Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~ ~23~
The present invention relates to the removal of heavy metals,
transition metals and actlnide metals from solution and in particular
to the removal of copper, lead or uranium from solution,
~ s a res~lt of previous refining processes, traces of copper
are sometimes present in distillate fuels such as automotive and
aviation gasolines and aviation kerosines. Copper is undesirable
because it is an oxidation catalyst which promotes the formation
of gums and resins which affect the performance of an engine.
It is current practice to combat the adverse effect of copper
by adding a copper deactivator to the fuel.
A further problem which is assuming increasing importance
from the point of view of environmental protection is the removal
of lead from automotive gasolines. As a result of pressure for
- the reduction of lead levels, low lead and lead~free gasolines
are becoming available, but these cannot be used in equipment
previously used to convey or dispense gasoline with higher lead
levels because of the risk of contamination unless the equipment
is thoroughly cleaned,
As a result of the growing demand for uranium as a nuclear
fuel, the recovery of uranium from solutions produced in the
hydrometallurgical processing of uranium bearing materials is also -~
of major importa~ceO
We have now discovered a material w~ich can be used for
removing metals from solutions,
Thus according to one aspect of the present invention there
i~ provided a product, suitable for the removal of heavy metals,
transition metals and actinida metals from solution, obtained
by reacting an inorganio solid containing surface hydroxyl groups
in a first stage with a compcund of formula (I)
3~
Y - Si - R - C~2 - X (l)
whexein R i~ a divalent organic group containing up to 20 oarbon
atoms, Rl and R are halogen atoms or organio radicals oontaining
up to 20 carbon atoms, Y i8 a halogen atom or an -OR~ group in
which ~3 repres0nts a H atom or an alkyl, aryl or acyl group
containing up to 20 carbon atoms, and X i~ a halogen atom; and ~ ~
reacting the product of the first stage with a polyamine of general ~ ~ -
formula (II)
~HR [ (CR 2~n NH ] m (CR 2)n NHR
wherein R4, R5, ~6 and R7 represent H atom~, alkyl or aryl group~
containing up to 20 oarbon atoms and may be the same of different7
n i9 an integer between l and 5, and m i~ an integer between l
and 5, or a polyamine of formula (III)
CH2 ~ \ ~CE _ (III)
C~2 T2 CIH2 :
NH2 NH2 NH2
The inorganio solid containing surfaoe hydroxyl groups may
be alumina, titania, zirconia, glass, sepiolite, or a zeolitic
moleoular sieve. Preferably the inorganio solld is ~ilica and
more preferably ~ilioa gel. In addition mixtures of inorganic
~olids may be u3ed. ~nle~s they have been sub~eoted to severe
treatment~, e,g " heating above 1000C, all oommercial silioas
contain ~urface hydroxyl group~. However for the removal of metal~
from alkaline media, under whioh condition~ ~ilica would be ohemioally
attacked, it is prefer~ed to employ an alkali resistant inorganic
~olid containing surfaoe hydro~yl group~.
~23f~i
R and R2 in the compound of formula (I) may be halogen
atoms or alkyl, aryl, arylo~y or alkoxy radicals and may be the
same or different. Preferably Rl and R are alkoxy or aryloxy
groupe~ Preferably the group Y i9 an alkoxy group and the groups
Rl and R2 and Y are identical alkoxy groups~
R in the compound of formula (I) i8 suitably an alkylene
group containing up to 6 carbon atoms and i~ preferably a dimethylene
group.
R4, R59 R and R7 are preferably H atoms, n is preferably
2 and m i9 preferably 1, 2 or 3.
In the case of 3ilica and the compound of formula (1) the
substrate is believed to be formed by the reaction represented
by the following equations-
Rl
Si - OH + Y - li - R - CH2 - X
- Si - - Si - R - CH2 - X ~ HY
R
~owsver the invention is not intended to be restricted in any way
by the above ~quation repre~enting the formation of the ~ubstrate.
In the fir~t stage the reaction may be effected by warming
the reactante together, e.g., t~tder reflt~ in the presence of an
inert ~olvent for the compound of formula (I) for 1 to 3 hours
and thereafter separating the product, A ~uitable solvent for
the compound of formula (I) i~ toluene.
In the second st~ge, the reaction between the first stage
product and the polyamine may take place in the absence or presence
of a solvent, The reaction takes place at elevated te~perature,
suitabl~ in the range 50-300C. Suitable solvents include ethers
~nd their derivativea 3uch as that sold under the Trade Name "Diglyme".
-- 4 ~
According to another aspect of the present invention there
i~ provided a proce~s for the removal of heavy metal~, transition
metals and actinide metal3 from 301ution, which process comprises
contacting the solution with the 0econd s-tage reaction product as
hereinbefore described and recovering an effluent of reduced metal
content.
The term heavy metal within the context of th0 present
application is intended to mean those metal~ in the B sub-groups
of Group~ I to VI of the Periodic ~able according to Mendeleef.
The process is particularly applicable to the removal of the heavy
metals copper and lead. ~ransition metal within the context of
this application i0 defined a~ a metal which has an incomplete
d-shell of electron3 in it~ electronic configuration. The term
transition metal may be further sub-divided into non-noble transition
metal~ e.g., manganese, iron and cobalt, and noble transition metals,
which are transition metals generally con3idered to be highly
reaiRtant to oxidation The term actinide metal i9 defined as
a metal with an atomic number equal to or greater than B9 in the
Periodic Table of Elements,
It is clearly economically advanta~eous to operate at ambient
temperature and in mo~t cases~ if not all, the product will function
effectively at thi~ temperature, It will also remove metals at
higher temperatures if the feedstock is ~upplied at elev~ated temperature.
~he BubBtrate i3 thought to remove the metal~ by complex compound
formation throu~h the donor ligands bonded to the inorganic surface,
Wh0n the substrate loses its activity for removing metals
it may either be disposed of without removing the metals or the
metals may be removed by means known to those skilled in the art.
One such method for removing the metal from tha sub~trate is to
¢ontact the metal loaded ~ubstrate with an aqueous 001ution of a
-- 5 --
3~;
mineral acid followed by separa-tion of the aqueous solution containing
the metal from the substrate. The mineral acid should be chosen so
that the resultirlg me-tal salt is soluble in the treating solution.
Thus for example9 hydrochloric acid is suitable for copper removal
but not for lead. Nitric acid shou~d be employed for the latter.
Thereafter the metal may, if desired, be recovered from the aqueous
solution by methods well known in the art.
~ he solution containing metals may be contacted with the
substrate batchwise, or9 preferably continuously by passing the
solution over a bed of the substrate mounted in a suitable reactor,
The invention is illustrated by the following Examples:-
Example 1
ane with Silica
Acid washed silica gel (lOO g) was suspended in toluene
(500 ml) and distilled water (50 ml) added. ~he mixture was stirred
at room temperature for 2 hours and then warmed to reflux. The
residual water was distilled from the reaction flask and collected
in a Dean and Stark receiver, which was periodically drained,
After cooling to room temperature ~-chloropropyl trimethoxy silane
(100 ml) was added to the fla~k and the mixture stirred and warmed
to reflux for 3 hours. ~he methanol liberated was distilled off
and collected in a Dean and Stark receiver, which again was periodically
drained. After cooling the silica was transferred to a Soxhlet
apparatus, extracted with methanol for 24 hours and finally dried
in vacuo.
On analysis the silica product contained 1.55 per cant weight
chlorine.
Example 2
The ohloro-silica (20 g) prepared as described in ~xample l,
- 6 --
23~6
was added to triethylene tetramine (lOO ml) contained in a 250 ml
flask under an atmosphere of dry ni-trogen The mixture was stirred
and warmed to 195 - 198 C for 24 hours. After cooling to room
temperature, the residual liquid was decanted and the silica
transferred to a Soxhlet apparatus. Soxhlet extraction using dry
methanol under a nitrogen atmosphere was maintained for 18 hours,
the silica finally being dried in vacuo.
On analysis the product contained 1.96 per cant weight nitrogen.
Reaction_of Chloro-silica with Tetraethylene Pentamine
Tetraethylene pentamine (100 ml) was added to the ohloro-
silica (20 g) prepared as described in Example 17 and contained
in a 250 ml flask under an atmosphere of dry nitrogen. The mixture ~-
was stirred and warmed to 195 - 200C for 24 hours. After cooling
to room temperature, the silica was transferred to a Soxhlet apparatus
was finallg dried in vacuo.
On analysls the product oontained 2.28 per cent weight nitrogen.
~ .
Reaction of_Chloro-silica with 2?Z~2"-triaminotrieth ~amine
The chloro~silica (20 g) prepared as described in Example 19
was suspended in Diglyme (75 ml) under a nitrogen atmosphere.
2,2',2"-triaminotriethylamine (20 ml) was added and the mixture
stirred and heated to reflux temperature for 24 hours~ After cooling,
the silioa was transferred to a Soxhlet apparatus, extracted with
methanol for 24 hours and finally dried in vacuo.
On analysis the product oontained 1,50 per oent weight nitrogen.
Conoentrated Jet A-1 Aviation Spirit oontaining 170 ppb of
soluble oopper was pumped at a liquid hourly spaoe velocity of
11~239L6
9,7 - lO,l and at ambient temperature and pressure, over a flxed bed
of amino-silica (2 ml), prepared as described in Example 2, which was
contained in a glass microreactor. Hourly product samples were collected
and analysed for copper content Analysis showed that the copper
content of the product samples was 25 ppb for the 7-hour duration
of the test.
am~le 6
Concentrated Jet A-l Aviation Spirit containing 120 ppb of
soluble copper was pumped at ~ liquid hourly space velocity of
lO, and at ambient temperature and pressure, over a fixed bed of
amino-silica (2 ml~, prepared as described in Example 3, which
was contained in a glass micro-reactor. Hourly product sa~ples
were collected and analysed for copper content. Analysis showed
that the copper content of the product samples was 20 ppb for the
7-hour duration of the test.
Example~
Concentrated Jet A-l Aviation Spirit containing 170 ppb of
soluble copper was pumped over the amino-silica (2 ml), prepared
aq described in Example 4, and using the same conditions as
de3cribed in Example 6, Analysis of the hourly product samples
showed that the copper oontent was 25 ppb for the 7-hour duration
of the test.
A solution of anhydrous ferrous chloride dissolved in acetone
was added to an acetone su~pension of a N-alkyl-triethylene tetramine
ligand-~ilica, prepared as described in Example 2, under an atmosphere
of dry, dsoxygenated nitrogen. After stirring the reaction mixture
for 2 hours at room temperature the silica was isolated by filtration.
Any residual f0rrous chloride was removed by washing the silica
with acetone, acetone oontaining a few drops of n-butyric acid and
-- 8 --
3~6
finally acetone again. The produce was finally dried in vacuo.
On analysis the silica contained 1.27 per cen-t weig~ht iron,
A solution of ferrous sulphate acidified to a pH of approximately
2 with diLute ~ulphuric acid, was added to a N-alkyl-triethylene
tetramine ligand-silica and the mixture stirred for 2 hours at
room temperature, under a nitrogen atmo phere The silica was filtered
off, washed free of any residual ferrous sulphate with very dilute
sulphuric acid, then water and finally acetone. 'rhe product was
finally dried in vacuo. On analysis the silica contained loO9
per cent weight iron.
A solution of anhydrous ferrous chloride dissolved in acetone
wa3 added to an acetone suspension of a N-alkyl-tetraethylene
pentamine ligand-silica, prepared as described in Example 3~ under
an atmosphere of dry, deoxygenated nitrogen. After stirring the
reaction mixture for 2 hours at room temperature the silica was
isolated by filtrætion. The silica ~la~ freed from any residual
ferrous chloride by washing with acetone7 then acetone containing
a few drops of n-butyrio acid, and finally acetone again. The
product was finally dried in vacuo. On analysis the silica was
found to contain 0 54 per cent weight iron.
~a~ :
A solution of anhydrou~ ferrous chloride dissolved in acetone
was added to an acetone suspension of a N-alkyl-2,2~,2";triaminotriethylamine
ligand-silica, prepared as deccribed in Example 4, and the reaction
mixture stirred for 2 hours at room temperature under an atmosphere
of dry, deoxygenated nitrogen. ~he silica was isolated by filtrationt
washed free from any re~idual ferrous chloride with acetone, acetone
containing a few drops of n-bu~yric acid and finally acetone again.
2~4~
The silica was finally dried in vacuo. On analysi6 the product was
fo~md to contain 0.19 per cent waight iron.
~1~ .
250 ml of an aqueous solution of uranyl nitrate containing
.79 K of Uo2(No3)26X2o was stirred with 1.59 g of the triethylene
tetramine functionalised ~ilica, prepared as described in Example 27
for 4 hours at room temperature. After allowing the mixture to
stand for 26 hours the silica product was transferred to a Soxhlet
appaxatu6 and extracted with water for 8 hours, followed by methanol
for 24 hours. ~he silica was finally dried in vacuo. On analysis
the silica was found to contain 3.1 per cent weight uranium.
~ . .
200 ml of a dilute sulphuric acid solution of uranyl sulphate
containing 1.69 g of U02S04~H20 was stirred with 1.39 g of lhe
triethylene tetramine functionalised silica, prepared as described
in Example 2, for 5 hours at room temperature. After allowing the
mixture to stand for 18 hours the silica product was transferred to a So~hlet
apparatus and extractcd with water for 18 hours followed by methanol
for 8 hours, The silica was finally dried in vacuo. On analysi~ the
silica was found to contain 0.9 per cent weight uranium.
200 ml of a dilute sulphurio ac1d solution of uranyl sulphate
containing 1.29 ~ U02S043~20 was stirred with 2.11 g of the acid
w~shed U30 silica ba~e for 5 hour~ at room temperature. After allowi
the ~ixture to stand for 18 hours the silica product was transferred
to a ~oxhlet apparatus and e~tracted with water for 18 hours followed
by methanol for 8 hours, ~he silica was finally dried in vacuo.
~n analy~is the ~ilica was found to contain 0.1 per cent weight
uranium.
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