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Optimal methods for quenching H2O2 residuals prior to UFC testing
Wenjun Liu1, Susan A Andrews, Mihaela I Stefan
1Department of Civil Engineering, NSERC Water Treatment, University of Waterloo, Waterloo, Ont., Canada N2L 3G1.
Water Research
|July 18, 2003
Summary
Catalase effectively quenches hydrogen peroxide (H2O2) residuals for Unconvetional Fuel Combustion (UFC) testing. This method is simple and avoids interference with disinfection byproduct formation and chlorine residual measurements.
Area of Science:
- Environmental Chemistry
- Analytical Chemistry
- Water Treatment
Background:
- Hydrogen peroxide (H2O2) is a common oxidant used in various industrial and environmental applications.
- Accurate measurement of residual H2O2 is crucial for subsequent analytical tests, such as Unconvetional Fuel Combustion (UFC) testing.
- Interference from H2O2 can affect the reliability of disinfection byproduct (DBP) analysis and chlorine residual measurements.
Purpose of the Study:
- To investigate and compare the effectiveness of different chemical agents for quenching hydrogen peroxide residuals before UFC testing.
- To evaluate the suitability of catalase, sodium hypochlorite, sodium thiosulfate, and sodium sulfite for H2O2 quenching.
- To assess the impact of the chosen quenching method on DBP formation and chlorine residual analysis.
Main Methods:
- Quenching of hydrogen peroxide (H2O2) using catalase, sodium hypochlorite, sodium thiosulfate, and sodium sulfite.
- Analysis of disinfection byproduct (DBP) formation, including trihalomethanes (TTHMs), haloacetic acids (HAAs), and aldehydes.
- Measurement of chlorine residuals using DPD reagents.
- Evaluation of the time and complexity of each quenching procedure.
Main Results:
- Sodium hypochlorite, sodium thiosulfate, and sodium sulfite were found to be unsuitable due to time-consuming procedures and complex multiple measurements.
- Catalase is a simple and effective quenching agent for H2O2 residuals.
- Low doses of catalase (< 0.2 mg/L) did not impact DBP formation in the UFC test.
- Complete quenching of 100 mg/L H2O2 with catalase at room temperature (pH 8.3) took less than 10 minutes.
- Hydrogen peroxide interferes with DPD reagents, potentially causing falsely elevated chlorine residual readings.
Conclusions:
- Catalase is the preferred method for quenching hydrogen peroxide residuals prior to UFC testing due to its simplicity and efficiency.
- The use of catalase avoids interference with DBP formation and chlorine residual measurements, ensuring more accurate analytical results.
- Other quenching agents like sodium hypochlorite, sodium thiosulfate, and sodium sulfite are not recommended for this application.