Chelant screening and refinement tests - Phase I, Task 2. Topical progress report, December 1993--June 1994 Page: 47 of 236
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7.0 RESULTS AND DISCUSSION - FOAM APPLICATION TESTING
A secondary part of the refinement testing was to run a series of tests with the selected
solvents to determine if they could be used effectively in the foam state. Some of the process
equipment requiring decontamination at DOE sites is very large; foam cleaning is an industrial
process used to clean large components. Additionally, foam decontamination technology is
currently being developed, as it has shown waste reduction of 70% over present decontamination
methods (Reference 31). In this method of solvent application, the foam is the transport medium
which carries the solvent to the metal surfaces, reducing the amount of solution required for
coverage. The normal procedure for generating foam is to add a surfactant to the solvent and
inject air (or an inert gas) below the liquid surface. Bubbles formed by the sparge are directed
to the vessel or component to be cleaned by the slight positive pressure of the sparge gas.
7.2 Laboratory Foaming Tests
A series of laboratory tests were run to determine if the selected solvents could be
applied in the foam state. A schematic of the equipment utilized is shown in Figure 7. A three-
liter reaction flask was equipped with a lid with four penetrations. Two of the penetrations were
sealed with single-hole rubber stoppers, which allowed the introduction of solvent and air. The
solvent was pumped into the reaction flask using a peristaltic pump. Solvent level was
maintained between 500 and 1000 milliliters during the test period. The second one-hole stopper
was fitted with a long glass tube and a fritted disc. The frit was placed near the bottom of the
reaction flask, and the other end of the tube was connected to. a compressed air supply.
A length of large diameter plastic tubing was placed over the third penetration, and the
other end of the tubing was placed in a reservoir for foam collection. The center penetration
in the lid was stoppered, but a wire was secured to it on the inside to allow for suspension of
test coupons in the reaction flask.
Prior to the first test, four carbon steel coupons were cleaned and weighed. Ten grams
of uranium dioxide powder was mixed with deionized water to form a paste. The test coupons
were coated with the paste, and placed in an oven to dry at 110*C. After drying, the coupons
were reweighed and found to have between 1.0 and 1.5 grams of dried uranium dioxide on their
For the first test, one coupon was suspended in the upper part of the reaction flask. One
liter of solvent with a composition of 50g/L EDTA, 20 g/L ammonium carbonate, 1.5 g/L
hydrogen peroxide, and 30 mL/L foaming agent (FOME-ADDI, DuBois USA) was pumped
into the reaction flask. Air was then introduced under the surface of the solvent through the
glass frit. The rate of air flow was regulated to provide a steady flow of foam. Solution
temperature was maintained at ambient throughout the testing. A photograph of this testing is
shown as Figure 8.
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Chelant screening and refinement tests - Phase I, Task 2. Topical progress report, December 1993--June 1994, report, July 1, 1995; United States. (https://digital.library.unt.edu/ark:/67531/metadc680875/m1/47/: accessed April 20, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.