Heterogeneous kinetics of the reduction of chromium (VI) by elemental iron

Journal of Hazardous Materials
António FiúzaCristina Delerue-Matos

Abstract

Zero valent iron (ZVI) has been extensively used as a reactive medium for the reduction of Cr(VI) to Cr(III) in reactive permeable barriers. The kinetic rate depends strongly on the superficial oxidation of the iron particles used and the preliminary washing of ZVI increases the rate. The reaction has been primarily modelled using a pseudo-first-order kinetics which is inappropriate for a heterogeneous reaction. We assumed a shrinking particle type model where the kinetic rate is proportional to the available iron surface area, to the initial volume of solution and to the chromium concentration raised to a power alpha which is the order of the chemical reaction occurring at surface. We assumed alpha=2/3 based on the likeness to the shrinking particle models with spherical symmetry. Kinetics studies were performed in order to evaluate the suitability of this approach. The influence of the following parameters was experimentally studied: initial available surface area, chromium concentration, temperature and pH. The assumed order for the reaction was confirmed. In addition, the rate constant was calculated from data obtained in different operating conditions. Digital pictures of iron balls were periodically taken and the image tr...Continue Reading

References

Apr 20, 2004·Environmental Pollution·J Kotaś, Z Stasicka
Jun 5, 2004·Journal of Hazardous Materials·Mehmet Erdem, Fikret Tumen
Aug 16, 2005·Journal of Hazardous Materials·Mehmet ErdemFikret Tümen
Jan 3, 2006·Journal of Hazardous Materials·M Gheju, A Iovi
Mar 21, 2006·Journal of Environmental Management·Biswajit MukhopadhyayRodney J Schmitz
Feb 20, 2007·Water Science and Technology : a Journal of the International Association on Water Pollution Research·J E YangK R Yoo
Mar 21, 2008·Environmental Science & Technology·Keith C K Lai, Irene M C Lo

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Citations

Jun 24, 2017·Environmental Science and Pollution Research International·Dandan HuangFei Liu
Jun 29, 2010·Langmuir : the ACS Journal of Surfaces and Colloids·António VegaFernanda Guimarães

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