CA2032256C - Biological method of deinking printed wastepaper - Google Patents
Biological method of deinking printed wastepaper Download PDFInfo
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- CA2032256C CA2032256C CA 2032256 CA2032256A CA2032256C CA 2032256 C CA2032256 C CA 2032256C CA 2032256 CA2032256 CA 2032256 CA 2032256 A CA2032256 A CA 2032256A CA 2032256 C CA2032256 C CA 2032256C
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- printed paper
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- 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
- D21C1/00—Pretreatment of the finely-divided materials before digesting
-
- 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
- D21C5/00—Other processes for obtaining cellulose, e.g. cooking cotton linters ; Processes characterised by the choice of cellulose-containing starting materials
- D21C5/02—Working-up waste paper
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/64—Paper recycling
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Abstract
A biological method of deinking printed wastepaper consisting of the steps of disintegrating of printed wastepaper in hot water containing cellulase or pectase and removing ink particles from fibers by froth flotation or washing.
Description
-~ 20322~~
The present invention rH~iates to a method of de inking printed wastepaper.
BACKGROUND OF THE INVENTION
Deink.ing of pulp fibre is essential iy a launder ing or cleaning process in which ink is considered to be the dirt.
Chemicals along with heat and mec:han:icai energy, are used to dislodge the ink pari_icles from fibers and to IG disperse them in the aqueous medium. Tree ink particulars are then separated from the pulp fibers; either. by washing or flotation or by using a modern hybrid process that combines the t:wo elements.
The chemicals used for the conventional deinking process are surfactants which function as detergents to remove ink from fiber, keep the ink particles dispersed to prevent redisposition on the fibers, and provide a foaming action for the froth :Flotation of ink particles.
A typical surfactant is a long chain molecule with a hydropt~ot~ic part to tale one end and a hydrophilic part to the other end. Tile hydrophobic part may be consist of fatty ac:.id, fatty alcohol , alkylpheruo.is or other of l soluble surfactants.
The hydrophilic part of ttie deinking surfactant usually consists of anion molecules such as carboxyl acid salts or sulfonic acid salts and nonionic molecules such as 3G polyoxyethylenated chains.
The typical surfactants c~ammon.ly used in the washing and froth flotation deinking- process are; sodium a.nd potassium sa.l.ts of strait chain fatty acid (soap); linear alkyloenzenesulfontate (LAS); o7_efine sulfonate, long chain _. 2~~~~~~
The present invention rH~iates to a method of de inking printed wastepaper.
BACKGROUND OF THE INVENTION
Deink.ing of pulp fibre is essential iy a launder ing or cleaning process in which ink is considered to be the dirt.
Chemicals along with heat and mec:han:icai energy, are used to dislodge the ink pari_icles from fibers and to IG disperse them in the aqueous medium. Tree ink particulars are then separated from the pulp fibers; either. by washing or flotation or by using a modern hybrid process that combines the t:wo elements.
The chemicals used for the conventional deinking process are surfactants which function as detergents to remove ink from fiber, keep the ink particles dispersed to prevent redisposition on the fibers, and provide a foaming action for the froth :Flotation of ink particles.
A typical surfactant is a long chain molecule with a hydropt~ot~ic part to tale one end and a hydrophilic part to the other end. Tile hydrophobic part may be consist of fatty ac:.id, fatty alcohol , alkylpheruo.is or other of l soluble surfactants.
The hydrophilic part of ttie deinking surfactant usually consists of anion molecules such as carboxyl acid salts or sulfonic acid salts and nonionic molecules such as 3G polyoxyethylenated chains.
The typical surfactants c~ammon.ly used in the washing and froth flotation deinking- process are; sodium a.nd potassium sa.l.ts of strait chain fatty acid (soap); linear alkyloenzenesulfontate (LAS); o7_efine sulfonate, long chain _. 2~~~~~~
fatty alcohol, polyoxyethylenenated alkylphenols;
alkyiphenolethoxylate~~, and palyoxyethylenated strait chain alcohols.
The Ma jor disadvantage of using the~~e surfactants in tree deinking process is excess foaming in the subsequent pulp stock flow and paper making process Lines. 7n addit:ian, some of tile above surfactants are re~;istant to biodegradati.on in the eff luent treatment: stages causing a serious environment=al problem.
In tt~e froth flotation deinking process; a collector is added to agglomerate ink into large particles and attach them to the air bubbles. Co.ll.ectors are required fc~r effective flotation and are usually anionic long-chain fatty acid soap.
rr~atty acid collectors are precipitated with calcium ions to form larger, insolub3.e ink. particles and collector particles.
With injection of air in 1=he flotation cells; floe agglomerated ink particles adhere to the bubbles; rise to the surface and are skimmed off from the system.
Major disadvantages of the flotation method using the fatty acid collector is a pitch deposition and calcium scaling problems in tree subsequent stock lines and paper making equipment. Besides the surfactants; other chemicals are caustic soda, sodium silicate, metal ion chelating agents and hydrogen peroxide.
The hydrogen peroxide blea~::hing agent has to be added in order to prevent a pulp colour yellowing caused by flue additions of caustic soda and to improve brightness of pulp fibers.
With t_he advance in the modern printing and photocopying technology; conventional deinking with the aid -- 2032~~u of surfactants encounters serious problems with the wastepaper printed with the use of heavily coated, highly polymerized; or nonimyact inks, such as ultraviolet, heatset;
Xerox; laser and ink jet. These inks usually contain cured polymer resins which bind ink particles so strongly on the fiber surface that it is impossible to dislodge the ink completely during the wastepaper defiberizing (pulping) stage wi th the convent Tonal deinking c:kiemica is . Exc:ess~ heat and mechanical energy <are also required along witkr the ip ine.ffect ive conventional ckiemicals.
In the convent Tonal f lot<it ion de inking process for newspririt wastepaper a major technical problem is experiencHd witki fine ink particles embedded in the fibre bundles and i5 between fibrils whicki are almost impossible t:o remove from the f fibers by a washing and,/or f lotat ion process .
SUNI~~1ARY OF THE INVENTION
This invention provides a view and much improved method 2p of deinking printed wastepaper. This method is effective in newsprint deinking, as well as the deink.ing of wood free printed wastepaper sucks as whiteledger, laser printed, xerographic copypaper and c:omputerr printout wastepaper.
25 This invented deinking method is to remove ink particles with the use of biological activity of enzyme on the cellulose fiber surface and a dispersing function of enzyme protein on ink particles.
3p In contrast to the conventional method no alkali and de.inking surfactants are required although some surfactants can be used along with the enzyme to enhance the deinking efficiency. In the froth flotation process the fatty acid collectors are not required. Since caustic soda is not used 20322~u in tile newsprint deinking, hydro~zen peroxide bleaching agent is not also required for yellowing prevention.
Tine elimination of the fatty acid collector in this biologica.i deinking process will solve the pers=istent pitch and scale deposition problem associated with the conventional flotation process using the fatty acid type soap and c:al.cium salts and silicates.
i0 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The method will now be described.
Printed Wastepaper, such as old newsprint or printed wood free wastepaper, is disintegrated in a conventional pulper (consistency ~~-'19F;) or in a high consistency pulper;
12-158;, at the water temperature ranging from room temperature up to 60 ~. The addit:i.on level of enzyme is 0.00584 to 5.09F; based on dry weic3ht of wastepaper; pH of the stock slurry is adjusted in thc~ range of 3.0 to 8Ø As compared to the conventional pulping process using caustic and surfactants in pulping, the process using enzymes can be completed in a relatively short period and ink particles are completely separated from the fiber surface and dispersed we i 1 . The dispersed inks are removed out of pu ip f fibers by conventional washing process equipment such as a vibration screen and a drum washer without the a.id of detergent surfactants. The ink particles dispersed with t: he ac t:i.on of enzyme protein can be a.l.so selectively removed out of the diluted pulp slurry with conventional flotation equipments in which air is injected into the pulp to provide bubbles to pick up the particles. i3o fatty acid col.iector is required in the case of waste newsprint. A small amount of fatty acid collector may be added to enhance the ink removal eff_i.ciency in the case of laser-printed wastepaper.
2032~~~
This biologi.cai deinki.ng process is t_o lower pulping energy to a large extent sine trte addition of enzyme results in a reduction in pulping time, a-s compared to tire pulping in the absence enzyme, of almost 50~; reduction. The observed faster and easier pulping in the presence of enzyme may be attributed to an unit;ue b-iologic:al activity o.f enzyme which is effective to debond tire fiber bonding and dislodge the inks bonded on the fiber surface as well as within the fibrils. A partial enzymatic hydrolysis of cellulose within i0 mic:ro st:ructure of fiber surface may occur during the pulping stage. This biological activity of enzyme takes out. fine ink particles embedded within fiber bundles, fibrils and fines which have been i-mpossible to be take out by convertti.onal deinking chemicals.
i5 According to this biological deinking method of old newsprint t:he addition of hydrogen peroxide to prevent the fiber yellowing is not required, which will result in a substantial reduction of deinkin.g chemical cost: as compared 20 tc~ the conventional de inking process using caustic soda, hydrogen peroxide; cheiat.ing ager~t and sodium silicates.
It should he pointed out that the phys.ica.l strength properties of the resulting pulp fiber prepared by this 25 invented method are found to b~e higher than t=hose of ttte corresponding pulp prepared by the conventional method; in addition to the much higher resulting pulp brightness. The enzyme addition does not appear to degrade the fiber strength; instead improving the fiber strength fox reasons Op that are as yet unknown.
.35 203225fi 6 ' "
Example 1.
Deinking of old newsprint with a cellulolytic enzyme.
A sample of old newsprint wastepaper was added to a pulper which was filled with 40 C water at the consistency of 4% and a cellulase was dissolved at the dosage level of 0.1% based on oven dry weight of wastepaper. The wastepaper was soaked for 10 minutes and then disintegrated for 5 minutes. After a. complete disintegration of wastepaper, one half of the:pulp slurry was diluted to a 1%
consistency.
The diluted pulp slurry was moved to an air flotation cell and then the dispersed ink particles were removed out of the pulp slurry by skimming off a froth containing ink particles out of the cell while injecting air through a porous plate. The flotation time for the complete removal of the ink froth was one minute.
The other half of the pulp slurry was washed on a laboratory vibration screen to remove the dispersed ink particles.
The resulting recycled pulp fibers obtained by the flotation and the washing step were evaluated for pulp brightness and mechanical strength properties. To compare this enzyme treated deinking pulp to the conventional deinking pulp, the same sample of wastepaper was treated in the pulper with the addition of 1.0% NaOH, 0.3% H O, 3%
, sodium silicate solution (water glass), 0.8% of SERFAX MT-, 0 (Trademark) (fatty acid soap) and 0.2% IGEPAL
(Trademark) -660 based on oven dry weight of wastepaper.
The pulping time was 1.0 minutes for a complete disintegration. After diluting to 1% consistency, _m_ ~~32256 the dispersed ink. particles were removed by the flotation method with the laboratory flotation cell as described above.
As shown in Table 1, the brightness of the pulp deinked with enzyme was much Higher than that of the pulp de.inked with the conventional chemicals and t=tie mechanical strength of the enzyme-deinkecl pulp was also superior to that. pulp deinked with the fatty acid collector and the di.spersant {IGEPAL 660). The microscopic oioservation revealed that the pulp prepared by the present invention contained more long fiber fractions and has smoother fiber surface and looked less mechanically damaged.
i5 Table 1. Comparison of properties of recycled pulp by method of pre~:ent invention and the conven-tional met_had.
brightness tensile index tear index ( ~; ) ( N.m/g ) { mN.m ,lg) KONP AONP KONP AONP KONP AONP
flotation 4?.1 45.2 28.9 32.4 1I.? 13.6 preserrt _..__.._..__.______.__.__..____._. r._.___. _.____.__ ___ ____.___~___._.__~___._____._____.____.._.._....__..__. _._ method washing 50.3 48.6 29.3 32.9 11.8 1.4.1 SERFAX MT-90 45.1 38.4 30.1 32.8 10.8 13.1 ,~0 KONP: Korean old newspaper AONP: American old newspaper The enzyme treated pulp gave cleaner and brighter pulp with the washing as compared to the flotation ink removal.
20~22~6 The enzyme addition ap~~eared to accelerate tine wastepaper disintegration to a large extent. When the old newspaper was disintegrated in the conventional pulper at the 4°c; consistency, the addition of 0.5:K enzyme reduced the pulping time from 5 minutes (no enzyme addition) to 30 seconds for a complete disintegrat ion as shown in Table 2 .
Table 2. Relation between enzyme addition and disintegration time.
Enzyme ( 96 ) 0.5 0.1 0 disintegration 30> 60-120 3OO<
time ( sec ) - _._...__. _._._.__~____._. ____._._ _..__._ __...____._.._____..___..
_____~..__.___._____.___._.__ __.._..___._____.______ Example 2.
Deinking of laser CPO (,computer printout) with cellulolytic enzyme.
It is almost impossible ac:h:ieve a complate removal of laser beam cured ink particles from laser CPO wastepaper with t:he conventional de>inking rhemica.Is, because the ink particles are so strongly adhered to the f. fiber surfacie that alkali and general deinking surfactants in the conventional deinking chemicals are not able to dislodge and disperse in the pulp water slurry.
A sample of laser CPO waste>paper was added to water in a laboratory high consistency pulper at the consistency of 12.5~C; and a cellu.iase was added to thH water at the dosage level of 0.2gr; based on the dry weight of paper. At stock water temperature of 20-35 C; the pulping was carried out for 2U322~6 20 minutes. The completely dig>integrated pulp slurry was diluted to 0.5~ and than dispersed ink particles were removed out of the pulp slurry using the laboratory flotation cell as explained in Example 1. In this case, to increase tHle lIlk removal efficiency and selectivity a small amount of the conventional fatty acid collector, SERFAX NT-90; of 0.39F;
based on dry weight of wastepaper was added prior to the air flotation and the flotation time was 3 minutes. To compare to enzyme deinked pulp, tile conventional deinked pulp was prepared by the same way bL~t the different chemical conditions as follow:
1~; NaOH on dry weight of wastepaper 0.19r; IGEPAh 660 disoersant 0.89f; SERFAri MT-90 pulping temperat=ure . 50 C
pulping time : 30 minutes calcium salt addition to tine flotation cell: 200 ppm flotation time . 3 minutes The brightness and the :strength properties of tree resulting pulp samples were compared in Tahle 3.
As shown in the of the paper tab3.e, the image analysis samples indicates that the number of the residual i.nk particles was much less; about 10 times; for pulp deinked the wi th the enzyme and tare tensi le st rerrgth was also higher as compared to the pulp prepared with tire conventional chemicals.
A recycled chemical pulp of high duality in terms of dirt count and fiber strength properties can be obtained with ,~0 ttre use of enzyme in a combinat ion of a small amount of fats=y acid collector by the flotation method.
Table 3. Comparison of pulp properties recyc..ied by the method of present invention and conventional method.
1~ 2~32~~~
brightness dirt amount tensile index 1 {count,/area) {N.mjg) enzyme : MT-90- { 0 . 39k ) '19 . 0 450 34 . 3 MT-90 { 90°6 ) 80 . 6 4 ; 330 26 . 3 Fxampie 3.
Deinkinc,~ of wast.-e newsprint by pectinolytic enzyme.
As the same method t=o example 2; tine waste newsprint containing 0.191, of pectase was soaked for 10 minutes at 40C
i5 and disintegrated for 5 minutes. Diluting the disintegrated pulp to i9K; the ink particles are removed by flotation for 1 minute.
As shown in Table 4; the brightness and tensile strength of paper sheet prepared by the method of the present invention are improved.
Table 4. Comparison the method of using pect.inolytic enzyme with c:onvent_ional method.
brightnes~> tensile index } { N.m,ig ) present method 44 . 29k 3 3 - ~3~'0 _______..___________....___..__r_.~..___._____.________.___.___.....__._...____ ._._._.______._ __.__._....____._._______._. ...__._.._..
MT-90 { 0 . 896 } 38 . 49F; 32 . 896
alkyiphenolethoxylate~~, and palyoxyethylenated strait chain alcohols.
The Ma jor disadvantage of using the~~e surfactants in tree deinking process is excess foaming in the subsequent pulp stock flow and paper making process Lines. 7n addit:ian, some of tile above surfactants are re~;istant to biodegradati.on in the eff luent treatment: stages causing a serious environment=al problem.
In tt~e froth flotation deinking process; a collector is added to agglomerate ink into large particles and attach them to the air bubbles. Co.ll.ectors are required fc~r effective flotation and are usually anionic long-chain fatty acid soap.
rr~atty acid collectors are precipitated with calcium ions to form larger, insolub3.e ink. particles and collector particles.
With injection of air in 1=he flotation cells; floe agglomerated ink particles adhere to the bubbles; rise to the surface and are skimmed off from the system.
Major disadvantages of the flotation method using the fatty acid collector is a pitch deposition and calcium scaling problems in tree subsequent stock lines and paper making equipment. Besides the surfactants; other chemicals are caustic soda, sodium silicate, metal ion chelating agents and hydrogen peroxide.
The hydrogen peroxide blea~::hing agent has to be added in order to prevent a pulp colour yellowing caused by flue additions of caustic soda and to improve brightness of pulp fibers.
With t_he advance in the modern printing and photocopying technology; conventional deinking with the aid -- 2032~~u of surfactants encounters serious problems with the wastepaper printed with the use of heavily coated, highly polymerized; or nonimyact inks, such as ultraviolet, heatset;
Xerox; laser and ink jet. These inks usually contain cured polymer resins which bind ink particles so strongly on the fiber surface that it is impossible to dislodge the ink completely during the wastepaper defiberizing (pulping) stage wi th the convent Tonal deinking c:kiemica is . Exc:ess~ heat and mechanical energy <are also required along witkr the ip ine.ffect ive conventional ckiemicals.
In the convent Tonal f lot<it ion de inking process for newspririt wastepaper a major technical problem is experiencHd witki fine ink particles embedded in the fibre bundles and i5 between fibrils whicki are almost impossible t:o remove from the f fibers by a washing and,/or f lotat ion process .
SUNI~~1ARY OF THE INVENTION
This invention provides a view and much improved method 2p of deinking printed wastepaper. This method is effective in newsprint deinking, as well as the deink.ing of wood free printed wastepaper sucks as whiteledger, laser printed, xerographic copypaper and c:omputerr printout wastepaper.
25 This invented deinking method is to remove ink particles with the use of biological activity of enzyme on the cellulose fiber surface and a dispersing function of enzyme protein on ink particles.
3p In contrast to the conventional method no alkali and de.inking surfactants are required although some surfactants can be used along with the enzyme to enhance the deinking efficiency. In the froth flotation process the fatty acid collectors are not required. Since caustic soda is not used 20322~u in tile newsprint deinking, hydro~zen peroxide bleaching agent is not also required for yellowing prevention.
Tine elimination of the fatty acid collector in this biologica.i deinking process will solve the pers=istent pitch and scale deposition problem associated with the conventional flotation process using the fatty acid type soap and c:al.cium salts and silicates.
i0 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The method will now be described.
Printed Wastepaper, such as old newsprint or printed wood free wastepaper, is disintegrated in a conventional pulper (consistency ~~-'19F;) or in a high consistency pulper;
12-158;, at the water temperature ranging from room temperature up to 60 ~. The addit:i.on level of enzyme is 0.00584 to 5.09F; based on dry weic3ht of wastepaper; pH of the stock slurry is adjusted in thc~ range of 3.0 to 8Ø As compared to the conventional pulping process using caustic and surfactants in pulping, the process using enzymes can be completed in a relatively short period and ink particles are completely separated from the fiber surface and dispersed we i 1 . The dispersed inks are removed out of pu ip f fibers by conventional washing process equipment such as a vibration screen and a drum washer without the a.id of detergent surfactants. The ink particles dispersed with t: he ac t:i.on of enzyme protein can be a.l.so selectively removed out of the diluted pulp slurry with conventional flotation equipments in which air is injected into the pulp to provide bubbles to pick up the particles. i3o fatty acid col.iector is required in the case of waste newsprint. A small amount of fatty acid collector may be added to enhance the ink removal eff_i.ciency in the case of laser-printed wastepaper.
2032~~~
This biologi.cai deinki.ng process is t_o lower pulping energy to a large extent sine trte addition of enzyme results in a reduction in pulping time, a-s compared to tire pulping in the absence enzyme, of almost 50~; reduction. The observed faster and easier pulping in the presence of enzyme may be attributed to an unit;ue b-iologic:al activity o.f enzyme which is effective to debond tire fiber bonding and dislodge the inks bonded on the fiber surface as well as within the fibrils. A partial enzymatic hydrolysis of cellulose within i0 mic:ro st:ructure of fiber surface may occur during the pulping stage. This biological activity of enzyme takes out. fine ink particles embedded within fiber bundles, fibrils and fines which have been i-mpossible to be take out by convertti.onal deinking chemicals.
i5 According to this biological deinking method of old newsprint t:he addition of hydrogen peroxide to prevent the fiber yellowing is not required, which will result in a substantial reduction of deinkin.g chemical cost: as compared 20 tc~ the conventional de inking process using caustic soda, hydrogen peroxide; cheiat.ing ager~t and sodium silicates.
It should he pointed out that the phys.ica.l strength properties of the resulting pulp fiber prepared by this 25 invented method are found to b~e higher than t=hose of ttte corresponding pulp prepared by the conventional method; in addition to the much higher resulting pulp brightness. The enzyme addition does not appear to degrade the fiber strength; instead improving the fiber strength fox reasons Op that are as yet unknown.
.35 203225fi 6 ' "
Example 1.
Deinking of old newsprint with a cellulolytic enzyme.
A sample of old newsprint wastepaper was added to a pulper which was filled with 40 C water at the consistency of 4% and a cellulase was dissolved at the dosage level of 0.1% based on oven dry weight of wastepaper. The wastepaper was soaked for 10 minutes and then disintegrated for 5 minutes. After a. complete disintegration of wastepaper, one half of the:pulp slurry was diluted to a 1%
consistency.
The diluted pulp slurry was moved to an air flotation cell and then the dispersed ink particles were removed out of the pulp slurry by skimming off a froth containing ink particles out of the cell while injecting air through a porous plate. The flotation time for the complete removal of the ink froth was one minute.
The other half of the pulp slurry was washed on a laboratory vibration screen to remove the dispersed ink particles.
The resulting recycled pulp fibers obtained by the flotation and the washing step were evaluated for pulp brightness and mechanical strength properties. To compare this enzyme treated deinking pulp to the conventional deinking pulp, the same sample of wastepaper was treated in the pulper with the addition of 1.0% NaOH, 0.3% H O, 3%
, sodium silicate solution (water glass), 0.8% of SERFAX MT-, 0 (Trademark) (fatty acid soap) and 0.2% IGEPAL
(Trademark) -660 based on oven dry weight of wastepaper.
The pulping time was 1.0 minutes for a complete disintegration. After diluting to 1% consistency, _m_ ~~32256 the dispersed ink. particles were removed by the flotation method with the laboratory flotation cell as described above.
As shown in Table 1, the brightness of the pulp deinked with enzyme was much Higher than that of the pulp de.inked with the conventional chemicals and t=tie mechanical strength of the enzyme-deinkecl pulp was also superior to that. pulp deinked with the fatty acid collector and the di.spersant {IGEPAL 660). The microscopic oioservation revealed that the pulp prepared by the present invention contained more long fiber fractions and has smoother fiber surface and looked less mechanically damaged.
i5 Table 1. Comparison of properties of recycled pulp by method of pre~:ent invention and the conven-tional met_had.
brightness tensile index tear index ( ~; ) ( N.m/g ) { mN.m ,lg) KONP AONP KONP AONP KONP AONP
flotation 4?.1 45.2 28.9 32.4 1I.? 13.6 preserrt _..__.._..__.______.__.__..____._. r._.___. _.____.__ ___ ____.___~___._.__~___._____._____.____.._.._....__..__. _._ method washing 50.3 48.6 29.3 32.9 11.8 1.4.1 SERFAX MT-90 45.1 38.4 30.1 32.8 10.8 13.1 ,~0 KONP: Korean old newspaper AONP: American old newspaper The enzyme treated pulp gave cleaner and brighter pulp with the washing as compared to the flotation ink removal.
20~22~6 The enzyme addition ap~~eared to accelerate tine wastepaper disintegration to a large extent. When the old newspaper was disintegrated in the conventional pulper at the 4°c; consistency, the addition of 0.5:K enzyme reduced the pulping time from 5 minutes (no enzyme addition) to 30 seconds for a complete disintegrat ion as shown in Table 2 .
Table 2. Relation between enzyme addition and disintegration time.
Enzyme ( 96 ) 0.5 0.1 0 disintegration 30> 60-120 3OO<
time ( sec ) - _._...__. _._._.__~____._. ____._._ _..__._ __...____._.._____..___..
_____~..__.___._____.___._.__ __.._..___._____.______ Example 2.
Deinking of laser CPO (,computer printout) with cellulolytic enzyme.
It is almost impossible ac:h:ieve a complate removal of laser beam cured ink particles from laser CPO wastepaper with t:he conventional de>inking rhemica.Is, because the ink particles are so strongly adhered to the f. fiber surfacie that alkali and general deinking surfactants in the conventional deinking chemicals are not able to dislodge and disperse in the pulp water slurry.
A sample of laser CPO waste>paper was added to water in a laboratory high consistency pulper at the consistency of 12.5~C; and a cellu.iase was added to thH water at the dosage level of 0.2gr; based on the dry weight of paper. At stock water temperature of 20-35 C; the pulping was carried out for 2U322~6 20 minutes. The completely dig>integrated pulp slurry was diluted to 0.5~ and than dispersed ink particles were removed out of the pulp slurry using the laboratory flotation cell as explained in Example 1. In this case, to increase tHle lIlk removal efficiency and selectivity a small amount of the conventional fatty acid collector, SERFAX NT-90; of 0.39F;
based on dry weight of wastepaper was added prior to the air flotation and the flotation time was 3 minutes. To compare to enzyme deinked pulp, tile conventional deinked pulp was prepared by the same way bL~t the different chemical conditions as follow:
1~; NaOH on dry weight of wastepaper 0.19r; IGEPAh 660 disoersant 0.89f; SERFAri MT-90 pulping temperat=ure . 50 C
pulping time : 30 minutes calcium salt addition to tine flotation cell: 200 ppm flotation time . 3 minutes The brightness and the :strength properties of tree resulting pulp samples were compared in Tahle 3.
As shown in the of the paper tab3.e, the image analysis samples indicates that the number of the residual i.nk particles was much less; about 10 times; for pulp deinked the wi th the enzyme and tare tensi le st rerrgth was also higher as compared to the pulp prepared with tire conventional chemicals.
A recycled chemical pulp of high duality in terms of dirt count and fiber strength properties can be obtained with ,~0 ttre use of enzyme in a combinat ion of a small amount of fats=y acid collector by the flotation method.
Table 3. Comparison of pulp properties recyc..ied by the method of present invention and conventional method.
1~ 2~32~~~
brightness dirt amount tensile index 1 {count,/area) {N.mjg) enzyme : MT-90- { 0 . 39k ) '19 . 0 450 34 . 3 MT-90 { 90°6 ) 80 . 6 4 ; 330 26 . 3 Fxampie 3.
Deinkinc,~ of wast.-e newsprint by pectinolytic enzyme.
As the same method t=o example 2; tine waste newsprint containing 0.191, of pectase was soaked for 10 minutes at 40C
i5 and disintegrated for 5 minutes. Diluting the disintegrated pulp to i9K; the ink particles are removed by flotation for 1 minute.
As shown in Table 4; the brightness and tensile strength of paper sheet prepared by the method of the present invention are improved.
Table 4. Comparison the method of using pect.inolytic enzyme with c:onvent_ional method.
brightnes~> tensile index } { N.m,ig ) present method 44 . 29k 3 3 - ~3~'0 _______..___________....___..__r_.~..___._____.________.___.___.....__._...____ ._._._.______._ __.__._....____._._______._. ...__._.._..
MT-90 { 0 . 896 } 38 . 49F; 32 . 896
Claims (22)
1. A method of de-inking waste printed paper, comprising a) pulping waste printed paper with an enzyme capable of dislodging ink particles from the waste printed paper in an aqueous medium at a pH resulting from not having added alkali prior to or during the de-inking process, and wherein the ink is dislodged from the waste printed paper by action of said enzyme; and b) removing dislodged ink particles from the resulting pulp containing medium.
2. The method of Claim 1 wherein dislodged ink particles are removed by flotation.
3. The method of Claim 1 wherein dislodged ink particles are removed by washing.
4. The method of Claim 1 wherein the amount of enzyme used is in the range of about 0.005 to about 5 percent-by-weight based on the dry weight of the wastepaper.
5. The method of Claim 1 wherein said enzyme is selected from the class consisting of cellulase, hemicellulase, pectinase, other carbohydrases and mixtures thereof.
6. The method of Claim 1 wherein said enzyme is a cellulase selected from the group consisting of cellulases derived from Trichoderma viride, Aspergillus niger and mixtures thereof.
7. The method of Claim 1 including controlling the pH of said aqueous medium from about 3 to about 8.
8. The method of Claim 1 wherein the pulping occurs at a high consistency of pulp.
9. The method of Claim 1 wherein the pulping occurs for a period of less than 1 hour.
10. The method of Claim 1 wherein the paper is pulped at a temperature in the range of about 20 degrees Celsius up to about 60 degrees Celsius.
11. The method of Claim 1 including controlling the pH of said aqueous medium from about 3 to about 7.
12. A method of recycling waste printed paper, comprising a) pulping waste printed paper;
b) contacting waste printed paper with an enzyme capable of dislodging ink particles from the waste printed paper in an aqueous medium at a pH resulting from not having added alkali prior to or during the de-inking process, and wherein the ink is dislodged from the waste printed paper by action of said enzyme; and c) removing dislodged ink particles from the resulting pulp containing medium.
b) contacting waste printed paper with an enzyme capable of dislodging ink particles from the waste printed paper in an aqueous medium at a pH resulting from not having added alkali prior to or during the de-inking process, and wherein the ink is dislodged from the waste printed paper by action of said enzyme; and c) removing dislodged ink particles from the resulting pulp containing medium.
13. The method of Claim 12 wherein dislodged ink particles are removed by flotation.
14. The method of Claim 12 wherein dislodged ink particles are removed by washing.
15. The method of Claim 12 wherein the amount of enzyme used is in the range of about 0.005 to about 5 percent-by-weight based on the dry weight of the wastepaper.
16. The method of Claim 12 wherein said enzyme is selected from the class consisting of cellulase, hemicellulase, pectinase, other carbohydrases and mixtures thereof.
17. The method of Claim 12 wherein said enzyme is a cellulase selected from the group consisting of cellulases derived from Trichoderma viride, Aspergillus niger and mixtures thereof.
18. The method of Claim 12 including controlling the pH of said aqueous medium from about 3 to about 7.
19. The method of Claim 12 wherein the pulping occurs at a high consistency of pulp.
20. The method of Claim 12 wherein the pulping occurs for a period of less than 1 hour.
21. The method of Claim 12 wherein the paper is pulped at a temperature in the range of about 20 degrees Celsius up to about 60 degrees Celsius.
22. The method of Claim 1 including controlling the pH of said aqueous medium from about 3 to about 7.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2287602 CA2287602C (en) | 1990-12-14 | 1990-12-14 | Biological method of deinking printed wastepaper |
| CA 2032256 CA2032256C (en) | 1990-12-14 | 1990-12-14 | Biological method of deinking printed wastepaper |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2032256 CA2032256C (en) | 1990-12-14 | 1990-12-14 | Biological method of deinking printed wastepaper |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2287602 Division CA2287602C (en) | 1990-12-14 | 1990-12-14 | Biological method of deinking printed wastepaper |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2032256A1 CA2032256A1 (en) | 1992-06-15 |
| CA2032256C true CA2032256C (en) | 2000-02-22 |
Family
ID=4146648
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2287602 Expired - Lifetime CA2287602C (en) | 1990-12-14 | 1990-12-14 | Biological method of deinking printed wastepaper |
| CA 2032256 Expired - Lifetime CA2032256C (en) | 1990-12-14 | 1990-12-14 | Biological method of deinking printed wastepaper |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2287602 Expired - Lifetime CA2287602C (en) | 1990-12-14 | 1990-12-14 | Biological method of deinking printed wastepaper |
Country Status (1)
| Country | Link |
|---|---|
| CA (2) | CA2287602C (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6426200B1 (en) | 1994-09-15 | 2002-07-30 | University Of Georgia Research Foundation, Inc. | Methods for enzymatic deinking of waste paper |
| US7282113B2 (en) | 2004-11-17 | 2007-10-16 | Tritexco, Inc. | Method for enzymatic deinking of waste papers, the waste papers so treated and the treating composition |
| AU2012328637B2 (en) | 2011-10-27 | 2016-06-02 | Buckman Laboratories International, Inc. | Method and composition for enzymatic treatment of fiber for papermaking, and paper products made therewith |
-
1990
- 1990-12-14 CA CA 2287602 patent/CA2287602C/en not_active Expired - Lifetime
- 1990-12-14 CA CA 2032256 patent/CA2032256C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CA2287602A1 (en) | 1992-06-15 |
| CA2032256A1 (en) | 1992-06-15 |
| CA2287602C (en) | 2007-07-03 |
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