Oxidation of diclofenac by potassium ferrate (VI): reaction kinetics and toxicity evaluation

Sci Total Environ. 2015 Feb 15:506-507:252-8. doi: 10.1016/j.scitotenv.2014.10.114. Epub 2014 Nov 20.

Abstract

The reaction kinetics and toxicity of diclofenac (DCF) oxidation by ferrate (VI) under simulated water disinfection conditions were investigated. Experimental results indicated that the reaction between DCF and Fe(VI) followed first-order kinetics with respect to each reactant. Furthermore, the effects of pH and temperature on DCF oxidation by Fe(VI) were elucidated using a systematic examination. The apparent second-order rate constants (kapp) increased significantly from 2.54 to 11.6M(-1)s(-1), as the pH of the solution decreased from 11.0 to 7.0, and the acid-base equilibriums of Fe(VI) and DCF were proposed to explain the pH dependence of kapp. The acute toxicity of DCF solution during Fe(VI) oxidation was evaluated using a Microtox bioassay. Overall, the DCF degradation process resulted in a rapid increase of the inhibition rate of luminescent bacteria. These toxicity tests suggest that the formation of enhanced toxic intermediates during the Fe(VI) disinfection process may pose potential health risk to consumers.

Keywords: Diclofenac; Ferrate (VI); Reaction kinetics; Toxicity; Water treatment.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Diclofenac / chemistry*
  • Diclofenac / toxicity
  • Hydrogen-Ion Concentration
  • Iron Compounds / chemistry*
  • Kinetics
  • Oxidation-Reduction
  • Potassium Compounds / chemistry*
  • Water Pollutants, Chemical / chemistry*
  • Water Pollutants, Chemical / toxicity

Substances

  • Iron Compounds
  • Potassium Compounds
  • Water Pollutants, Chemical
  • Diclofenac
  • potassium ferrate