Table 16. Minimum treatment required to remove organic contaminants

CONCLUSIONS - SR97_240019

LITERATURE CITED - SR97_240021

SR97_24
Page Navigation
14

Table 16. Minimum treatment required to remove organic contaminants.

Sorption/desorption times

Contaminants

Material

10 min/10 min 24 hr/10 min

plus unspecified addi-

tional treatment needed4

Hot wash3

P(VDF-HFP)

"Cold wash" was room temperature water containing 1% detergent.

"Hot wash" was ~100C water containing 1% detergent.

1 Oven dry for 4 hours.

2 Rinsing was not sufficient to remove pesticides, but a room temperature wash was not

tested.

3 Only a hot detergent water wash and rinse was tested.

4 A hot detergent water wash, hot water rinse, and oven drying (~117C, 24 hr) removed

most (>99.7%), but not all of the contamination.

step (i.e., solvent rinsing) serves no useful pur-

taminated. For these materials, ease of decontam-

pose and thus could be eliminated from all

ination is a function of the analyte, the rigidity

decontamination protocols.

and sorptive nature of the material, and the con-

The data from this study also indicate that

tact time for sorption and desorption.

washing is not necessary to remove VOCs and

Volatile organics are readily removed from

nitroaromatic compounds if the materials are

PVC test pieces that have been exposed to low

oven dried for four hours at 105C. We did not

ppm levels for up to 24 hours simply by washing

pursue testing the effectiveness of using only

with a hot detergent solution and rinsing with

oven drying for removing pesticides, because we

hot DI water. For more sorptive polymers, such as

felt that detergent washing was essential to

PTFE, additional oven drying is necessary for

remove other contaminants, such as metals, silt,

effective decontamination. Apparently oven dry-

oil, etc.

ing speeds diffusion of the organic contaminants

This study shows the importance of hot air

out of the polymer.

drying for decontaminating the more sorptive

Pesticides are readily removed from most

materials. While it would be a departure from

polymeric materials by using a hot detergent

currently used protocols, there are several ways

wash and hot water rinse. LDPE was found to be

that equipment could be heated in the field. A gas

the exception to this, and could not be adequately

oven or an electric oven with a generator could be

cleaned using this method if the exposure times

set up in the field. Another possibility would be

were 24 hours. This tubing material was also the

to place an oven in a small trailer or in any build-

most sorptive material tested. Washing followed

ing on site that has either gas or electricity. Per-

by oven drying did substantially improve remov-

haps even a hair dryer could be used. Our next

al of these contaminants. Again it appears that

study will examine this issue further.

oven drying speeds diffusion of the organic out of

There are two decontamination issues that

the polymer.

have not been explored at this time but should be

This study also showed that solvent rinsing

addressed at a later date: the effect of even longer

did not aid in the removal of VOCs from these

exposure times and the effect of exposure to

surfaces. While solvent rinsing did improve

either neat organic chemicals or to aqueous or-

removal of pesticides from LDPE slightly, oven

ganic solutions at very high concentrations.

drying was much more effective. These findings

Longer exposure times may be significant when

are important because this means that a consider-

decontaminating devices that have been left in a

ably cumbersome, expensive, and hazardous

Index

Privacy Statement
Press Release
Contact