DK141713B - Process for preparing a filter for removing cadmium and cadmium compounds from gases, especially tobacco smoke. - Google Patents

Description

(11) PRESENTATION 141713

Qff) DENMARK (61) lnt c'3 A 24 0 3/16 • (21) Application No. 1510/73 {22) Filed on 20 Mar. Ig ^ (23) Race day 20, Mar 1975 (44) The application presented and the petition published on 2 July. 19¾)

DIRECTORATE OF

PATENT AND TRADE MARKET (30) Priority requested from it

Mar 20 1972, 5554/72, SE

i ........ 11 i (71) matti JUHANI OSKAR SIREN, Ritobergsvaegen 16 H, Helsinki, FI.

(72) Inventor: Same.

(74) Plenipotentiary in the proceedings:

The company Chas. Hude.

(54) Process for producing a filter for removing cadmium and cadmium compounds from gases, Iseqa? tobacco smoke.

The present invention relates to a process for producing a filter for removing cadmium and cadmium compounds from gases, especially tobacco smoke, characterized in that a powder-permeable salt of calcium is freely embedded in a gas-permeable mass without the use of binder.

A filter made according to the invention can advantageously be used for filtration of all gas types containing cadmium or cadmium compounds such as combustion gases, industrial waste gases, pyrolysis gases and the like, but particularly relates to a filter suitable for use in the following. coherently meets or forms an integral part of a tobacco product, whereby the gas to be filtered is constituted by the smoke generated by the burning of the tobacco or the like in the tobacco product and which is inhaled by the smoker.

According to recent experiments, it has become increasingly apparent that cadmium is probably a more significant health hazard than previously believed. In preliminary physiological studies on the effect of cadmium on biological tissue, it has been found in connection with the invention that this metal is concentrated in the tissues of animal bodies according to a specific pattern which clearly indicates health hazards, especially since it has just been found that cadmium has an unusual long biological half-life. Cigarette smoking has long been considered a major health hazard, especially with regard to cancer and cardiovascular disease, and attention has been directed mainly to nicotine and tar material in tobacco, but in connection with this invention it has been discovered that said materials are hardly may constitute the only health hazard factor, and initially gained experience has directly identified cadmium as the most important if not the only dangerous factor in this context, at least for cardiovascular disease.

In view of this, it has emerged in the context of the invention as something extremely required to remove or harm cadmium and cadmium compounds in gases which come into contact with biological systems. The gases may be combustion gases, e.g. from industries, distillation products, etc., and in this connection, the combustion gases from tobacco products also have particular relevance. Regarding cadmium, it is found that, in addition to being highly toxic, it has an ionic radius of 0.97 Angstrom. In connection with the invention, it has been found to attach particular importance to this ion radius. Comparisons with other materials with an ionic radius of the same magnitude as cadmium and with the same valence have specifically focused attention on calcium, whose ionic radius amounts to 0.99 Angstrom. It turns out that both materials cadmium and calcium can occupy each other's place in biological tissue under certain conditions. There has even been some recent suspicion that cadmium itself may play a key role in the emergence of at least some cancers.

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In studies in connection with the present invention, it has just been found that one of the major sources of calcium delivery to the human body is inhaled. smoke free e.g. cigarettes.

In cigarettes, cadmium occurs, among other things, because of the heavy fertilizer that has long been taking place and continues to take place to a growing extent. It should therefore be important to find methods to remove cadmium and cadmium compounds from said smoke.

It is already known to remove tar material, nicotine and the like from cigarette smoke using various filters that the smoke goes through before being inhaled by the smoker.

Such filters usually consist of cellulose, especially of cellulose acetate, or of coal and silicates. However, none of the now known cigarette filter types have been able to remove cadmium in a sufficiently effective manner in the context. However, the disclosure of U.S. Patent No. 2,940,456 discloses a type of filter which contains magnesium and chloride compounds for the removal of tar, nicotine and other undesirable materials. On the other hand, nothing is mentioned about the removal of cadmium * It is now found, in connection with the invention, that filters containing an active form material capable of binding and retaining cadmium and cadmium compounds from gases can be produced. .

Even surprisingly, it has been found that a flue gas filter can be provided which essentially completely removes cadmium and cadmium compounds thereof. A filter according to the invention is therefore characterized in that it mainly contains an additive factor which is active at the current temperature, which neither decreases the taste of the tobacco nor contributes to the development of harmful ingredients in the inhaled smoke, and which factor is capable of binding and retaining cadmium and cadmium compounds present in the smoke in the tobacco product.

Thus, such a gas filter must contain a material capable of absorbing or isolating cadmium. The material must not be saturated with cadmium and should preferably be substantially completely cadmium free. The filter made according to the invention should constitute in a tobacco product a special separate part of the tobacco product, but may also in certain applications substantially constitute an integral part of the tobacco product itself. Suitable additives for the filter include inorganic calcium salts and especially calcium phosphates. Other materials that absorb cadmium include inorganic salts of lanthanides. The proposed materials should be included in the filter in an amount of 1-75% by weight, preferably between 1.0 and 10% by weight. Drilling a filter in a tobacco product is usually 5-8% by weight a satisfactory and effective amount.

In order for the supplied material to have the desired effect, it is necessary that it be fed to or retained in the filter, respectively, in such a form that it can act as a cadmium-absorbing material.

Thus, if the inorganic salts mentioned in U.S. Patent No. 2,940,456 are added to the filter in the manner set forth therein, the filter will not remove cadmium from the smoke, which is because the utilized method of application contributes to inactivating the salts with respect to the salts. to their ability to absorb cadmium. Thus, it is essential that the filter contains the cadmium-absorbing agent in an active form, which is obtained if the cadmium-absorbing material is applied to the gas filter in the manner prescribed by the present invention, especially for tobacco products filters.

According to the present invention, the active materials are placed in powder form of suitable grain size, which depends inter alia on the fiber material or corresponding carriers in the filter. It is important that the grains are not bonded to the tobacco or filter material or cover the surface or are absorbed. This can be done by spraying fine grained material on the dry carrier in the filter. It is even possible to spray the material suspended in a portion of volatile organic solvent such as an alcohol, e.g. ethylal = carbon, which does not deactivate the cadmium-absorbing material. Further, the said salts may be added to a less volatile medium such as water, but in this case a drying device may be required.

Heretofore, efforts have been made to firmly apply various absorbent particles with the filter material to prevent it from being separated from the filter material during industrial manufacture or e.g. to avoid getting the particles into the mouth during smoking. In this way, certainly acceptable effects with regard to the removal of, for example, tar materials and nicotine, etc., are obtained from the smoke, but on the other hand it has proved quite impossible in the same way to clear cadmium and cadmium compounds by means of a filter constructed in accordance with the previously known method ·

The invention will now be elucidated in principle with an example in which all attempts have been made with cigarettes and cigarette filters. It is, of course, within the scope of normal skill to apply the conditions set forth herein as a rule for filtering cadmium-containing gases of a different kind.

Example of preparation of a filter according to the method according to the invention

Conventional type cellulose acetate filter material is used * and to this is added a slurry of calcium phosphate in ethanol so that the amount of calcium phosphate in the material amounts to 5% by weight of the filter material. From the material thus treated, filters were then prepared by a conventional filter-making technique.

Sample with filters made by the method of the invention

The filters made in this way were placed adjacent to and, if applicable, in place of existing filters in a number of ί 'cigarettes of commercially available brands, after which the cigarettes were smoked in a smoker. The same cigarettes were tested without any filter according to the invention. The results of the tests are given below.

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Sample Total Amount of Cd Total Amount of Cd Total Amount of Cd by Ancigarette Determined in Non-Inhaled Smoke Using a Filter No. of Inhaled Smoke and µg According to the Present Ash Jig Inhalation Smoke __ | qg 1 0.2 0.5 <0.001 2 0.25 0.6 <0.001 3 0.18 0.7 0.003 4 0.25 0.65 <0.001 5 0.21 0.48. 0.002 6 0.15 0.7 <0.001 3 0.20 0.67 <0.001 4 0.35 0.75 <0.001 The amounts were measured with a Perkin Elmer atomic absorption spectrophotometer with graphite furnace and with deuterium lamp as a background corrector.

Sample Comparison Example This example describes the results of a comparison of a filter made according to the invention with known filters.

The tobacco cigarettes tested contained 1.5-2.1 µg of Cd (700 mg of tobacco). The cigarettes were smoked to a 23 mm shutter in a standard smoking machine. The following results were obtained (mean of 8 cigarettes):

Cigarette type with a cadmium in tobacco Cadmium in the invention made inhaled smoke filter in yg 2.1 µg Cd 0.079 "1.9 µg Cd 0.050" 1.7 µg CD 0.032 1.5 ua Cd 0.027

with filter according to DTAB

1082542 2.1 ug Cd 1.5 1.5 ug Cd 1.03 without filter 1.7 ug Cd 1.4 n 1.6 ug Cd 1.3