METHOD FOR THE DEMOLITION AND THE REMOVAL OF HALOGENATED AND AROMATIC HYDROCARBONS FROM MATERIALS THAT CONTAIN THEM

METHODE DE DESTRUCTION ET D'ELIMINATION D'HYDROCARBURES HALOGENES ET AROMATIQUES DANS DES MATERIAUX LES RENFERMANT

English Abstract

Method for the demolition and the removal of halogenated and aromatic
hydrocarbons from materials that contain them, characterised in that the
material to be treated is made to react - in an acid and/or alkaline
environment, or vice versa - with a reagent selected from the group comprising
zinc, iron, iron disulphide, ferrous sulphide, ferrous sulphate and mixtures
thereof.

French Abstract

Cette invention concerne une méthode de destruction et d'élimination d'hydrocarbures halogénés et aromatiques dans des matériaux les renfermant. Cette méthode se caractérise en ce que l'on fait réagir le matériau en milieu acide et/ou alcalin, ou vice versa, avec un réactif pris dans le groupe comprenant du zinc, du fer, du bisulfure de fer, du sulfure ferreux, du sulfate ferreux et un mélange de ces substances.

Claims

7
CLAIMS
1. Method for the demolition and the removal of halogenated and aromatic
hydrocarbons from materials that contain the, characterised in that the
material to treat
is made reacting - in an acid and/or alkaline environment, or viceversa - with
a reagent
selected from the group comprising zinc, iron, iron disulphide, ferrous
sulphide, ferrous
sulphate and mixtures thereof.
2. Method for the demolition and the removal of halogenated and aromatic
hydrocarbons from materials that comprise them according to claim 1, wherein
the acid
environment treatment is carried out at a pH lesser than 6.
3. Method according to claim 1 or 2, wherein the acid environment is obtained
by
the addition of a mineral acid.
4. Method according to claim 3, wherein the mineral acid is selected from the
group comprising sulphuric acid, hydrochloric acid and combinations thereof.
5. Method according to any one of the preceding claims, wherein the alkaline
environment treatment is carried out at a pH greater than 8.
6. Method according to claim 5, wherein the alkaline environment is obtained
with the addition of an alkaline or an alkaline earth base.
7. Method according to claim 6, wherein the alkaline or alkaline earth base is
selected from the group comprising sodium hydroxide, potassium hydroxide,
calcium
hydroxide and combinations thereof.
8. Method according to any one of the preceding claims, wherein the treatment
duration in an acid as well as in an alkaline environment is above one hour.
9. Method according to claim 8, wherein the treatment duration in an acid as
well
as in an alkaline environment is comprised within the range 1-1.5 hours.


8
10. Method according to any one of the preceding claims, wherein the treatment
temperature in an acid as well as in an alkaline environment is higher than
0°C.
11. Method according to claim 10, wherein the treatment temperature in an acid
as well as in an alkaline environment is comprised within the range 10-
50°C.
12. Method according to claim 11, wherein the treatment temperature in an acid
as well as in an alkaline environment is room temperature.
13. Method according to any one of the preceding claims, wherein the reagent
is
in dispersed form and is mixed to the material to be treated.
14. Method according to any one of the claims from 1 to 12, wherein the
reagent
is placed inside a column or container wherein the material to be treated is
circulated
forcibly.
15. Method according to any one of the preceding claims, wherein the iron
disulphide is the one contained in the mineral pyrite.
16. Method for the demolition and the removal of halogenated and aromatic
hydrocarbons from materials that contain them, as previously described,
exemplified
and claimed.

Description

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Method for the demolition and the removal of halogenated and aromatic
hydrocarbons
from materials that contain them.
The present invention relates to the field of the processing of wastes, both
of
aqueous and of solid matrix, contaminated by halogenated and aromatic
hydrocarbons.
As it is known, according to current laws such wastes must be destroyed by
thermal way or, alternatively, may be incorporated in semisolid materials and
dumped
in specially provided dangerous waste dumps. The latter technique, whose
safety
however, from the point of view of the guarantee of stability over time, has
not been
proved once and for all, presents the drawback of utilising dumps, in case
usable for
more suitable materials, and to postpone the natural transformation, essential
to avoid
negative effects on our planet.
On the contrary, thermal destruction technique constitutes the most widely
encouraged solution for a radical and final elimination of the disposal
problem.
However, given the delicacy of the treatment (formation of demolition
intermediates
and/or of highly toxic substances) this technique requires a particular care,
thereby
making essential the resorting to sophisticated plants with very high costs.
Therefore, in this specific field the demand exists for the availability of a
simple
and low-cost method capable of transforming halogenated and aromatic
hydrocarbons
present in wastes into atoxic materials, without thereby causing negative
environmental
impacts.
The present invention allows to meet this demand thoroughly, further showing
other advantages that shall be evident hereinafter.
Therefore, the subject of the present invention is a method for the demolition
and
the removal of halogenated and aromatic hydrocarbons from materials that
contain
them, characterised in that the materials to be treated is made to react - in
an acid
and/or alkaline environment, or viceversa - with a reagent selected from the
group
comprising zinc, iron, iron disulphide, ferrous sulphide, ferrous sulphate and
mixtures
thereof.
Treatment in acid invironment is preferably carried out at a pH lesser than 6.
The acid environment may be obtained with the addition of a mineral acid,
preferably selected from the group comprising sulphuric acid, hydrochloride
acid and
combinations thereof.

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2
Treatment in alkaline environment is preferably carried out at a pH greater
than 8.
The alkaline environment may be obtained with the addition of an alkaline or
an
alkaline earth base, preferably selected from the group comprising sodium
hydroxide
(NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH)2) and
combinations thereof.
The duration of the acid environment treatment is greater than one hour, and
is
usually comprised within the range 1-1.5 hours. The temperature of the acid
environment treatment is higher than 0°C and is usually comprised
within the range 10-
50°C, room temperature being preferable.
The duration of the alkaline environment treatment is greater than one hour,
and
is usually comprised within the range 1-1.5 hours. The temperature of the
alkaline
environment treatment is higher than 0°C and is usually comprised
within the range 10-
50°C, room temperature being preferable.
Iron disulphide may be the one contained in the mineral pyrite.
The reagent can be utilised in a dispersed form to be admixed to the material
to
be treated, or placed inside a column or container wherein the material to be
treated is
circulated forcibly.
The method according to the present invention presents, besides the advantages
explicitly and implicitly aforementioned, the advantage of preventing the
formation of
new toxic substances and above all, not being a thermodistructive method, of
not
generating new emissions, containing hydrochloric acid and carbon dioxide
among
other things.
The method of the present invention can be advantageously adopted in the
treatment of wastes of different origin, among which the ones hereinafter are
indicated
by way of explanation:
- petrochemical industry tailings;
tailings deriving from craft and tertiary activities that imply the
utilisation of
chloroalkyls and chloroaromatics;
- pitches and distillation tails of chlorinated solvents;
- production wastes contaminated by polychlorodicoumarones,
polychlorodibenzodioxins, active principles made of organic aliphatic and
aromatic
molecules chemically bound with halogens (chlorine, bromine, iodine).

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So far, only a general disclosure of the present invention was given. With the
aid
of the examples hereinafter, a more detailed description will now be given of
its
embodiments, directed towards making the objects, features, advantages and
operative
modalities of the present invention better understood.
Example 1
An oily emulsion originated from a petrochemical plant with the composition
hereinafter expressed as mg/1:
Trans 1-2 dichloroethyl 0.96
Cis 1-2 dichloroethyl 0.81
Chloroform 3.60
1-2 Dichloroethane 313.92
Trichloroethylene 0.16
1-1-2 Trichloroethane 2.40
is treated according to the invention with a mixture constituted of 33.3 % by
weight Fe,
16.7 % Zn and 50 % FeSZ in a ratio of 3 g of mixture per 100 ml of oily
emulsion.
The post-treatment aqueous phase contains 0,18 mg/1 chloroform and 0.05 mg/1
1-2 dichloroethane. The post-treatment solid phase contains only 0.37 mg/1 1-2
di-
chloroethane.
Therefore it is observed that in the aqueous phase the chlorinated products
were
abated from 321.85 mg/1 to 0.23 mg/1 (with a 99.93 % yield), whereas in the
solid
phase the chlorinated products were abated from 321.85 to 0.71 mg/1 (with a
99.88
yield).
Example 2
An oily emulsion originated from a petrochemical plant with the composition
hereinafter expressed as mg/l:
Trans 1-2 dichloroethyl 2.30
Chloroform 6.00
1-2 Dichloroethane 470.00

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Trichloroethylene 0.31
1-2-3 Trichloroethane 4.02
Perchloroethylene 0.24
o-xylene 0.43
is treated according to the invention with a mixture constituted of 75 % by
weight Fe,
25 % Zn in a ratio of 3 g of mixture per 100 ml of oily emulsion. The post-
treatment
aqueous phase contains only 0,17 mg/1 chloroform and 0.13 m1/1 1-2
dichloroethane.
The post-treatment solid phase contains only 0.31 mg/1 chloroform and 0.25
mg/1 1-2
dichloroethane.
Therefore it is observed that in the aqueous phase the chlorinated and
aromatic
products were abated from 482.87 to 0.30 (with a 99.94 % yield) and from 0.43
to 0.00
mg/1 (with a 100 % yield), respectively, whereas in the solid phase the
chlorinated and
aromatic products were abated from 482.87 mg/1 to 0.56 mg/1 (with a 99.88 %
yield)
and from 0.43 mg/1 to 0.00 mg/1 (with a 100 % yield), respectively.
Example 3
An artificial mix prepared in laboratory with water and solid sludge (about 70
%)
and having the composition in mg/1 hereinafter:
1-2 Dichloroethane 729.94
Benzene 370.90
Trichloroethylene 825.47
Toluol 698.08
Perchloroethylene 1358.27
o-xylene 854.04
is treated according to the invention with a mixture constituted of 25 % by
weight
FeS04 and 75 % FeS2 in a ratio of 3 g of mixture per 100 ml of the artificial
mix to be
3 0 treated.
The post-treatment aqueous phase contains only 0.17 mg/1 1-2 dichloroethane.
The post-treatment solid phase contains only 0.43 mg/1 1-2 dichloroethane,
0.01 mg/1
benzene and 0.18 mg/1 o-xylene.

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Therefore it is observed that in the aqueous phase the chlorinated and
aromatic
products were abated from 2913.68 mg/1 to 0.17 mg/1 (with a 99.99 % yield) and
from
1923.02 to 0.00 mg/1 (with a 100 % yield), respectively, whereas in the solid
phase the
chlorinated and aromatic products were abated from 2913.68 mg/1 to 0.43 mg/1
(with a
5 99.99 % yield) and from 1923.02 mg/1 to 0.19 mg/1 (with a 99.99 % yield),
respectively.
Example 4
An artificial mix prepared in laboratory with water and solid sludge (about 70
%)
and having the composition expressed in mg/1 hereinafter:
Trans 1-2-dichloroethyl 0.92
Cis 1-2 dichloroethyl 1.24
Chloroform 4.16
1-2 Dichloroethane 11.66
Benzene 0.76
Trichloroethylene 3.72
1-1-2 Trichloroethane 3.28
Toluol 0.70
Perchloroethylene 5.58
Ethylbenzol 0.98
p-xylene 0.91
o-xylene 0.99
is treated according to the invention with a mixture constituted of 16.7 % by
weight Zn,
33.33 % by weight FeS04, and 50 % FeS2 in a ratio of 3 g of mixture per 100 ml
of the
artificial mix.
The post-treatment aqueous phase contains only 0.07 mg/1 trans 1-2
dichloroethyl, 0.13 mg/1 1-2 dichloroethane and 0.02 mg/1 trichloroethane. The
post-
treatment solid phase contains only 0.43 mg/1 trans 1-2 dichloroethyl, 0.86
mg/1 cis 1-2
dichloroethyl and 1.07 mg/1 1-1-2 dichloroethane.
Therefore it is observed that in the aqueous phase the chlorinated and
aromatic
products were abated from 30.58 mg/1 to 0.22 mg/1 (with a 99.27 % yield) and
from

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4.34 mg/1 to 0.00 mg/1 (with a 100 % yield), respectively, whereas in the
solid phase
the chlorinated and aromatic products were abated from 30.58 mg/1 to 2.36 mg/1
(with a
96.28 % yield) and from 4.34 mg/1 to 0.00 mg/1 (with a 100 % yield),
respectively.