TABLETS FOR TREATING AND DISINFECTING WATER

Abstract

Tablets for treating and disinfecting water, particularly for water of swimming pools and spas comprising a halogenated derivative of isocyanuric acid together with a volatile additive, chemically incompatible with the latter, encapsulated in a microporous or mesoporous material which has a certain pore size, pore volume and a specific surface. The tablets are chemically stable, while maintaining the expected activity of both the halogenated derivative of isocyanuric acid and the additive.

Claims

1. A tablet comprising a) a halogenated derivative of isocyanuric acid selected from trichloroisocyanuric acid, dichloroisocyanuric acid and a salt of any of these; and b) a volatile additive, chemically incompatible with the halogenated derivative of isocyanuric acid, encapsulated in a microporous or mesoporous material; wherein the microporous or mesoporous material has a pore size of between 0.3 nm and 50 nm; a pore volume of between 0.05 cm3/g and 2 cm3/g; and a specific surface of between 100 m2/g and 5000 m2/g.

2. The tablet according to claim 1, wherein the volatile additive chemically incompatible with the halogenated derivative of isocyanuric acid has the capacity to cause the release of at least 15 mg Cl2 gas when said additive without encapsulation is put into contact with the halogenated derivative, the measuring method of said chlorine gas release comprises the steps: i) preparing a mixture of additive and halogenated derivative, wherein the quantity of additive is 0.1% by weight in the mixture, ii) placing in the stove at 60±2° C. for 15 hours, iii) bubbling the gas released into a recipient containing a mixture of potassium iodide 10% by weight and sulphuric acid 10% by weight, and iv) titrating the iodine released with sodium thiosulphate 0.1 N.

3. The tablet according to claim 1, wherein the halogenated derivative of isocyanuric acid is selected from trichloroisocyanuric acid and sodium dichloroisocyanurate.

4. The tablet according to claim 1, characterised in that the quantity of halogenated derivative of isocyanuric acid is between 90% to 99% by weight of the total of the tablet.

5. The tablet according to claim 1, characterised in that the microporous or mesoporous material is selected from a mica, a metal oxide, a silicate, an aluminium silicate, an aluminium phosphate, a clay, a metal-organic framework (MOF), a mesoporous organosilica and a zeolite.

6. The tablet according to any claim 1, wherein the microporous or mesoporous material is selected from a mica, a microporous silica, a mesoporous silica, a pyrogenic swilica, a crystalline silica, a precipitated silica, a gel silica, an alumina, MCM-41, SBA-15, kaolin, smectite, vermiculite, attapulgite, sepiolite, clinoptilolite, mordenite, ZSM-5, HKUST-1, MIL-53, MIL-88 A (Al).

7. The tablet according to claim 1, wherein the tablet comprises a quantity of additive of between 0.05% and 1% by weight.

8. The tablet according to claim 1, wherein the tablet comprises a quantity of additive of between 0.1% and 0.2% by weight.

9. The tablet according to claim 1, wherein the quantity of additive encapsulated in the microporous or mesoporous material is between 0.1 g additive/g material and 1.5 g additive/g material.

10. The tablet according to claim 1, wherein the additive is selected from one or more insect repellents, one or more fragrances, or one or more perfumes or essences.

11. The tablet according to claim 1, wherein the additive is an insect repellent selected from citronellic acid, geranic acid, geraniol, IR 3535 (ethyl 3-[acetyl(butyl)amino]propanoate) and icaridin.

12. The tablet according to claim 1, wherein the microporous or mesoporous material has a pore size of between 0.4 nm and 15 nm, a pore volume of between 0.1 cm3/g and 1.5 cm3/g; and a specific surface of between 150 m2/g and 2000 m2/g.

13. The tablet according to claim 1, wherein it also comprises other additional components selected from the group consisting of lubricants, flocculants, algaecides, scavengers of ions responsible for the hardness of the water, and combinations of the same.

14. The tablet according to claim 13, wherein said additional components are present in the tablet in a quantity of between 1% and 8% by weight with respect to the total of the tablet.

15. A of method of using the tablet as defined in claim 1 for treating and disinfecting water, the method comprising adding the tablet to a water to be treated and disinfected.

16. A method for preparing a tablet as defined in claim 1, comprising a) encapsulating the additive in the microporous or mesoporous material; b) mixing the halogenated derivative of isocyanuric acid with the additive encapsulated in the microporous or mesoporous material; and c) compressing the mixture.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Particular embodiments of the present invention are described below by way of a non-limiting example, with reference to the attached drawings, in which:

[0044] FIG. 1. Graph of the infrared spectroscopy analysis (FTIR using an IRAffinity-1 device) of the silica, the additive and the additive encapsulated in the silica of example 1, revealing the presence of the additive in the material called additive@silica.

[0045] FIG. 2. Thermogravimetric analysis (using a TGA/STDA 851e device from Mettler Toledo) of the silica, the additive and the additive encapsulated in the silica of example 1, which allows the quantity of additive encapsulated to be quantified, reflects 56% of additive encapsulated in the silica (additive@silica).

[0046] FIG. 3. Graph of the infrared spectroscopy analysis (FTIR using an IRAffinity-1 device) of the activated MOF, the additive and the additive encapsulated in the MOF of example 2, revealing the presence of the additive in the material called additive@MOF.

[0047] FIG. 4. Thermogravimetric analysis (using a TGA/STDA 851e device from Mettler Toledo) of the MOF, the additive and the additive encapsulated in the MOF of example 2, which allows the quantity of additive encapsulated to be quantified, reflects 19% of additive encapsulated in the MOF (additive@MOF).

[0048] FIG. 5. Graph of the infrared spectroscopy analysis (FTIR using an IRAffinity-1 device) of the MOF, the additive and the additive encapsulated in the MOF of example 3, revealing the presence of the additive in the material called additive@MOF.

[0049] FIG. 6. Thermogravimetric analysis (using a TGA/STDA 851e device from Mettler Toledo) of the MOF, the additive and the additive encapsulated in the MOF of example 3, which allows the quantity of additive encapsulated to be quantified, reflects 26% of additive encapsulated in the MOF (additive@MOF).

[0050] FIG. 7. Graph of the infrared spectroscopy analysis (FTIR using an IRAffinity-1 device) of the MOF, the additive and the additive encapsulated in the MOF of example 4, revealing the presence of the additive in the material called additive@MOF.

[0051] FIG. 8. Thermogravimetric analysis (using a TGA/STDA 851e device from Mettler Toledo) of the MOF, the additive and the additive encapsulated in the MOF of example 4, which allows the quantity of additive encapsulated to be quantified, reflects 14% of additive encapsulated in the MOF (additive@MOF).

DETAILED DESCRIPTION OF EMBODIMENTS

[0052] In spite of only some particular embodiments and examples of the invention having been described here, a person skilled in the art will understand that other alternative embodiments and/or uses of the invention, as well as obvious modifications and equivalent elements are possible. Furthermore, the present invention encompasses all the possible combinations of the specific embodiments which have been described. The scope of the present invention should not be limited to specific embodiments, but rather it should only be determined by appropriate reading of the attached claims.

Example 1

Silica+Additive

[0053] 500 mg of previously desiccated silica was prepared in a Petri dish and on this was poured the volume corresponding to 500 mg of additive previously dissolved in 2.5 mL of ethanol to facilitate the mixture and have better homogenisation. With the aid of a spatula, both substances were mixed until a homogenous mixture was obtained which was left to dry in the air. The silica used had a specific BET surface area (using a Tristar device from Micromeritics) of 182.3±0.6 m.sup.2/g, a pore volume of 0.62 cm.sup.3/g and an average pore size of 13.6 nm.

[0054] FIG. 1 presents the infrared spectroscopy analysis (FTIR, using an IRAffinity-1 device) of the silica, the additive and the additive encapsulated in the silica, revealing the presence of the additive in the material called additive@silica.

[0055] Thermogravimetric analysis (using a TGA/STDA 851e device from Mettler Toledo), which allows the quantity of encapsulated additive be quantified, reflects 56% of encapsulated additive in the silica (additive@silica), as shown in FIG. 2.

[0056] Even having a pore size (13.6 nm) much greater than the encapsulants, which will be seen further on, the silica has the capacity to homogenously disperse the additive on the surface thereof and then in the tablet formulated with the silica.

[0057] The results obtained for different additives encapsulated in silica following the method previously described are gathered in table 1:

TABLE-US-00001 TABLE 1 % Encapsulated Additive (g additive/g solid total) × 100 Geranic acid 55.7 Citronellic acid 56.9 Icaridin 53.5 IR3535 58.7 Geraniol 55.0

Example 2

MOF+Additive (In Two Steps)

[0058] 100 mg of activated MOF (MIL-53 or MIL-88 A (Al)) was prepared in a vial and 1 mL of the additive of interest was poured on the same. Said vial was left under agitation at 60° C. for one, two, four or seven days. After this time, the solid was recovered by centrifuging at 10,000 rpm for 10 minutes, it was washed once with ethanol and was recovered again by means of centrifugation under the same conditions and was left to dry in the air.

[0059] Both the FTIR spectroscopy and the thermogravimetry analysis can be observed in FIGS. 3 and 4, in this specific case with 19% of encapsulated additive.

[0060] This same thermogravimetry analysis was carried out for all the encapsulations using MIL-53 as MOF and with various additives and with different encapsulation times. In table 2 below, the results obtained are shown:

TABLE-US-00002 TABLE 2 % Encapsulated (g additive/g dry solid) × 100 Additive 1 day 2 days 4 days 7 days Geranic acid 17.2 33.4 35.3 44.0 Citronellic acid 19.2 22.5 25 25.1 Icaridin 27.0 20.5 24.9 24.9 IR3535 26.0 22.1 26.1 25.2 Geraniol 22.1 32.0 29.1 36.7

[0061] In the case of MIL-88 A (Al), the encapsulation was only carried out for a period of 3 days. Like for MIL-53, FTIR analysis was carried out on the samples to check for the presence of the additive in the MOF and thermogravimetry was carried out to determine the quantity of encapsulated additive. Table 3 gathers the results of encapsulation obtained.

TABLE-US-00003 TABLE 3 % Encapsulated (g additive/g dry solid) × 100 Additive 3 days Geranic acid 10.6 Citronellic acid 8.9 Icaridin 16.0 IR3535 21.0 Geraniol 11.3

Example 3

MOF+Additive (In One Single Step)

[0062] In this type of encapsulation, the additive is added to the synthesis medium with the intention of the latter being retained in the pores during the formation of the framework of the MOF. This has the advantage that the synthesis and the encapsulation are carried out in one single step, thus avoiding the need to first synthesise the material, activate it and subsequently carry out the encapsulation.

[0063] In this case in particular, the MIL-53 was synthesised with geranic acid in one single step: 5.20 grams (1.38 10-2 moles) of nonahydrated aluminium nitrate was added into a ball flask together with 1.12 grams (6.74 10-3 moles) of terephthalic acid, 10 mL of distilled water and 9 mL of ethanol. In a separate receptacle, the volume corresponding to 1 gram of additive was added together with 1 mL of ethanol and it was agitated until the complete dissolution thereof, then pouring the contents of the same on the flask. Said flask is placed under agitation under reflux for 3 days at 85° C. The solid was recovered by centrifugation at 10,000 rpm for 10 minutes, it was washed once with ethanol and was recovered again by centrifugation under the same conditions. It was left to dry in the air.

[0064] Both the FTIR spectroscopy analysis and thermogravimetry can be observed in FIGS. 5 and 6, in this case with 26% of encapsulated additive.

Example 4

MOF+Additive (In One Single Step)

[0065] In this type of encapsulation, the additive is added to the synthesis medium with the intention of the latter being retained in the pores during the formation of the structure of the MOF. This has the advantage that the synthesis and the encapsulation are carried out in one single step, thus avoiding the need to first synthesize the material, activate it and subsequently carry out the encapsulation.

[0066] In this case in particular, MIL-88 A (Al) was synthesised with any of the additives in one single step:

[0067] Two solutions were prepared, namely: [0068] 1. 2.98 grams (7.94 10-3 moles) of nonahydrated aluminium nitrate was added together with 10 mL of distilled water into a ball flask. [0069] 2. 0.92 grams (7.94 10-3 moles) of fumaric acid was added together with 4.8 mL of a solution of 0.1 g/mL of sodium hydroxide and 10.2 mL of distilled water into a receptacle.

[0070] Both receptacles were placed under agitation until transparent solutions were obtained, at this time the content of the receptacle, which contained the fumaric acid, was poured on the ball flask. In the other receptacle, 1 mL of ethanol and the volume corresponding to 1 gram of the additive of interest was added and it was agitated until the total dissolution thereof. The content of the latter was also added to the ball flask which was placed under reflux at 60° C. for 1 hour. The solid was recovered by centrifugation at 10,000 rpm for 10 minutes, it was washed once with ethanol and was recovered again by means of centrifugation under the same conditions. The solid obtained was left to dry in the air.

[0071] Both the FTIR spectroscopy analysis and the thermogravimetry can be observed in FIGS. 7 and 8, in this case with 14% of additive encapsulated.

[0072] The results of in-situ encapsulation obtained for each one of the additives used are gathered in table 4.

TABLE-US-00004 TABLE 4 % Encapsulated Additive (g additive/g dry solid) × 100 Geranic acid 13.4 Citronellic acid 12.2 Icaridin 16.6 IR3535 21.7 Geraniol 10.9

Example 5

Chemical Compatibility of Various Encapsulated Additives With TCCA and Comparison With That of the Other Additives

[0073] A total of 100 grams of mixture of TCCA and different encapsulated additives, in variable proportions, was weighed—according to the quantity of additive encapsulated in the encapsulating matrix so that the quantity of additive was 0.1% by weight in the mixture. The different mixtures were placed in a 500 mL grinding Erlenmeyer. It was covered with the appropriate device and the latter was fixed with a clamp to the Erlenmeyer.

[0074] The Erlenmeyer was placed in the stove at 60±2° C. and was maintained for 15 hours, after which it was dried and it was left to cool at room temperature for one hour.

[0075] With the aid of a vacuum pump, the gas contained in the Erlenmeyer was bubbled through three wash bottles, one security vacuum, another which contained approximately 70 mL of potassium iodide 10% by weight and 30 mL of sulphuric acid 10% by weight and the third also a security vacuum. This operation lasted five minutes, sufficient time for the pressure at the end to be less than 100 mm of Hg.

[0076] The wash bottles were disconnected from the Erlenmeyer and the content was drawn off from the second bottle, together with the water from the washing thereof, to another 500 mL Erlenmeyer.

[0077] The iodine released was titrated with sodium thiosulphate 0.1 N until the disappearance of the yellow colour.

[0078] The results obtained with the microencapsulated additives in contact with TCCA are gathered in table 5, expressing said result in grams of chlorine released as a function of the additive used. The result of chlorine release of 100 g of TCCA also appears under similar conditions as a reference standard.

TABLE-US-00005 TABLE 5 TCCA mixtures + encapsulated additives (100 g of TCCA + 0.1% additive) mg Cl.sub.2 TCCA + citronellic acid encapsulated in silica 11.7 mg  by impregnation TCCA + IR3535 encapsulated in MOF by 5.3 mg impregnation (two steps) TCCA + IR3535 encapsulated in MOF in-situ 7.6 mg (one single step) TCCA + geranic acid encapsulated in MOF 7.0 mg in-situ (one single step) TCCA 1.4 mg

[0079] Table 6 shows the results obtained from the direct contact of TCCA with some of the additives without encapsulation.

TABLE-US-00006 TABLE 6 TCCA mixtures + additives without encapsulation (100 g of TCCA + 0.1% additive) mg Cl.sub.2 TCCA + IR3535 58 mg TCCA + icaridin 219 mg  TCCA + geranic acid 29 mg

[0080] Table 7 shows the results obtained of TCCA compatibility with the porous material used. As can be observed, some porous materials were chemically incompatible with TCCA since they cause a degassing (release of chlorine gas) greater than 15 mg Cl.sub.2 measured under the conditions previously described.

TABLE-US-00007 TABLE 7 Mixture 0.2 g material + 100 g TCCA Nature Degassing [mg Cl.sub.2] HKUST-1 MOF 8.7 MIL-53 MOF 1.1 MIL-88 A (Al) MOF 2.8 ZSM-5(Zeolyst) Zeolite 9.7 Silica Precipitated silica 4.4 ZIF-8 MOF 51 UiO 66 MOF 35.4 MIL-88 A (Fe) MOF 48.5 MIL-68 MOF 63.8 Faujasite (zeolite Y, Zeolite 69 Zeolyst)

[0081] HKUST-1 is an MOF, the composition of which is [Cu.sub.3(BTC).sub.2(H.sub.2O).sub.3].sub.n wherein the metal is copper and the organic ligand is BTC (benzene-1 3 5-tricarboxylate). The structure thereof consists of [Cu.sub.2(O.sub.2CR).sub.4] units (wherein R is an aromatic ring) which are interconnected to form a three-dimensional skeleton with channels with a pore size of around 0.6 nm. The BET specific surface thereof is around 1000 m.sup.2/g.

[0082] ZSM-5 is a synthetic zeolite, the chemical formula thereof is Na.sub.nAl.sub.nSi.sub.96-nO.sub.192 16H.sub.2O. The BET area thereof is around 400 m.sup.2/g. The pore size thereof is between 0.5 and 0.6 nm.

[0083] Synthetic zeolites are achieved by way of a hydrothermal synthesis process, that is to say, there is an aqueous medium where the precursors are found which are subjected to high temperatures in an autoclave for a determined time.