Interim Report - Hanford Site

(Absorbance × 10 5 )
50
40
30
20
Abs = [(2.94 ±0.20) × 10 6 ] × 31 P Concentration
10
Tripoly Doublet
Plot 1 Regr
0
0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16
31 P Concentration
Figure 10. A 31 P NMR Spectrum Integrated
Peak Area as a Function of a Known Aqueous
Concentration of Tripolyphosphate. These
results are based on the tripolyphosphate doublet
and were used to develop a linear equation that
could be used to quantify the amount of
tripolyphosphate at a given time.
The resulting regression coefficient is (2.94 ± 0.20) ×
10 6 with a R 2 = 0.99. A similar technique was used
for developing equations to quantify the degradation
products, pyro- and orthophosphate.
Results from homogeneous 31 P NMR
experiments suggest the presence of aqueous cations;
Al 3+ , Ca 2+ , Fe 3+ , and Mg 2+ do not have any significant
effect on the rate of tripolyphosphate hydrolysis at
the cation concentrations used for these experiments
(Figure 11). These results are consistent with the
findings of an independent homogeneous experiment
conducted with Hanford Site groundwater, where the
groundwater had no catalytic effect on tripolyphosphate
degradation (Figure 11). Also shown in
Figure 11 are the results collected for the heterogeneous
experiments conducted with naturally
occurring mineral FeOOH, as well as with native
Hanford sediments. The only statistically significant
deviations in the phosphate percentages were for the
heterogeneous experiments. These results suggest
the presence of FeOOH and native Hanford Site sediment had a measurable catalytic effect on the
hydrolysis of sodium tripolyphosphate, evident by a 12% and 24% decrease in the tripolyphosphate
concentration, respectively.
75
% of P as Tripolyphosphate
70
65
60
55
Al 3+
Ca 2+
Fe 3+
Mg 2+
FeOOH
Hanf. Sed.
Hanf. GW
50
0 200 400 600 800
Time, hours
Figure 11. Percentage of Phosphorus as Tripolyphosphate as a Function of Time for Homogeneous
Experiments Conducted with Aqueous Cations, Al 3+ , Ca 2+ , Fe 3+ , Mg 2+ , and Hanford Site
Groundwater; and Heterogeneous Experiments Conducted with Solids, FeOOH, and
Hanford Site Sediment
3.2