Metal ion-catalyzed mineralization and biodetoxification studies of Calconcarboxylic acid in aqueous solution: effect of –COOH group

Abstract

Mineralization and biodetoxification studies of Calconcarboxylic acid (CCA), an azo dye, were undertaken by metal ion-catalyzed oxidation processes, viz. Fenton and Fenton-like processes and the effect of presence of –COOH group thereon were established. The metal ions used were Fe²⁺ and Ag⁺ and the oxidants used were hydrogen peroxide (HP) and ammonium persulfate (APS). For a given oxidant, Fe²⁺ is found to be the most suitable catalyst and among the oxidants, APS proves to be most suitable one. As all the systems yield maximum mineralization at pH 1, Fe²⁺/APS at pH 1 is the most suitable system. It is observed that mineralization is favored by Fe²⁺/HP process due to the presence of –COOH group in CCA and by Fe²⁺/APS process in its absence. Removal of –COOH group causes a shift in optimum pH, for Fenton process, to 3 accompanied by a corresponding drop in mineralization from 70.6 to 35.6% and an increase from 73.2 to 91.1% in Fe²⁺/APS system. Bioassay experiment reveals that the treated solutions are ≥50% biotoxic than the untreated dye, which could be reduced to 22.7 and 26.7% in Fe²⁺/APS and Ag⁺/APS systems, respectively, when the –COOH group is removed.

Keywords:

• Calconcarboxylic acid
• Fenton and Fenton-like processes
• Effect of –COOH group
• Mineralization
• Biodetoxification

Acknowledgments

The authors gratefully acknowledge the use of facilities acquired through the DAE-BRNS grant (2008/37/49/BRNS/3082, dated 20.03.2009) to MKS.