Note: Descriptions are shown in the official language in which they were submitted.
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SELF-INDICATING NEUTRALIZING COMPOSITIONS
Background of Invention
Wash water that has been used to clean equipment that has been exposed to
substances
which are highly alkaline or acidic, for example, water used to wash cement
mixing
equipment, will o$en not be at a neutral pH at the end of washing. The wash
water will thus
require neutralization before disposal, to comply with environmental
regulations, This is
usually achieved by addition of a neutralizing agent, and the achievement of
an appropriate
pH is verified by testing. This can be time-consuming. In addition, in the
case of cement
mixing equipment, such as mixer trucks, stationary mixers and chutes at job
sites, the
quantity of residual material is variable, and this makes estimating the
amount of
neutralizing agent difficult. This means that multiple additions of
neutralizing agent and
subsequent testing are often needed.
What is needed in the art is a neutralizing agent that can indicate when the
solution is
neutralized without the need for measuring pH.
Summary of Invention
The present invention provides a unitized, self indicating, neutralizing
composition
comprising a neutralizing agent, a binding agent, and a pH indicator.
The present invention also provides a method of neutralizing a solution to
about a neutral pH
comprising adding a sufficient amount of a unitized, self indicating,
neutralizing
composition comprising a neutralizing agent, a binding agent, and a pH
indicator to the
solution, until the solution has about a neutral pH as indicated by the pH
indicator, wherein
the neutralizing composition dissolves into the solution to effect
neutralization.
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Brief Description of Drawings
Figure 1 illustrates one embodiment of the present invention wherein the self
indicating
neutralizing composition is severable into smaller units.
Detailed Description
The composition is unitized to provide ease of use for adding the composition
to the
solution. By "unitized" it is meant that the composition is solid and in a
single unit of
suitable size, as opposed to, say, a powder. Such units are generally prepared
by
compaction. Any known method of compacting powdered or flake solid materials
may be
used to produce the self indicating neutralizing compositions. Examples of
such methods
include extrusion moulding ofthe self indicating neutralizing composition,
pressing,
stamping or tabletting, and moulding, such as by melting and pouring into a
shaped mould.
The composition can be unitized into any desired shape, preferably a tablet or
puck shape.
There are cases where compaction is unnecessary; these will be further
discussed
hereinunder.
The result of any such compaction should be that the composition has
sufficient strength to
allow handling, but is also sufficiently friable to break down under
conditions of use and
allow the composition to perform its function.
The composition is added to a solution that is not at a neutral pH to bring it
to a pH that is
about neutral, that is, between about 5.5 and about 8.5.
The neutralizing agent may be an acid or a base. Preferably, the neutralizing
agent comprises
an organic chemical.
Examples of suitable neutralizing agents include, but are not limited to,
citric acid, acetic
acid, phosphoric acid, succinic acid, phthalic acid, uric acid, stearic acid,
lauric acid, pahnitic
acid, oleic acid, oxalic acid, tartaric acid, malic acid, lactic acid,
carbonic acid, boric acid,
sulfuric acid, nitric acid, hydrochloric acid, benzoic acid, monosodium
citrate,
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monopotassium citrate, KHS04, NaHS04, KHZPO~, and mixtures thereof. Generally,
the
neutralizing agent is present to the extent of from 45% to 85% based on the
weight of the
composition. Preferably, the neutralizing agent is present to the extent of
from 65% to 75%
based on the weight of the composition.
Examples of the binding agent include, but are not limited to, polyethylene
glycol,
polyoxypropylene glycol adducts, polyoxyethylenestearate, polyvinylbutyral,
polyvinyl
alcohols, paraffin, polyvinylacetate, polyvinyl methyl ether-malefic anhydride
(PVMIMA),
cellulose,~talc, clays, silicates, silica fume, fumed silica such as "Aerosil"
(trade mark),
precipitated silica gel, organic pigments, synthetic resins, and mixtures
thereof. Generally,
the binding agent is present from 5% to 25% based on the weight of the
composition.
Preferably, the binding agent is present from 6% to 15% based on the weight of
the
composition.
Examples of the pH indicator include, but are not limited to, phenol red,
phenolphthalein,
cresol red; metanil yellow; m-nitrophenol; curcurmin; alizarin; alizarin
yellow R; alizarin
blue; methyl orange; litmus; Congo red; bromthymol blue; chlorphenol red;
cresol purple;
brilliant diazol yellow; salts of phenolphthalein; neutral red; acid R
phosphine, Gleves acid;
coumaric acid; 3,6-dioxyphthalic dinitrile; magnesium 8-hydroxyquinolinate; j3-
methylumbelliferone; 1-naphthol 4-sulfonic acid; orcinaurine; patent
phosphine; thioflavine;
umbelliferone; and mixtures thereof. Preferably, the salts of phenolphthalein
are selected
from the group consisting of sodium, disodium, potassium, and mixtures
thereof. Generally,
the pH indicator is present from 0.001% to 0.8% based on the weight ofthe
composition.
Preferably, the pH indicator is present from 0.1 % to 0.8% based on the weight
of the
composition. More preferably, the pH indicator is present from 0. I % to 0.4%
based on the
weight of the composition.
Additionally, the composition may include a disintegrant to aid in dissolving
the
composition in the solution. Preferably, the disintegrant is an effervescing
disintegrant,
activated by contact with the aqueous solution to be neutralized. Examples of
suitable
disintegrants include, but are not limited to, lithium carbonate, lithium
bicarbonate, sodium
carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate,
caesium
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carbonate, caesium bicarbonate, ammonium carbonate, ammonium bicarbonate,
lithium
phosphate, sodium phosphate, potassium phosphate, caesium phosphate, ammonium
phosphate, borax, magnesium carbonate with citric acid, potassium bitartrate,
potassium
biphtbalate, potassium oxalate, potassium hydrogen phthalate, alkaline
perborates,
perchlorates, permaganates, chlorates, potassium tetraborate, sodium carbonate
peroxide,
tarfiaric acid, Rochelle salt (potassium sodium tarixate), citric acid,
potassium hydrogen
tartrate, NR.q.+ carbonate ((NR4~ZC03), NR4''~ bicarbonate ({N12~.~2C03),
peroxides,
hyperoxides, materials that liberate nitrogen, and mixtures thereof, wherein R-
-C,lH2n+1,
~6H4CnH2n+1~ or C6H4X,.~'c'herein n is an integer from 1 to 24, and X is
selected from the
group consisting of COOH, polyethylene oxide, alkyl sulfonate, and mixtures
thereof.
Preferably, n is an integer from 8 to 18. Suitable examples of materials that
liberate nitrogen
include, but are not limited to, hydrazine, compounds containing an azo group,
and azides.
Generally, the disintegrant is present to the extent of from 1% to 30% based
on the weight of
the composition. Preferably, the disintegrant is present to the extent of from
3% to 21%
based on the weight of the composition.
The composition can also include other additives for manufacturing as needed.
Examples of
the other additives include, but are not limited to, dyes, pigments, dyeing
assistants,
colorants, tannins, colloidal material, toners, clays, tales, barytes,
whitening agents, mould
release agents, lubricants, and mixtures thereof. Generally, the quantity of
additives present
is up to 70% based on the weight of the composition. Preferably, the additives
are present to
the extent of up to 12% based on the weight of the composition.
When the unitized composition is to be formed by compaction, it is preferable
to add inert .
fillers to the self indicating neutralizing composition. This helps render
individual units
structurally stable for physical handling and storage, and/or facilitate the
rapid breakdown by
dissolution and/or fragmentation of the unit when added to an aqueous
solution. These
characteristics are obtained by balancing the addition percentage of inert
filler and the
compacting pressure, to provide a self indicating neutralizing composition
unit of desired
physical integrity and stability, and of desired solubility, friability or
fragmentability. The
provision of a suitable structural stability is within the routine skill of
the art.
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Fillers may be present in the self indicating neutralizing composition in an
amount of up to
50% by the weight of the composition, if the sole function of the filler is as
a filler.
However, if the filler performs another function in the composition in
addition to acting as a
filler, it can be present in an amount of up to 95% based on the weight of the
composition.
Preferably, the amount of filler in the composition is from 5% to 15% based on
the weight of
the composition.
Examples of suitable fillers include silica sand, silica fume, other natural
or synthetic silica-
based materials, "Micro-Cell" (trade mark) E silica (Celite Corp.), silicates,
calcium
aluminosilicate, aluminosilicates, clays, alumina, .ALUNDUM (trade mark)
aluminosilicates
(Norton), zeolites, ceramic spheres, ffy ash, limestone powder, and finely
divided or
powdered plastic.
Preferably, the neutralizing agent, the pH indicator, the binder, the
disintegrant, and any
other additive in the composition are solids. If it is desired to use liquid
components, these
may be processed into solid compacted units by adsorbing them on to carriers,
which are
advantageously the inert fillers hereinabove described. The carriers are
contacted by the
liquid components, and preferably at least partially dried, such as by air
drying, prior to
compaction. For water-alcohol-borne materials, the carriers are fully dried to
prevent
reaction with other components when compacted. Carriers are preferably present
in the
composition from 5% to 25% by weight of the composition.
In yet another embodiment of the present invention, soluble solid self
indicating neutralizing
composition materials may be dissolved in a suitable liquid solvent, such as
water, and the
resulting solution impregnated or adsorbed on to carriers by contacting the
carrier with the
solution, and preferably at least partially drying, prior to compaction.
Similarly, insoluble
solid admixtures may be slurried in a liquid and the carrier contacted with
the slurry to form
a coated carrier prior to compaction.
The self indicating neutralizing composition units according to the present
invention are
sized so as to deliver a selected amount of pre-measured self indicating
neutralizing
composition to a desired or standardized volume of aqueous solution.
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It is within the scope of the invention to use multiple units for a given
volume of aqueous
solution. It is further within the scope of the present invention for the self
indicating
neutralizing composition 11 to be compacted into a unit 10 which is severable,
such as by
S providing perforations 12 of the compact or the like, to provide selected,
structurally stable
fractions for smaller volumes of aqueous solution. (Fig. l .)
For practical considerations, the unit size is preferably small, so as to
provide the most
efficient packing and ease of handling. A preferred size of the unit is such
that it can deliver
sufficient self indicating neutralizing composition for about 15 litres.
For ease of handling and storability, the self indicating neutralizing
composition compacted
units are preferably somewhat moisture resistant. Such moisture resistance may
be imparted
by the selection of an appropriate binder, preferably a binder which breaks
down at a pH
experienced by the unit in the aqueous solution, which may be at pH 11 and
above. If such a
binder is used, it is possible to produce a self indicating neutralizing
composition article
without compaction.
For situations where the composition units must be stored in a substantially
water-free
environment, they may be stored individually, but preferably in number, in a
sealable plastic
bag such as those sold under the trademark "Zip-Loc". Any water-insoluble
container,
however, is suitable for such storage, so long as it is water-impermeable and
not water-
degradable.
In a further embodiment of the invention, the compacted unit is coated with a
material that is
at least partially insoluble in water. Coating the compacted unit with a
material that is
substantially insoluble in water enhances the storage capabilities of the
compacted unit in a
moist environment and protects any hydroscopic components present in the self
indicating
neutralizing composition. Such a water-insoluble coating should be capable of
breaking or
dissolving at the pH of the aqueous solution, and should preferably be thin,
of the order of
0.025-0.25mm. In addition, the material should not be deleterious to the
properties desired
for the final product. The coating may be selected so as to protect the
compacted unit,
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and/or to protect the user from any hazardous materials in the self indicating
neutralizing
composition. Examples of suitable substantially water-insoluble materials
include clays,
latexes, polystyrenes, polyurethanes, and celluloses wherein the hydroxyl
groups have been
substituted with alkyls.
More information regarding unitization of materials can be found in United
States Patent No.
5,728,209 to Bury et al., which is incorporated herein by reference.
The present invention also includes a method of neutralizing a solution to
about a neutral pH.
A unitized composition is added to the solution and allowed to dissolve in the
solution. If
the pH indicator does not change color to indicate a pH of about neutral, then
additional
unitized compositions may be added until the pH indicator indicates a pH of
about neutral.
A further advantage of the compacted units of self indicating neutralizing
composition
according to the present invention, is that, unlike liquid compositions, they
are not prone to
freeze, slush or separate at low temperature. The use of compacted units of
self indicating
neutralizing composition according to the present invention overcomes job site
dusting
problems associated with powders, avoids the use of bullcy measuring
dispensing equipment
at the job site for liquids or solid free-flowing components, and overcomes
spillage concerns
associated with using components of the self indicating neutralizing
composition separately.
