GB2063228A - Process for producing carbonaceous sorbent - Google Patents
Process for producing carbonaceous sorbent Download PDFInfo
- Publication number
- GB2063228A GB2063228A GB7939047A GB7939047A GB2063228A GB 2063228 A GB2063228 A GB 2063228A GB 7939047 A GB7939047 A GB 7939047A GB 7939047 A GB7939047 A GB 7939047A GB 2063228 A GB2063228 A GB 2063228A
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- GB
- United Kingdom
- Prior art keywords
- film
- forming polymer
- solvent
- liquid
- particles
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M1/00—Suction or pumping devices for medical purposes; Devices for carrying-off, for treatment of, or for carrying-over, body-liquids; Drainage systems
- A61M1/36—Other treatment of blood in a by-pass of the natural circulatory system, e.g. temperature adaptation, irradiation ; Extra-corporeal blood circuits
- A61M1/3679—Other treatment of blood in a by-pass of the natural circulatory system, e.g. temperature adaptation, irradiation ; Extra-corporeal blood circuits by absorption
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/30—Active carbon
- C01B32/354—After-treatment
- C01B32/372—Coating; Grafting; Microencapsulation
Abstract
A carbonaceous material, for selective adsorption of low-molecular weight substances from a mixture thereof with high-molecular weight compounds, as produced by a process of impregnating particles of the material with a liquid containing no film-forming polymer; separating the excessive liquid, dispersing particles of the material in a solution of a film- forming polymer in a solvent; separating the particles with a layer of the film-forming polymer deposited thereonto from the solution and drying.
Description
Process for producing carbonaceous sorbent
The present invention relates to processes for the production of carbonaceous sorbents.
Carbonaceous sorbents are useful in the chemical industry and medicine for selective adsorption of low-molecular weight substances from a mixture thereof with high-molecular weight compounds.
There is known in the art a process for producing a carbonaceous sorbent by polymerization of monomer from a monomer solution in which particles of activated charcoal are dispersed (cf M
Morishita, M Fukushima, J Inaba in: Microencapsulation, Processes and Application, Ed by J E Vandegaer, Plenum Press, New York-London, 1974, p.116-il 7).
A disadvantage of this process resides in fillage, by the monomer solution, of the volume of the porous structure of the charcoal and subsequent polymerization of the monomer inside the pores, whereby the active surface area of the charcoal accessible for the following absorption of low-molecular weight substances is reduced.
Also known in the art is a process for producing a carbonaceous sorbent for selective absorption of low-molecular weight compounds from a mixture thereof with high-molecular ones, the process comprising dispersing particles of active charcoal with a diameter of from 100 to 5,000 mem in a 5~30% solution of a film forming polymer in a hydrophylic solvent (acetone, methanol, methylethylketone, dimethylsulphoxide), introducing the resulting dispersion into a liquid medium (settling agent) used in excess and not capable of dissolving the film-forming polymer; separating activated particles with a layer of the film-forming polymer deposited thereon from the settling agent and from the polymer solution, and drying said particles (cf US Patent No 3,953,360).As the film-forming polymers in this prior art process, use is made of cellulose derivatives, vinyl hydrophobic polymers and copolymers, polyvinylacetals, polystyrene and other water-insoluble polymers and mixtures thereof. As the liquid medium (settling agent) use is made of, for example, water. The process is based on absorption of a film-forming polymer from solution at the surface of activated charcoal particles and an additional codeposition thereon of the film-forming polymer in the presence of a liquid medium (settling agent) which does not dissolve the polymer.
This prior art process has a disadvantage residing in filling, by the polymer solution, a macropores, medium-size pores and a portion of micro-pores of active coal, thus causing lowered absorption capacity of active charcoal and a longer time for achieving an equilibrium saturation of the charcoal active surface with the absorbate during the selective absorption of substances from the mixtures to be separated and, eventually, a reduced activity of the carbonaceous sorbent.
It is an object of the present invention to provide a process for producing a carbonaceous sorbent for selective absorption of low-molecular weight substances from a mixture thereof with high-molecular weight compounds which process would make it possible substantially to reduce the degree of reduction in the activity of a carbonaceous sorbent and increase selectivity thereof due to a lowered degree of filling of the porous structure of carbon with the film-forming polymer.
This and other objects of the present invention are accomplished by a process for producing a carbonaceous sorbent for selective adsorption of low-molecular weight substances from a mixture thereof with high-molecular weight ones, the process involving dispersing active charcoal particles in a solution of a film-forming polymer in a solvent, separation from the solution of said film-forming polymer of the particles with a layer deposited thereon of the film-forming polymer, and drying said particles, wherein according to the present invention the active charcoal particles are impregnated, prior to dispersing, with a liquid containing no film-forming polymer, whereafter excess of liquid is separated from the particles.
In accordance with the present invention, to produce a carbonaceous sorbent, the liquid for impregnation of particles of active charcoal may be a solvent e.g. chloroform of ethyl ether partially miscible with the solvent for the film-forming polymer; it is then advisable to use, as the film-forming polymer, polyvinyl alcohol or methylcellulose respectively and, as the solvent for the film-forming polymer, use should be preferably made of water.
Furthermore, as the liquid for impregnation of the particles of active charcoal, use may be made of a solvent completely miscible with the solvent for the film-forming polymer, such as water or hexane; it is then advisable to use in this case, as the film-forming polymer, acetylcellulose or polyvinylchloride respectively and as the solvent for the film-forming polymer use should preferably be made of acetone or cyclohexanone respectively.
The charcoal for use in a process according to the present invention may be made of virtually any type of charcoal possessing a developed surface and porous structure, for example, active birch charcoal, recuperation charcoal, gas-type active carbon.
These active charcoals have a microporous structure and, in addition to micro-pores, also medium-size and macro-pores. These pores are capable of retention of the liquid penetrated thereinto and, depending on the pore size, absorb substances of various molecular masses and chemical nature.
It has been found that virtually any polymers employed as a film-forming material and having different molecular mass dispersion are capable of filling macro-pores medium pores and, to a certain extent, the bulk of micro-pores upon contact of their solutions with an active charcoal, in addition to adsorption at the external surface of the particles.
The lowered degree of filling of the pore structure with the film-forming polymer upon its deposition onto the surface of charcoal particles may be ensured, according to the present invention, by a preliminary fillage of the pores with a liquid at most partially miscible with the solvent for the filmforming polymer, for example chloroform, methylene chloride, benzene, hexane and other non-polar s21vents when using aqueous solutions of polymers. In the case of utilization of hydrophobic polymers, as the liquid use may be made of water, while as the solvent for the film-forming polymer it is possible to use, for instance, chloroform, methylene chloride, benzene, hexane and other non-polar solvents.
Furthermore. a lowered degree of filling of charcoal pores may be ensured, according to the present invention, by means of a preliminary treatment of the charcoal with a liquid which is completely miscible with the solvent for the film-forming polymer. For example, (i) as the above-mentioned liquid use may be made of acetone or ethanol; as the film-forming polymer acetyl- or acetylphthalyl-cellulose, while as the solvent for the film-forming polymer - acetone or mixtures of acetone with ethanol and chloroform; (ii) as said liquid use may be made of water, methanol or ethanol, acetone; as the filmforming polymer polyvinyl alcohol, methylcellulose or polyvinyl-pyrrolidone; (iii) as said liquid~ dichloroethane, chloroform, cyclohezanone; as the film-forming polymer - polyvinylchloride, polyvinylidenechloride or polyalkyl(phenyl)siloxanes, and - as the solvent for the film-forming polymer ~cyclohexanone, chloroform, acetone, dichloroethane and mixtures thereof. Said liquid may be the same as the solvent for the film-forming polymer.
The process for producing a carbonaceous sorbent can be performed in the following manner.
The starting activated charcoal is dried in a vacuum to a residual moisture content of 2~10% and placed in the liquid. The mixture is kept in a vacuum to ensure filling of the pores with the liquid. Then the excess liquid is drained off and the charcoal surface dried by maintaining the charcoal in the air or by purging air over the charcoal layer. Then a solution of a film-forming polymer in a solvent is added to the charcoal and the mixture is retained to ensure adsorption of the polymer on the particles to achieve an adsorption equilibrium between the dissolved film-forming polymer and the polymer adsorbed on the charcoal, or to achieve a desired value of the polymer adsorption on the charcoal. The amount of the adsorbed polymer may be also adjusted by the concentration of the polymer solution.After adsorption of the plymer, excess polymer solution is decanted from the particles and the particles dried by keeping them in the air and then heating them in a vacuum.
The following specific Examples illustrate certain embodiments of the process according to the present invention for hydrophilic and hydrophobic film-forming polymers and liquids with a limited or complete miscibility with a solvent for the film-forming material, as well as properties of the resulting carbonaceous sorbent intended for a selective adsorption of low-molecular weight substances from a mixture thereof with high-molecular weight cmpounds.
Example 1
10 g of an active charcoal with particle size of 0.5mm, total porosity of 1.1 1 cm3/g, micro-pore volume of 0.6 cm3/g, medium-size pore volume of 0.28 cm3/g and macro-pore volume of 0.23 cm3/g were mixed with 50 ml of water. The mixture was kept in a vacuum of 100 mm Hg for 10 seconds.
Excess water was then drained off and the wet charcoal#maintained open to the air for 48 hours. The resulting charcoal had 68% of its pore structure filled with water. To it was added 20 ml of a 1% solution of acetylcellulose in acetone. The mixture was maintained for 48 hours at a temperature of 2000 and the excess solution drained off. The charcoal particles were then stirred in a current of air for 8 hours and thereafter dried at a temperature of 800C for three hours, and in a vacuum of 10 mm Hg for 48 hours.
Example 2
10 g of an active charcoal similar to that described in the foregoing Example 1 were placed in 50 ml of chloroform. The mixture was maintained in a vacuum of 100 mm Hg for 10 seconds. Thereafter the chloroform was drained off and the charcoal kept open to the air for 3 hours. To the resulting charcoal, with 82% of its pore structure volume filled with chloroform, there were added 20 ml of a 1% solution of polyvinyl alcohol in water. The mixture was held for 48 hours at a temperature of 20 C, whereafter the excess solution was drained off. The particles were next stirred in a current of air for 48 hours, then dried at a temperature of 8000 for 40 hours and in vacuum of 10 mm Hg and 8000 for 48 hours.
Example 3
10 g of an active charcoal with a particle size of 1-2 mm, total porosity of 0.7 cm3/g, micro-pore volume of 0.33 cm3/g, volume of medium-size pore of 0.07 cm3/g and macro-pore volume of 0.3 cm3/g were placed in 50 ml of hexanes. The mixture was maintained in a vacuum of 300 mm Hg for 5 seconds, excess hexane drained off and the charcoal kept open to the air for 1 8 hours. To the resulting charcoal having 70% of the pore structure volume thereof filled with hexane there was added 20 ml of a 1% solution of polyvinylchloride in cyclohexanone. The mixture was kept for 48 hours at a temperature of 2000 and then the excess solution drained off. The particles were then stirred in a current of air for 36 hours and thereafter dried at 800C for 3 hours and in vacuum at 1 mm Hg and a temperature of 10000 for 48 hours.
Example 4
10 g of an active charcoal with a particle size of 1-2 mm, total porosity of 1.8 cm3/g, micro-pore volume of 1.1 cm3/g, medium-size pore volume of 0.31 cm3/g and macro-pore volume of 0.39 cm3/g were placed in 50 ml of ethyl ether. The mixture was kept in a vacuum of 500 mm Hg for 5 seconds, the excess ethyl ether drained, and the charcoal maintained in the air for 5 hours. To the resulting particles, with 70% of the pore structure volume being filled with ethyl ether, there were added 20 ml of a 1% solution of methylcellulose in water. The mixture was kept for 48 hours at a temperature of 200 C, whereafter the excess solution was drained off.The charcoal particles were stirred in a current of air for 8 hours and then dried at 800C for three hours and in vacuum at 10 mm Hgat a temperature of 800C for a period of 48 hours.
Example 5
A carbonaceous sorbent was produced in a manner similar to that described in Example 1 except that use was made of a 2% solution of acetylcellulose in acetone.
Comparative Example
A carbonaceous sorbent was produced following the process described in U.S. Patent No.
3 953 360. To this end, to 10 g of an active charcoal similar to that described in Example 1 and having a residual moisture content of 2%, there were added 20 ml of a 2% solution of acetylcellulose in acetone; the mixture was left over 48 hours at a temperature of 200 C, whereafter is was added, under stirring, to 1 litre of water (settling agent). The mixture was stirred for one hour, and the particles filtered-off and dried following the procedure described in Example 1.
Adsorption studies
To study the adsorption properties of carbonaceous sorbents obtained by the process according to the present invention (Examples 1 to 5), and by the process as taught in U.S. Patent No 3 953 360 and reproduced in the comparative Example hereinabove, as well to study the adsorption properties of an active charcoal not treated with a polymer solution, a weighed portion (0.1-0.2 g) of each of said samples was placed in a 25 ml adsorption cell connected to a peristaltic-action pump and to a cell of a
UV-spectrophotometer.The system was filled with 20 ml of an alcoholic solution containing (7-8)x10-4g/ml of phenol and 1.10-3 g/ml of polystyrene with a mean molecular mass of 250,000 (contains 59% of the fraction with a molecular mass of 422,000,7%~with molecular mass of 180,000; 21.4% with a molecular mass of from 127,000 to 46,200; 7%~with the molecular mass of 1 6,000 and 5.6%~with the molecular mass of 5,000) and the solution passed through a closed circuit and through the weighed portion of the sample for 48 hours while continuously measuring the intensity of the solution adsorption at the wavelength of 270 nm. The resulting data are shown in the following Table 1.
TABLE 1
Adsorption of phenol, Adsorption of polystyrene Example No. mg/g of the charcoal mg/g of the charcoal 30 min. 3 hours 48 hours 30 min. 3 hours 48 hours 1. 22 230 230 1.3 6.1 7.2 2. 40 285 265 1.4 6.1 6.86.1 3. 22 210 252 1.3 5.8 6.3 4. 19 180 220 1.4 6.0 6.6 5. 12 130 162 0.8 5.5 5.5 Comparative 1 50 150 1.0 6.1 8.0 Example Control * 18 160 160 10 18 25 * Note: active charcoal, not treated with the polymer solution.
The results shown in the above Table on the separation of a low-molecular and high-molecular weight compounds show that the absorption of a low-molecular weight compound on particles of a carbonaceous sorbent produced by the process according to the present invention occurs 1.5-2 times more effectively and the adsorption equilibrium is attained faster (within 3-5 hours) than in the case of using of the carbonaceous sorbent produced according to the process of US Patent No 3 953 360.
Similar results are obtained upon separation of a mixture of polysaccharides with urea, uric acid, bilirubin and other low-molecular weight compounds.
The carbonaceous sorbents produced by the processes according to the present invention have been tested under clinical conditions for hemosorption. They efficiently adsorb toxic low-molecular metabolites from blood which are formed upon a liver-kidney insufficiency; they possess a substantially lower traumatizing effect on blood components including those most traumatized by charcoals not protected by polymers - thrombocytes - and do not change basic physiological blood parameters.
Claims (10)
1. process for producing a carbonaceous sorbent for selective adsorption of low-molecular weight substances from a mixture thereof with high-molecular weight substances, the process comprising impregnating active charcoal particles with a liquid containing no film-forming polymer, separating any excess liquid from the particles, dispersing the impregnated particles in a solution of a film-forming polymer in a solvent, separating the particles with a layer of the film-forming polymer deposited thereonto from the solution, and drying said particles.
2. A process according to claim 1 wherein the liquid is a solvent at most partially miscible with the solvent for the film-forming polymer.
3. A process according to claim 2, wherein the liquid is chloroform, the film-forming polymer is
polyvinyl alcohol and the solvent for the film-forming polymer is water.
4. A process according to claim 2, wherein the liquid is ethyl ether, the film-forming polymer is methylcellulose and the solvent for the film-forming polymer is water.
5. A process according to claim 1, wherein the liquid is a solvent completely miscible with the solvent for the film-forming polymer.
6. A process according to claim 5, wherein the liquid is water, the film-forming polymer is acetylcellulose and the solvent for the film-forming polymer is acetone.
7. A process according to claim 5, wherein the liquid is hexane, the film-forming polymer is polyvinylchloride and the solvent for the film-forming polymer is cyclohexanone.
8. A process for producing a carbonaceous sorbent according to any of the foregoing claims 1 to 7 substantially as described generally hereinbefore or in any of Examples 1 to 5 hereinbefore.
9. A carbonaceous sorbent for selective adsorption of low-molecular weight substances from a mixture thereof with high-molecular weight compounds whenever produced by a process according to any of the foregoing claims 1 to 8.
10. A process for the selective adsorption of low-molecular weight compounds from a mixture thereof with high-molecular weight compounds which comprises contacting the mixture with carbonaceous sorbent as claimed in claim 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7939047A GB2063228B (en) | 1979-11-12 | 1979-11-12 | Process for producing carbonaceous sorbent |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7939047A GB2063228B (en) | 1979-11-12 | 1979-11-12 | Process for producing carbonaceous sorbent |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2063228A true GB2063228A (en) | 1981-06-03 |
| GB2063228B GB2063228B (en) | 1983-05-18 |
Family
ID=10509129
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7939047A Expired GB2063228B (en) | 1979-11-12 | 1979-11-12 | Process for producing carbonaceous sorbent |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2063228B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0119925A2 (en) * | 1983-03-16 | 1984-09-26 | Calgon Carbon Corporation | Carbon molecular sieves and a process for their preparation and use |
| US4535004A (en) * | 1982-03-31 | 1985-08-13 | Basf Aktiengesellschaft | Consolidating the surface of a granular adsorbent |
| US4535005A (en) * | 1982-03-30 | 1985-08-13 | Basf Aktiengesellschaft | Consolidating the surface of a granular adsorbent |
| WO1993013018A2 (en) * | 1991-12-23 | 1993-07-08 | E.I. Du Pont De Nemours And Company | Particulate material suitable for the removal of heavy metals |
-
1979
- 1979-11-12 GB GB7939047A patent/GB2063228B/en not_active Expired
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4535005A (en) * | 1982-03-30 | 1985-08-13 | Basf Aktiengesellschaft | Consolidating the surface of a granular adsorbent |
| US4535004A (en) * | 1982-03-31 | 1985-08-13 | Basf Aktiengesellschaft | Consolidating the surface of a granular adsorbent |
| EP0119925A2 (en) * | 1983-03-16 | 1984-09-26 | Calgon Carbon Corporation | Carbon molecular sieves and a process for their preparation and use |
| EP0119925A3 (en) * | 1983-03-16 | 1985-05-15 | Calgon Carbon Corporation | Carbon molecular sieves and a process for their preparation and use |
| WO1993013018A2 (en) * | 1991-12-23 | 1993-07-08 | E.I. Du Pont De Nemours And Company | Particulate material suitable for the removal of heavy metals |
| WO1993013018A3 (en) * | 1991-12-23 | 1993-08-05 | Du Pont | Particulate material suitable for the removal of heavy metals |
| US5296293A (en) * | 1991-12-23 | 1994-03-22 | E. I. Du Pont De Nemours And Company | Particulate material suitable for the removal of heavy metals |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2063228B (en) | 1983-05-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |