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Патент USA US2407262

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Patented Sept. 10, 1946
2,407,262
UNITED STATES PATENT OFFICE’
2,407,262
PROCESS FOR STABILIZING OR DEACTIVAT
ING SLUDGES, PRECIPITATES, AND RESI
DUES OCCURRING 0R USED IN THE MAN- "
UFACTURE OF TETRAALKYL LEADS
Adrian L. Linch, Wilmington, DeL, assignor to
.
E. I. du Pont de Nemours & Company, Wil- _ .
mington, DeL, a corporation of Delaware
N0 Drawing. Application September 16, 1942,
Serial No. 458,579
8 Claims.
1
This invention relates to a process for stabiliz
ing or deactivating sludges, precipitates and resi
dues occurring or used in the manufacture of
tetraalkyl leads, and which normally tend to pr -
mote decomposition and ignition of the tetraalkyl
leads that may be contained therein.
It is known that alkyl metal compounds in
general are quite unstable and decompose readily,
(Cl. 260—43’7)
2
' such as by controlled blowing with air or oxygen
with agitation, preferably under a layer of water;
followed by separation of the precipitated sludge,
as more particularly described in copending ap
plication Ser. No. 393,680. However, even in
these cases the sludges which are deposited by
the action of the oxidizing agent and which» in
variably contain tetraethyl lead, tend to ignite
particularly in the presence of air or oxygen. It
when exposed to air thus presenting serious igni
has also been found that these alkyl metal com 10 tion hazards, making it desirable that even these
pounds are particularly unstable when adsorbed
sludges should be deactivated during their forma
on materials which present a large surface area
tion or afterwards to permit of their removal
per unit Volume such as silica gel, clays, alumina,
earths, asbestos, charcoal, and materials of simi
and disposal in a safe manner.
It is therefore an object of this invention to
lar structure which materials appear to exert a 15 provide a process for stabilizing sludges, precipi
catalytic effect in the decomposition of these
tates and residues occurring in the manufacture
alkyl metal compounds.
Even tetraalkyl leads
of tetraalkyl lead compounds whereby the igni
tion hazard presented by the lead alkyl com;
somewhat more stable than some of the other
pounds in contact with such catalytic surfaces
alkyl metal compounds decomposes and often 20 is reduced‘or completely overcome.
such as tetraethyl lead which is known to be
ignites in the presence of oxygen when small
amounts are adsorbed on materials that o?er
It is a still further object of the invention to
render inactive materials which tend to exert a
extended surface areas,- particularly when the
catalytic-effect in the decomposition of tetra
masses containing the tetraethyl lead are exposed
alkyl leads in the presence of air thus permitting
to temperatures somewhat higher than normal 25 the safe use of such materials as ?lter aids in
atmospheric temperatures. The tendency to oxi
the manufacture of tetraalkyl lead.'
dize and ignite of course varies with the sub
I have found that the sludges, precipitates and
stance with'which the alkyl metal compound is
residues occurring or involved in the production
incorporated,'s‘ome materials apparently exerting
of tetraalkyl leads, which offer large surface
a greater catalytic e?ect than others in promot; 30 areas per unit volume and which normally tend
ing ignition of the alkyl lead compounds.
to/exert'a catalytic e?ect and cause decomposi
In the manufacture of tetraalkyl leads, such
tion and ignition of the tetraalkyl lead which
as tetraethyl lead, tetramethyl lead and the mixed
may be contained therein, can be rendered inac
ethyl-methyl lead compounds, sludges are formed
tive conveniently and economically by washing
from which it is diflicult and, from a practical 35 or otherwise treating them with solutions or dis
standpoint, impossible to entirely free from the
persions of polyfunctional phenols. These stabi
alkyl lead compounds during the normal steam
lizing agents appear to be preferentially absorbed
distillations or decantation operations. There is,
by the active materials which appearpto retain
therefore, carried through the process very ?nely
their capacity to absorb the alkyl lead although
divided lead and impurities such as bismuth com 40 they are no longer effective to induce ignition of
pounds which, although present in very small
the tetraalkyl lead absorbed therein.
amounts, ?nally are deposited as sludges in the
By the terms sludges, precipitates and residues
pipes and tanks and other processing equipment
I include those ?lter aids which may be employed
and these sludges which contain tetraethyl lead
in the production of the tetraalkyl leads and
adsorbed therein when exposed to oxygen or air 45 which o?er a large surface area per unit volume
often ignite, thus presenting serious ignition and
and are known to accelerate decomposition of
explosion hazards in the process.
the tetraalkyl leads on exposure to air or oxygen
Methods have been advanced for the removal
such as clays, silica, earths, charcoal, etc. These
of practically all the sludge forming materials
?lter aids are rendered inactive by treating them
from ‘the tetraethyl lead after its distillation,
with polyfunctional phenols either before or
2,407,262
3
hydroxy
(-—OI-I),
alkoxy
(—OR),
as with air or oxygen is more particularly dis
closed in copending application Ser. No. 393,680.
The precipitated sludges from this process collect
in the aqueous layer from which the puri?ed tet
raethyl lead is separated by decantation. Al
though dispersed in the Water layer the sludge
retains su?icient tetraalkyl lead absorbed therein
to ignite on contact with oxygen or air, particu
larly at slightly elevated temperatures. In order
to permit the safe handling and disposition of
carboxy
these sludges it has been found desirable to de
activate them before they are removed from the
(-—-COOH) _ aldehyde
system. This can be done conveniently by adding
H
(-<‘>=o)
.15 a quantity of one of the deactivating agents to
ketone
R
4
crude tetraethyl lead with oxidizing agents such
after they are employed in the process. The
effectiveness of the polyfunctional phenols in the
deactivation of these active materials is not ma
terially reduced by washing the deactivated ma
terials with water or other solvents or by drying
them down prior to use.
The term “polyfunctional phenols” is used in
this speci?cation to cover that group of aromatic
compounds which contain a hydroxy group and
in addition at least one of the following groups:
\.
Lao)
nitro (—~NO2), nitroso (-NO), hydroxy benzyl
the aqueous sludge dispersion and then agitat
ing the mass to assure complete contact of all
the sludge with the deactivating material, or an
aqueous solution of the deactivating agent may
20 be used to cover the tetraalkyl lead during the
accelerated sludge precipitation treatment so that
the sludge is deactivated as fast as it is formed.
(—-CH2.CsI-I4.OH) , phenolic ester
The deactivating material may be employed in
an aqueous solution or suspension or in other
25 solvents.
Where the sludges or precipitates settle out in
and long chain aliphatic radicals of at least 4
the pipe lines or other processing equipment dur
carbon atoms. The derivatives of the above com
pounds which produce such polyfunctional com
pounds by hydrolysis, for example, picryl chlo
ride, hydroquinone diacetates, etc., are also effec
ing the manufacture or puri?cation of the tetra
alkyl leads they may be deactivated, to insure
safety in their removal or during repair of the
equipment, by pumping a solution of‘ one of the
tive.
deactivating materials through the apparatus for
Further, the diketones, formed from the
polyfunctional phenols by simple oxidation or
tautomerization such as chloranil, benzoquinone;
quinhydrone;
alpha - nitroso - beta - naphthol;
para-nitroso phenol, etc., are effective deactivat
ing agents.
The polyfunctional phenol deactivators are
preferably used as aqueous solutions which con
tain the deactivating agent in an amount equiv
alent to approximately one-third of the dry
weight of the material to be stabilized. The
amount of deactivator employed may of course -
be varied over a wide range with equally good
results. By employing the stabilizer in an amount
ranging from 0.05% to more than 100% of the
dry weight of the active material satisfactory results have been obtained. The stabilizing effect
may be obtained in some cases by using even
smaller amounts of the deactivating agent, al
though a suf?cient amount should always be
used to insure complete deactivation of the ac
tive material. The use of excessively large quan
tities over that actually required to deactivate
the active materials merely contributes unneces
sarily to the cost of the process and serves no
useful purpose.
The deactivating agent is preferably employed
in a solution of a concentration of from 1 to 5%
although lower or higher concentrations may
be used. It is of course advantageous to employ
a sufficient amount of solution to insure com
plete contact of all the material to be deactivated.
To prevent the use of unnecessary large amounts
of the deactivating polyfunctional phenol, it will
usually be found desirable to use a relatively
large Volume of solution of a concentration of less
than 5%. Where there is an advantage of em
ploying a lesser volume of solution the concen
tration may of course be increased.
An important use of the present invention in
the commercial manufacture of tetraethyl lead
is to deactivate the sludges which are precipi
tated and removed from the crude tetraethyl lead
in the puri?cation step. A method of precipitat
a suf?cient period of time to insure complete
contact with all the sludge to be deactivated,
which is usually accomplished in from 15 to 30
minutes.
The filter aids may be washed with a solution
of the deactivating agent prior to their use in
the process. They may be employed either before
or after drying, for it has been found that they
do not again become active even after being
dried, or by being washed vby the solutions that
are ?ltered therethrough.
In view of the fact that these polyfunctional
phenols are in the main volatile with steam they
can be added to the crude tetraalkyl lead mass
at the time of steam distillation so that they are
carried over with the tetraalkyl lead and con
tinually effect the stabilization of any residues
' that may occur in the process.
A further use of the invention is found in the
storage of crude tetraalkyl lead before it is de
sludged by accelerated sludge precipitation. An
_ aqueous solution of one of the deactivators dis
closed may be used to cover the crude tetra
alkyl lead.
Any sludge which precipitates at
the surface of the lead alkyl on standing is sta
bilized by contact with the aqueous layer. If de
sired, all of the precipitated sludge may be
60 brought into the aqueous layer by suitable agita
tion since the stabilized sludge particles readily
disperse in the water layer.
In this way the
sludge may be deactivated as soon as it is formed.
Stabilization of sludge formed in crude tetra~
ethyl lead on standing is also accomplished with~
out the use of an aqueous layer over the ma
terial. Some of the deactivating agents men
tioned are soluble in tetraethyl lead and may be
dissolved directly in the crude tetraethyl lead.
Any sludge which precipitates while the tetra
ethyl lead is in storage is immediately rendered
safe by the reagent.
The following examples are given to illustrate
ing and removing these sludges by treating the 75 the invention. The parts used are by weight.
2,407,262
5
EXAMPLE 1
Approximately 25,000 parts of tetraethyllea'd
the clear tetraethyl lead was decanted from the
water layer after the ?ltration was complete. A
were processed» in a washer to precipitate the
sample of the sludge retained on the ?lter was
sludge forming impurities by the method de
tested for ignition activity as previously described,
and was found to be inactive. Sludge obtained
scribed in the co-pending application, Serial
using the same crude tetraethyl lead and the
Number 393,680. The-precipitated sludge which,
same process, exceptthat potassium alizarinate
by laboratory analysis of a small sample of the
was omitted, ignited the tetraethyl lead which it
tetraethyl lead, had been calculated to weigh 30
retained when placed on the steam bath.
parts, was collected in 2,500 parts of water.’ The
Although I use potassium alizarinate in this
puri?ed tetraethyl lead was then decanted from H)
example, the same procedure may be employed
the water layer. Approximately 25 parts of hy
with the other deactivating agents mentioned.
droquinone were added to the aqueous phase pro
It is also to be understood that'the quantities and
ducing a solution of about 1.0% hydroquinone.
concentrations given are not to be construed as
The mixture was agitated for 15 minutes and ?l-l
terecL
l5 limits to. the invention for they may be varied
A small portion of the?lter cake was then
wldelr wtthout modlfytng the results
tested for ignition activity by placing it on a
WP“? m the preceilmg examples]: ,ha've used
?lter paper, wetting the cake with a smauquan;
stabilizing agents WhlCh. are soluble in neutral
tity of tetraethyl lead and heating on a, steam
.aquemls 591111310115’ deactwa‘tmg age?“ that are
bath <95°-100° 0.). No signs of ignition or char- 2“ 11150121318 m miutral aqua)?“ 50mm? may be
ring of. the ?lter paper were noted even after 24
e?eqtlvely apphed from. Suitable Solutlons! Such
hours on the Steam bath.
as dilute sodium hydroxide, or from organic sol
A sample of the same sludge which was taken
‘tents’ I ha“? found that dlsPerslf’nsi suspetl‘
before the hydroqumone was added to the water
sions or solutions of the deactivating agent in
layer was tested for activity as outlined above. 25 Solvents °ther.tha'n Water may be e?ectlvply us.ed'
Ignition occurred shortly after the initial sample
when Water 15 used as the sqlvent or dlspfersmg
was placed on the Steam bath
medium, the method of applying the deactivator
In regular plant application of this method of
.
.
.
tohpgeipg?tgd teiraflfyllufild sgldges 11s eflregtlge
_
we
pie
asse
o
in
xampes
r.
sludge deactlvatlon’
lt-ma‘y analysis
not always
be conto 30 However, when solvents other than water are
venient
to run a laboratory
in order
used, the aqueous layer containing the sludge may
determine the amount of sludge to be expected.
be ?ltered off, and the ?lter cake then agitated
I have found that under usual conditions the
with the solution containing the deactivating
quantity of sludge formed per 1,000 parts of tetra
agent for a period of from 15 to 30 minutes in a
ethyl lead seldom exceeds 2 parts and this ?gure
suitable receptacle, or the solvent solution may
be added directly to the aqueous sludge suspen
sion. Results obtained on agitating 10 parts of
an active sludge with 50 parts of a solution of
may be used as a basis for calculating the quan
tity of deactivator needed. Since tetraethyl lead
manufactured in various plants may vary in
sludge formation, depending on the quality of raw
materials employed for any particular plant the
quantity will be relatively constant the amount of 40
Table
I
Compound
representative polyfunctional phenols in various
solvents are listed in the table below.
I
concem
tration,
Steam bath stability
Solvent
Initial .
percent
Hydroquinone ___________ __- _____________ _-
5
After 24 hours
5% N21200:“.-- No decomposition--. N0 decomposition-..
8-hydroxy quinoline _ _ . _
_ ._
_
1
1% NaOzCzHg..- _-___do __________________ ._d0 _____________ __
Alpha-nitroso beta-naph
ol
_
1
Ethyl alcohol. _ _
_
2
Water _______ . .
2
____.do _______ __
Pyrogallol ____________ _ _
Sodium picrate __________ __
_
__do
_
After 72 hours
No decomposition.
Do.
Do.
Do.
D0.
Chloranil _________________________________ __
2
Ethyl alcohol. .
Do.
4,4’-dihydroxy diphenyl methane.
2
Cello
Do.
Catechol-mono-ethyl ether ______ . _
__
_
2
5-methyl-2-liydroxy acetophenona
_
2
Do.
4-Iaur0yl resorcinol ____________ __
_
2
Do.
l-hydtoxy-é-napthoxy acetic acid._
__
Do.
2
D0.
Para-stearylphenol ________________________ __
2
Do.
Leuco-2,2'-dimethoxy dibenzan
1
Do.
Picryl chloride ______ __
1
Salicylal aldoxime- _ __
1
No deactivator (control)_____
Do.
Ethyl alcohoL _ _ .___.do ____ __
Do.
Water _________ __
Do.
Ignited... _
deactivator required for that plant per unit weight to As previously stated the invention may be em
of tetraethyl lead may be readily determined.
ployed to stabilize active ?lter aids which are
to be used in tetraalkyl lead ?ltration. These
EXAMPLE 2
materials may be washed in a solution of one of
Approximately 1,000 parts of crude tetraethyl
lead were placed in a suitable container provided
with means for agitating its contents. About
200 parts of water were added, and the sludge
was precipitated and collected in the water layer
as disclosed in the previously mentioned appli
all
cation, Serial Number 393,680.
After the precipitation treatment was complete,
one part of potassium alizarinate was added and
the contents of the container were agitated for
about 15 minutes. The tetraethyl lead and the
aqueous layer were then ?ltered together, and 75
the deactivators and rendered suitable for tetra
alkyl lead ?ltration. The following ?lter aids as
well as a number of other materials of similar
structure were wet with tetraethyl lead and placed
on a steam bath as described in Example 1 above.
All were found to initiate the ignition of tetra
ethyl lead. Ten parts of each of these‘ materials
were then agitated for several hours with 50 parts
of the solution of various polyfunctional phenols
of the concentrations given in Table 2. After the
agitation period, the solutions were ?ltered and
portions of the ?lter cakes were wet with tetra~>
2,407,262
‘7
In testing the activity of the sludges before or
after treatment with the deactivating agents it
will be noted that tetraethyl or other alkyl lead
ethyl lead and placed on a steam bath. Results
of the tests are given below:
' '
was added to the residues. This was to make
sure there was suf?cient tetraalkyl lead present
Table II
Cl
Material
Wash solution
Filter aid (clay) _________ __
None _________________ __
Do __________________ __
1% sodium alizarinate_
No decompo
Filter aid (silica) ________ __
None _________________ -_
Ignited.
Do __________________ __ 2% alpha-nitroso beta-
naphthol.
Yelyl?w lead oxide (N. F.
5% N21200:;
Bismuth subnitrate _____ __
'
None _________________ __
Do _________________ __,. 3% chloranil in ethyl
alcohol.
Bismuth oxide (prepared
by
hydrolysis
ited.
sition.
No decompo
sition.
None ............... _,_._ Ignited.
Do__________________ __ 5% hydroquinone in
.
steagssath
to ignite under the conditions employed, if the
sludge was not fully inactivated, for in some in
stances, it is possible that the amount of alkyl
lead may be reduced to such a small amount that
10 ignition might not be noted. While the elimina
tion of the alkyl lead from the residues to such
an extent does not ordinarily take place, the tests
were made under conditions favoring ignition pro
vided the sludge or ?lter aid was active.
No decompo
sltion.
15
Ignited.
No decompo
sion.
None _________________ __ Ignited.
of
Bi(NOs):l._
decompo
Bismuth oxide (prepared 2% d-lauroyl resorcinol NoS1011.
in ethyl alcohol.
'
by hydrolysis of
BKNOg);
Activated Alumina _____ __
None _________________ __
Do __________________ __ 2% guaiacol in ethyl
alcohol.
Decolorizing charcoal ____ __
None _________________ __
Do__________________ _. 2% picric acid in 2%
NaOH.
Ignited.
No decompo'
sition.
Ignited.
No decompo
sition.
EXAMPLE 3
This invention makes possible the deactivation
of theignitable sludges and residues occurring in
the manufacture or tetraalkyl lead compounds '- "
and is of particular value, in eliminating ?re and
explosion hazards involved in the removal and
disposal of such sludges from the process and in
overcoming the potential ?re hazard arising from
the collection of such sludges and precipitates
which accumulate in various places in the
processing equipment and which when exposed
to air often ignite with considerable damage. The
invention also permits the use of ?lter aids which
unless rendered inactive tend to cause ignition of
any absorbed tetraethyl lead when they are ex
Approximately 2,000 parts of crude tetraethyl
posed to the air. Any other absorbent materials
lead were placed in a suitable tank or washer, and
an approximately equal weight of water was
which for any reason may become saturated with
tetraethyl lead in or about the plant in which
it is being manufactured may be rendered in
added to the tetraethyl lead. Some 40 parts of
NaOI-I and 40 parts of guaiacol were then added
to the water layer, and the sludge was precipitated
and removed from the tetraethyl lead by blow
ing with air as more particularly disclosed in the
active by washing or otherwise treating with
stabilizers of the type described so that potential
?re hazards may be removed as far as possible.
Lagging on pipe which due to leaks may become
copending application, Serial Number 393,680.
saturated with tetraethyl lead and which have
After this operation was complete, the tetraethyl
been known to cause its ignition can be in
activated by treating such lagging with the de
lead was removed by decantation, and the aqueous
layer containing the sludge was ?ltered. A por
tion of the ?lter cake was tested on the steam
bath as described in Example 1. No decomposi
tion or ignition of the tetraethyl lead was noted.
1. The process for inhibiting the spontaneous
ignition of tetraalkyl lead compounds adsorbed on
EXAMPLE 4
sludges which are precipitated from crude tetra
As previously stated, sludges found in tetra
ethyl lead are also found in other lead alkyls
which are manufactured from commercial lead.
An example of these alkyls is the mixed tetra
methyl-ethyl compounds of lead, formed when a
mixture of methyl chloride and ethyl chloride are '
reacted with lead sodium alloy. All examples in
which tetraethyl lead is speci?ed are equally
workable with these mixed lead alkyls.
Approximately 8,000 parts of crude mixed tetra
methyl-ethyl lead compounds (tetramethyl lead,
trimethyl ethyl lead, dimethyl diethyl lead,
methyl triethyl lead and tetraethyl lead) were
placed in a suitable tank or washer, and 2,000
parts of water containing 10 parts of sodium
alizarinate were added. The contents of the tank
were aerated and agitated for two hours as dis
closed in the copending application, Serial Num
ber 393,680. After a settling period of a few
minutes, the clear mixed lead alkyls were de
canted from the aqueous layer and the aqueous
mixture was ?ltered. A portion of the ?lter cake
activating agents.
1 claim:
alkyl lead compounds and which sludges normally
tend to cause spontaneous ignition of the tetra
alkyl lead compounds adsorbed thereon'when ex‘
posed to oxygen, which comprises incorporating
with such sludges a phenol containing at least one
substituent of the group consisting of hydroxy,
alkoxy, carboxy, aldehyde, ketone, nitro, nitroso
and ester groups attached to ring carbon atoms
and which otherwise consists of carbon, hydrogen
and oxygen.
2. The process for inhibiting the spontaneous
ignition of tetraethyl lead adsorbed on sludges
which are precipitated from crude tetraethyl lead
and which sludges normally tend to cause spon
taneous ignition of the tetraethyl lead adsorbed
60 thereon when exposed to oxygen, which comprises
incorporating with such sludges a phenol contain
ing at least one substituent of the group consist
ing of hydroxy, alkoxy, carboxy, aldehyde, ketone,
nitro, nitroso and ester groups attached to ring
carbon atoms and which otherwise consists of car
bon, hydrogen. and oxygen.
3. The process for inhibiting the spontaneous
was tested on the steam bath as described in‘
ignition of tetraethyl lead adsorbed on sludges
Example 1 except that the ?lter cake (sludge)
which are precipitated from crude tetraethyl lead
was wet with mixed lead alkyl compounds rather
than with tetraethyl lead. No decomposition or 70 and which sludges normally tend to cause spon
taneous ignition of the tetraethyl lead adsorbed
ignition of the lead alkyls was noted. A similar
thereon when exposed to oxygen, which comprises
experiment was carried out in which no sodium
washing such sludges with a solution of a phenol
alizarinate was placed in the water layer. This
containing at least one substituent of the group
sludge ignited the mixed alkyls when the steam
75 consisting of hydroxy, alkoxy, carboxy, aldehyde,
bath stability test was made.
2,407,262
10
ketone, nitro, nitroso and ester groups attached
ignition of tetraethyl lead adsorbed on sludges
which are precipitated from crude tetraethyl lead
and which sludges normally tend to cause spon
taneous ignition of the tetraethyl lead adsorbed
thereon when exposed to oxygen, which comprises
to ring carbon atoms and which otherwise con
sists of carbon, hydrogen and oxygen,
4. The process for inhibiting the spontaneous
ignition of tetraethyl lead adsorbed on sludges in
which are precipitated from crude tetraethyl lead
incorporating with such sludges guaiacol in an
and which sludges normally tend to cause spon
amount equivalent to at least 0.05 per cent of the
taneous ignition of the tetraethyl lead adsorbed
dry weight of the sludge.
thereon when exposed to oxygen, which comprises
7. The process for inhibiting the spontaneous
washing such sludges with an aqueous solution H) ignition of tetraethyl lead adsorbed on sludges
of a phenol containing at least one substituent
which are precipitated from crude tetraethyl lead‘
of the group consisting of hydroxy, alkoxy, car
and which sludges normally tend to cause spon
boxy, aldehyde, ketone, nitro, nitroso and ester
taneous ignition of the tetraethyl lead adsorbed
groups attached to ring carbon atoms and which
thereon when exposed to oxygen, which comprises
otherwise consists of carbon, hydrogen and oxy
incorporating with such sludges picric acid in an
gen.
amount equivalent to at least 0.05 per cent of the
5. The process for inhibiting the spontaneous
dry Weight of the sludge.
ignition of tetraethyl lead adsorbed on sludges
8. The process for inhibiting the spontaneous
which are precipitated from crude tetraethyl lead
ignition of tetraethyl lead adsorbed on sludges
and which sludges normally tend to cause spon_ " which are precipitated from crude tetraethyl lead
taneous ignition of the tetraethyl lead adsorbed
and which sludges normally tend to cause spon
thereon when exposed to oxygen, which comprises
taneous ignition of the tetraethyl lead adsorbed
incorporating with such sludges hydroquinone in
thereon when exposed to oxygen, which comprises
an amount equivalent to at least 0.05 per cent of
washing such sludges with an aqueous solution of
the dry weight of the sludge.
hydroquinone.
6. The process for inhibiting the spontaneous
ADRIAN L. LINCH.
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