1.0

0.8

0.6

0.4

5

10 ft

1 0 ft

0.2

500 ft

00 ft

0

100

200

300

400

Time (h)

min. (Appendix Table A2 gives the mean normal-

effect a faster flow rate had on sorption. Because

ized concentrations of TCE, and Appendix Table

of physical limitations we had with the delivery

B2 gives the concentrations of TCE [in mg/L] in

system, only three tubings could be used in this

the water before and after pumping it through

study. We selected PP1, LDPE, and PVDF. We

the tubing.) For this length of tubing, sorption

eliminated PP 2 because its performance was

was much more pronounced initially, with 92%

very similar to PP1 and P(VDF-HFP) because its

loss after 10 min. Equilibration appears to occur

performance was very similar to PVDF.

after 48 hr of pumping, with residual losses of

Figure 9 shows the relative concentrations of

1015%. For comparison, Figure 8 also shows

TCE in water that was pumped through 100-ft

losses of TCE from water pumped through the

sections of these tubings at a flow rate of 1 L/

100-ft, 50-ft, and 10-ft lengths. The relationship

min. (Appendix Table A3 gives the mean normal-

ized concentrations and Appendix Table B3 gives

the initial and final concentrations [in mg/L] and

the results of the statistical analyses.) Statistical

analyses indicated that the concentrations of TCE

in samples pumped through the PP1 tubing were

significantly lower than the controls. However,

these losses were always less than 10%. In gener-

r†

al, concentrations of TCE in water pumped

through the PVDF and LDPE tubings did not dif-

10

1

0.709

fer significantly from the controls.

50

5

0.890

Figures 10a and 10b compare sorption of TCE

100

10

0.954

500

50

0.975

in water pumped through 100 ft of LDPE and PP1

tubing, respectively, at the two flow rates (1 L/

* Time for water to pass through tubing.

† Correlation coefficient.

min and 100 mL/min). The relationship between

the pumping time and the relative concentration

between the pumping time (*t*) and the relative

of TCE for each of the two tubings and flow rates

concentration (*C*t) for the various lengths of tub-

is given in Table 5. We see a similar trend to the

ings is given in Table 4. It is clear that for the

one we observed with the longer lengths of tub-

longer tubings or contact times, sorptive losses

ing, namely that at the slower flow rate (or long-

can be adequately described by a log function.

er contact time) sorption can be adequately de-

scribed by a log function. There is good agree-

ment between the expression for the relative con-

In this study, we wanted to determine what

centration of TCE in water pumped through 100

10

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