chloride was not added to this test solution.) The
PESTICIDE STUDIES
solution was filtered through a 0.45- Nylon 66
General information
membrane filter to remove any undissolved pes-
Four pesticides (lindane [γ-BHC], dieldrin,
ticides.
heptachlor, and aldrin) were chosen for this
Two pieces of a casing material were placed in
study. These compounds were selected because
individual 40-mL borosilicate glass vials. Thirty
they varied in their hydrophobicity (i.e., Kow val-
mL of the pesticide test solution was added to
ues and aqueous solubilities) (Table 2).
each vial and the vial was capped with Teflon-
A weighed amount of each pesticide was add-
lined plastic screw caps. The casing-surface area/
solution volume ratio was 0.92 cm2/mL. After
ed to a 2-liter volumetric flask containing deion-
ized water, and the solution was mixed on a mag-
soaking in the pesticide solution for a specified
time (Table 3), the test pieces were removed from
netic stirring device for one week. (Mercuric
Table 2. Range in reported log octanolwater partition
coefficients, aqueous solubilities, melting points, and
boiling points of pesticides.*
Aq. solubility
Melting
Boiling
(at 25C) (mg/L)
Pesticide
Log Kow
point
point
104107C
145C†
Aldrin
5.25.7
0.0110.180
112113C
323.4C
Lindane
3.23.9
6.87.8
150176C
Dieldrin
3.75.5
0.1950.200
decomposes
4696C
135145C**,
Heptachlor
4.45.4
0.0560.180
decomposes
* Taken from Montgomery and Welkom (1990).
† Boiling point at 11.5 mm.
** Boiling point at 2 mm.
Table 3. Summary of experimental design for pesticide decontamination experiments.
Exp.
Materials
Sorption/desorption
no.
Decontamination treatment
tested*
times*
1
No treatment.
PTFE
10 min/10 min
PVC
24 hr/10 min
SS
24 hr/24 hr
Rinsed with DI† water (from a squirt bottle) for 15 sec.
2
PTFE
10 min/10 min
PVC
24 hr/10 min
SS
24 hr/24 hr
3
Brief 5-sec rinse with DI water (from squirt bottle), soak in (100 mL) solution of
PTFE
10 min/10 min
1% Liqui-Nox detergent at 100C for 5 min, rinsed 5 sec with DI water (from squirt PVC
24 hr/10 min
bottle), soaked in (100 mL) DI water at 100C for 5 min, then rinsed for 5 sec
SS
24 hr/24 hr
with DI water (from a squirt bottle).
4
Same as Experiment 3.
PVDF
10 min/10 min
LDPE
24 hr/10 min
P(VDF-HFP)
24 hr/24 hr
5
(a) Wash procedure same as Experiment 3 except tubing was kept submerged by
LDPE
24 hr/24 hr
placing a glass beaker on top of tubing.
(b) Same wash procedure, soak in 20 mL methanol for 30 sec, rinse with DI water
for 10 sec (from a squirt bottle).
(c) Same wash procedure, soak in 20 mL hexane for 30 sec, rinse with DI water
for 10 sec (from a squirt bottle).
(d) Same wash procedure, oven dry at ~117C for 24 hr.
* All the materials were tested for all three sorption/desorption times.
† DI = deionized.
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