Note: Descriptions are shown in the official language in which they were submitted.
2~7~
The present invention relates to a proce~ for the dis-
po~al of chlorinated organic product~. More particularly, the
present invention relates to a proces~ for the disposal of
chlorinated organic product~ by an oxidation treatment with
hydrogen peroxide (~2) ~ in th~ pre~ence of F~(II) ion~,
optio~ally a~sociated with other transition metal ion~, and of
a phaae tran~fer agent.
Chlorinated organic product~ are a clas~ of 9ub-
sta~ce~ widely u~ed in varlou~ technological f ielda . Among
them, the compound~ ha~ing alkyl, aromatic, or alkylarornatic
structure, such as polychlorobiphenyl~ (PCB~), 1,1,1-
trichloro-2 , 2 -bis (p-chlorophenyl) e~hane (DDT),
tetrachloroethane, dlchloroberLzene~3, chlorophenol~,
hexachlorocyclohexane, or ole~inic ~tructure, ~uch aa
~richloroethylene, are mor~ ~ommo~.
Generally, chlorinated organic products are toxic and
highly polluting products, whose disposal after us~ involves
many problems. In fact, it is necessary to utilize a disposal
process, applicable also on a large scale, which is as m~ch as
possible efficacious, economical and free from risks for the
en~ironment. It is particularly difficult to reach this
optimum objective, since the chlorinated organic products are
very stable and, when treated with chemical and/or physical
means, form highly polluting by-products.
~1~7~
For in9tance, polychlorobiphenyls (PC~) are highly toxic
and cancerogenou3 chloroaromatic compounds, which were broadly
utilized even recently, due to their dielectric properties, as
oils for electrical equipment, and in particular for
capacitors. Due to their high toxicity, the regulations in
foxce impose the elimina~ion o~ PCBs and sub~ti~ution therefor
with hydrocarbon mineral oils. This nec~s~itates removal ~
great amounts o~ PCB~, which usually are either dissolved in
organic solvents (for ~xample h~xachloroben~ene), or
impregnated in isolating and/or supporting materials, such as
paper, paper-board, wood, etc. Further, it i5 oft~n necessary
to remove the PCBs from mineral oils, which could be
contaminated in consequence o~ inadequate cleaning of the
electrical equipment before the replacement.
The mo~t commo~ly utilized trea~ment for the dispo~al of
chlorinated organlc product~ is burning, w~ich i~ carried out
in properly equipped plants in order to prevent the ~ormation
o~ utmo8t toxic chloro-organic compound~, ~uch a~ parachloro-
dibenzodioxine~, parachlorodibenzofuran~ ~nd the like. In any
event, thi~ i~ an expen~ive proces~, not free from risk~ for
thq en~ironment, apart from the fact that it in~olveY the
elimination not only of the chlorinated compou~ds, but al~o of
the materials polluted by them.
The Applican~ has now found a proce~s for the di~posal of
chlorinated organic product~, which compri~es oxidating such
2 ~
products with ~2 in the presence of suitable catalysts and
phase tran~fer agents, with forma~ion of non-toxic sub~tance~
and possibility of reco~ering the polluted material, with con-
~iderable economical and environmental advantages in compari-
son with the processes utilized 80 far.
Accordingly, in one of its a~pects, the present invention
provides a proces~ for the disposal o~ chlorinated organic
products, which comprises treating the product~ with a H20~
aquaous solution, in the pre~encQ of Fe(II) ion~, optionally
in association with one or mor~ transition ~etal ions s~lected
from Cu(II), Ti(IV, Mn(II), Co(II), Ni(II3, ~(IV) and Mo~IV),
and in the presence of a pha~e tran~er ag~nt.
Non-limiting examples of the chlorinated pr~duots to
which the process of the present invention can be applied
include thos~ compounds having:
(a) an aromatic structure, such a~ polyc~lorobiphe~yl~
(PC3s), chlorobe~zene~ t~or i~stance, ortho- and me~ha-
dichlorobenzene), chlorophenols (for instance para-, tri-
and penta-chlorophenol), etc.;
(b) an alkylaromatic ~tructure, ~uch as 1,1,1-trichloro-2,2-
bis(p-chlorophenyl)ethane (DDT), and other~;
(c) an olefinic structure, such a~ trichloroethylene,
perchlorobutadiene, etc.;
(d) an aliphatic or cycloaliphatic atructure, such a~
tetrachloroethane, hexachlorocyclohexane, hydrated chlor-
2 1 ~
al, hexachloroethane, perchloroacetone, e~c.
The reaction involved in the procesl of the present
invention i9 an oxidation reaction in heteroyeneous phase, as
the chlori~ated orgarlic product~3 ar~ inloluble irl the aqueou~
pha~e cont~lning the ~02/F~+ ox~dizing 0y~em. It is important
therefore to include a pha e transfer agent, i.e. o a
produce whiCh act~ a~ a "}:~ridge " b~twe~n ~h~ molecule~ of thechlorinated organic product and the oxldlzing ~y~tem. For an
exhau~ive di~CU~ioA of such product~ ~e~ C. ~tark~, C. ~iot-
ta, RPha~a ~ra~er ca~aly~t~, Acad~ic Pre~ 7a).
Among th~ product~ known i~ th~ art a~ phas~ tran~f er
agent~, the one~ whlch are ad~a~tageou~ly utilizable in the
proce~ of the prese~t i~v~io~ are th@ ~mmo~lum, pho~phonium
or arsonium salt~ of ge~eral ~ormula~/
~ 1 ~"
R~ R4 ~,
,, R9
wherei~:
elected fro~ No P and A~;
Rl, R2, R3 and ~, like or different fro~ one another, are
selec~ed from hydrogen, C~-C35, preferably Cl-C12, alkyl groups,
C6-C,O aryl group~, ~-C~, preferably ~-CI2, arylalkyl or
alkylaryl group~, on condition ~hat at least one out of Rl, ~,
R3 and ~ i~ different ~rom hydrogen;
X~ i~ ~elected from OH-~ Cl-, ~r~, I- and B~-.
Another class of pha~e transfer agen~ useful in the
process of the pre~ent invention i~ repre~ented by th~
pyridinium salts of formula:
R -+N ~ X~
wherein R i~ a Cl-C~ alkyl group, while X~ i~ the same a~
defined above.
A further cla~ of products useful a~ pha~e tran~fer
agents in ~he proce~ of the pre3en~ invention i~ the one of
ephedri~e salt3 ha~ing the formula:
tC~- C~I - C~I - N ( Rg) 3~ + X--
OH C~3
wherein:
R3, like or different ~rom each other, are C,-C6 alkyl group~;
X- i9 the ~ame a~ defined above. ~uch product~ are de~cribed
by Gani V., Tapinte C., Viout P. in ~Tetrahedron Let~ers", p.
4435, 19~3, and by Bun o~ C., Robi~o~ L., Stam M. i~
nTs~rahedro~ ~etter~q, p. 121, 1971.
I~ iB al~o po~ible to utilize mixtureæ of different
pha~ tran~fer agent~, ~o a~ to combine i~ the be t way the
charac~eris~ iC8 of each type of transfer agent, in order ~o
obtain a good mineralization of the chlorine a~om~ a~ well as
a complet2 elimina~ion of the chlorinated orga~ic product~.
Examples of pha e tran~fer agent~ useful ln the pro-
ces~ of the pre~ent in~ren~ion are:
~C4E~9)4N+ X~; tC~ )3N~C3H~ X-- ; (C~ 7)3N+C~
2~7 1~
~C~I}I37)lN ~CH3~2 X~; (C~H9)3P+C~6H33 X~ )3N~CH3 X-;
(C~H~)3AJ3+CH3 X-; (C~H~CH2)N+ (CH3)~ X ; C~l33-+l~ X~; e~cc~
Particularly prefarred embodiments of the phass transfer
agents are the tQtraalkylammonium salts, in which the
alkylff, like or ~i~ferent from one another, have ~ to 35 car-
bon ato~E~, preferably 1 to 12 carbon a~om~.
U~ually, the chlorinateca orgaIl~c produc~ to b~ remo~ad
are pre~ent in amount~3 raLnging ~ro~n 100 ~o 5, OOû ppm, while
the phakle transfer agent ia utilized in conce~tration~,
relative t~ ttle aqueous phase, ranging from 20 to 500 ppm
pre~erably from 100 ~o 300 ppm.
In additiorl to the phase transfer agents, the prs~cess of the
presen~ invention cQmpriQe~3 ~he u~ o Pe ( II ) iOI~ a~ cata -
lyst~, optionally a~3~0clated with one or rnor~ tra~sition metal
ion~3 ~elec~ed from Cu(II), T~ (IV), ~n(II), Co(II), Ni (II),
W(IV) and Mo(IV). Among ~che~, Cu(II) ioIl~ are pre~erred. Me~al
ion~ are added in amount~ uflually rasging rom 50 to 1, 000 ppm
for the Fe (II) ion~ and ~rom 0 to 400 ppm for the other tran-
eition metal iorl~ indicated above. In a preferred e~dbodiment,
mixture~ of Fe(II) ion~3 ar~.d Cu(II), Ti(IV~, P~tII), Co(II),
Ni (~I), W~IV), or ~o (IV~ ion~3 are utilized in equimolar
amounts, each o:E th~m in concentration~3 ranging from 50 to 400
ppm, preferably ~rom 150 to 250 ppm.
The above men~ioned metal ion3 are added in the form of
80~ e ~alts. In particular, a~ to Fe (II) ions, it i3 pO~38-
~1074~
ible to use for in3tance: ferrous sulphate, ferrous chloride,~errou~ nitrate, a~runonium ferrous ~ulphate, etc. E~eptahydrate
~errous sulphate FeSO~ 7H20 i9 preferred ~rom the operative and
economic viewpoint. Among the Cu(II) ~alts, for in~tance
pentahydrate cupric sulphate CuS04- 5H2O can be used.
A~ regards hydrogen peroxide, it i~ utilized in the form
of an aqueous solution, in such amount~ that the molar ratio
of added H22 to initially presen~ chlorina~ed product gen-
erally ranges from 0.2 to 100, preferably from 0.2 to 30. The
concentration of the hydrogen peroxide aqueous ~olution i8 not
a discriminating parameter. To simpli~y the operative
modalities, hydroge~ peroxide solution~ at 30-50~ by volume
are generally u~ed. The hydrogen peroxide ~olution i~ prefer-
ably added gradually and continuou ly to the reaction mixture
in order to more ea~ily control the reac~ion conditions, in
particular temperature and pH. The addition rate usually
ranges from 0.2 to 3 ml/min, but it can b* varied over a wider
range, depending on the ~pecific reaction condition~.
The reaction temperature can vary over a wide range, gen-
erally from 40 to 200C, preferably from 70 to 120C. The p~
generally ranges from 2 to 7, approximately, preferably from 3
to 4, approximately, and it i9 maintained in such range~ dur-
ing the reaction by adding small amounts of a aqueous
solution of an acid (for example H2SO4) or of a base (for
example NaOH).
2~ ~7~
The process of the present lnvention lead~ to a
quantitative conver~ion o~ the chlorinated organic product
into non-toxic products, accompanied with a good
mineralization level of the chlorine atoms, i.e. conversion of
the organic chlorine into chlorine ions.
In the case that th2 chlorinated product to be disposed is
dissolved in an organic solvent or in a mineral oil of hydro-
carbon type, the reaction mixture i~ heated to the prefixed
reaction temperature and then it i9 intensely atirred in order
to bring the two phases into intima~e co~tact, ~hereby obtain-
ing a wa~er/oil macroemul~ion ~the predominaut pha3e being the
organic phase).
The pre~ent invention i~ illu~trated more in detail by
the following Ex~mples, which are given ~erely to illu~-trate and
not to limit the scope o~ the invention.
In each Example, the progress of the reaction wa followed
by withdrawing, after programmed additions o~ hydrogen peroxide,
small amounts of the reaction mixture and by determining the
following parameters thereof:
(a) Concentration of the chlorinated o~ 'c ~roduct.
It i9 determined by gas chromatographic analy~is (2-meter
packed column with fixed phase Tenax~; carrying ga~:
nitrogen temperature program: isotherm at 100C for 2
minutes; gradient at 10C/min. up to 180C; isothenm at
laOC for 25 minutes). Each injection (0.6 ~ carried
2~7~
out with a sample diluted with CH~Cl~ in a 1:1 ratio, to
which CH30H is added a~ an in~ernal standard.
A~ regards PC~s, all the calculati4ns have been referred
to the three main PC~s isomer~, for which the following
compo~i~ion has been determined:
Cl2~7Cl3 : 21.21
C,2H,Cls : O . 95~
Cl2~6 : 77.83%
On ~he basis of ~uch compo~i~ion, an average molecular
weight of 280.5 haY been detenmined, the average number
of chlorine atom~ being equal to 3.74.
(b) Chl~rine ipn conce~ratioa~
The chlorine ions are recovered by mea~ of extraction
with H20 acidi~ied with 0.1~ of HN03 and are analyzed
through voltimetric titration in an acid medium with
AgNO3 .
(c) CO~ (~hemisal Oxy~ ~ Demand).
It is determined by oxidation with pota2siu~ bichromate
in acid medium and titration with ferrous ~ulphate,
according to the method described by N.W.Hanson in "Offi-
cial, Standardized and Recommended Methods o~ Analy~
(page 333, The Society for Analytical Chemistry, 1973).
ExAMpLE~ 1-3
455 ml of a mineral oil contaminated with PCBs (3~31 ppm)
were introduced into a reaction flask equipped wi~h condensex,
2107A55
dropping funnels, pH-meter and magnetic stirrer. There~fter, an
aqueous solution was added consistiny of 45 ml of H2O, in which
~here were dis~olved: FeSO~7H2O and CuS04 5H2O in ~uch amounts
a~ to obtain a concentration of 200 ppm for both the Fe2~ ions
and the Cu2~ ions; tetrabutylammonium hydroxlde (IT~A) in
amount~ equal to:
- 150 ppm (Example 1);
- 300 ppm (Example 2);
- O ppm (Example 3, comparative).
The re~ulting mixture wa~ heated in an oil bath to 95C
and the p~ was adjusted by mean~ of 3mall addition3 of a 10%
NaOH aqueous solution or of a 15~ ~S04 aqueou3 solutions until
a value of about 3.0 wa~ obtained. The mixture wa3 inten~ely
stirred in order to form a water-in-oiil macroemul~ion. Then, a
~2 aqueou~ solution (45% by volume) was gradually added at a
rate of about 0.6 ml/min. After programmed addition~ of hydro-
gen peroxide (as indicated in Table I), reaction mixture
3amples (5 ml each) were drawn for the analysis. For each
~ample, the residual PC~s concentration ([PCB~) and the
chlorine ion concentration ([Cl-]) were determined according
to-the above described modalities. The results are reported in
Table I, where also the mineralization per cent (~[Cl-]) is
indicated, expressed as ratio between the actually obtained
Cl- ion concentration and the maximum obtainable Cl- ion con-
centration.
2~7'1~
During the reactiOn, the pH was maintained around 3.0 by
means of 9mall addi~ionS (0.1-0.3 ml) o~ the NaOH or H2SO~ sol-
utions, while the temperature was maintained constant at 94C.
The reaction with 150 ppm of ITBA (Exc~mple 1) and the one
without ITBA (Example 3) lasted 60 minute~, while the reaction
with 300 ppm of IT~A (Example 2~ la~ted 95 minute~.
From ~ comparison between the obtained data, it is
noteworthy, first of all, that, without the aid of the phase
transfer agent, no PCBs oxidation occurs. With the addition of
the phase transfer agent~ an almost complete PC~s elimination
i~ obtained, with a satisfactory mineralization degree, in
particular in the case of the reactlon with a low ITBA concen-
tration (Example 1).
EX~MPLES 4-
~
Following the same modalities de~cribed for Examples 1-3,
the effectivenes5 of another pha~e tran3fer age~t, tetrabutyl-
ammonium bromid~ (TBA~), was checked by comparing the follow-
ing reac~ion~:
- with 150 ppm of TBA~ (Example 4);
- with 472 ppm of T~AB (Example 5);
- . without T~A~ (Example 6, comparative).
The data obtain~d are reported in Table II. As for Examples
1-3, it is possible to observe that without the phase
trans~er agent the reaction does not occur and that ~he be~t
result~, in terms of PC~8 oxidation a~ well a~ of PCBs
2~7'1~5
mi~eralization, are obtained with low concentrations o~ trans
~er agent ( E.YamP1e 4 ) .
EXAMP L E S 7 - 9
Following the sante modalities described for Examples 1-3,
the effectiveness of another phase transfer agent,
tetrabu~ylammonium iodide (TBAI), was checked by comparing the
following reac~ions:
- with 166 ppm of TBAI (Example 7~i
- with 460 ppm of TBAI (Example a);
- without TB~ (Example 9, compara~ive).
The data obtained are reported in Table III.
EXA~PL~S lQ-ll
Following the same modalities described for Examples 1-3,
the effective~e~s of a phase tran~fer age~t mixture (ITB~ +
TBA~) was checked by comparing the following reactions:
- with 100 ppm of ITBA ~ 100 ppm of ~AB (Example 10);
- wi~hout pha~e tran~fer age~ts (Example 11, comparative).
The data obtained are reported in Table IV.
From a comparison of the result~ of Example 10 with the
ones obtained in Examples 1, 4 and 7, it i9 evident that the
coupling of the two phaqe transfer agents of Example 10
permits the desirable combination of a subs~antially quantitative
PCBs oxidatio~ with a good PCBs mineralization degree.
EXAMP~ 12
The same reactor utilized for the preceding Examples was
~7~
filled with 500 ml of H~O, irl which the following products
were dissol~ed: FeSO, 7H~O and CuS04 5H~O in such amounts as to
ohtain a 200 ppm concentration for both Fe3~ and Cu2~ ions;
tetrabutylammonium hydroxide (IT~A) in an amount equal to 150
ppm.
20 g of PCBs-contamined paper, which had been previously
cut into small pieces, were then introduced into the reactor.
The PC~s concentration in the paper was equal to 106~ ppm. It
was determined on a paper sample (1 g) by means of continuous
extrac~ion at room temperature for 14 hours with 20 ml or
CH~Cl2. The PCBs-containing solvent was then analyzed via gas
chromatography usi~g methanol as internal standard.
Maintaining the solution under inten3e ~tirring, a 45~
hydrogen peroxide aqueous ~olution was gradually addad until a
total ~2 concentration equal to 127.5 g/l was obtained. On
conclu ion of the reaction, the chloride ion concentration was
determined in the aqueous phase through voltimetric titration
in an acid medium with AgNO3. The residual PCBs concentration
both in the aqueous pha~e and in the paper pulp wa~ determined
via ga3 chromatography after extraction with CH2Cl2, as
described hereinabove. The data obtained are reported in
Table V.
EX~MPLE 13 loxidation of hexachlorocyclohexane~
0.5 g of hexachlorocyclohexane ~ECE) were introduced into
a 250 ml round-bottomed reaction fla~k equipped with dropping
- 13 -
2 1 ~ 7 1 ~ ~
funnel~, pH-meter and magnetic stirrer. Thereafter, an aqueous
solution was ~ddeà corlsistlng of 100 ml o~ H20, in which:
FeSO~-7H20 and CuS04- 5H20 in such amounts to obtain a concentra-
cion equal to 200 ppm for both Fe2+ and CuZ+ ions;
tetrabutylammonium hydroxide (ITBA~ in amounts equal to 500
ppm, had been dis~olved.
The re3ulting mixture was heated in an oil bath to 95C;
the pH was adjusted at a value o~ about 3.4-3.5 by means of
9mall additions of a 15~ H2SO4 aqueous solution or of a 10%
NaOH aqueou~ solu~ion. The mix~ure wa~ in~en~ely stirred in
order to dissolve all ECE. Then, a H202 aqueous qolution (56%
by volume) wa~ gradually added at a rate of about O.4 ml/min.
A~ter programmed addi~ions Of ~2 (as indicated in Table VI),
reaction mixture ~amples (5 ml each) were drawn for analy3i~.
In Table VI, the added amounts of H202 are reported a~ nu~ber of
stoichiometric equivalents. By stoichiometric equivalent is
meant the theoretical amount o~ H202 (100%) necessary for the
complete oxidation of the organic ~ub~tances to CO2 and H20.
For each 3ample, the residual ECE concentration ([ECE]),
the COD and the chlorine ion concentration ([Cl-]) were deter-
mined according to the above described modalities. The result~
are reported in Table VI, where al~o the mineralization per
cent (~[Cl-]) i9 indicated, expresged as ratio between the
actually obtained Cl- ion concen~ration and the maximum
obtainable Cl ion concen~ration.
- 14
2~07ll55
During the reaction, the pH was maintained around 3.4 by
means of small additions (0.1-0.2 ml) of the NaOH or H2SO~ sol-
utions, while the ~emperature was maintalned constant at 97C.
EXAMPLE 14 (oxidatlon of metha-chl~Qr~Qa~gç~
1 g (O.766 ml) of metha-dichlorobenzene (MDB) was intro-
duced into a sOo ml round-bot~omed reaction fla~k equipped
with dropping funnels, pH-meter and magnetic stirrer. There-
after, an aqueou~ 301ution wa~ added consisting of 200 ml of
H20, in which: FeSO4 7H20 and CuS04 5~0 in ~uch amounts to
obtain a concentration equal to 200 ppm for both Fe2* and Cu2~
ions; tetrabutylammonium hydroxide (ITBA) in amounts equal to
500 ppm, had been dissolved.
The resulting mixtur~ wa~ heated in an oil bath to 95 c and
the pH was adjusted at a value of about 3.5 by means of small
additions of a 15% H~S04 aqueous 301ution or of a 10% NaOH
aqueou~ solution. The mixture was inten~ely ~tirred in order
to dissolve all MDB. Then, a H2O2 aqueous solution (60~ by vol-
ume) was gradually added at a rate of about 0.44 ml/min. After
programmed additions of H2O2 (as indicated in Table VI), reac-
tion mixture samples (20 ml each) were drawn for analysis. For
each sample, the residual MD~ concentration ([MD~]) and the
chlorine ion concentration ([Cl-]) were determined according
to the above described modalities. The re~ults are reported in
Table VI, where al~o the mineralization per cent (~[Cl-]) is
indicated, e~pres~ed as ratio between the actually obtained
- 15 -
~a7 ~5a
Cl ion concentration and the maximum obtainable Cl- ion con-
c~ntration.
During the reaction, the pH was maintained around 3.5 by
means of small additlons (0.1-0.2 ml) of the NaOH or H2S04 sol-
utions, while the ~emperature was maintained constant at 97C.
EXAMPLES 15-17 (oxidatiQn of chlorophen~s~
6.25 g of para-chlorophenol (PCF) (Example 15), or 0.25 g
of trichlorophenol (TCF) (Example 16), or 0.25 g of
pentachlorophenol (PECF) (Example 17), were introduced into a
500 ml round-bottomed reac~ion flask equipped with dropping
funnels, p~-meter and magnetic stirrer. Thereafter, an aqueou~
~olution was added con3i~ting of 250 ml of H20, i~ which:
FeSO4-7H20 a~d CUS04- 5~0 in ~uch amounts to obt~in a concentra~
tion equal to 200 ppm for both Fe2+ and Cu2+ ions;
tetrabutylammonium hydroxide (ITBA) in amounts equal to 500
ppm, had been di~301ved.
Th~ resulting mixture wa heated in an oil bath to 95 C and
the pH was adjusted at a value of about 3.0 by mean~ of small
additions of a 15% H2S04 aqueous 301ution or of a 10% NaOH
aqueous solution. The mixture was intensely ~tirred in order
to dis~olve all PCF, TCF, or PECF. Then, a H2O2 aqueous 301-
ution (50~ by volume) was gradually added at a rate of about
O.2 ml/min. After programmed additions of H2O2 (as indicated in
Table VII), reaction mixture samples (5 ml each) ~ere drawn
for analysis. For each sample, the residual PCF, TCF, or PECF
- 16 -
21 ~ 7 1 5 t~
concentratiOn ([PCF], [TCF], [PECF]), the COD and the chlorine
ion concentration ([Cl-]) were deter~ined according to the
above described modalities. The results are reported in Table
VII, where also the mineralization per cent (~[Cl-]) is indi-
cated, expressed as ratio between the actually obtained Cl-
ion concentration and the maximum obtainable Cl- ion concen-
tration.
During the reaction, the pH wa~ maintained around 3.0 by
means of small additions (0.1-0.2 ml) o~ the NaOH or H2S04 ~ol-
utions, while the temperature wa~ maintain~d con~tant at 97C.
2~07'~
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