US3719552A - Bleaching of lignocellulosic materials with oxygen in the presence of a peroxide - Google Patents
Bleaching of lignocellulosic materials with oxygen in the presence of a peroxide Download PDFInfo
- Publication number
- US3719552A US3719552A US00154689A US3719552DA US3719552A US 3719552 A US3719552 A US 3719552A US 00154689 A US00154689 A US 00154689A US 3719552D A US3719552D A US 3719552DA US 3719552 A US3719552 A US 3719552A
- Authority
- US
- United States
- Prior art keywords
- peroxide
- pulp
- oxygen
- bleaching
- pressure
- 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.)
- Expired - Lifetime
Links
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/1026—Other features in bleaching processes
- D21C9/1036—Use of compounds accelerating or improving the efficiency of the processes
Definitions
- the present invention relates to the manufacture of paper pulp. More particularly, it relates to an improvement in the bleaching of sulfate process lignocellulose in oxygenated alkaline aqueous medium.
- Lignocellulose is cellulose which carries a sufiicient amount of ligning substituents to render it unacceptable for some papermaking purposes.
- Sulfate process lignocellulose is lignocellulose which has been produced by digestion of wood cellulose with sodium hydroxide and sodium sulfide, and differs in certain respects from the lignocellulose produced by other processes.
- Hoh, US. Pat. No. 3,382,149 discloses the treatment of sulfite pulp with alkaline hydrogen peroxide solution, with or without alkali pretreatment of the pulp. While the pulp becomes brighter as a result of the treatment, no lignin is removed therefrom.
- lignocellulose can be brightened by the action of an aqueous alkaline medium having a temperature of about 50 C.l50 C. and containing dissolved oxygen under pressure.
- the oxygen severs the bonds which connect the lignin substituents to the cellulose and the alkali carries the released lignin substituents (which are acidic) into solution.
- the process is termed bleaching.
- the process is performed batchwise in large pressure vessels and is slow.
- the time required in any instance to effect a given amount of bleaching depends chiefly upon the temperature and pressure of the oxygen. High temperatures and high oxygen pressures favor rapid and extensive liberation of the lignin substituents, but depolymerize the cellulose to such an extent as to seriously decrease the value of the cellulose for papermaking purposes.
- the oxygen-peroxide combination is effective at very low oxygen pressure. Good results have been obtained merely by bubbling oxygen through an aqueous alkaline suspension of the pulp containing peroxide, the absolute pressure of oxygen in the process being only a few pounds per square inch. The process therefore can be performed without need of a pressure vessel.
- the invention does not require the use of any specific amount of peroxide.
- the beneficial effect of peroxide is proportional to the amount introduced into the aqueous medium and to the length of time the fibers are in contact therewith.
- peroxide As a practical matter, we prefer to add an appropriate amount of peroxide to the water intended for use as the aqueous medium in the process.
- a suitable amount of peroxide can be found by laboratory trial, employing as a start an amount shown in the examples below.
- 0.2% peroxide. calculated as H 0 and based on the dry weight of the fibers produces a noticeable acceleration in the rate at which the lignin is liberated. so that evidently there is no amount however small, which will not impart some improvement.
- the maximum practical amount of peroxide appears to be about 15%, as larger amounts do not appear to impart correspondingly larger improvements.
- An amount within the range 0.5%- 5% generally produces satisfactory results. Within this range, it is preferred that the amount of peroxide be sufficient so that at least some peroxide remains in the aqueous medium after the bleaching process has been completed.
- the peroxide may all be added at the start (immediately prior to introducing the pulp into the pressure vessel), or it may be injected into the pressure vessel as the bleaching proceeds. It is within the scope of the invention to generate the peroxide in the pulp during the bleaching step.
- peracetic acid can be generated, for example, by adding hydrogen peroxide and acetyl chloride or acetic anhydride to the pulp. and sodium peroxide by adding hydrogen peroxide.
- t-butylhydroperoxide can be generated from hydrogen peroxide and ti-butyl chloride. Because of the alkalinity of the pulp the peroxides are at least partly in ionized form.
- the pressure of the oxygen may be high, up to the point where it causes danger of combustion (approximately 200 lb./in. absolute).
- a pressure in the range of 50-150 lb./in. is preferable as providing very rapid bleaching with little danger of combustion.
- the 0 oxygen pressure may be less than atmospheric, down to about 2 lb./in. absolute.
- oxygen pressure approximately 3 lb./in. absolute
- EXAMPLE 1 The following illustrates the process of the present invention performed on a laboratory scale.
- a laboratory rocking autoclave is charged with 6 g. (dry basis) of hardwood kraft pulp having a brightness as determined by reflectance under a General Electric glossmeter, of 26.6%, 293 ml. of water containing 0.264 g. of t-butylhydroperoxide (4.1% on the dry weight of the fibers), and 1.23 g. (7.5 millimols) of trisodium phosphate as alkali.
- the autoclave is sealed and heated to 95 C., and pure oxygen is supplied under a pressure of 120 lb./in. for 1.5 hours. The pulp is then removed and washed with hot water. It has a brightness of 61.4%.
- EXAMPLE 3 The following illustrates the process of the present invention using a peroxide which is generated in situ while the pulp is under oxygen pressure.
- Example 1 The procedure of run A of Example 1 is repeated except that 0.3 g. of tetrahydrofuran is added in place of the t-butylhydroperoxide.
- the oxygen converts part of the tetrahydrofuran to ot-tetrahydrofuranhydroperoxide which acts as promoter of the bleaching effect of the oxygen in the same manner as the t-butylhydroperoxide.
- EXAMPLE 4 The procedure of Example '3 is repeated except that the tetrahydrofuran is replaced by cumene. The oxygen converts part of the cumene to cumene hydroperoxide, and superior bleaching is achieved.
- EXAMPLE 5 The following illustrates the effectiveness of the method of the present invention wherein the aqueous alkaline medium is oxygenated at atmospheric pressure.
- a laboratory beaker is charged with 200 cc. of water at C. containing 6 g. of hardwood kraft pulp having a brightness (reflectance) of 26.6%. To this is added concentrated NaOH solution containing 0.8 g. of NaOH and 0.3 g. of t-butylhydroperoxide. Oxygen is bubbled through the suspension by the use of a stainless steel sparger at the bottom of the vessel. The temperature is maintained at 90 C. and water is added from time to time to keep the level constant. After two hours the pulp is recovered by filtration, washed with Water at room temperature and dried. The pulp has a brightness of 49.1%.
- Example 6 The procedure of Example 5 is repeated except that the t-butylhydroperoxide is replaced 'by 0.2 g. of hydrogen peroxide.
- EXAMPLE 7 The following illustrates the practice of the present invention by the use of air under pressure in a closed vessel.
- An aqueous fibrous suspension according to Example 3 (containing t-butylhydroperoxide and trisodium phosphate) is charged into a 600-cc. laboratory rocking autoclave. The autoclave is sealed and the contents are maintained at 90 C. for two hours under an air pressure of 40 lb./in.
- the autoclave is opened and the pulp is recovered, Washed and dried. It has a brightness of 51%.
- EXAMPLE 8 The following illustrates the effect of increasing amounts of peroxide.
- a laboratory beaker is charged with 200 cc. of water 5 at 90 C. containing 6 g. of hardwood kraft pulp having a brightness (reflectance) of 26.6%. To this is added 0.3 g. of t-butylhydroperoxide, and the pH of the suspension is observed. Oxygen is bubbled through the suspension from a stainless steel sparger at the bottom of the beaker. The temperature of the suspension is maintained at 90 C., and water is added from time to time to keep the level constant. After two hours the pulp is recovered by filtration, washed with water at room temperature and dried. The reflectance (brightness) of the pulp is then determined by use of a glossmeter.
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Wood Science & Technology (AREA)
- Paper (AREA)
Abstract
THE RATE AT WHICH SULFATE-PROCESS PULP IS BRIGHTENED BY OXYGENATED AQUEOUS MEDIUM IS ACCELARATED BY THE PRESENCE IN THE MEDIUM OF A DISSOLVED PEROXIDE WHEN THE PH OF THE MEDIUM IS IN EXCESS OF 11.
Description
' US. Cl. 162-65 United States Patent BLEACHING 0F LIGNOCELLULOSIC MATERIALS WITH OXYGEN IN THE PRESENCE OF A PEROXIDE Charles Edward Farley, Norwalk, and Martin Grayson, Stamford, Conn., assignors to American Cyanamid Company, Stamford, Conn.
No Drawing. Continuation-impart of abandoned applications Ser. No. 34,543, May 4, 1970, and Ser. No. 145,567, May 20, 1971, the latter being also a confinuation-in-part of the former. This application June 18, 1971, Ser. No. 154,689
Int. Cl. D21c 9/16 11 Claims ABSTRACT OF THE DISCLOSURE The rate at which sulfate-process pulp is brightened by oxygenated aqueous medium is accelerated by the presence in the medium of a dissolved peroxide when the pH of the medium is in excess of 11.
This is a continuation-in-part of my copending application Ser. No. 34,543 filed on May 4, 1970, and its continuation-in-part application Ser. No. 145,567 filed on May 20, 1971, now both abandoned.
The present invention relates to the manufacture of paper pulp. More particularly, it relates to an improvement in the bleaching of sulfate process lignocellulose in oxygenated alkaline aqueous medium.
Lignocellulose is cellulose which carries a sufiicient amount of ligning substituents to render it unacceptable for some papermaking purposes. Sulfate process lignocellulose is lignocellulose which has been produced by digestion of wood cellulose with sodium hydroxide and sodium sulfide, and differs in certain respects from the lignocellulose produced by other processes. Hoh, US. Pat. No. 3,382,149, discloses the treatment of sulfite pulp with alkaline hydrogen peroxide solution, with or without alkali pretreatment of the pulp. While the pulp becomes brighter as a result of the treatment, no lignin is removed therefrom. It is known that lignocellulose can be brightened by the action of an aqueous alkaline medium having a temperature of about 50 C.l50 C. and containing dissolved oxygen under pressure. The oxygen severs the bonds which connect the lignin substituents to the cellulose and the alkali carries the released lignin substituents (which are acidic) into solution. In the art, the process is termed bleaching.
It is a disadvantage of the process that the oxygen causes partial depolymerization of the cellulose, decreasing the strength which paper made therefrom would otherwise possess.
The process is performed batchwise in large pressure vessels and is slow. The time required in any instance to effect a given amount of bleaching depends chiefly upon the temperature and pressure of the oxygen. High temperatures and high oxygen pressures favor rapid and extensive liberation of the lignin substituents, but depolymerize the cellulose to such an extent as to seriously decrease the value of the cellulose for papermaking purposes.
The discovery has now been made that the rate of which the aforesaid bleaching occurs is accelerated at any given temperature and oxygen pressure when the aqueous medium has a content of an alkali-soluble peroxide (i.e., a peroxide which is soluble in aqueous alkali solution), and when the pH of the medium is in excess of 11. The invention accordingly permits the duration of exposure of the cellulose to oxygen to be decreased with de- "ice crease in the depolymerization of the cellulose for attainment of any given improvement in brightness, and increases the daily output of any given plant.
Furthermore, it permits superior bleaching to be achieved under normal commercial conditions. Better bleaching is achieved by the use of oxygen and a peroxide in combination than is accomplished by either used separately or by both in sequence. It appears, therefore, that in the process the water-soluble peroxides act synergistically with the oxygen, functioning both as a bleaching reagent and as an accelerator of the bleaching action of the oxygen. The invention thus permits a maximum level of brightness to be attained more rapidly than would otherwise be the case.
It is a feature of the invention that the oxygen-peroxide combination is effective at very low oxygen pressure. Good results have been obtained merely by bubbling oxygen through an aqueous alkaline suspension of the pulp containing peroxide, the absolute pressure of oxygen in the process being only a few pounds per square inch. The process therefore can be performed without need of a pressure vessel.
The foregoing beneficial results are achieved only when the pulp under treatment is a sulfate process pulp, and preferably when the pulp is a kraft pulp (a sulfate process pulp under-cooked to produce a dark-colored pulp of exceptional strength). The use of peroxide as an additive in the alkali-oxygen bleaching of other pulps does not produce a significant benefit. As a practical matter, the process of the present invention is limited to the bleaching of kraft pulps.
The invention does not require the use of any specific amount of peroxide. In general, the beneficial effect of peroxide is proportional to the amount introduced into the aqueous medium and to the length of time the fibers are in contact therewith.
As a practical matter, we prefer to add an appropriate amount of peroxide to the water intended for use as the aqueous medium in the process. A suitable amount of peroxide can be found by laboratory trial, employing as a start an amount shown in the examples below. We have found that 0.2% peroxide. calculated as H 0 and based on the dry weight of the fibers, produces a noticeable acceleration in the rate at which the lignin is liberated. so that evidently there is no amount however small, which will not impart some improvement. The maximum practical amount of peroxide appears to be about 15%, as larger amounts do not appear to impart correspondingly larger improvements. An amount within the range 0.5%- 5% generally produces satisfactory results. Within this range, it is preferred that the amount of peroxide be sufficient so that at least some peroxide remains in the aqueous medium after the bleaching process has been completed.
The peroxide may all be added at the start (immediately prior to introducing the pulp into the pressure vessel), or it may be injected into the pressure vessel as the bleaching proceeds. It is within the scope of the invention to generate the peroxide in the pulp during the bleaching step. Thus, peracetic acid can be generated, for example, by adding hydrogen peroxide and acetyl chloride or acetic anhydride to the pulp. and sodium peroxide by adding hydrogen peroxide. Similarly, t-butylhydroperoxide can be generated from hydrogen peroxide and ti-butyl chloride. Because of the alkalinity of the pulp the peroxides are at least partly in ionized form.
No special steps need be taken to decompose or remove the residual peroxide on completion of the bleaching. The amount ordinarily left is so small. and its life so short, that it hardly affects the cellulose. It is customary to wash the pulp after the bleaching, and any residual peroxide is removed at that time. In the absence of a washing step, the peroxide is removed with the white water when the pulp is used for the manufacture of paper.
In the process, we have found that the action of the peroxide is very slight until the pH of the pulp is raised to about 11, at which point the peroxide commences to exert its synergistic action on the oxygen-pulp bleaching reaction. The elfectiveness of the peroxide increases as the pH is increased beyond 11, and We therefore prefer to perform the bleaching at a pH as high as practical (about 13). Above pH 13 the bleaching action of the oxygenperoxide combination proceeds rapidly, and alkali deterioration of the cellulose is not an important consideration.
In the process, the pressure of the oxygen may be high, up to the point where it causes danger of combustion (approximately 200 lb./in. absolute). A pressure in the range of 50-150 lb./in. is preferable as providing very rapid bleaching with little danger of combustion. If preferred, the 0 oxygen pressure may be less than atmospheric, down to about 2 lb./in. absolute. In practice we have obtained good results simply by bubbling air at atmospheric pressure through the aqueous alkaline medium (oxygen pressure approximately 3 lb./in. absolute), so that that pressure is preferred. As a result the use of strong pressure vessels become unnecessary, and deploymerization of the cellulose occurs to at most a negligible extent.
The invention is further described in the examples which follow. These examples are best embodiments of the invention and are not to be construed as limitations thereon.
EXAMPLE 1 The following illustrates the process of the present invention performed on a laboratory scale.
(A) A laboratory rocking autoclave is charged with 6 g. (dry basis) of hardwood kraft pulp having a brightness as determined by reflectance under a General Electric glossmeter, of 26.6%, 293 ml. of water containing 0.264 g. of t-butylhydroperoxide (4.1% on the dry weight of the fibers), and 1.23 g. (7.5 millimols) of trisodium phosphate as alkali. The autoclave is sealed and heated to 95 C., and pure oxygen is supplied under a pressure of 120 lb./in. for 1.5 hours. The pulp is then removed and washed with hot water. It has a brightness of 61.4%.
(B) The procedure is repeated except that the peroxide is omitted. The pulp after washing has a brightness of 50.7%.
(C) Procedure A is repeated except that the oxygen is omitted. The brightness of the pulp after washing is 55.4%, showing that the oxygen and the peroxide cooperate to provide a result better than the results provided by the two materials acting separately.
(D) The procedure of run A is repeated with oxygen omitted and the resulting pulp is treated with oxygen in the manner of run A but with peroxide omitted. The brightness of the resulting pulp after washing is 48.2%, showing that it is critical for the pulp to be treated with oxygen and peroxide simultaneously.
EXAMPLE 2 The procedure of run A of Example 1 is repeated successively with equal weights of hydrogen peroxide, sodium peracetate, sodium m-chloroperbenzoate and cumene hydroperoxide being employed in place of the tbutylhydroperoxide. Results are substantially the same.
EXAMPLE 3 The following illustrates the process of the present invention using a peroxide which is generated in situ while the pulp is under oxygen pressure.
The procedure of run A of Example 1 is repeated except that 0.3 g. of tetrahydrofuran is added in place of the t-butylhydroperoxide. The oxygen converts part of the tetrahydrofuran to ot-tetrahydrofuranhydroperoxide which acts as promoter of the bleaching effect of the oxygen in the same manner as the t-butylhydroperoxide.
EXAMPLE 4 The procedure of Example '3 is repeated except that the tetrahydrofuran is replaced by cumene. The oxygen converts part of the cumene to cumene hydroperoxide, and superior bleaching is achieved.
EXAMPLE 5 The following illustrates the effectiveness of the method of the present invention wherein the aqueous alkaline medium is oxygenated at atmospheric pressure.
A laboratory beaker is charged with 200 cc. of water at C. containing 6 g. of hardwood kraft pulp having a brightness (reflectance) of 26.6%. To this is added concentrated NaOH solution containing 0.8 g. of NaOH and 0.3 g. of t-butylhydroperoxide. Oxygen is bubbled through the suspension by the use of a stainless steel sparger at the bottom of the vessel. The temperature is maintained at 90 C. and water is added from time to time to keep the level constant. After two hours the pulp is recovered by filtration, washed with Water at room temperature and dried. The pulp has a brightness of 49.1%.
EXAMPLE 6 The procedure of Example 5 is repeated except that the t-butylhydroperoxide is replaced 'by 0.2 g. of hydrogen peroxide.
A similar brightening is obtained.
EXAMPLE 7 The following illustrates the practice of the present invention by the use of air under pressure in a closed vessel.
An aqueous fibrous suspension according to Example 3 (containing t-butylhydroperoxide and trisodium phosphate) is charged into a 600-cc. laboratory rocking autoclave. The autoclave is sealed and the contents are maintained at 90 C. for two hours under an air pressure of 40 lb./in.
The autoclave is opened and the pulp is recovered, Washed and dried. It has a brightness of 51%.
EXAMPLE 8 The following illustrates the effect of increasing amounts of peroxide.
To cc. of water at 95 C. are added 18.25 g. of unbleached hardwood kraft pulp having a brightness (re flectance) of 29.6%, followed by 5.0% of NaOH and 1.0% of MgCO based on the dry weight of the fibers. The suspension is charged into a laboratory rocking autoclave and kept under an oxygen pressure of lb./in. (gauge) for 45 minutes. The autoclave is opened and the pulp is washed and dried and its brightness is determined. The procedure is repeated with t-butylhydroperoxide added in amounts shown in the table below.
The foregoing procedure is repeated except that pine kraft pulp having a brightness of 21.0% is used in place of the hardwood kraft pulp, and the autoclave treatment is extended to two hours.
Results are as follows:
Brightt-CAHDOOH ness, Kappa Run No Pulp used added 1 percent N 0. Viscosity None 51. 5 8. 1 11.3
None 49. 1 7. 6
1 Percent, based on dry weight of pulp.
5 EXAMPLE 9 The following illustrates the eifect of pH on the action of peroxides as accelerators of the bleaching action of oxygen.
A laboratory beaker is charged with 200 cc. of water 5 at 90 C. containing 6 g. of hardwood kraft pulp having a brightness (reflectance) of 26.6%. To this is added 0.3 g. of t-butylhydroperoxide, and the pH of the suspension is observed. Oxygen is bubbled through the suspension from a stainless steel sparger at the bottom of the beaker. The temperature of the suspension is maintained at 90 C., and water is added from time to time to keep the level constant. After two hours the pulp is recovered by filtration, washed with water at room temperature and dried. The reflectance (brightness) of the pulp is then determined by use of a glossmeter.
The procedure is repeated except that sufficient alkali is added in each instance along with the peroxide to adjust the pH of the suspension to the values shown in the table below. Results are as follows:
Brightness Percent Alkali improveadded 1311 Found ment Control 26. 6 Run No.:
1 None 8. 28. 7. 2
200 lb./in. absolute: the improvement wherein said medium has a pH above 11 and contains a small but effective amount, less than 5% calculated as H 0 based on the dry weight of the pulp, of an alkali-soluble peroxide as agent which accelerates the rate at which said fibers are bleached.
2. A process according to claim 1 wherein the fibers are kraft pulp fibers.
3. A process according to claim 1 wherein the medium is oxygenated with air at atmospheric pressure.
4. A process according to claim 1 wherein the medium is under an O pressure of 150 lb./in. absolute.
5. A process according to claim 1 wherein the pH of said medium is above 13.
6. A process according to claim 1 wherein the peroxide is t-butylhydroper'oxide.
7. A process according to claim 1 wherein the peroxide is hydrogen peroxide.
8. A process according to claim 1 wherein the peroxide is sodium peracetate.
9. A process according to claim 1 wherein the peroxide is sodium m-chloroperbenzoate.
10. A process according to claim 1 wherein the peroxide is cumene hydroperoxide.
11. A process according to claim 1 wherein the peroxide is a-tetrahydrofuranperoxide and said peroxide is generated in said pulp while said pulp is under 0 pressure.
References Cited UNITED STATES PATENTS 2,777,749 1/1957 Young 162---78 X 2,859,087 11/1958 Hawkinson et a1. 162-78 1,998,389 4/1935 Scheller 162-78 3,384,533 5/1968 Robert et a1. 162-65 3,423,282 1/1969 Rerolle et al. 1626=5 2,865,701 12/1958 Schroeder 16278 3,663,357 5/1972 Liebcrgott 162-65 S. LEON BASHORE, Primary Examiner A. L. CORBIN, Assistant Examiner US. Cl. X.R. 811l; 162-78
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US15468971A | 1971-06-18 | 1971-06-18 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3719552A true US3719552A (en) | 1973-03-06 |
Family
ID=22552344
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US00154689A Expired - Lifetime US3719552A (en) | 1971-06-18 | 1971-06-18 | Bleaching of lignocellulosic materials with oxygen in the presence of a peroxide |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US3719552A (en) |
Cited By (36)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3867246A (en) * | 1972-04-21 | 1975-02-18 | Degussa | Chlorine-free multiple step bleaching of cellulose |
| US4008120A (en) * | 1973-12-21 | 1977-02-15 | Groupement Europeen De La Cellulose | Process of delignification and bleaching a lignocellulose product |
| US4022965A (en) * | 1975-01-13 | 1977-05-10 | Crown Zellerbach Corporation | Process for producing reactive, homogeneous, self-bondable lignocellulose fibers |
| JPS5277202A (en) * | 1977-01-08 | 1977-06-29 | Jisuke Hayashi | Process for refining pulp |
| US4459174A (en) * | 1979-05-25 | 1984-07-10 | Interbox (Societe Anonyme) | Process for the delignification and bleaching of chemical and semi-chemical cellulosic pulps |
| EP0171575A1 (en) * | 1984-08-01 | 1986-02-19 | Degussa Aktiengesellschaft | Process for the delignification and bleaching of cellulose pulps |
| JPS61138793A (en) * | 1984-12-03 | 1986-06-26 | インタ−ナシヨナル ペ−パ− コンパニ− | Reinforcing oxidation extraction method |
| EP0185858A1 (en) * | 1984-12-19 | 1986-07-02 | Degussa Aktiengesellschaft | Process for delignifying sulphate pulp |
| EP0206560A2 (en) * | 1985-06-17 | 1986-12-30 | Pulp and Paper Research Institute of Canada | Alkaline-peroxide-oxygen treatment for unbleached and chlorinated chemical pulps |
| US4661205A (en) * | 1981-08-28 | 1987-04-28 | Scott Paper Company | Method of bleaching lignocellulosic material with peroxide catalyzed with a salt of a metal |
| US4756798A (en) * | 1984-06-15 | 1988-07-12 | Air Liquide | Process for bleaching a mechanical pulp with hydrogen peroxide |
| EP0401149A1 (en) * | 1989-05-19 | 1990-12-05 | Fmc Corporation | Hydrogen peroxide reinforced oxygen delignification |
| US5274139A (en) * | 1993-02-26 | 1993-12-28 | University Of Florida | Method for effective reaction between oxygen and organic substance utilizing regenerable hydroperioxide oxidant |
| US5858170A (en) * | 1994-12-08 | 1999-01-12 | Kvaerner Pulping Technologies Ab | Method for pressurized peroxide bleaching |
| US5916415A (en) * | 1995-12-07 | 1999-06-29 | Beloit Technologies, Inc. | Oxygen delignification of medium consistency pulp slurry |
| US5954066A (en) * | 1995-01-25 | 1999-09-21 | Kvaerner Pulping Ab | Method for controlling chemical reaction |
| US6007680A (en) * | 1994-12-08 | 1999-12-28 | Kvaerner Pulping Ab | Apparatus for safely conducting pressurized peroxide bleaching |
| US6096170A (en) * | 1997-04-30 | 2000-08-01 | Kvaerner Pulping Aktiebolag | Pressurized peroxide bleaching vessel having a rotatable scraper arm and cleaning device |
| US6149766A (en) * | 1993-06-08 | 2000-11-21 | Kvaerner Pulping Technologies, A/B | Process for peroxide bleaching of chemical pulp in a pressurized bleaching vessel |
| US6162324A (en) * | 1995-12-07 | 2000-12-19 | Beloit Technologies, Inc. | Oxygen delignification of medium consistency pulp slurry using two alkali additions |
| US6221207B1 (en) * | 1996-03-26 | 2001-04-24 | Valmet Fibertech Aktiebolag | Oxygen delignification of pulp in two stages with low pressure steam heating between stages |
| US6231718B1 (en) | 1992-02-28 | 2001-05-15 | International Paper Company | Two phase ozone and oxygen pulp treatment |
| US6569284B1 (en) * | 1996-09-24 | 2003-05-27 | International Paper Company | Elemental-chlorine-free bleaching process having an initial Eo or Eop stage |
| US20040016525A1 (en) * | 2002-02-22 | 2004-01-29 | Gervais Gibson W. | Process of treating lignocellulosic material to produce bio-ethanol |
| US6958108B1 (en) * | 1998-04-30 | 2005-10-25 | M-Real Oyj | Method of producing a fiber product having a strength suitable for printing paper and packaging material |
| US20080308239A1 (en) * | 2007-06-12 | 2008-12-18 | Hart Peter W | Fiber blend having high yield and enhanced pulp performance and method for making same |
| US20170159237A1 (en) * | 2015-12-07 | 2017-06-08 | Clean Chemistry | Methods of pulp fiber treatment |
| US10000889B2 (en) | 2007-06-12 | 2018-06-19 | Westrock Mwv, Llc | High yield and enhanced performance fiber |
| US10259729B2 (en) | 2014-09-04 | 2019-04-16 | Clean Chemistry, Inc. | Systems and method of water treatment utilizing reactive oxygen species and applications thereof |
| US10472265B2 (en) | 2015-03-26 | 2019-11-12 | Clean Chemistry, Inc. | Systems and methods of reducing a bacteria population in high hydrogen sulfide water |
| US10501346B2 (en) | 2012-09-07 | 2019-12-10 | Clean Chemistry, Inc. | System and method for generation of point of use reactive oxygen species |
| US10577698B2 (en) | 2011-05-31 | 2020-03-03 | Clean Chemistry, Inc. | Electrochemical reactor and process |
| US10883224B2 (en) | 2015-12-07 | 2021-01-05 | Clean Chemistry, Inc. | Methods of pulp fiber treatment |
| US11001864B1 (en) | 2017-09-07 | 2021-05-11 | Clean Chemistry, Inc. | Bacterial control in fermentation systems |
| US11136714B2 (en) | 2016-07-25 | 2021-10-05 | Clean Chemistry, Inc. | Methods of optical brightening agent removal |
| US11311012B1 (en) | 2017-09-07 | 2022-04-26 | Clean Chemistry, Inc. | Bacterial control in fermentation systems |
-
1971
- 1971-06-18 US US00154689A patent/US3719552A/en not_active Expired - Lifetime
Cited By (51)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3867246A (en) * | 1972-04-21 | 1975-02-18 | Degussa | Chlorine-free multiple step bleaching of cellulose |
| US4008120A (en) * | 1973-12-21 | 1977-02-15 | Groupement Europeen De La Cellulose | Process of delignification and bleaching a lignocellulose product |
| US4022965A (en) * | 1975-01-13 | 1977-05-10 | Crown Zellerbach Corporation | Process for producing reactive, homogeneous, self-bondable lignocellulose fibers |
| JPS5277202A (en) * | 1977-01-08 | 1977-06-29 | Jisuke Hayashi | Process for refining pulp |
| US4459174A (en) * | 1979-05-25 | 1984-07-10 | Interbox (Societe Anonyme) | Process for the delignification and bleaching of chemical and semi-chemical cellulosic pulps |
| US4661205A (en) * | 1981-08-28 | 1987-04-28 | Scott Paper Company | Method of bleaching lignocellulosic material with peroxide catalyzed with a salt of a metal |
| US4756798A (en) * | 1984-06-15 | 1988-07-12 | Air Liquide | Process for bleaching a mechanical pulp with hydrogen peroxide |
| EP0171575A1 (en) * | 1984-08-01 | 1986-02-19 | Degussa Aktiengesellschaft | Process for the delignification and bleaching of cellulose pulps |
| US4626319A (en) * | 1984-08-01 | 1986-12-02 | Degussa Aktiengesellschaft | Process for the delignification and acid bleaching of cellulose with oxygen and hydrogen peroxide |
| JPS61138793A (en) * | 1984-12-03 | 1986-06-26 | インタ−ナシヨナル ペ−パ− コンパニ− | Reinforcing oxidation extraction method |
| JPH0670315B2 (en) | 1984-12-03 | 1994-09-07 | インタ−ナシヨナル ペ−パ− コンパニ− | Enhanced oxidation extraction method |
| EP0185858A1 (en) * | 1984-12-19 | 1986-07-02 | Degussa Aktiengesellschaft | Process for delignifying sulphate pulp |
| EP0206560A2 (en) * | 1985-06-17 | 1986-12-30 | Pulp and Paper Research Institute of Canada | Alkaline-peroxide-oxygen treatment for unbleached and chlorinated chemical pulps |
| EP0206560A3 (en) * | 1985-06-17 | 1988-07-20 | Pulp and Paper Research Institute of Canada | Alkaline-peroxide-oxygen treatment for unbleached and chlorinated chemical pulps |
| US5011572A (en) * | 1989-05-19 | 1991-04-30 | Fmc Corporation | Two stage process for the oxygen delignification of lignocellulosic fibers with peroxide reinforcement in the first stage |
| EP0401149A1 (en) * | 1989-05-19 | 1990-12-05 | Fmc Corporation | Hydrogen peroxide reinforced oxygen delignification |
| US6231718B1 (en) | 1992-02-28 | 2001-05-15 | International Paper Company | Two phase ozone and oxygen pulp treatment |
| US5274139A (en) * | 1993-02-26 | 1993-12-28 | University Of Florida | Method for effective reaction between oxygen and organic substance utilizing regenerable hydroperioxide oxidant |
| US6149766A (en) * | 1993-06-08 | 2000-11-21 | Kvaerner Pulping Technologies, A/B | Process for peroxide bleaching of chemical pulp in a pressurized bleaching vessel |
| US5858170A (en) * | 1994-12-08 | 1999-01-12 | Kvaerner Pulping Technologies Ab | Method for pressurized peroxide bleaching |
| US6007680A (en) * | 1994-12-08 | 1999-12-28 | Kvaerner Pulping Ab | Apparatus for safely conducting pressurized peroxide bleaching |
| US5954066A (en) * | 1995-01-25 | 1999-09-21 | Kvaerner Pulping Ab | Method for controlling chemical reaction |
| US6162324A (en) * | 1995-12-07 | 2000-12-19 | Beloit Technologies, Inc. | Oxygen delignification of medium consistency pulp slurry using two alkali additions |
| US5916415A (en) * | 1995-12-07 | 1999-06-29 | Beloit Technologies, Inc. | Oxygen delignification of medium consistency pulp slurry |
| US6221207B1 (en) * | 1996-03-26 | 2001-04-24 | Valmet Fibertech Aktiebolag | Oxygen delignification of pulp in two stages with low pressure steam heating between stages |
| US6569284B1 (en) * | 1996-09-24 | 2003-05-27 | International Paper Company | Elemental-chlorine-free bleaching process having an initial Eo or Eop stage |
| US6096170A (en) * | 1997-04-30 | 2000-08-01 | Kvaerner Pulping Aktiebolag | Pressurized peroxide bleaching vessel having a rotatable scraper arm and cleaning device |
| US6958108B1 (en) * | 1998-04-30 | 2005-10-25 | M-Real Oyj | Method of producing a fiber product having a strength suitable for printing paper and packaging material |
| US20040016525A1 (en) * | 2002-02-22 | 2004-01-29 | Gervais Gibson W. | Process of treating lignocellulosic material to produce bio-ethanol |
| US7189306B2 (en) | 2002-02-22 | 2007-03-13 | Gervais Gibson W | Process of treating lignocellulosic material to produce bio-ethanol |
| US20080308239A1 (en) * | 2007-06-12 | 2008-12-18 | Hart Peter W | Fiber blend having high yield and enhanced pulp performance and method for making same |
| US20150211184A1 (en) * | 2007-06-12 | 2015-07-30 | Meadwestvaco Corporation | Fiber blend having high yield and enhanced pulp performance and method for making same |
| US10000889B2 (en) | 2007-06-12 | 2018-06-19 | Westrock Mwv, Llc | High yield and enhanced performance fiber |
| US10060075B2 (en) * | 2007-06-12 | 2018-08-28 | Westrock Mwv, Llc | Fiber blend having high yield and enhanced pulp performance and method for making same |
| US10577698B2 (en) | 2011-05-31 | 2020-03-03 | Clean Chemistry, Inc. | Electrochemical reactor and process |
| US10501346B2 (en) | 2012-09-07 | 2019-12-10 | Clean Chemistry, Inc. | System and method for generation of point of use reactive oxygen species |
| US10875799B2 (en) | 2012-09-07 | 2020-12-29 | Clean Chemistry, Inc. | System and method for generation of point of use reactive oxygen species |
| US10259729B2 (en) | 2014-09-04 | 2019-04-16 | Clean Chemistry, Inc. | Systems and method of water treatment utilizing reactive oxygen species and applications thereof |
| US11827543B2 (en) | 2014-09-04 | 2023-11-28 | Clean Chemistry, Inc. | Method for continuous supply of superoxide-containing peracetate oxidant solution |
| US10875798B2 (en) | 2014-09-04 | 2020-12-29 | Clean Chemistry, Inc. | Systems and method for oxidative treatment utilizing reactive oxygen species and applications thereof |
| US10472265B2 (en) | 2015-03-26 | 2019-11-12 | Clean Chemistry, Inc. | Systems and methods of reducing a bacteria population in high hydrogen sulfide water |
| US10941063B2 (en) | 2015-03-26 | 2021-03-09 | Clean Chemistry, Inc. | Method for down-hole treatment of a production well for sulfur based contaminants |
| US10883224B2 (en) | 2015-12-07 | 2021-01-05 | Clean Chemistry, Inc. | Methods of pulp fiber treatment |
| US10611656B2 (en) | 2015-12-07 | 2020-04-07 | Clean Chemistry, Inc. | Methods of microbial control |
| US11111629B2 (en) | 2015-12-07 | 2021-09-07 | Clean Chemistry, Inc. | Methods of pulp fiber treatment |
| US11225755B2 (en) | 2015-12-07 | 2022-01-18 | Clean Chemistry, Inc. | Methods of paper mill processing using recycled white water with microbial control |
| US11795615B2 (en) | 2015-12-07 | 2023-10-24 | Clean Chemistry, Inc. | Methods of pulp fiber treatment |
| US20170159237A1 (en) * | 2015-12-07 | 2017-06-08 | Clean Chemistry | Methods of pulp fiber treatment |
| US11136714B2 (en) | 2016-07-25 | 2021-10-05 | Clean Chemistry, Inc. | Methods of optical brightening agent removal |
| US11001864B1 (en) | 2017-09-07 | 2021-05-11 | Clean Chemistry, Inc. | Bacterial control in fermentation systems |
| US11311012B1 (en) | 2017-09-07 | 2022-04-26 | Clean Chemistry, Inc. | Bacterial control in fermentation systems |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US3719552A (en) | Bleaching of lignocellulosic materials with oxygen in the presence of a peroxide | |
| US4576609A (en) | Process for the treatment of cellulosic materials with oxidizing agents and microwaves | |
| US4804440A (en) | Multistage brightening of high yield and ultra high-yield wood pulps | |
| US5002635A (en) | Method for producing pulp using pre-treatment with stabilizers and refining | |
| US3888727A (en) | Treatment of lignocellulosic material in an alkaline pulping liquor containing anthraquinone sulphonic acid followed by oxygen delignification | |
| US3944463A (en) | Pulping of lignocellulosic material with oxygen in two stages at increasing pH | |
| US3867246A (en) | Chlorine-free multiple step bleaching of cellulose | |
| US3382149A (en) | Bleaching of hardwood sulfite pulp with hydrogen peroxide, including pretreatment with alkali | |
| US2716058A (en) | Deresination of wood pulp | |
| US3661699A (en) | Bleaching of lignin-containing cellulose materials such as pulp | |
| US2394989A (en) | Manufacture of cellulose | |
| JPH08511308A (en) | Improved ozone / peracid method for delignification of lignocellulosic materials | |
| US4363700A (en) | Process for pulping lignocellulosic material with an alkaline sulfide cooking liquor containing an accelerating additive and reducing assistant | |
| US4826568A (en) | Process for delignification of cellulosic substances by pretreating with a complexing agent followed by peroxide prior to kraft digestion | |
| US3462344A (en) | Superbleaching of wood pulps | |
| US4113553A (en) | Sodium sulfide pulping with hydrogen sulfide generation | |
| US3645840A (en) | Method for peroxide bleaching of pulp | |
| SE8200756L (en) | SET TO MAKE CHEMICAL PAPER PAPER | |
| US3284283A (en) | Production of wood pulps including treatment of cellulosic fibers with bisulfite ion followed by alkali metal borohydride | |
| US3576710A (en) | Brightening of white water sludge | |
| US2290601A (en) | Bleaching of ground wood pulp with preliminary bisulphite treatment | |
| US2862784A (en) | Oxidative-reductive multi-stage bleaching of ground wood pulp | |
| US1831032A (en) | Production of refined wood pulp | |
| US3795574A (en) | Impregnation of wood with a formaldehyde free alkaline solution of sodium hydroxide at a ph between 12.4 and 13 | |
| US2947657A (en) | Extraction of cellulose from vegetable matter |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| AS | Assignment |
Owner name: FMC CORPORATION, PENNSYLVANIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:AMERICAN CYANAMID COMPANY A CORP. OF ME;REEL/FRAME:004968/0748 Effective date: 19881021 Owner name: FMC CORPORATION, 2000 MARKET STREET, PHILADELPHIA, Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:AMERICAN CYANAMID COMPANY A CORP. OF ME;REEL/FRAME:004968/0748 Effective date: 19881021 |