Methods for Detection of Residual Concentrations of Hydrogen Peroxide in Advanced Oxidation Processes
Program: Tailored Collaboration
Funding Partners: Bureau of Reclamation, Orange County Water District, West Basin Municipal Water District
Total Investment: $109,990 (Cash)
Principal Investigator: Philip Brandhuber, Ph.D., HDR Engineering Inc.
Advanced oxidation processes (AOPs), coupling either ultraviolet (UV) irradiation or ozonation in the presence of hydrogen peroxide, are advanced treatment techniques that have been installed by several utilities to meet California Department of Public Health regulations. Of prime importance in monitoring the performance of AOPs is the ability to accurately measure residual hydrogen peroxide concentrations.
Goals and Objectives
The project developed a laboratory method for reliable quantification of hydrogen peroxide in the 0.5- to 5-mg/L concentration range that is effective in a natural water matrix as well as in the presence of combined chlorine (chloramine).
A step-by–step process was used to select and test peroxide detection methods. First, the performance requirements for the detection method were defined, and a literature review of existing methods was completed. The methods were prioritized for their likelihood of meeting the performance requirements. Two methods then underwent preliminary bench level evaluation. Based on this evaluation, the titanium oxalate detection method was determined to be most effective. Additional evaluations of the method were performed in which the method detection level (MDL) was determined. Lastly, an interlaboratory evaluation of the titanium oxalate method was performed by two different laboratories, using both two water sources. Method bias and precision for peroxide quantification using the titanium oxalate method was calculated for the analyses performed by these labs.
Findings and Conclusions
The titanium oxalate method is an effective detection method for hydrogen peroxide. The basis of the method is the formation of a titanium(IV) – peroxide complex in the presence of sulfuric acid. Potassium titanium oxalate (K2TiO(C2O4)2·H2O), a commercially available titanium(IV) salt, is used as the source of titanium(IV). The titanium(IV) – peroxide complex is yellowish orange in color and its concentration can be quantified by spectrophotometric analysis with a maximum response at 390 nm. This method was found to have a method detection level (MDL) of 0.05 mg/L, with a precision of 5% and bias of -2% when detecting peroxide in the milligram per liter range in reuse water.