Note: Descriptions are shown in the official language in which they were submitted.
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Case 1-12178/BSG/-~
Method of removing halogenated or nitrated h~drocarbons or
aromatic h drox com ounds from water
Y Y P _ _ ~ _ _
Although halogenated and nitrated hydrocarbons and aromatic
hydroxy compounds are in effect water-immiscible, they are
nonetheless dissolved or suspended in water in measurable
amounts. Water containing such contaminants, e.g the waste-
water occurring in the steam distilLation of organic solvents,
is hazardous and is even highly undesirable in the influent
of a biological treatment plant.
The present invention is concerned with the removal of the
above contaminants from water, especially from wastewater
before it flows into a biological water treatmen~ plant. A
known method is e.g. activated carbon adsorption. However,
this is an expensive method, because the adsorptive capacity
of activated carbon is limited and regenerationinvolves
heavy costs.
To solve thls problem, the present invention provides a
method of removing halogenated or nitrated hydrocarbons or
aromatic hydroxy compounds, or mixtures thereof, from water,
especially from wast~waters, which method comprises bringing
said wastewaters into contact with fatty oils or waxes.
The fatty oils or waxes which are used as extractants in
the method of the invention can be of natural or synthetic
origin.
Suitable extractants of natural origin within the scope of
this invention are mineral, vegetable, or animal oils or
waxes. Preferred extractants are mineral oils or waxes, e.g.
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paraffin oil, white oil or paraffin wax~ Preerred mineraL
~ s and waxes are alipha~ic hydrocarbons having a morecular
weight o~ 130 to 450, preferably 140 to 250, and a boiling
point of 180 to 380C. Paraffin oils having a pour point
below -15C and a boiling point above 350C are especially
preferred.
Suitable animal oils and waxes are e.g. lanolin and tallow
fat.
Examples of suitable vegetable oils and waxes are soybean
I oil, coconut oil and castor oil. Of the synthetic oils
and waxes, ~licon oil is preferred.
With the aid of the ad~orptivc oils and waxes it is possible
to remove the contaminants referred to at the outset
substantially from wastewaters which occur in the textile
and fibre industry and in dry cleaning, such as residual
liquors, spent liquors, rinsing and wash waters. In particu-
lar, wastewaters to be treated are those formed in the
steam distillation of halogenated or nitrated organic
solvents. Depending on the circumstances, the method of the
invention can also be employed for purifying process water.
Halogenated solvents contained in wastewaters can be bromin-
ated, fluorinated or chlorinated aliphatic hydrocarbons,
e.g. methylene chloride, chloroform, carbon tetrachloride,
methylene bromide, di~ loroethane, trichloroethane,
trichloroethylene, tetrachloroethane~ perchloroethylene,
- penta hloroethane, chloropropane, dichloropropane, trichloro-
prop~ne, chlorobutane, dichlorobutane, l-chloro-2-methyl-
propane, dichlorohexane, and perfluoro-n-hexane, trifluoro-
trichloroethane, trifluoropentachloropropane and octafluoro-
cyclobutane.
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The wastewaters purified are especially those which contain
aromatic halogenated hydrocarbons as halogenated solvents,
e g. chlorobenzene, dichlorobenzene, trichloroben~ene,
fluorobenzene, chlorotoluene and benzotrifluoride. It is
preferred to treat a wastewater containing chlorobenæene,
e.g. a wastewater obtained in the phase separation of
chlorobenzene and water after steam distillation. Nitrated
hydrocarbons are e.g. nitromethane, nitrocyclohexane and~
in particular, nitroben2ene.
The method of the invention can also be employed for puri-
fying wastewaters which contain aromatic hydroxy compounds,
by which are meant aromatic organic compounds containing
one or more hydroxyl groups bonded direct to an aromatic ring,
especially a benzene ring. Examples of such hydroxy compounds
are phenol or phenol derivatives, e.g. cresols, xylenols,
chlorophenols, nitrophenols, resorcinol, hydroquinone, and
naphthols.
The fatty oils or waxes can be combined with an anioninc,
cationic or non-ionic surfactant. A preferred embodiment of
the invention consists in carrying out the treatment of the
wastewaters in the presence of a non-ionic surfactant. This
latter can be employed by itself, as a mixture or in
admixture with an anionic and/or cationic surfactant.
Nonionic surfactants are advantageously alkylene oxide
adducts of 1 to 50 moles of alkyLene o~ide, e.g, ethylene
oxide and/or propylene oxide, with 1 mole of an aliphatic
monoalcohol containing at least ~, preferably 8 to 22,
carbon atoms, of a trivalent to he~avalent aliphatic alcohol
containing 3 to 6 carbon atoms, of a phenol which is
unsubstituted or substituted by Cl-C16alkyl, preferably
C4-C12alkyl, or by phenyl, or of a sat~rated or unsaturated
fatty acid containing 8 to 22 carbon atoms.
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Preferred alkylene oxide reaction products can be illustrated
by the formula
0--o
o- (C}~2C~2~m ~
Dn~
wherein R is octyl or nonyl and m is an integer from 2 to
15.
Suitable cationic surfactants are e.g. amines or polyamines
containing 2 or more, preferably 2 to 5~ basic nitrogen
atoms, and having at least one polyglycol ether chain and at
least one lipophilic su~stituent and which can be partially
or completely quaternised.
The anionic surfactants are preferably sulfonated adducts Of
alkylene oxides~ e.g. adducts containing acid ether groups
or èster groups of organic or inorganic acids of alkylene
oxides, especially ethylene oxide and/or propylene oxide
or also styrene oxide, with organic hydroxyl, carboxyl,
amino or amido compounds containig aliphatic hydrocarbon
radicals having a total of at least 8 carbon atoms, ox
mixtures thereof, These acid esters can be in the form of
free acids or salts, e.g. alkali metal, alkaline earth
metal, ammonium or amine salts.
The treatment of the wastewaters with the fatty oils or
waxes can be carried out up to a temperature which is below
the boiling point of the substance which it is desired to
remove. Preferably the treatment is carried out in the
temperature range from 10 to 80C and especially at room
temperature (15 to 30C). The pH of the wastewaters can vary
within wide limits, e.g. between 2 and 12. Usually the
wastewaters which are treated have a pH value of 6 to 8.
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The wastewat~s contain the con~aminants which it is desired
to remove by the method of the invention in a concentration
which can likewise vary within wide limits. Normally they
are industrial wastewaters which contain 0.1 to 1 g of
halogenated or nitrated hydrocarbons or 0.1 to 10 g of
aromatic hydroxy compounds, or mixtures thereof, per litre
of wastewater.
The extractant employed in the method of the inven~ion can
be added in solid or preferably in liquid form to the water
which it is desired to treat. Preferably the extractant is
employed in an amoun~ of 1 to 10 g per litre of water.
The method of the invention can be carried out ~
discontinuously, semicontinuously or continuously, the
latter two alternatives being preferred. The fixed bed
method, in which the wastewater to be purified is conducted
through the extraction material, has proved to be
advantageous. Moreover, the following three alternatives
with respect to the apparatus employed are especially
suitable;
1. The treatment apparatus is firmly connected to the
extraction device.
2. The extraction device is movable and can be coupled, as
required, with any treatment apparatus.
3. The wastewaters originating from the treatment liquors
are combined in a suitable container and then jointly
conducted through the extraction material.
A liquid-liquid extraction is especially suitable, in which
case the unpolar fatty oils or waxes employed have the
necessary miscibility gap with the wastewater.
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By appropriate choice of extractant it is possible to
remove 80 to 95 ~/0 by weight of the contaminants originally
present in the wastewaters. The extraction efficiency can
be improved by the addition of an anionic, cationic and
especially of a nonionic surfactant, preferably a nonyl-
phenyloxypoly(ethyleneoxy)ethanol. The surfactant is
preferably added to the wastewa~ers to be treated in an
amo~nt of 0.05 to 0.5 g per litre of wastewater.
Whenever it does not prove possible to remove the contami-
nants to a satisfactory degree, it is advisable to repeat
the purification procedure or to employ a multi-step
system.
The method of this invention for treating polluted liquid
media with the fatty oils or waxes can also optionally be
only part of a purification or recovery process. Certain
wastewater treatments can be carried out by several steps,
in one of which the above mentioned fatly oils or waxes can
be employed as extraction agents.
After the extraction of the impurities, the extractive
capacity of the fatty oils or waxes employed can be par-
ti~lly or completely recovered, for example by steam
distillàtion or extractive distillation, while the extracted
materials can also be separated.
The method of the invention is illustrated by the following
Examples, in which parts and percentages are by weight.
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Example 1:
A glass U-tube having a diameter of 8 mm is filled with
2.5 g of paraffin chips. Then a wastewater containing 0.03 %
of chlorobenzene is passed through the tube at rOom tempera- ,
ture and a rate of 1.2 litres per hour. The treated waste-
water contains only 0.01 % of chlorobenzene.
Example 2:
An extraction vessel having a diameter of 75 mm is one third
fiUed with 10 g of paraffin oil. Then a wastewater con-
taining 0.013 % of chlorobenzene is passed through the
vessel at room temperature and a rate of 1.'~ litres per hour~
The treated wastewater contains only 0.002 % of chloro-
benzene. The concentration of chlorobenzene in the paraffin
oil is 5.7 %, based on dry paraffin oil.
Example 3:
0,08 g/l of a polyethylene oxide adduct of the formula
Cg~Ilg ~ O~ 2C~20 9~
is added to the wastewater of Exam~le 2 and the procedure
described in Example 2 is repeated. The treated wastewater
contains only 0.001 % of chlorobenzene.
7;~:~
Example 4:
A wastewater which contains 200 mg/l of 1,2-dichloroethane
is passed through the sam~ assembly as in Example 29 except
that it consists of two identical stages. The treated waste-
water contains only 100 mg/l of 1,2-dichloroethane, The con-
centration of 1,2-dichloroethane is reduced further by
employing additional stages.
Example 5:
Using the same assembly as in Example 4, a wastewater con-
taining 290 mg/l of chlorobenzene is treated with an ali-
phatic hydrocarbon having an average molecular weight o
170 (boiling range 190-250C; density 0.78 at 20C; flash
point 68-72C), The concentration of chlorobenzene is
likewise reduced to lO0 mg/l.
Example 6:
A wastewater containing 39 mg/l of chlorobenzene is treated
with white oil using the same assembly as in Example 4. The
content o~ chlorobenzene in the treated wastewater is reduc-
ed to 6 mg/l.
Example 7:
A wastewater containing 155 mg/l of nitrobenzene is
treated with paraffin oil using the same assembly as in
Example 4. The content of nitrobenzene in the treated
wastewater is reduced to 16 mg/l.
