WO2003070367A1

WO2003070367A1 - Method for production of a pseudoboehmite adsorbing agent, the adsorbent product and its application

Info

Publication number: WO2003070367A1
Application number: PCT/HU2002/000004
Authority: WO
Inventors: Mihály TÖRÖCSIK
Original assignee: Blaskovics, Tamás; Kesch, Julius; Szöllösi, Péter; CSAPLÁROS, László
Priority date: 2002-01-29
Filing date: 2002-02-01
Publication date: 2003-08-28
Also published as: HU0200306D0; HUP0200306A2; AU2002232026A1

Abstract

Subject matter of the invention is a method for producing an adsorbing agent, as well as an adsorbent produced by the said method and its application as smoke filtering insert of filter tip of tobacco products, advantageously cigarettes. The method for producing of the adsorbent is characterised by the following steps. Carbon dioxide gas is lead into solution of sodium aluminate in several steps, reaction mixture is treated with heat, the precipitated product is filtered, washed, dried. A pseudo boehmite on the base of aluminium oxy-hydroxide is obtained in this way, containing water of 20 to 24 mass % in the form of bound crystalline water, metal oxides of 0.01 to 0.4 mass %, among them Na2O, Fe2O3, if desired CaO and MgO, furthermore in given case SiO2 of 0.01 to 0.1 mass % and the rest part of mass consists of Al2O3 up to 100 mass %, the produced pseudo boehmite is heat treated, if desired.

Description

ETHOD FOR PRODUCTION OF A PSEUDOBOEHMITE ADSORBING AGENT, THE ADSORBENT PRODUCT AND ITS APPLICATION

The subject matter of invention is a method for producing an adsorbing

agent, as well as an adsorbent product produced by the said method and its

5 application as smoke filtering insert of filter tip of tobacco products,

advantageously cigarettes.

The Hungarian patent specification of No. 213 305 describes a smoke-

filtering insert for cigarettes or cigars containing a mixture of clinoptilolite

and mordenite as filling.

10 The U.S. patent specification of No. 4 662 384 describes an application of

zeolite as filling of filter tips of cigarettes.

The U.S. patent specification of No. 4 830 641 describes an insert of

cigarette filter tip which consists mainly of clinoptilolite.

During our experiments we found that benzpyrene and its derivatives in the

15 smoke of cigarette (the multitude of these compounds are named hereinafter

BAP. This abbreviation is used for benzpyrene and its derivatives, primarily

4, 5 oxide derivative, respectively -6-OHCH₂-derivative of benzpyrene)

have strong carcinogenic effect and the known adsorbents do not bind them

adequately.

20 During our research work we managed to find an absorbent on the base of

pseudo boehmite, which binds BAP much more effectively than the

formerly known adsorbents. The benzpyrene and its derivatives have carcinogenic effect and the

multitude of these compounds can be regarded as one of causative factors

of pulmonary cancer.

A number of publications describe the carcinogenic effect of the

compounds BAP.

Up to now nobody could find an adsorbent which could bind these

compounds with high effect.

During our research work we aimed to produce such an adsorbent and to

apply it as filling material of smoke filtering inserts of filter tips of tobacco

products, expediently cigarettes.

Consequently, the subject matter of invention is a method for producing an

adsorbent.

The characteristic features of the method according to invention are as

follows: carbon dioxide is lead into sodium aluminate solution preferably

into solution of sodium aluminate originated from alumina production. The

precipitated product is filtered, washed, then transformed into slurry with

water, then treated with carbon dioxide again, the reaction mixture is heat

treated at temperature 80 to 90 C°, the precipitated product is filtered then

washed with water in several steps and dried. The product obtained in this

way is a aluniinium oxy-hydroxide based pseudo boehmite, which contains

20 to 24 mass % of water bound as crystalline water, 0.01 to 0.4 mass % of

metal oxide, among them Na₂0, Fe₂0₃, if desired CaO, MgO, furthermore in given case 0.01 to 0.1 mass % of Si0₂, and the rest of mass up to 100 %

consists of A1₂0 . The pseudo boehmite obtained by the said method is

heat-treated at the temperature 110 to 125 C° if necessary.

It is expedient to use a thin solution of sodium uminate (of concentration

less than 100 g 1 of Na₂0, preferably less than 40 g 1 of Na₂0) as initial

material.

The grain size of pseudo boehmite obtained by the said method is between

0.01 to 0.1 mm.

An adsorbent of extraordinarily high adsorption capacity can be produced,

if the product resulted after leading in of carbon dioxide and washing is

tempered at a temperature from 110 to 125 C°. The carbonate

contamination of the absorbent is namely eliminated, and the adsorption

capacity of the product can be increased up to 93 to 95 % in this way.

The duration of heat treatment at temperature from 110 to 125 C° is

expediently 1 to 6 hours.

The subject matter of the invention is furthermore the adsorbent itself of the

following characteristic features: it is a pseudo boehmite based on

aluminium oxide and hydroxide, which contains 20 to 24 mass % of water

bound as crystalline water, 0.01 to 0.4 mass % of metal oxide among them

Na₂0, Fe₂0₃, CaO and MgO if required, furthermore 0.01 to 0.1 mass % of

Si0₂ and the rest of mass up to 100 % consists of A1₂0₃. The subject matter of the invention is furthermore a smoke filtering insert

for tobacco products, preferably for filter-tip cigarettes, with the feature that

it contains an insert filled either with pseudo boehmite of the above-

mentioned composition or a mixture of 10 to 90 mass % of pseudo

boehmite of the above-mentioned composition and 90 to 10 mass % of

activated carbon in addition to the known paper or viscose insert.

An insert of smoke filter contains expediently 20 to 120 mg of pseudo

boehmite of the above-mentioned composition.

The Figure 1 shows a cigarette containing a filter-paper insert 1, a filling of

smoke filtering insert 2 according to invention and tobacco 3.

The diameter of smoke filtering insert 2 is 7.83 mm, its length is 5 mm

according to an advantageous embodiment. This insert contains an

adsorbent filling of 24.07 mg of grain size 0.1 mm according to invention.

The pseudo boehmite produced according to the invention constitutes a

dyscrystalline intermediate phase between the gel of aluminium hydroxide

and the crystalline uminium hydroxides containing well-defined quantity

of crystalline water.

The properties of the product change within wide ranges like those of all

intermediate phases and its composition depends on the composition of the

initial material and the parameters of the method of production.

The method of production of the adsorbent according to invention is

described below in the examples of production Example 1

A thin sodium uminate solution originated from alumina production with

concentration of Na₂0 of 50 g/1 is loaded into a reactor, then carbon dioxide

gas is lead into reactor until aluminium hydroxide gel precipitation takes

place.

The product fallen out is filtered, washed with water then mixed with water

to make sludge again.

The sludge is loaded again into the reactor and carbon dioxide gas is lead

again into reactor until the pH value 6.8 to 7.2 is reached.

The product fallen out is then treated with heat at the temperature 80 to 90

C° during 30 minutes, then filtered and the filtrate is washed.

The washed product is again mixed with water to make sludge, then filtered and washed. The above-described steps are repeated several times until pure product is obtained. The filtrate obtained in the last step is spray-dried.

Example 2

All the operations are the same as in the Example 1 then the product

obtained by the spray drying is heated in an oven at the temperature of 120

C° during 5 hours.

The obtained product is a loose white fine-grained powder having large

specific surface. The chemical composition of pseudo boehmite produced according to the

invention is as follows:

• loss of weight measured at 1100 C°, ** loss of weight measured at 110

C° (the composition specified in form of oxides relates to the material

dried at HO C⁰).

The physical and physicochemical characteristics of pseudo boehmite are

described in the table below.

** The aluminium hydroxides have amphoteric characteristic, i. e. they are

soluble in strong acids and alkali liquors. The amorphous material has the

highest solubility, the pseudo boehmite is less soluble, and the gibbsite is

the least soluble. The amorphous aluminium hydroxide and that of

boehmite structure dissolves practically completely at pH 4 and at pH 12. Example 3

Experiments were carried out to determine the BAP binding capacity of the

absorbent produced according to the invention.

During the experiments pseudo boehmite prepared according to Example 1

was dosed according to the table below to the aqueous solution of BAP of 3

cm³ having concentration of 54.4 μg/cm³.

For the sake of comparison another series of experiments was carried out to

determine the adsorption capacity of the natural mineral clinoptilolite,

which is traditionally applied as smoke filtering insert of cigarettes.

The clinoptilolite was dosed according to the table below in the series of

experiments.

The aqueous mixtures were shaken about 10 minutes up to the

establishment of adsorption equilibrium.

The suspension is filtered with a membrane filter of pore size of 0.2 μm and

the BAP content is determined with an UV adsorption spectrophotometer.

The UV adsorption spectrum of BAP was previously determined applying a

solution of concentration of 23 μg/cm³ of said compounds in order to

calibrate the measurement technique.

The spectrum is shown in the Figure 2. It shows two adsorption maximums

in the wavelength range between 320 and 400 nm.

The measurements were carried out at 380 nm on the base of said result. A calibration curve was established to determine the BAP concentrations of

solutions obtained from the experiments. The curve is shown in the Figure

3.

A thin-layer chromatograph containing cellulose thin layer and a HPLC

apparatus were used to separate BAP from the solutions and to identify it.

The developing mixture used for thin layer consists of toluene, water and

ethanol in mass proportions 10 : 63 : 35.

The chromatograms were developed to 130 mm at BAP Rf: 0.79-81 in the

system.

A Nucleosil C18 column and a mobile phase of acetonitrile and water in

mass proportion 80 : 20 were used for the apparatus Gibson HPLC.

The results of experiments are shown in the table below.

Adsorption of BAP from aqueous solution with adsorbent produced

according to Example 1

Adsorption of BAP from aqueous solution with adsorbent clinoptilolite

The specific BAP binding capacity of the adsorbents

It seems from the above-described example that the adsorbent according to

the invention has significantly higher BAP binding capacity than the filling

material of traditionally used smoke-filtering insert.

Example 4

In the experiment "A" pseudo boehmite produced according to Example 1

is applied as filling material of smoke filter insert 2 of the cigarette shown

in the Figure 1 using the quantity in the table below.

In the experiment "B" pseudo boehmite produced according to Example 2

is applied as filling material of smoke filter insert 2 using the quantity in the

table below.

In the experiment "C" a mixture of pseudo boehmite produced according to

Example 1 of 60 mass % and active carbon of 40 mass % is applied as

filling material of smoke filter insert 2.

We aimed during experiments "A", "B" and "C" to determine the BAP

binding capacities of filling materials of smoke filtering inserts. During the experiments 5 cigarettes produced by each above-mentioned

method are inserted into a burning apparatus functioning under vacuum and

the produced smoke gases are entrapped in alcohol of 5 cm³.

Each cigarette is burned during 11 minutes.

The BAP binding capacity of the filtering insert filled with traditional

aerosol was determined as control value ("K").

The results of experiments are as follows:

Experiment "A"

Experiment "B"

Experiment "C"

The experimental results show that the best results were obtained with a

filling material containing pseudo boehmite produced and subsequently

heat treated according to invention.

Claims

1. Method for producing an adsorbent from sodium aluminate solution

characterised by that carbon dioxide gas is lead into solution of sodium

aluminate, preferably into solution of sodium aluminate originated from

alumina production, then the precipitated product is filtered, washed,

converted into sludge with water, then treated again with carbon dioxide,

the reaction mixture is treated with heat at a temperature of 80 to 90 C°, the

precipitated product is filtered then washed with water in several steps and

dried, a pseudo boehmite on the base of alurninium oxy- hydroxide is

obtained in this way, containing water of 20 to 24 mass % in the form of

bound crystalline water, metal oxides of 0.01 to 0.4 mass %, among them

Na₂0, Fe₂0₃, if desired CaO and MgO, furthermore in given case Si0 of

0.01 to 0.1 mass % and the rest part of the mass consists of A1₂0₃ up to 100

mass %, then the produced pseudo boehmite is heat treated at a temperature

of 110 to 125 C°, if desired.

2. The method according to Claim 1 characterised by that the grain

size of the produced pseudo boehmite is between 0.01 and 0.1 mm.

3. The method according to Claims 1 and 2 characterised by that

the heat treatment at the temperature between 110 and 125 C° is carried out

during 1 to 6 hours.

4. An adsorbent, characterised by that it is a pseudo boehmite on

the base of aluninium oxide and hydroxide containing water of 20 to 24

mass % in the form of bound crystalline water, metal oxides of 0.01 to 0.4

mass %, among them Na₂0, Fe₂0₃, CaO and MgO if desired, furthermore

Si0₂ of 0.01 to 0.1 mass % if desired, and the rest part of the mass consists

ofAl₂0₃ up to 100 %.

5. A smoke-filtering insert for tobacco products, preferably for

cigarettes with filter tip of paper or viscose filling characterised by that

in addition to the known paper and/or viscose filling the filter contains a

filtering insert with a filling consisting of either the pseudo boehmite

according to Claim 4 or a mixture of pseudo boehmite according to Claim 4

of 10 to 90 mass % and of active carbon of 90 to 10 mass %.

6. The smoke-filtering insert according to Claim 5 characterised by

that it contains 20 to 120 mg of pseudo boehmite produced according to

Claim 1 per cigarette.