Cr(VI)-biosorbent from agricultural biowaste

• Published in: Bioresource technology 2008-12, Vol.99 (18), p.8810-8818
• Main Authors: Park, Donghee, Lim, Seong-Rin, Yun, Yeoung-Sang, Park, Jong Moon
• Format: Article
• Language: English
• Subjects: Adsorption; Agricultural biowaste; Agriculture; alginates; Alginates - metabolism; Applied sciences; aqueous solutions; Arachis hypogaea; bananas; binding capacity; Biocompatible Materials - metabolism; Biodegradation, Environmental; Biological and medical sciences; bioremediation; Biosorption; Biotechnology; Chromium; Chromium - analysis; Chromium - isolation & purification; Cr(VI)-biosorbent; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Gels; Glucuronic Acid - metabolism; hexavalent chromium; Hexuronic Acids - metabolism; Hydrogen-Ion Concentration; Juglans; Kinetics; leaching; mechanism of action; microencapsulation; Models, Chemical; Musa; Musa - metabolism; Oryza sativa; Oxidation-Reduction; peels; plant byproducts; Pollution; powders; Reduction; simulation models; Solutions; sorption; Spectrum Analysis; Waste Products; waste utilization; Wastes; wastewater treatment
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2008.04.042

Among useless but abundant agricultural biowastes such as banana skin, green tea waste, oak leaf, walnut shell, peanut shell and rice husk, in this study, banana skin was screened as the most efficient biomaterial to remove toxic Cr(VI) from aqueous solution. X-ray photoelectron spectroscopy (XPS) study revealed that the mechanism of Cr(VI) biosorption by banana skin was its complete reduction into Cr(III) in both aqueous and solid phases and partial binding of the reduced-Cr(III), in the range of pH 1.5–4 tested. One gram of banana skin could reduce 249.6 (±4.2) mg of Cr(VI) at initial pH 1.5. Namely, Cr(VI)-reducing capacity of banana skin was four times higher than that of a common chemical Cr(VI)-reductant, FeSO 4 · 7H 2O. To diminish undesirable/serious organic leaching from the biomaterial and to enhance removal efficiency of total Cr, its powder was immobilized within Ca-alginate bead. The developed Cr(VI)-biosorbent could completely reduce toxic Cr(VI) to less toxic Cr(III) and could remove almost of the reduced-Cr(III) from aqueous phase. On the basis of removal mechanisms of Cr(VI) and total Cr by the Cr(VI)-biosorbent, a kinetic model was derived and could be successfully used to predict their removal behaviors in aqueous phase. In conclusion, our Cr(VI)-biosorbent must be a potent candidate to substitute for chemical reductants as well as adsorbents for treating Cr(VI)-bearing wastewaters.