PMID: 11918015Mar 29, 2002Paper

Reduction of hexavalent chromium by H2O2 in acidic solutions

Environmental Science & Technology
Maurizio PettineFrank J Millero

Abstract

The rates of the reduction of Cr(VI) with H2O2 were measured in NaCl solutions as a function of pH (1.5-4.8), temperature (5-40 degrees C), and ionic strength (I = 0.01-2 M) in the presence of an excess of reductant. The rate of Cr(VI) reduction is described by the general expression -d[Cr(VI)]/dt = k2[Cr(VI)](m)[H2O2](n)[H+](z), where m = 1 and n and z are two interdependent variables. The value of n is a function of pH between 2 and 4 (n = (3 x 10(a))/(1 + 10(a)), where a = -0.25 - 0.58pH + 0.26pH2) leveling off at pH < 2 (where n approximately = 1) and pH > 4 (where n approximately = 3). The rates of Cr(VI) reduction are acid-catalyzed, and the kinetic order z varies from about 1.8-0.5 with increasing H2O2 concentration, according to the equation z = 1.85 - 350.1H2O2 (M) which is valid for [H2O2] < 0.004 M. The values of k2 (M(-(n+z)) min(-1)) are given by k2 = k/[H+](z) = k1/[H2O2](n)[H+](z), where k is the overall rate constant (M(-n) min(-1)) and k, is the pseudo-first-order rate constant (min(-1)). The values of k in the pH range 2-4 have been fitted to the equation log k = 2.14pH - 2.81 with sigma = +/- 0.18. The values of k2 are dependent on pH as well. Most of the results with H2O2 < 3 mM are described by log k2 = 2.8...Continue Reading

References

Oct 1, 1989·The Science of the Total Environment·R A Anderson
Jan 1, 1995·Environmental Science & Technology·C Seigneur, E Constantinou

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Citations

May 24, 2005·Journal of Hazardous Materials·Tiangui Wang, Hongbin Xu
Oct 13, 2011·Environmental Science & Technology·Alok D Bokare, Wonyong Choi
Nov 22, 2012·Environmental Science & Technology·Joan D WilleyRalph N Mead
May 23, 2013·Environmental Science & Technology·Zhaohui WangJianshe Liu
Jan 4, 2013·Electrochimica Acta·Hussam SarahneyAkram N Alshawabkeh
Jul 17, 2009·Journal of Environmental Management·Masoud KayhanianJohn Harvey
Sep 1, 2015·Environmental Science & Technology·Kitae KimJungwon Kim
Apr 17, 2021·Journal of Colloid and Interface Science·Manoj P RayarothYoon-Seok Chang
Oct 16, 2008·Environmental Science & Technology·Nataliya ShevchenkoAlain Walcarius
Jan 11, 2003·Environmental Science & Technology·Robert J KieberSuzanne D Zvalaren
Apr 23, 2010·Environmental Science & Technology·Alok D Bokare, Wonyong Choi
Oct 6, 2004·Environmental Science & Technology·Sinead T Farrell, Carmel B Breslin
Nov 28, 2021·Environmental Science and Pollution Research International·Eric Tobechukwu Anthony, Nurudeen Abiola Oladoja

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