Variation of ORP during p-nitrophenol degradation by Fenton oxidation process

Degradation of p-nitrophenol(PNP) in aqueous medium by Fenton reagent was conducted to monitor the variation of oxidation-reduction potential(ORP) during Fenton oxidation process.Results showed that under the condition of initial pH value was 3,H2O2 dosage was 3 mmol/L and Fe2+ dosage was 0.3 mmol/L,PNP could decreased to 5 mg/L in 5.0 min,giving the removal rate of 95%.The biodegradability of wastewater was greatly improved for the BOD5/COD value increased from 0.073 to 0.390.ORP could reflect the oxidative redox status of Fenton system perfectly;Fe2+,·OH,H2O2,Fe3+ and hydroquinone were main oxidation-reduction materials,but which one could be reflect by ORP need further verification.ORP was distinctly corresponded with Fe2+/Fe3+,it was also found to be an effective indicator to monitor the beginning,quick reaction and ending of p-nitrophenol degradation by Fenton oxidation process.