Effect of Fe(III) on the bromate reduction by humic substancesin aqueous solution
XIE Li , SHANG Chii , ZHOU Qi
DOI:
Received May 09, 2007,Revised September 30, 2007, Accepted , Available online
Volume 20,2008,Pages 257-261
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Humic substances are ubiquitous redox-active organic compounds of environment. In this study, experiments were conducted to
determine the reduction capacity of humic acid in the matrix of bromate and Fe(III) solutions and the role of Fe(III) in this redox
process. The results showed that the humic acid regenerated Fe(II) and reduced bromate abiotically. The addition of Fe(III) could
accelerate the bromate reduction rate by forming humic acid-Fe(III) complexes. Iron species acts as electron mediator and catalyst
for the bromate reduction by humic acid, in which humic acid transfers electrons to the complexed Fe(III) to form Fe(II), and the
regenerated Fe(II) donate the electrons to bromate. The kinetics study on bromate reduction further indicated that bromate reduction by
humic acid-Fe(III) complexes is pH dependent. The rate decreased by 2-fold with the increase in solution pH by one unit. The reduction
capacity of Aldrich humic acid was observed to be lower than that of humic acid or natural organic matter of Suwanne River, indicating
that such redox process is expected to occur in the environment.
