Application of mid IR-Spectroscopy: Measuring of Hydrogen Peroxide Concentration in Bleaching Baths

Application of mid IR-Spectroscopy: Measuring of Hydrogen Peroxide Concentration in Bleaching Baths Hydrogen peroxide is commonly used in bleaching processes (e.g. in textile and paper treatment), chemical oxidation processes in general and for sterilization purposes. The determination of the concentration of hydrogen peroxide in these solutions is of great technological, ecological and economical importance. The methods and instruments for the determination of this substance, which are commercially available, are time consuming, costly, cannot be used for on-line monitoring or are not applicable for hydrogen peroxide concentrations used in the mentioned applications. The work presented here applies the technique of attenuated total reflection (ATR) of infrared light for measuring of hydrogen peroxide. The infrared spectrum of hydrogen peroxide displays the OH-stretching and deformation vibrations. Additionally the O-O streching vibration can be found. These specific vibrations were used for quantitative determination of hydrogen peroxide in aqueous solutions. The spectrum of water does not interfere with these measurements. A linear correlation between the peak areas or the peak heights and the hydrogen peroxide concentration in the range of 1 - 10 % (weight in water) was obtained. The performances of different ATR-crystals, inserted in a flow through cell, were tested in the presence of hydrogen peroxide. Finally the optimized method was used to measure different hydrogen peroxide concentrations in industrial samples (i.e. different bleaching solutions) spiked with known amounts of hydrogen peroxide. The results fitted quite well with the calibration graphs established with neat hydrogen peroxide solutions.