DE2504688A1 - Softening and improving the taste of drinking water - by treatment with zeolites - Google Patents

Abstract

The taste of drinking water is improved and the water is partially softened by passing it through paper bags contg. synthetic zeolites of the NaA or NaX types having a particle size of >0.08 mm. Used esp. in the domestic prodn. of tea or coffee. The colour of the drink is unaffected and the ion exchanger can withstand the action of boiling water.

Description

"Process for the production of drinking water with improved taste It is known that the taste of the water can be influenced with the help of ion exchangers to be carried out, as the substances in tap water, in particular the hardness builders, exert an adverse influence. The taste quality of the water works are particularly useful when preparing coffee, tea and other infusions. So far, drinking water treatment has essentially been carried out in the household with help of drinking water treatment devices that contain organic ion exchangers. In general, full softening or

Complete desalination carried out. This way of working has the disadvantage that the resulting water has a pH value of the pH range desired for consumption purposes deviates from 6 - 9. When making tea, this also means that through the more acidic reaction, the beverage infusion turns an undesirably light color. Even Difficulties can arise when using the ion exchanger to soften boiling drinking water is carried out. Furthermore, there is the risk of post-mortification of the organic ion exchange material.

It is known to improve the way of working described above by that initially a softening of the drinking water is carried out with ion exchangers and then again a minimum salt content by adding a defined salt mixture will be produced.

However, this procedure is quite cumbersome in practice.

It has now been found that the process can be used to improve the taste of drinking water with the help of ion exchangers when preparing coffee, Tea and other infusions can be improved significantly by using the infusion water with coarse-particle synthetic zeolites, preferably packed in paper fleece bags (Particle size over 0.08 mm) of the NaA or NaX type treated and partially softened.

Partial softening is preferably carried out until the water hardness has fallen to 40 eOmg CaO / l, since it has been found that in this range the best results will be obtained.

Zeolites of the NaA and NaX type have long been known (see where appropriate Grubner, Jiru and Ralek "Molecular Sieves" 1968, pages 24-27). They are crystalline and have a cubic structure.

The entrance pores are> 4 # in size. The production takes place according to known methods such as those described in DBP 1038 016 and 1038 017, for example are. Type A zeolites correspond to the formula 1.0 # 0.2 Na 2 O: Al 2 O 5: 1.85 + 0.5 SiO2: YH2O where Y is any value up to 6.

Type X zeolites correspond to the formula 0.9 + 0.2 Na20: Al20: 2.5 i 0.5 SiO 2: YH 2 O where Y is any value up to 8.

Most of the zeolites described fall in finely crystalline form at. For the present purposes, however, only coarse zeolites of the named Types apply. This is understood to mean those whose particle size is greater than 0.08 mm.

In particular, the coarse-particle synthetic zeolites used are which have been granulated beforehand. The granulation also takes place by itself known methods.

In particular, clays such as bentonite are used as granulating agents and montmorillonite. However, sodium silicate / aluminum sulfate are also possible and sodium silicate / aluminate combinations in question.

The amount of granulating agent is about 5 - 25 based on the synthetic zeolites.

It is further advantageous and the preferred embodiment that to pack coarse-grained or granulated synthetic zeolites in paper fleece bags.

The usual paper fleece bags have an average mesh size from 0> 05 - 0.1 mm. The particle size of the zeolites must in each case be greater than the largest Mesh size. There are therefore coarse zeolites with a grain size of at least 0.08-1.5 mm, preferably 0.2-0.8 mm, are used. The application coarse-particle synthetic zeolites obtained are in quantities of about 3 - 20 jl related. If desired, mixtures of the two zeolite types (NaA and NaX) are used. It has been found that zeolites of the NaA type in general are most effective, so that they find preferred application.

The dimensions of the porous paper fleece bags depend on the Amount of the beverage to be prepared, such as a cup, glass or jug. That The bags are closed in a known manner by edging or gluing.

When preparing tea, but especially coffee, can you also proceed so that the infusion material in the usual way with the help of a The paper filter is filtered through, after having previously received an appropriate amount of it synthetic zeolites before pouring on the water. Another, Particularly suitable embodiment for coffee and tea is that the Coffee filter made of two water-permeable material layers that form a gap like paper, in which the coarse-grained synthetic zeolites are located.

For practical purposes, however, it is generally more advantageous to work with pre-packed paper fleece bags. It is useful if this at the same time tea or coffee, preferably soluble coffee, and zeolites, if necessary separated in double chambers. The amount of coffee or tea used in each case depends on personal needs. In general, a lot will 1 - 3 g of coffee or tea per 150 ml of water are used.

The drinking water is often in a strongly chlorinated state from the aqueduct taken. In such cases it can be advantageous to use non-woven paper bags Zeolites should be used, which are still activated carbon, but preferably in combination with the other ingredients, contain activated carbon. This can also be done in this way that the paper bag contains a special chamber for the activated carbon.

For the purposes mentioned, activated carbon with a grain size of 0.1 - 1 mm and a BET surface area of over 600, preferably 2 over 1100 m2 / g, proved suitable.

The working methods according to the invention using coarse, preferably synthetic zeolites of the NaA or NaX type, which are preferably in paper fleece bags are packaged together or separately with the infusion goods are, inter alia. the following: Larger Apparatus such as exchanger columns or water softeners are not necessary. You can work with boiling water without difficulty. In terms of hygiene, this is because of compared with conventional methods the associated killing of germs is particularly advantageous.

A particularly favorable exchange speed and exchange capacity are obtained when using the special zeolites. The handling of the paper fleece bags as disposable items is problematic for the housewife.

Example 1 The results are summarized in Table 1 below, those for partial softening with various zeolites of the types specified in Depending on the temperature were obtained.

The initial hardness was 160 d in each case. H. corresponding to a quantity of 160 mg CaO / l. The exposure time was 5 minutes for one volume of water of 150 ml. The results show - especially over a wide temperature range - the superiority of zeolites of the NaA and NaX types.

Table 1 Residual hardness ° d example product 0.1 g / 150 ml zeolite Note 25 ° C 90 ° C 1 NaA type 5.8 4.0 2 NaX type 8.7 5.8 3 NaA / NaX 6.7 5.0 ratio 1: 1 4 zeolite P 12.7 5 amorphous 11.8 6.7 6 sodalite 13.8 12.2 Example 2 Table 2 below summarizes the results obtained during partial softening with ion exchangers of the specified types with various weights and grain sizes.

Granulated ion exchangers were used, which have a share contain about 20% binding agent (montmorillonite). The ion exchangers were packed in small paper fleece bags. The experiments were carried out at a water temperature carried out at 90 ° C.

During the duration of the experiment, the pouches were used about eight to ten times moved back and forth to achieve a certain degree of mixing.

Beis'oiel In the following table 3 the results are summarized, those for partial softening with ion exchangers with different weights and Grain sizes were obtained. Granulated ion exchangers were used which contained about 20 ffi of binder (montmorillonite). The ion exchange were packed in small paper fleece bags and contained in a separate one Part of the specified amount of activated carbon. The experiments were carried out at a water temperature carried out by 900 C. During the duration of the experiment, the bags were about 8-10 mouthfuls moved back and forth to achieve a certain degree of mixing. In all cases a tasteless water was contained.

Example 4 Table 4 shows the results which were obtained in an analogous procedure as in Example 3, but with the The amount of activated carbon in the paper fleece bag was replaced by 2 g of tea.

Example 5 Table 5 contains the results for one procedure as in example 3, except that the activated carbon is replaced by 2 g of soluble coffee was replaced.

Table 2 Ion exchanger starting residual partial pH value of the exposure time single-use hardened treated hardness hardness Water-water volume Type Grain size weighed-in [mm] [g] [° d] [° d] [ml] [min] NaA 0.3-0.5 0.5 16 5.4 150 7.4 5 NaA 0.3-0.5 1.0 16 4.7 150 7.5 5 NaA 0.3-0.5 1.5 16 4.1 150 7.6 5 NaA 0.2-0.4 1.5 16 4.0 150 7.4 5 NaA 0.5-0.8 2.0 16 4.5 150 7.4 5 NaX 0.4-0.7 1.5 16 4.8 150 7.4 5 NaX 0.4-0.7 2.5 16 4.5 150 7.6 5 NaX 0.4-0.7 2.5 20 5.9 150 7.7 5 NaA / NaX 0.3-0.5 2.0 16 4.2 150 7.3 5 1: 1 NaA / NaX 0.2-0.4 2.0 16 4.1 150 7.5 5 1: 3 Table 3 Ion exchanger activated carbon + initial residual pH value of the exposure time of the hardness hardness of treated disposable item Water Type Grain size Weighed in grain size mm g mm ° d ° d min NaA 0.1-0.3 1.0 0.2-0.5 16 3.9 7.5 5 NaA 0.3-0.5 1.0 0.3-0.8 16 4.8 7.6 5 NaX 0.2-0.4 1.5 0.2-0.5 16 4.4 7.7 5 NaA / NaX 0.2-0.5 5 0.2-0.5 20 5.7 7.6 5 1: 2 + The initial weight of activated charcoal was 0.5 g in all experiments.

The surface of the activated carbon, measured according to the BET method (Chem. Ing. Technik 1959, p. 799/80) was above 1100 mg2 / g in all cases.

The water volume was as in Table 2 in each case 150 ml.

Table 4 Ion exchanger initial residual partial pH value pH value exposure time hardness hardness hardness of the accessories of the disposable article Water traders rode volume of water teas Type Grain size weighed-in mm g ° d ° d ml min NaA 0.3-0.5 1.5 16 4.2 150 7.5 4.9 5 NaA 0.1-0.3 5 20 5.8 150 7.6 4.7 5 NaX 0.4-0.7 2.0 16 4.7 150 7.5 5.1 5 NaX 0.3-0.5 1.5 16 4.1 150 7.8 5.0 10 Table 5 Ion exchanger initial residual partial pH value pH value pH value exposure hardness hardness hardened hardness of endurance Water-traded prepared disposable items Type Grain size Weighing volume of water and coffee mm g ° d ° d ml min NaA 0.3-0.5 1.5 16 4.5 150 7.4 5.6 4 NaA 0.2-0.4 1.0 16 4.8 150 7.3 5.8 4 NaX 0.3-0.5 1.5 16 4.7 150 7.5 5.7 4 NaX 0.3-0.5 2.5 20 5.7 150 7.5 5.8 4 NaA / NaX 0.3-0.5 1.5 16 4.6 150 7.5 5.8 4 1: 2

Claims (5)

Claims ns method for improving the taste of the Drinking water with the help of ion exchangers when preparing coffee or tea and other infusions, characterized in that the infusion water with preferably coarse synthetic zeolites packed in paper fleece bags (particle size over 0.08 mm) of the NaA or NaX type treated and partially softened. 2) Method according to claim 1, characterized in that the Partial softening is carried out until the water hardness has dropped to 4o to 60 mg CaO / l is. 3) Porous paper fleece bags for carrying out the method according to Claims 1 and 2, characterized in that it is coarse, preferably granulated synthetic zeolites from NaA or NaX type and preferably a serving of tea or coffee at the same time, optionally contained in a separate part of the infusion bag. 4) Porous paper fleece bag according to claim 3, characterized in that that they also contain activated carbon, optionally in a separate part. 5) coffee filter for performing the method according to claim 1 and 2, characterized in that it consists of two water-permeable ones forming an intermediate space There are layers of material in which the coarse synthetic zeolites are located.