Chemistry of inorganic compounds – Carbon or compound thereof – Oxygen containing
Reexamination Certificate
2000-04-27
2002-12-10
Silverman, Stanley S. (Department: 1754)
Chemistry of inorganic compounds
Carbon or compound thereof
Oxygen containing
C422S120000, C422S123000
Reexamination Certificate
active
06491890
ABSTRACT:
The present invention concerns a dosing method for the controllable and continuous generation of carbon dioxide (CO
2
) and its issue in biologically used systems as well as a set and a reequipment set which make possible the implementation of this method.
In various fields of the maintenance of biological systems there is a need for an even and targeted supply of CO
2
over a lengthy period. For example, this is the case in the cultivation or preservation of plants in closed premises, such as for example in greenhouses, and in particular in aqueous systems, for example in ponds or aquaria.
To supply ponds or aquaria with CO
2
, various processes are known in the prior art.
For example, the supply can be carried out by gas dosing systems from gas cartridges which are pressure charged with CO
2
. But this method has the drawback that with decreasing gas pressure in the cartridge, the amount of CO
2
which is supplied per unit of time continuously decreases without later control of the dosing system. In addition, a CO
2
dosing system requires a large amount of space when using gas cartridges and is aesthetically unsatisfactory. This is disadvantageous, especially in the case of ornamental pools and aquaria.
A further known method is the in situ generation of CO
2
from a carbonate due to the influence of a mineral acid, which is usually hydrochloric acid in a Kipp's apparatus. However, such a device can only be operated suitably outside the water which is to be supplied, and it is therefore linked with the same spatial and aesthetic inadequacies as the method which was described above. In addition, the handling of mineral acids such as hydrochloric acid by inexperienced users is not without its problems.
In addition, a method was suggested in which from an effervescent tablet of sodium hydrogen carbonate and citric acid CO
2
is released in doses by the slow addition of water. The disadvantage of this method is that with a slow supply of water in a short time an impermeable citrate layer is formed on the effervescent tablet, which impedes a further reaction. Thereby the continuous generation of CO
2
can only be ensured for a short period of a few days.
To overcome the problems named above, a method is made available which makes possible the controlled generation of CO
2
which is constant over a long period, i.e. a method for the .continuous long term dosing of CO
2
in media which are used biologically, comprising the steps below:
i) expulsion of an aqueous acid solution from a storage container by means of a chemical reaction generating gas pressure,
ii) dripping the acid solution into a solid and/or liquid carbonate or hydrogen carbonate composition, and
iii) supplying the resultant CO
2
to the medium in use biologically.
In addition, the object above is achieved by the set made available in accordance with the invention for implementation of the process, which comprises a storage container (
1
), a unit amount of a carbonate or hydrogen carbonate or a mixture of two or more such compounds and a storage container (
2
) to be placed thereon or therein for the aqueous acid solution with an exit aperture, which permits the dripping into the (hydrogen) carbonate or its solution; and which is charged with a composition which comprises (i) a solid water soluble acid, (ii) a water soluble and preferably solid compound, which can be catalytically decomposed with the development of gas, and (iii) a catalyst.
In addition, a reequipment set is used to solve the problem above, which comprises the necessary initial substances for carrying out the method as well as replacement parts of the apparatus which is used. More precisely, the reequipment set of the present invention comprises a unit amount of a carbonate or hydrogen carbonate or a mixture of two or more such compounds and a storage container (
2
) for the aqueous acid solution with an exit aperture, which permits the dripping into the carbonate solution, and which is charged with a composition, which comprises (i) a water soluble acid, (ii) a compound which can be decomposed catalytically with the development of gas, and (iii) a catalyst.
Additional aspects and preferred features of the invention are defined in the appended claims. It will be appreciated that where a preferred feature is described or defined with respect to one aspect of the invention, it is equally applicable to other aspects of the invention without requiring explicit mention thereof.
The method in accordance with the invention for the continuous dosing of CO
2
has the following steps:
i) expulsion of an aqueous acid solution from a reserve container by means of a chemical reaction which generates gas pressure,
ii) dripping the acid solution into a solid and/or liquid carbonate or hydrogen carbonate composition and
iii) supplying the resultant CO
2
to the biologically used medium.
The following advantageous effects are achieved by this method and by the sets and reequipment sets which are used for its implementation:
the release of CO
2
is carried out economically and in the smallest space.
A large amount of CO
2
can be stored in the initial substances and can be issued over a lengthy period.
The generation of CO
2
can be adjusted in accordance with the requirement of the user and it is constant over a long period.
In aquaria, the CO
2
can be issued into the water without hose connections, and without impurities with other substances resulting.
The reference to “carbonate” or to “carbonate solution” also includes in following hydrogen carbonates and all their solutions, to the extent that nothing else is stated.
The above named aqueous solution of an acid can be a solution of any discretionary acid, which is in a position to form an adequately stable aqueous solution, and which is also suitable to release CO
2
by reaction with a carbonate or its aqueous solution. Preferably the acid which is used is a solid compound in its pure form, from which the aqueous solution is only produced directly before use.
Equally it is preferred that due to the reaction of the acid with the carbonate, a salt is formed, the solubility of which is so high that it does not precipitate out of the aqueous mixture, which is formed by dripping the acid solution into the carbonate or its solution. Moreover, mixtures of two or more acids can be used.
The carbonate in which or in the solution of which the aqueous acid solution is dripped is a discretionary carbonate or hydrogen carbonate compound. As stated above, it is preferable that the salt which results from the reaction with the acid which is dripped in remains dissolved. Mixtures of two or more carbonate compounds can also be used.
In addition, preferably both the initial compounds as well as the resultant salt should be unproblematic as to health and ecology, and the amount of CO
2
which can be released therefrom, based on the weight of the initial substances, should be as large as possible.
Carbonate compounds which are to be used for preference are the carbonates and hydrogen carbonates of the alkali metals, and special preference is given to sodium hydrogen carbonate.
An acid used with special preference is citric acid.
The named components have moreover the advantages that they are economically obtainable and are easy to store and to transport.
The gas pressure generating reaction which is used to expel the acid solution from the storage container is the reaction of a compound which is dissolved or suspended in the aqueous acid solution with the release of a gaseous reaction product. Preferably this concerns the decomposition of a metastable compound, e.g. a peracid compound, such as hydrogen peroxide or derivates thereof. Mixtures of two or more compounds which are compatible with each other can also be used.
The decomposition can be catalyzed by a suitable catalyst. Due to suitable dosing of the catalyst, the amount of the gas volume which is generated can be adjusted per unit of time and therefore the expulsion speed of the acid solution can be exactly adjusted within a broad range. Here it must be taken into c
Johnson Edward M.
Kunz Todd W.
McGee Sheldon M.
Nath Gary M.
Silverman Stanley S.
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