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FY97 Summary Report
SR1-6-MW-32, Task A
used for the first scrub and a charcoal filter in-line at the off-gas exit point to the hood are
submitted for dioxin analysis.
The water wash was found to contain a total of 0.2 ppm mixed ketones. Ketones are
generally thought of as neutral, mobile volatile liquids that are the second step in the
oxidation of a hydrocarbon. No chlorinated or aromatic compounds were found. No
residue was found in the activated carbon filter downstream of the water and peroxide
washes.
The residual concentrated phosphoric acid batch liquid was analyzed following the
completed series of eight wet oxidations of paper, neoprene, and other waste types. The
residual batch solution contained both chlorinated pyridine and nitrochlorobenzene, but
no other related compounds The amount of chlorinated pyridine was determined to be
about 5 ppm and nitrochlorobenzene at 0.037 ppm.. There were no phenols or dioxins
identified in solution.
A wrap-up bench scale test subsequent to the series of pilot and bench tests was
conducted with a mixture of TCP and PCP as dioxin precursors. The test evaluated a
mixture of 3.5 g paper, 1 g polyethylene, .1 g neoprene, 1 mL HCl and 10 mg each of TCP
and PCP. Temperature and pressure were at 185*C and 8-10 psig. A number of analytes
was detected in the water sample but not in the charcoal filter. There were no phenols or
other dioxins present above to the limit of detection. Alkyl nitrates were present in the
water sample at 7.7 mg/ml of sample water concentration, as well as 440 ug/ml. of short
straight chain chlorinated hydrocarbons, such as dichloropentane and dichloropentanol;
these are likely products from neoprene destruction. The limit of detection for all
analytes, including dioxins, phenols, aromatics, alkyl nitrates, and other alkyl substituted
organics in the water sample was 2.0 ug/ml. No analytes were detected in the charcoal
tube, at a limit of detection of 10 ug/tube.
Subsequent tests were conducted in the 40-liter pilot system. Two tests were conducted
with batch samples of 22 g cellulose, 5.2 g PE, 3.5 g neoprene, and 3.5 g PVC in 16.5 L
of phosphoric acid. The waste batch was added at 155*C for one test and 170*C for the
second. A third test was conducted with 30 g cellulose, 15 g neoprene, 4.5 g
polyethylene, and 5 mg each of TCP and PCP. The phenol mixture was added at 155*C
and later ramped to 170*C. First water wash and charcoal filter in the off-gas were
analyzed after the second test and after the third test.
The water wash for both tests had an organic mix of 2-4 ppm alkyl nitrates and 0.02-0.10
ppm parachloronitrobenzene. It is postulated that chlorobenzene was released from the
batch at about 1304C and reacted with nitrous oxides in the gas phase before condensing
in the water wash. Also, because the benzene compound was present both from the test
with and without phenols but not from small-scale tests not using PVC, it is believed that
it is an impurity used. in PVC manufacturing. Throughout pilot testing, there were no
dioxins or phenols detected.
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