Measurements of Transmittance
of "Purex" Bleach Solutions
Carlos Hojvat
Fermilab
February 27, 1996
Abstract
Transmittance measurements of solutions of a commercial bleach were performed to evaluate its effect if used as an additive to the water.
Introduction
The use of low concentrations of bleach has been proposed as a way to inhibit the growth of bio-active contamination in the water tanks. For a limited test, commercial bleach ("Purex") was introduced in a small test tank at a concentration of 10 ppm. A decreased of the collected light of about 20% was registered.
Transmittance measurements were performed with a HP8451A Diode Array Spectrometer from the Particle Detector Group at Fermilab. Illumination was provided by a built in Deuterium lamp having a wide frequency spectrum. The light traverses a 1cm liquid sample in a quartz container. The transmitted light is registered by a diode array. Relative transmittance are obtained by the spectrometer by dividing the sample transmitted spectrum with a reference spectrum.
Results
The relative transmittance measurements are shown in the following figures.
Figure 1 is the transmittance of a sample of de-ionized water relative to the transmitted spectrum through air.
Figures 2 through 5 are from different concentration s of Purex bleach, obtained with reference to the transmitted water spectrum.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Conclusions
A significant absorption of UV light is observed even for low concentrations of the Purex bleach. To obtain from these measurements an estimate of the effect on the pulse height observed in the water tank PMT's would require further simulation studies.
Acknowledgments
The assistance of Anna Pla-Dalmau of the Research Division Particle Detector group is gratefully acknowledge.