Determination of hydrogen peroxide by differential pulse polarography in advanced oxidation processes for water treatment

Knowing the concentration of hydrogen peroxide (H2O2) is crucial for the monitoring and optimizing the Fenton reaction in advanced oxidation processes. Several analytical methods exist to determine these concentrations, but their applications can be difficult because of low selectivity (interaction with other metals), the use of toxic compounds, or low concentrations (mu mol LmmolL(-1)). To overcome these problems, we developed a differential pulse polarographic (DPP) method at the dropping mercury electrode (DME) with the following conditions: tg = 1.0 s, Delta E = -100 mV and v = 10 mV s(-1). Calibration curves had very high correlation coefficients (R-2 > 0.999). The limits of detection and quantification were evaluated respectively at 13 and 21 mu mol L-1 with peak area measurements of hydrogen peroxide reduction (Ap). The DPP method was compared with other analytical methods (iodometric titration and spectrophotometry) for determining at low concentrations of H2O2 (in the order of mmol L (1) to mu mol L-1) in Fenton and electro-Fenton processes. The method developed here allows measure low concentrations of hydrogen peroxide in Fenton and electro-Fenton processes in acidic solutions (similar to 3) and the presence of interfering species such as Fe3+ and dissolved oxygen.