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Kinetic studies on Sb(III) oxidation by hydrogen peroxide in aqueous solution
François Quentel1, Montserrat Filella, Catherine Elleouet
1Laboratoire de Chimie Analytique, UMR-CNRS 6521, Université de Bretagne Occidentale, 6, Avenue V. Le Gorgeu, BP 809, F- 29285 Brest, France.
Environmental Science & Technology
|June 24, 2004
Summary
Antimony(III) oxidation by hydrogen peroxide (H2O2) is pH-dependent, requiring the formation of the antimonate(III) ion, Sb(OH)4-. This reaction is significant in environmental waters and water treatment systems.
Area of Science:
- Environmental Chemistry
- Inorganic Chemistry
- Water Treatment
Background:
- Understanding antimony (Sb) redox kinetics is vital for assessing its environmental impact and developing effective removal strategies.
- Antimony contamination in water poses risks to ecosystems and human health.
Purpose of the Study:
- To investigate the kinetics of antimony(III) [Sb(III)] oxidation by hydrogen peroxide (H2O2).
- To determine the influence of various factors including Sb(III) and H2O2 concentrations, pH, temperature, and ionic strength on the oxidation rate.
- To elucidate the reaction mechanism and derive rate laws applicable to environmental conditions.
Main Methods:
- Kinetic experiments were conducted in 0.5 mol L(-1) NaCl solutions.
- The rate of Sb(III) oxidation by H2O2 was measured under varying conditions.
- Rate laws were determined through systematic analysis of reaction data.
Main Results:
- The oxidation rate follows the expression -d[Sb(III)]/dt = k[Sb(III)][H2O2][H+](-1) in NaCl solutions, with log k = -6.88.
- The reaction requires the formation of the Sb(OH)4- species, as Sb(OH)3 does not react with H2O2.
- In acidic HCl, the rate law is -d[Sb(III)]/dt = k[H2O2][H+][Cl-], with log k = 4.44.
Conclusions:
- Sb(III) oxidation by H2O2 is significant in environments with high H2O2 and alkaline pH, or in water treatment processes.
- The derived rate laws provide valuable insights for predicting Sb fate and optimizing Sb removal from contaminated water.