Reduction of hexavalent chromium with the brown seaweed Ecklonia biomass.
A new type of biomass, protonated brown seaweed Ecklonia sp., was used for the removal of Cr(VI). When synthetic wastewater containing Cr(VI) was placed in contact with the biomass, the Cr(VI) was completely reduced to Cr(III). The converted Cr(III) appeared in the solution phase or was partly bound to the biomass. The Cr(VI) removal efficiency was always 100% in the pH range of this study (pH 1 to approximately 5). Furthermore, the Cr(VI) reduction was independent of the Cr(III) concentration, the reaction product, suggesting that the reaction was an irreversible process under our conditions. Proton ions were consumed in the ratio of 1.15 +/- 0.02 mol of protons/mol of Cr(VI), and the rate of Cr(VI) reduction increased with decreasing the pH. An optimum pH existed for the removal efficiency of total chromium (Cr(VI) plus Cr(III)), but this increased with contact time, eventually reaching approximately pH 4 when the reaction was complete. The electrons required for the Cr(VI) reduction also caused the oxidation of the organic compounds in the biomass. One gram of the biomass could reduce 4.49 +/- 0.12 mmol of Cr(VI). From a practical viewpoint, the abundant and inexpensive Ecklonia biomass could be used for the conversion of toxic Cr(VI) into less toxic or nontoxic Cr(III).
Park
Donghee
D
Department of Chemical Engineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang 790-784, Korea.
Yun
Yeoung-Sang
YS
Park
Jong Moon
JM
D001673:Biodegradation, Environmental; D018533:Biomass; D002857:Chromium / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007723:Korea; D010084:Oxidation-Reduction; D000459:Phaeophyceae / Q000378:metabolism*; D013057:Spectrum Analysis / Q000379:methods; D013696:Temperature; D014874:Water Pollutants, Chemical / Q000378:metabolism*; D014965:X-Rays
D014874:Water Pollutants, Chemical; D002857:Chromium; C074702:chromium hexavalent ion