WO1994017907A1 - Improved respirator carbon for protection against acid gases and formaldehyde - Google Patents
Improved respirator carbon for protection against acid gases and formaldehyde Download PDFInfo
- Publication number
- WO1994017907A1 WO1994017907A1 PCT/US1993/009042 US9309042W WO9417907A1 WO 1994017907 A1 WO1994017907 A1 WO 1994017907A1 US 9309042 W US9309042 W US 9309042W WO 9417907 A1 WO9417907 A1 WO 9417907A1
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- Prior art keywords
- potassium
- carbonate
- formaldehyde
- activated carbon
- carbon
- Prior art date
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Classifications
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- A—HUMAN NECESSITIES
- A62—LIFE-SAVING; FIRE-FIGHTING
- A62B—DEVICES, APPARATUS OR METHODS FOR LIFE-SAVING
- A62B19/00—Cartridges with absorbing substances for respiratory apparatus
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
- B01J20/20—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising free carbon; comprising carbon obtained by carbonising processes
Definitions
- the present invention relates to an impregnated adsorbent for adsorption of acid gases, formaldehyde and other like aldehydes and, in particular, to a carbon impregnated with a guanidine salt and at least one compound selected from potassium carbonate, potassium phosphate, potassium hydroxide, sodium carbonate, and sodium hydroxide.
- Formaldehyde is a relatively stable water soluble, colorless gas with a pungent odor. Its main decomposition products are carbon monoxide, hydrogen and carbon dioxide. It is an OSHA regulated carcinogen with an STEL of 2.0 ppm and PEL of 0.75 ppm which requires that worker exposure be minimized or eliminated. While various methods have been used to remove formaldehyde and certain
- Adsorbents for the removal of formaldehyde in respirators are known. However, to be safe and meet the OSHA limits, adsorbents using a gas phase removal mechanism must effect removal rapidly and irreversibly at room temperature and over a wide range of relative humidity. The removal mechanism must also involve reactants which are substantially nonflammable, nontoxic and nonvolatile and which are compatible with activated carbon and water.
- a wide range of impregnants have been used with activated carbon to enhance removal, but relatively few are effective in removing formaldehyde completely without subsequent desorption.
- low levels of sulfate salts have been found to enhance the capacity of carbon to remove formaldehyde.
- Transition metal oxides such as copper, zinc, molybdenum, vanadium, and iron also adsorb formaldehyde.
- Metal-and sulfate-containing products show good removal capacities for formaldehyde. Even moisture present on activated carbon is effective in removing formaldehyde.
- an object of the present invention to provide an impregnated adsorbent material such as alumina, silica, zeolite and carbon for the irreversible removal of formaldehyde and other light aldehydes such as acetaldehyde, propionaldehyde, butyraldehyde, and acrolein. It is a further object of the invention to provide an impregnated adsorbent for use in respirators and like apparatus for protection against not only formaldehyde and light aldehydes but also acid gases such as sulfur dioxide, chlorine, hydrogen chloride, bromine, hydrogen bromine, iodine and hydrogen iodide and like gases. A further object of the invention is to provide impregnants which have low toxicity and flammability and are inexpensive for use with carbon containing respirators and adsorption devices.
- the present invention provides an impregnated carbon and a method for impregnating such carbon.
- Activated carbon is impregnated with a guanidine salt, such as guanidine carbonate or guanidine phosphate, and at least one of potassium or sodium phosphate or potassium or sodium carbonate.
- a guanidine salt such as guanidine carbonate or guanidine phosphate
- potassium or sodium phosphate or potassium or sodium carbonate is from about 4.0 to 12% by weight preferably about 6.0% to 9.0%.
- the preferred percentage of potassium carbonate is from about 2 to 8% and more preferably from 4 to 5% by weight and the preferred range of potassium phosphate is from about 2 to 10% and more preferably from 3.5 to 5.5%.
- the use of potassium and sodium hydroxide in amounts up to 9.0% is also useful in the removal of sulfur dioxide.
- the impregnants of the present invention have provided an improved carbon which is effective in irreversibly removing formaldehyde and sulfur dioxide. It has particular advantages in respirators, but other advantages of the improved carbon will be seen from a perusal of the following detailed description of presently preferred embodiments of the carbons of the present invention.
- Samples described herein were prepared by slowly adding a solution containing the various impregnants to 12 x 20 or 12 x 30 mesh coal-based granular activated carbon. Samples were dried in a laboratory forced air convection oven at 130 C unless otherwise specified. In some cases, more than one impregnation step was needed to achieve the desired level of impregnants.
- mesh sizes of carbon other than those described above also can be utilized in conjunction with this invention with advantages and disadvantages that will be known to those skilled in the art.
- Other forms of carbon such as pellets or spheres, as well as carbon derived from alternate sources, such as coconut or wood can also be used.
- dibasic potassium phosphate has been utilized, other forms can be used.
- results of tests show the advantages of the present invention of an impregnant comprising guanidine carbonate and a potassium salt.
- results using carbons impregnated with guanidine carbonate and potassium carbonate and/or potassium phosphate show a significant enhancement of formaldehyde removal over guanidine carbonate impregnation alone.
- S0 2 protection which is only minimally provided in the absence of the potassium salts, is dramatically improved.
- Table IV shows the results of a number of tests using the impregnants of the present invention. These tests were carried out with samples dried at 130° and demonstrate the effectiveness of the invention over a range of impregnant loadings.
- Table V is similar to Table IV except the drying temperature of the carbon has been varied.
- Table VI shows the effectiveness of the invention using potassium and/or sodium hydroxide in removing S0 2 .
- impregnated carbons of the present invention show greatly improved removal of formaldehydes and sulfur dioxide over the prior art.
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- Health & Medical Sciences (AREA)
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- General Health & Medical Sciences (AREA)
- Business, Economics & Management (AREA)
- Emergency Management (AREA)
- Inorganic Chemistry (AREA)
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Abstract
An activated carbon for irreversible removal of formaldehyde, lower aldehydes and acid gases. The activated carbon is impregnated with guanidine, preferably guanidine carbonate and at least one compund selected from potassium or sodium carbonate, potassium or sodium phosphate, and potassium or sodium hydroxide.
Description
TITLE OF INVENTION
Improved Respirator Carbon For Protection Against Acid Gases and Formaldehyde
FIELD OF THE INVENTION
The present invention relates to an impregnated adsorbent for adsorption of acid gases, formaldehyde and other like aldehydes and, in particular, to a carbon impregnated with a guanidine salt and at least one compound selected from potassium carbonate, potassium phosphate, potassium hydroxide, sodium carbonate, and sodium hydroxide.
BACKGROUND OF THE INVENTION
Formaldehyde is a relatively stable water soluble, colorless gas with a pungent odor. Its main decomposition products are carbon monoxide, hydrogen and carbon dioxide. It is an OSHA regulated carcinogen with an STEL of 2.0 ppm and PEL of 0.75 ppm which requires that worker exposure be minimized or eliminated. While various methods have been used to remove formaldehyde and certain
acid gases and organic vapors from the atmosphere, it has proven to be very difficult to remove effectively and irreversibly.
Adsorbents for the removal of formaldehyde in respirators are known. However, to be safe and meet the OSHA limits, adsorbents using a gas phase removal mechanism must effect removal rapidly and irreversibly at room temperature and over a wide range of relative humidity. The removal mechanism must also involve reactants which are substantially nonflammable, nontoxic and nonvolatile and which are compatible with activated carbon and water.
A wide range of impregnants have been used with activated carbon to enhance removal, but relatively few are effective in removing formaldehyde completely without subsequent desorption. For example, low levels of sulfate salts have been found to enhance the capacity of carbon to remove formaldehyde. Transition metal oxides such as copper, zinc, molybdenum, vanadium, and iron also adsorb formaldehyde. Metal-and sulfate-containing products show good removal capacities for formaldehyde. Even moisture present on activated carbon is effective in removing formaldehyde. Activated carbons impregnated with salts of copper and hexavalent chromium have been utilized to effectively remove formaldehyde, but because of their disposal and health related problems are not approved for respirator use by NIOSH. Those impregnants that are
approved, however, do not provide an irreversible adsorption in that the adsorbed formaldehyde is liberated when the carbon bed is purged with a dry air stream. More recently, the use of guanidine compounds had been found to be effective in removing lower aldehydes: Japanese Patent Application 89/219099.
Therefore, it is an object of the present invention to provide an impregnated adsorbent material such as alumina, silica, zeolite and carbon for the irreversible removal of formaldehyde and other light aldehydes such as acetaldehyde, propionaldehyde, butyraldehyde, and acrolein. It is a further object of the invention to provide an impregnated adsorbent for use in respirators and like apparatus for protection against not only formaldehyde and light aldehydes but also acid gases such as sulfur dioxide, chlorine, hydrogen chloride, bromine, hydrogen bromine, iodine and hydrogen iodide and like gases. A further object of the invention is to provide impregnants which have low toxicity and flammability and are inexpensive for use with carbon containing respirators and adsorption devices.
SDMMARΪ OF THE INVENTION
Generally, the present invention provides an impregnated carbon and a method for impregnating such carbon. Activated carbon is impregnated with a guanidine salt, such as guanidine carbonate or guanidine phosphate,
and at least one of potassium or sodium phosphate or potassium or sodium carbonate. The preferred range of guanidine (calculated as the carbonate) is from about 4.0 to 12% by weight preferably about 6.0% to 9.0%. The preferred percentage of potassium carbonate is from about 2 to 8% and more preferably from 4 to 5% by weight and the preferred range of potassium phosphate is from about 2 to 10% and more preferably from 3.5 to 5.5%. The use of potassium and sodium hydroxide in amounts up to 9.0% is also useful in the removal of sulfur dioxide.
The impregnants of the present invention have provided an improved carbon which is effective in irreversibly removing formaldehyde and sulfur dioxide. It has particular advantages in respirators, but other advantages of the improved carbon will be seen from a perusal of the following detailed description of presently preferred embodiments of the carbons of the present invention.
PRESENTLY PREFERRED EMBODIMENTS
Experimental
Samples described herein were prepared by slowly adding a solution containing the various impregnants to 12 x 20 or 12 x 30 mesh coal-based granular activated carbon. Samples were dried in a laboratory forced air convection
oven at 130 C unless otherwise specified. In some cases, more than one impregnation step was needed to achieve the desired level of impregnants.
It is to be understood that mesh sizes of carbon other than those described above also can be utilized in conjunction with this invention with advantages and disadvantages that will be known to those skilled in the art. Other forms of carbon, such as pellets or spheres, as well as carbon derived from alternate sources, such as coconut or wood can also be used. Also, while dibasic potassium phosphate has been utilized, other forms can be used.
Samples were tested against S02 and CH-0 under NIOSH test conditions. Tests were conducted in glass tubes under NIOSH conditions as set forth in Tables I and II. All samples were tested as prepared. Desorption of formaldehyde was tested after CH-0 challenge by purging the sample with clean air.
TABLE I CH-0 Test Conditions
CH20 challenge (ppm) 100
Breakthrough level (ppm) 1
Temp. (Degrees C) 25-30
Tube diameter (cm) 5.8 Bed depth (cm) 2.1
Linear velocity (cm/sec) 12.07
Test R.H. (%) 25
TABLE II
S02 Test Conditions
Challenge (ppm) 500
Breakthrough level (ppm) 5
Temp (Degrees C) 25
Tube diameter (cm) 5.8
Bed depth (cm) 2.1
Linear velocity (cm/sec) 12.07
Test R.H. 50
Results
In Table III, the results of tests show the advantages of the present invention of an impregnant comprising guanidine carbonate and a potassium salt. In particular, the results using carbons impregnated with guanidine carbonate and potassium carbonate and/or potassium phosphate show a significant enhancement of formaldehyde removal over guanidine carbonate impregnation alone. Similarly, S02 protection, which is only minimally provided in the absence of the potassium salts, is dramatically improved.
TABLE III
GUANIDINE POTASSIUM DIBASIC so2 CH20
CARBONATE CARBONATE POTASSIUM SERVICE SERVICE
(%) (%) PHOSPHATE LIFE (MIN) LIFE (MIN)
' 7.76 4.41 4.61 50 195
7.76 4.41 0.00 50 156
7.76 0.00 4.61 40 178
7.76 0.00 0.00 23 106
7.76 8.13 0.00 54 130
Table IV shows the results of a number of tests using the impregnants of the present invention. These tests were carried out with samples dried at 130° and demonstrate the effectiveness of the invention over a range of impregnant loadings.
TABLE IV
GUANIDINE POTASSIUM DIBASIC so2 CH20
CARBONATE CARBONATE POTASSIUM SERVICE SERVICE
(%) (%) PHOSPHATE (%) LIFE (MIN) LIFE (MIN)
7:76 4.41 2.76 52 178
7.76 4.41 6.45 41 123
7.76 2.10 4.61 44 162
7.76 6.71 4.61 52 NA**
6.21 5.60 4.61 60 170
9.31 3.22 4.61 56 219
12.20 6.91 0.00 62 NA**
7.76* 4.41* 4.61* 79* 240*
*Sample impregnated on a 12x30 mesh carbon substrate. **Not available
Table V is similar to Table IV except the drying temperature of the carbon has been varied.
TABLE V
DIBASIC
GUANIDINE POTASSIUM POTASSIUM so2 CH20 DRYING
CARBONATE CARBONATE PHOSPHATE SERVICE SERVICE TEMPERATURE (X) (X) (X) LIFE (MIN) LIFE (MIN) (C)
8.51 6.41 0.00 65 172 110
8.25 0.00 9.28 50 154 110
7.50 4.61 1.85 42 122 150
10.50 2.30 4.61 NA* 114 150 4.50 2.30 1.85 NA* 71 150
*Not available
Finally, Table VI shows the effectiveness of the invention using potassium and/or sodium hydroxide in removing S02.
TABLE VI
GUANIDINE so2
CARBONATE NaOH KOH SERVICE LIFE
(%) (%) (%) (MIN)
7.6 6.0 32
7.6 8.0 50
A sample (12 x 20 mesh) of approximate composition 7.8% guanidine carbonate, 4.4% potassium carbonate, and 4.6% dibasic potassium phosphate was tested against the challenges of chlorine and hydrogen chloride according to the conditions shown in Table VII. The test results show good removal capability for halogens and hydrogen halides.
TABLE VII TEST RESULTS FOR CHLORINE AND HYDROGEN CHLORIDE
NIOSH
INLET REQUIREMENT BREAKTHROUGH BREAKTHROUGH
TEST CONC TIME CONC TIME
GAS PPM MIN PPM MIN
CL2 500 35 5 >108
HCL 500 50 5 >102
TEST CONDITIONS: A SINGLE CARTRIDGE WAS TESTED AT 50Z RH, 25 OC AND 32 LPM. THE CARTRIDGE CONTAINED 115 ML OF CARBON (2.3 CM DEEP AND 8.0 CM IN DIAMETER .
The impregnated carbons of the present invention show greatly improved removal of formaldehydes and sulfur dioxide over the prior art. Thus, while presently preferred embodiments of this invention have been discussed in particularity, the invention may be otherwise embodied within the scope of the appended claims.
Claims
1. An adsorbent material impregnated with about 2.6 to 8% by weight guanidine and at least one of up to 8% by weight potassium or sodium carbonate, up to 10% by weight potassium or sodium phosphate, and up to 9% by weight potassium or sodium hydroxide.
2. An adsorbent material as set forth in Claim 1 wherein said adsorbent is activated carbon.
3. An activated carbon impregnated with 4 to 12% by weight guanidine carbonate and 2 to 10% by weight potassium or sodium phosphate.
4. An activated carbon impregnated with 4 to 12% by weight guanidine carbonate and 2 to 8% by weight potassium or sodium carbonate.
5. An activated carbon impregnated with about 4 to 12% by weight guanidine carbonate, about 2 to 8% by weight potassium carbonate and about 2 to 10% by weight potassium phosphate.
6. An activated carbon impregnated with about 6 to 9% by weight guanidine carbonate, about 3 to 6% by weight potassium carbonate and about 3 to 6% potassium phosphate.
7. An activated carbon impregnated as set forth in Claim 1 wherein said guanidine carbonate is present in an amount of 4.5 to 8.5%.
8. An activated carbon for use in respirators or other adsorption devices impregnated as set forth in Claim 1 or 2.
9. A adsorption device having an activated carbon impregnated as set forth in Claim 1 or 2.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US1357893A | 1993-02-04 | 1993-02-04 | |
| US08/013,578 | 1993-02-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO1994017907A1 true WO1994017907A1 (en) | 1994-08-18 |
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ID=21760664
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/US1993/009042 WO1994017907A1 (en) | 1993-02-04 | 1993-09-23 | Improved respirator carbon for protection against acid gases and formaldehyde |
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| Country | Link |
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| WO (1) | WO1994017907A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0908230A2 (en) * | 1997-10-13 | 1999-04-14 | Hitachi Zosen Corporation | Nitrogen dioxide absorbent and its use for purifying ventilation gas |
| JP2014050416A (en) * | 2012-09-04 | 2014-03-20 | Suminoe Textile Co Ltd | Flame-retardant deodorant filter |
| US10307706B2 (en) | 2014-04-25 | 2019-06-04 | Ada Carbon Solutions, Llc | Sorbent compositions for use in a wet scrubber unit |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4443354A (en) * | 1982-03-26 | 1984-04-17 | Minnesota Minning And Manufacturing Company | Sorbent material for reducing formaldehyde emission |
| JPH02180695A (en) * | 1988-12-28 | 1990-07-13 | Kuraray Co Ltd | Removing agent and method for aldehydes |
| JPH03262532A (en) * | 1990-03-14 | 1991-11-22 | Ebara Corp | Aldehyde collecting material |
| GB2251432A (en) * | 1990-11-30 | 1992-07-08 | Takeda Chemical Industries Ltd | Adsorbent comprising saturated cyclic secondary amine and carrier |
-
1993
- 1993-09-23 WO PCT/US1993/009042 patent/WO1994017907A1/en active Application Filing
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4443354A (en) * | 1982-03-26 | 1984-04-17 | Minnesota Minning And Manufacturing Company | Sorbent material for reducing formaldehyde emission |
| JPH02180695A (en) * | 1988-12-28 | 1990-07-13 | Kuraray Co Ltd | Removing agent and method for aldehydes |
| JPH03262532A (en) * | 1990-03-14 | 1991-11-22 | Ebara Corp | Aldehyde collecting material |
| GB2251432A (en) * | 1990-11-30 | 1992-07-08 | Takeda Chemical Industries Ltd | Adsorbent comprising saturated cyclic secondary amine and carrier |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0908230A2 (en) * | 1997-10-13 | 1999-04-14 | Hitachi Zosen Corporation | Nitrogen dioxide absorbent and its use for purifying ventilation gas |
| EP0908230A3 (en) * | 1997-10-13 | 1999-08-11 | Hitachi Zosen Corporation | Nitrogen dioxide absorbent and its use for purifying ventilation gas |
| US6171372B1 (en) | 1997-10-13 | 2001-01-09 | Hitachi Zosen Corporation | Nitrogen dioxide absorbent |
| JP2014050416A (en) * | 2012-09-04 | 2014-03-20 | Suminoe Textile Co Ltd | Flame-retardant deodorant filter |
| US10307706B2 (en) | 2014-04-25 | 2019-06-04 | Ada Carbon Solutions, Llc | Sorbent compositions for use in a wet scrubber unit |
| US10421037B2 (en) | 2014-04-25 | 2019-09-24 | Ada Carbon Solutions, Llc | Methods for treating a flue gas stream using a wet scrubber unit |
| US10682605B2 (en) | 2014-04-25 | 2020-06-16 | Ada Carbon Solutions, Llc | Methods for treating a flue gas stream using a wet scrubber unit |
| US11590446B2 (en) | 2014-04-25 | 2023-02-28 | Ada Carbon Solutions, Llc | Methods for treating a flue gas stream using a wet scrubber unit |
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