Kinetics of hexavalent chromium reduction by scrap iron.
The kinetics of Cr(VI) reduction by scrap iron was investigated in batch system, for aqueous solutions having low buffering capacities, as a function of pH (2.10-7.10), temperature (10-40 degrees C) and Cr(VI) concentration (19.2-576.9 microM). The results obtained using only the experimental data at initial times indicate zero-order kinetics at pH 2.10 and first-order kinetics over the pH range of 2.98-7.10. The reaction order with respect to H(+) concentration, over the pH range of 4.17-7.10 and Cr(VI) concentration range of 19.2-38.4 microM, was found to be 0.31. The effects of pH, Cr(VI) initial concentration and temperature were investigated; the observed Cr(VI) reduction rates increased with decreasing pH, increasing temperature and decreasing initial Cr(VI) concentration. The observed and overall rate coefficients were determined, and a kinetic expression was developed to describe reduction of chromium by scrap iron over the pH range of 4.17-7.10 and Cr(VI) concentration range of 19.2-38.4 microM.
Gheju
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M
Politehnica University of Timisoara, Faculty of Industrial Chemistry and Environmental Engineering, Bd. V. Parvan Nr 6, Et.1, 1900 Timisoara, Romania. mariusgheju@yahoo.com
Iovi
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A
D002857:Chromium / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D010084:Oxidation-Reduction; D011522:Protons; D013232:Steel; D013696:Temperature
D007220:Industrial Waste; D011522:Protons; D002857:Chromium; D013232:Steel; C074702:chromium hexavalent ion; D007501:Iron