Characterization of low molecular weight products desorbed from polyethylene tubings

371

The Science of the Total Environment, 47 (1985) 371-384 Elsevier Science Publishers B.V., Anlsterdam -Printed in The Netherlands

CHARACTERIZATION OF LOW MOLECULAR WEIGHT DESORBED FROM POLYETHYLENE TUBINGS i’. .

.wSELME

!.~ntre i8 rue

, ii .

N'GUYEN.

de I;;ecr~er-the du prP.:ident

A.

BRtKHET,

Lvonnaise Wilsori,

PRODUCTS

J.

MALLEVIALLE

des Eaux-Deqt-Cmont 78113C LE Fecq, France

ABSTRACT A case study is reported which demonstrates the appearance of numerous orqanic compounds associated with an intense taste and through a odor problem during the passaqe of a drinking water Batch experiments show that two 300 m Qolyethylene pipe. principal mechanisms are involved in the occurence of orqanoleptic c‘nanqes caused by defective polyethylene tubinqs ; dissolution oi the Qolymer additives (e.q. alkylphcnols... ) and oxidation of the internai surface of the during extrusion with subsequent QiQe reiease of the resulting polar compounds taldehydes, ketones... I. Twenty pe Y cent of the piQes tested (n = 264) appeared to be defective and the total release time exceed several months may under low flow rates conditions. INTRODUCTION Over

the

last

polyethylene)

few for

increasing

their

polyethylene

(HDFE)

properties,

ease

permeability

to

some

cases,

been

noticed.

identified

the

- Dissolution - Oxidation the

resulting

- Migration

use

high

density

mechanical

1984).

and

low

However

in

properties

these

internal

additives

changes

surface

compounds

(Flogstad, of

the

(Flogstad,

have

have

been

contaminants

1984),

pipe 1984),

through

1984).

0048-969'7/85/$03.%l

rapidly

: polymer

external

of

manufacture

organoleptic

1 eg

corrosion

favorable

(Didier,

for

been

to case

during

causes

pipes

has

the

by

water

principle

the the

in

motivated

drinking

synthetic

addition

contaminants

polar of

extensive

literature of

of

In

handling

of

of

distribution,

1983).

are

external

Three

use

water

of

changes

in

the

drinking

(Montiel,

considerations,

of

years,

0 1985 Elsevier SciencePublishers B.V.

and

dissolution

and the

pipe

(Mehens,

372 This

reports

paper the

unambiguously the

passage

in

relashionship

MATERIAL Both

of

laboratory

sections

of

34

southern

the

from

of

odor

during pipe,

problem.

developed

of

analysis. organoleptic

of

odor

four

analysis distillation

analysis bath

and

according

to

(AFNOR,

1983).

industry

(Arthur

analysis

of

odor

free

and

more

trained

standards The D.

tastes

and

until

evaluated

descriptives.

The

scale

for

intensity

and

was

later

(SDE).

trap

5 intermediate

involved

similar

closed

supplemented The to

temperatures

technique

that

used were

lOOF

by

CLSA

the

an intensity to

initially

a

Samples

"tasters"

with

odors and

refrigerated

and

FFA

Little)

evaluations.

a description

12 (strong)

various

flasks

kept

a

(FPA)

the

regard

was carbon

for

in

Analysis

with

extraction

spectrum

the

Erlenmeyer

1983).

or

of

observed,

analyses (CLSA)

the

samples

iocated

sensation

1 (threshold),

Chemical

to

giving

and 25

food

adopted

qualities

approximately (absent),

the

headspace

A panel

taste,

Community

(Krasner, were

systems

Profile

of

Field

qualities

(TTN)

various

respectively

3 m/mn.

a Flavor

Number

extended

45'C

was

Laboratsr-y through

diameters

distribution

both

for

recently

water

tap

Organoleptic

using

tested.

were

velocity of

European

collected

water

and

internal

Faris.

samples

temperature

each

compounds

a 3Oil m polyethyiene

passing

water

Taste

the

been

were

demonstrates

organic

conditions

HDPE portions

was

water

The

evaluated

for

technique

field

with

Threshold

specified

in

taste

by

40 mm.

were

has

an intense

pipes

suburb

and

through

and

HDPE

taken

and

numerous

water

obtained

and

samples

of

which

AND MEX'HODS

were

were

a drinking

study

case

appearence

with

samples

26

a

used

by Grob maintained

for

a list

of was

0

values. stripping simultaneous for

broad

(1976). at

The 45oc

373

=53c _)_

and r1966j,

respectively.

was

followed

obtained

data

The

by

extraction

CLSA.

(approximately columns.

compounds

than

of

The

resuiting 4160,

Italyi

Malmaison,

France).

In

as

:

- on column column

injection

ichrompack

of

OV1701

two

lpi 50

concentration distillation expected

higher

to

polarity

particularly

by

W/MS

Ribermag

cases,

analytic

long

are

phases

2

SDE is

both

on

m

they

adapted

to

technique.

analyzed and

ml

(50

into

and

is

GC!"sniffing"

these

which

Dufton

weight

anaiysis

were

after

technique,

molecular

the

extracts

fractovap

follows

the

this by

small

the

a batch

solvent

subsequent

of

to

and

separates for

of

higher

measurements

Water

a set

nature

Moreover,

CLSA.

sensory

using

the

BY

coilect

recovered

Nicker-son

invoisles

separately,

is

by

complement

technique

water.

condensate

250~1)

a

C'DE
SEE

The

solvent

the

the

heated

are

together.

described

The of

chloride)

condensed

and

appl.ying

3 liters

of

methylene

in

methodology

a or

GCiFID

Erba

RIO-1OC.

Rueii

methodology

capillary J and

(Garbo

was

chromatographic W scientific

DB5 30 m

long) - electronic

impact

-

20-400.

mass

range

at

70 eV

RESULTS Study

Case

The

connection

three month The probably samples

HDPE later low

in

the

sections in

to

numerous

water

velocities

favoured

the

were

South

collected

of

a cast

Paris steel

complains in appearance as

pipe

due this

indicated

this in

summer

(Figure

to

part of

during

intense of

the

1)

Figure

resulted

plastic

1 in

one tastes.

distribution

phenomenon.

system

Four each

of

1384

section

water of

374 t'ne

1iDPE and

specific

in

the

oraani,:s

cast

pipe.

steel

for

-2

l

section

Sampling

Case

along

-4

II I

I

_ SECTION

2

SECTION

3

J

Study (Table

i)

1

and

section

showed

that

occured

at

a

plastic

the maximum

intensity

2.

TABLE1 Flavor

and

point

evaluation

appeared

ion

PIPE -3

II I

100 meters_ SECTION 1

Sensnry

iuat

analysis.

POLYETHYLENE

Fig.1.

ev.3

sensory

Profile

Analysis

CAST STEEL PIPE

HDPE SECTION

1 SECTION

BURNT TASTE

PIPE

PLASTIC

12 PLASTIC

B PLASTIC

THRESHOLD

ODOR NUMBER

1

5

50

3

BURNT

BURNT 4

AND ODOR

2 SECTION

30

odor in

375 The

iLSA

t Fiaure

~:hromatoqrams

2)

indicate

with

nipe. seen

AS

the

hiqhest

peak

in

Table

correspond ic+S4)

to

caldehydes).

EMT.

the

at

high

the

pipe

concentrations 1 to

(0.2

section

in

Analysis

of

Some

water

;

Di

of

last

with these

are two

RETENTION

samples

also

sections.

TIME

CLSA/GC/FID

3.

GC -MS

Pasquale, and

polar

may be derived

from

antioxidant residual

chlorine

additives

progressively

Aldehydes

RELATIVE

2.

detected

lyq/l,

the

by

1982

HDPE

2 and

phenolic

ppm).

3.

sections

agents)

reacted

exceeding

concentrations

Fig.

quinone

the

identified

stabilizing

The

organic

alonq

in

(Stepek,

additives

well-known

the

water

products

point

numerous

detected

main

sampling

of

drinking

intensities

2,6-di-T-butylphenol) in

section

of

antioxidants,

cc*mpounds

present

2,

each

for

appearance

passage

polymer

(iubricants,

(4 -methyl-

the

during

contaminants

ctbtained

were increasing

found

at

found from

unusually

376 TABLE 2 Additive

Concentrations

in HDPE Pipe

ADDITIVES

CONCENTRATION

I

NG/L

HDPE PIPE CAST STEEL PIPE

SECTION

SECTION

,

SECTION

2

3

LUBRICANT ALKYL NAPHTALENE -.-.-.--.-_--.-

-

-

350

900

-

-

70

120

-

90

500

1800

4 METHYL-2.6-DI-T-EUTYL OUINONE

-

500

2000

3300

ALDEHYDES

50

80

500

600

ANTIOXIDANTS/STABILIZlNG AGENTS 4 ETHYL-2.6~DI-T-EUTYL PHENOL ALKYL

THIOPHENE

To get a better section

of

these

of the additives,

and cut

were placed

and allowed

stripping Table

2 was obtained

slices

France)

understanding

in

a

3)

allowed

additives

:

several

the

confirmed.

This

may be derived Qualit

to the

Since

the

were product the

of

various

role

of

was

the quality

of the pipes

of 264 hundred

to the

following

water

(flow

rate

(Figure

broader

3

and

range

of

mentionned,

previously the

closed-loop

presence

of BHT was

used as an antioxidant

or

HDPE samples the

evidenced, delivered

meters

procedure :

and

IEvian,

commonly used thiobisphenols.

clearly

total

a

compounds

HDPE in

properties

water

of

found

water

Subsequent

soak

may be directly

from

control

the

Ten grams of

mineral

48 hours.

of

HDPE sample

slices.

of

identification

in addition

plasticizers

thin

liter

to soak for

and GC-MS analysis

into

a

of

:

700 L/h)

degradation it

by

seemed necessary the

French

HDPE samples 2 m sections during

of organolePtic

were

were

12 hours

to control

suppliers. tested

A

according

rinsed

with

tap

and then

sealed

with

377

Fig.

3.

TABLE

GC-MS

analysis

of

section

2 soak

water

3

Additive

Concentrations

in

HDPE Maceration

ADDITIVES

CONCENTRATION

LUBRICANT ALKYL NAPHTALENE ANTIOXYDANT 4-METHYL-2.6~DIT-BUTYL 4 ETHYL-2.6-DIT-EUTYL 1,5-DI-T-BUTYL-3.7DIMETHYL BICYCLO ALKYL THIOPHENE PLASTICIZERS 2,2,4-TRIMETHYL ,1,3-DIOL

PHENOL PHENOL HEXANE-2-ONE

I

1600

PENTANE

DI ISOBUTYRATE

TRIWTYL PHOSPHATE PHTALATES

250 160 660

NO/I

378 brass

caps

and

twelve

hours.

samples

are

pipes

reported

more

contact

with

threshold in

4.

a

TTN

(threshold

than

50% showed

tap

taste

Table

presented

communities

pipes, TABLE

in The

tested

European

left

over

water numbers

It

can

be seen

that

the

higher

these of

fixed

the

by

the

defective

the

than

of

for 20%

limit

Among

25OC).

TTN values

period

determined

exceeding 3 at

a

30.

4

Threshold

Taste

Number

(TI'N)

of

264

HDPE Samples

NUMBER OF HDPE SAMPLES

TTN

% OF TOTAL a

3-10

13

5.0

1 O-20

2

0.8

20-30

6

30-40

11

50 TOTAL

2o

Complementary samples ati

absorbance intensity

or

100

not of

compounds

intensity,

it

determining

role

were

and Table

CH2 index

does

concentrations polar

in

the

seem

in

taste

5,

Nonspecific

to

be

assumed

establishing

the

determined

directly

final

as

the with

polar organoleptic

by such

;

related ;

these

typical

parameters

increase that

three

increased

additives ketones:

for

intensity

significantly

released

be

measured

low

are

(aldehydes, can

20

7.6

. 264

medium

summarized

2.3 4.2

parameters

(high,

are

52

’

FPA)

as

the

taste

with total

UV

the

yields

increased compounds

of taste

play

sensation.

a

379

TABLE

5

Comparative

Analyses

of

Various

HDPE Pipes

PIPES PLASTIC

TASTE INTENSITY

CH2 INDEX

)JG/L

uv 220

NM

uv 270

NM

ALOEHYDES KETONES

NG/C NG/L

ALKYL PHENOLS

NG/,.

ALKYL NAPTHALEN ALKYL QUINONE

In

order

itself

to

and

determine

were

10 g/l,

48 h),

Compared

with

was this

of

internal

Flogstad,

1984

the

;

the

that

the into

operator

two

nose.

480

570

220

500 3000

500

530

3150

250

120

520

100

of

extrusion), with

raw

2

but

the

polar formed

during

presence

the

of

air

Chan,

of

iEvisn, -

GC

water,

found,

are

granules

CLSA

soak

of

polymer

water

by

were

;

the

mineral

analyzed

1977

was

used

-

MS.

similar

the

striking compounds.

by

oxidation

cooling

phase

(Flogstad,

1984

;

1967).

as an attempt

involved of

the

in

the

capillary

30% supplied Figure

0.194 1400 1100

1000

pipe

the

0.405

additives

were

parts,

0.19 0.171

compounds

the in

effluent

0.16 0.091

section

these

method

additives

300

absence

of

&he

12

80

additives

Le Poidevin,

A GC - Sniffing

split

same

C

influences

then

complete

of

8

80

(pipe

of

extrusion,

evalution

procedure,

was

surface

the

specific

the

2

contact

extract

indicates

following

Sensory

in

the

B

relative

process

left

of

indeed the

the

which

concentrations difference

NG/L

manufacturing

polyethylene

NG/,m

A

4 represents

odor

to

the the

FID

which

problem.

chromatographic to

identify

Detector

GC - Odor

In

this

column and

is

70% to

chromatogram

380

a

sample

chloride

with

of

compounds mind

detected

also

revealed

a plastic

molecules

the

consumers

Furthermore, does

not

such

as account

a

the

could

the

was

in

it

case

the of

- isobutyrate a

pure

probably

particular

the

polar

by-products.

(1) (2)

3- HEXEN -Z-ONE 1,2,4-TRIMETHYL-CG-METHYLETHENYL BENZENE

(3)

1,2,4-TRIMETHYLBENZENE

ISOPROPYL

(4) 4-METHYL-2,6-DI-TBUTYL-PHENOL

Fig.

4.

RETENTION

TIME

SDE extract

of

chromatogram

section

2 soak

water

aromatic be kept in

final the

odor 3.2.4

-

iplasticizer),

separately,

effects

found

threshoid

be the

with

was

must

odor in

smelled

The

other

involved

checked

are

synergistic

mixture,

- di

'Two

their

been

methyienc:

studied

However,

below

have

compounds

BHT.

by technique.

waters

odor.

this

which

extracted

the

4 :

- dial

of

for

complex

:

1.3

property

in

found also

may

-

odorous

detected number

other

water,

.. extraction

component

trimethylpentane thr

odor

extract, by

soak

to

that

33E

the

2

- distillation

plastic

be due

in

section

a steam

hurnt

basic to

of

W/odor

standard. the

method

actinq oxidation

in

381

Evolution o_f_&zsmt~ti~on rsxU.i.cLc LG a p.@3reCt_h4r_l._e_r?.e ti.Fs Ijurinq

the

case

still

problem

of

periods

study

reporrcd after

remained rinsing)

above,

which

four

finally

the

months

led

to

use

the

taste

and

odor

(even

after

long

replacement

of

the

pipe. To

get

information

polyethyiene volume

48 h

of

peak

of

corresponding to

On

additives

is

observed very

at

high

observed

volume! ratio

other

more

gradual

TOC and

phenol

release,

was then

flushed

5 indicates

After

area/soak

water

the

release

and

20% of

the

7500.

'ITN at

of

passacre

volume/volume

of of

initial

the

the of

4

pipe

Fig. pipe

5.

4 RINSING

Evolution

VOLUME

of

20 IN CUBIC

desorption

release

i.s still

this

point

in

a polyethylene

30 METERS

products

equal

phenolic

59 units.

8

m3,

total

i

0

the

initial

-TOC IN SOAK WATER *--* TOC IN RINSE WATER PHENOLS IN SOAK WATER

0’

a

sealed.

that

the

a with

concentrations

hand,

of

the

contact

after

rinsinq

ratio

about

and

polymer

disappears

the

of

diameter)

Figure

a ratio

a rinsing

at

a

duration

internal

determined.

to

1000.

the

crinsinq

1 cm -1 , the

were

TOC

mm

with

at

water of

water

soaking

fixed

soak

(26

pipe

given

volume

on

remains

382 CONCLUSIONS IL‘~*SC study

lhc!

deqr1d2tioi:s . L

t!lc?

Fassac7e

nilnpctabie

water

with

11ommunities.

pt-escnts

concentrations

concentration ,aminoantipyrine the

The

problem

Tabie

6.

TABLE

the

phenols

more

sources

HD?E

values

their

pipe

icads

of

to

maximum

allowed

t he

stand.srd

high

values of

is

required.

remedies

the

water

quinones)

information possible

this

the

-

3

of

TTN.

by

Considering

toxicological and

distribut<.cn

the

iphenols

of

water

llndetrcted

iS8.j!.

esampie

specifications

apprcaohing

remain

(AFNOR,

a typical

standard

transformation

compounds,

is

dr inK.ins

esceedinag

which

method

rile

to

of

pXpcr

tief~+cti\~e

Besides

possible

desorbed

a

regard

tlO/ug/lj

this

in

through

European

and

in

rrccuring

systems.

in

repc;t.ted

are

some

summarized

6 ORGANOLEPTIC PROBLEM

QUALITY SOURCE

- LOW

WATER

IN THE

DISTRIBUTION

- RELEASE

REMEDY

VELOCITIES SYSTEM

OF HDPE

ADDITIVES

- USE

OF ANTIOXIDANT

WITH l-HAN - SURFACE HDPE

OXIDATION

LOWER SOLUBILITY THIO-BIS-PHENOL

. EXTRUSION

OF

PIPES

NITROGEN

IN ATMOSPHERE

- AUTOMATIC

CONTROL

OFEXTRUDEURS

If

the

to

water

velocities

control,

the

thiobisphenols should prohibited

be

use

seems noted the

in of to that

antioxidant

the

distribution

system

an antioxidant be the

the

most

with

appropriate

US Food

and

4,4

thiobis(3

-

lower

Drug

are

difficult

solubility

than

solution.

It

Administration -

methyl

(FDA) -

6

-

383

1:.2~~ic~~~.ltviniii?nol couid

be pt'eve nted

'rkl,.:

latter

rhus

l;lJt

of

by

solution

z~rr'zemenc

suppli~~rs

(Flocnitsd,

:

use

French

provide3

manuf actured

c?f an

a _P 12 _e a r 5 ,

between

now

the

19t34,.

tubinus

inert

during

organoieptie the

.

expensive

and {quality

bv

\nitrogenr

too

distributors

, ensured

extrusion

atmosphere

unfortunately,

water

f.rr

Oxidation

HDPE

contt-01

est t-tudeurs

and pipes #of each

themse!.ves.

REFERENCES -

AFNOk i l! , 19Y.y. Norme NF T Sd .. 035. Evaluation Recueil de5 n'3rmes francaises des eaux. Methodes :>me edition. Far-is la Defense.

-

AE‘NOR CL), 1383. i iridice phenol. M@thodes d'essais.

-

Arthur l?eport.

-

Ghan. M.G. and Lincoln, r; f Reaction Rate with .is Indic,aced by I.R. Science. October. pp.

-

Did-ier, informations

-

and Di Pasquale, G. Additives in Polyolefins Journal of High Resolution Communications. Vol 7.

-

Flogstad, H. World Water,

D.

Little, Cambridge,

2..

du gout. d'essais.

Norme NF T 90 - 109. Determination Recueil des normes francaises des 2Pme edition. Paris ia Dbfense. iNC. The Flavor Massachussetts, W.. 1967. Oxygen and Analysis. 264-268.

Frofile CiSA.

Panel.

haute

Galli,

M., 1934. by Capillary Chromatography pp. 484-486.

pp.

Plastic 27.

Internal

The Relationship between ihemical Change in Poiymers Engineering and Poiymer

1984. Le polyethylene Chimie n"256. pp. 193-203

(i), 1984. December.

de eaux.

Pipe

Determination Gas Chromatography. and Chromatography

Can

Transmit

-

FLogstad, H. (21, 1984. Penetration of Plastic and Solvents. Gases AIDE International by Special Subject n013. Monastir, Tunisia.

-

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