AU641494B2 - Process for the enzymatic bleaching of celluloses - Google Patents

Abstract

The present invention concerns a process for the enzymatic bleaching of celluloses in which a) a redox potential in the range between 200 and 500 mV is set with the simultaneous dosed addition of oxidation and reducing agents and the addition of salts and complex formers to provide an aqueous cellulose-containing solution; b) a bleaching reaction is initiated by the addition of lignolytic enzymes; and c) the reaction is maintained for 15 minutes to 12 hours under continuous agitation.

Description

OPI DATE 21/10/91 APPLN.- I D 75432 91 PCi' AOJP DATE 21/11/91 PCT NUMBER PCT/EP91/00540 I NTERNATION E INTERNATIONALE ZUSAMMENARBEIT AUF DEM GEBIET DES PATENTWESESCT (51) Internationale Patentklassifikation 5 (11) Internatlonale Verdffentlichungsnurnmer: WO 91/14823 D21C 9/10 Al (43) Internationales Ver~ffentlichungsdatum: 3. Oktober 1991 (03.10.91) (21) Intem ~ationales Aktenzeichen: PCT/EP9 1/00540 Veriiffentlicht Mit internationalern Rechercljenbericlu.

(22) Internationales Anmeldedatum: 19. Midrz 1991 (19,03.9 1) Prioritfitsdaten: P 40 08 893.6 20. M~irz 1990 (20.03.90) DETA (71X(72) Annielder id Erfinder: CALL, Hans-Peter (DE/DE]; 61 Heinsbergerstr. 14a, D-5132 Obach- Palen berg (DE).

(74) Anwalt: FITZNER, Ulrich; Am Eichfi~rstchen 2a, D-4030 Ratingen.- "v -)rf (DE).

(31) Bestimmungsstaaten: AT (europiiisches Patent), AU, BE (europ~isches Patent), BR, CA, CH (europliisches Patent), DE (europiiisches Patent), DK (europiiisches Patent), ES (europ~isches Patent), Fl, FR (europliisches Patent), GB (europisches Patent), GR (europliisches Patent), HU, IT (europaisches Patent), JP, LU (europaisches Patent), NL (europttisches Patent), NO, SE (europklisches Patent), SU, US.

(54) Title: PROCESS FOR THE ENZYMATIC BLEACHING OF CELLULOSES (54) Bezeichnung: VERFAHREN ZUM ENZYMATISCHEN BLEICHEN VON ZELLSTOFFEN (57) Abstract The present invention cumcemns a process for the enzymatic bleaching of celluloses in which a) a redox potential in the range between 200 and 500 mY is set with the simultaneous dosed addition of oxidation and reducing agents and the addition of salts and complex formers to provide at, aqueous cellulose-containing solution; b) a bleaching reaction is initiated by the addition of lignolytic enzymes; and c) the reaction is maintained for 15 minutes to 12 hours under continuous agitation.

(57) Zusammenfassung Die vorliegende Erfindung betrifft ein Verfahren zumn enzymatischen Bleichen von Zellstoffen, bei demn a) unter gleichzeitiger Zudosierung von Oxidations- und Reduktionsmitteln und Zusatz von Saizen und Komplexbildnern zu einer wlissrigen zell.

stoffhaltigen Lbsung emn Redoxpotential mm Bereich zwischen 200 und 500 mV eingestellt, b) durch Zugabe von lignolytischen Enzymen eine Bleichreaktion gestartet und c) die Reaktion unter st~ndigem Rflhren lber 15 Minuten bis 12 Stunden aufrechterhalten wird.

March 18, 1991 Dr. Hans-Peter Call Heinsberger Strasse 14a D-5132 Uebach-Palenberg A process for Enzymatic Bleaching of Celluloses The present invention concerns a process for enzymatic bleaching of celluloses.

The biological processes for cellulose production known so far work with micro-organisms, especially fungi. From DE-PS 31 10 117, for example, there is known a process for obtaining cellulose from wood or other plant fibre materials where the lignocellulose is decomposed with the aid of pocket rot fungi. However, the processes working with micro-organisms have considerable disadvantages. For example, it is still not possible to achieve decomposition and separation of the lignine from its accompanying polymers (cellulose) without simultaneous growth of the micro-organisms and without loss of cellulose. The simultaneous growth of the fungus causes long decomposition periods which can last up to several weeks.

Owing to the above-described difficulties of using micro-organisms, the possibilities of using isolated enzyme systems have been examined during the last few years. Especially, the enzymes of the pocket rot fungus Phanerochaete chrysosporium were researched and clarification obtained in many details. For example, it is known from "Biotechnology in the Pulp and Paper Industry, 3rd International Conference, Stockholm, 1986" that the equilibrium of the reaction is on the polymerisate side during the decomposition of lignine, i.e. noncell systems do not decompose lignine, but contribute to its polymerisation.

Since the discovery of the lignolytical enzymes of the pocket rot fungus Phanerochaete chrysosporium, a number of enzymatical processes for bleaching cellulose by means of living fungus systems or non-cell systems, too, have become known in literature. Also, a number of experiments were carried out to bleach by means of haeme systems. All these systems require reaction times of more than 12 hours. This means that all these systems require considerable time and are costly. The latter applies especially to the pure heame systems.

Today, bleaching is still carried out purely chemically in several stages by adding chlorine. However, chlorine .bleaching causes considerable environmental problems. In the general bleaching processes, the kappa number, i.e.

the lignine content, is reduced by removing the chromophore residual lignine condensation products that occur during the boiling process for lignine removal, and the cellulose is thus lightened.

The present invention now has the object of providing a process for the enzymatical bleaching of celluloses which no longer has the disadvantages of the biological and chemical bleaching processes described above.

nThi:e bjrt e ewlved by a) adju ting; a rda po onreial- -in thC range btwccn 200 and 500 mV whilc motcred adedi- 2a According to the present invention there is provided a process for the enzymatical bleaching of celluloses, in which a) a redox potential ranging between 200 and 500 mV is adjusted while simultaneously carrying out metered addition of oxidants and reductives and the addition of salts to an aqueous solution and b) a bleaching reaction is started by adding lignolytical enzymes, characterized by adding as the salt copper(II) sulfate or a mixture consisting of copper(II) sulfate with Mn(II) sulfate, Mn(II) acetate, Fe(II) sulfate, Ti(III) chloride, Ce(III) nitrate and/or Ce(IV) ammonium nitrate, phenolic compounds as well as complexing agents to the aqueous solution containing cellulose and maintaining the reaction under constant stirring for 15 minutes up to 2 hours.

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t 93G709,popree,75432LcaPe,2 -tei -f-e--oxidants and reductivcs and the addition osalts and complexing agents to an aqueous so on containing cellulose takes place ssaneously, b) starting a bleaching reac y adding lignolytical enzymes, and c) aining the reaction for a period of -minutec up te-12 hours during which time it is con tantly ctirrcd. This type of process prevents repolymerisation of the lignine and makes possible depolymerisation in the first place.

The redox potential is preferably in the range between 250 and 450 mV. In the process according to the invention, it can be determined with the aid of a redox electrode and, by means of a control unit and an actuator, can be kept constant during the entire reaction time by adding oxidants and reductives, salts and phenolic compounds.

Hydrogen peroxide, oxygen and ozone are preferably used as oxidants. Suitable reductives are ascorbic acid, dithionite and sodium bisulphite.

The salt added to the aqueous solution containing cellulose is cupric sulphate. Mn(II)sulphate, Mn(III)acetate, Fe(II)sulphate, Ti(III)chloride, Ce(III)nitrate and Ce(IV)ammonium nitrate can additionally be used as salts. Salts containing the elements of zinc, antimon and lead are also suitable.

Possibly, phenolic compounds can be added to the aqueous solution containing cellulose. Especially proven compounds of this type are veratryl alcohols.

Further, fatty acids such as oleic acids, haeme compounds such as haemoglobin and bleaching reagents such as sodium perborate can be added to the aqueous solution '3 .,0 containing cellulose. Moreover, an after-bleach can be carried out with conventional bleaching agents such as sodium hypochlorite, 02, chlorine dioxide, ozone, H 2 0 2 and sodium dithionite.

Further, it is pointed out that the addition of complexing agents is very important for the success of the process according to the invention. Preferably, ethylene diamine tetraacetic acid (EDTA) or diethylene triamine pentaacetic acid (DTPA) are used as such complexing agents. As s-on as the required redox potential has been adjusted, the bleaching process sets in comparatively quickly. This process can already be completed after a few minutes, but in that case the kappa figure which, depending on the cellulose content, can be decreased up to 90 after several hours is hardly reduced.

In addition to the above-mentioned substances, further substances can be added to the aqueous solution containing cellulose. These can be sodium hypochlorite, sodium perborate, detergents, surface-active agents and polysaccharides such as glucanes and xanthane.

Lignolytical enzymes are preferably used as enzymes in the process according to the invention. Among others, these are phenol oxidases, laccases and peroxidases. The effectiveness of the process can be further increased by using pectinases and/or hemicullases. Especially suitable lignolytical enzymes are those obtained from the pocket rot fungus Phanerochaete chrysosporium. However, the use of such enzymes is already known from U.S.-PS 4 692 413, 4 690 895 and 4 687 741. However, enzymes obtained from special mutants cf Phanerochaete chrysosporium are used for bleaching according to these printed patent specifications. This is not necessary in the process according to the invention. Rather, all lignolytical enzymes known today can be used if the abovedescribed prerequisites are complied with. The main difference can be found in the function of the reductives or oxidants added by metered addition as well as the mediators which capture the radicals. This is because these substances prevent repolymerisation and therefore make possible the decomposition of lignine in the above-described manner and quantity within the stipulated short period of time in the first place.

The pH value is generally between 2 and 5 in the process according to the invention. A pH value of 3 is preferred. The temperature is 20 to 0 0 preferably 40 0 C. If these conditions are complied with, a redox potential of 200 to 500 mV is adjusted when the above-mentioned substances are added. It is determined by the ratio of the different substances added to the reaction vessel.

It can be maintained during the entire reaction period, if the addition of cxidants and reductives, salts and possibly phenolic compounds is monitored and controlled accordingly.

With the aid of the bleaching process described above, it was possible for the first time to bleach celluloses within a very short period of time (15 minutes to 2 hours), at physiological temperatures (40 0 without pressure and with a minimum of chemical substances added in a manner which is inexpensive and, especially important, does not affect the environment. Another advantage of the process according to the invention is the possibility of operating the process continuously.

The process according to the invention is illustrated by the following examples.

g abs.dry (atro) cellulose (sulphate cellulose) are stirred in a stirring vessel at 1 consistency, approx.

500 rpm and 40 0 C. The pH value is adjusted to pH 3 by means of 1 n HCL. 0.1 -1.5 H 2 0 2 based on abs.dry substance, approx 2 x 10 5 to 2 x 10 3 veratryl alcohol 0.1 EDTA or DTPA and 0.001 0.01 cupric sulphate based on abs.dry substance are added. After 500 5,000 IU lignolytical enzymes (1 IU turnover of 1 nmol VA/min. to veratryl aldehyde) have been added, the bleaching process is started by simultaneous metered addition of H 2 0 2 and sodium bisulphite solution. The redox potential of approx. 400 mV is maintained. Once the process has been initiated, it is continued for 2 hours. Process control and adjustment is carried out by means of a redox electrode and a pump control.

Claims (13)

1. A process for the enzymatical bleachilg of celluloses, in which a) a redox potential ranging between 200 and 500 mV is adjusted while simultaneously carrying out metered addition of oxidants and reductives and the addition of salts to an aqueous solution and b) a bleaching.reaction is started by adding lignolytical enzymes, characterized by adding as the salt copper(II) sulfate or a mixture consisting of copper(II) sulfate with Mn(II) sulfate, Mn(II) acetate, Fe(II) sulfate, Ti(III) chloride, Ce(III) nitrate and/or Ce(IV) ammonium nitrate, phenolic compounds as well as complexing agents to the aqueous solution containing cellulose and maintaining the reaction under constant stirring for 15 minutes up to 2 hours.

2. A process according to claim 1, wherein ethylenediamine tetraacetic acid (EDTA) or diethylenetriamine pentaacetic acid (DTPA) is used as the complexing agent.

3. A process according to claim 1 or 2, wherein polysaccharides are added to the aqueous solution containing cellulose.

4. A process according to claim 3, wherein the polysaccharides are glucanes an/or xanthane. A process according to any one of claims 1 to 4, wherein detergents are added to the aqueous solution containing cellulose.

6. A process according to any one of claims 1 to 5, wherein surface-active agents are added to the aqueous solution containing cellulose.

7. A process according to any one of claims 1 to 6, wherein fatty acids are added to the aqueous solution containing cellulose. S93(Y709,p:\oper\ee,75432caL 9 -8-

8. A process according to claim 7, wherein the fatty acids used are oleic acids.

9. A process according to any one of claims 1 to 8, wherein haeme compounds are added to the aqueous solution containing cellulose. A process according to claim 9, wherein haemoglobides are used as the haeme compound.

11. A process according to any one of claims 1 to 10 wherein phenolic compounds are added to the aqueous solution containing cellulose.

12. A process according to claim 11 wherein said phenolic compounds are veratryl alcohols.

13. A process according to claim 1 substantially as hereinbefore described with reference to any one of the examples. DATED this 9th day of July, 1993. HANS-PETER CALL By Its Patent Attorneys DAVIES COLLISON CAVE .93 I 930709,p:\oper\ee,75432ca5p(C8 Summary The present invention concerns a process for the enzy- matical bleaching of celluloses wherein a) a redox potential in the range between 200 and 500 mV is adjusted while metered addition of oxidants and reductives and addition of salts and complexing agents to an aqueous solution containing cellulose takes place simultaneously, b) a bleaching reaction is started by addition of lig- nolytical enzymes and c) the reaction is maintained for a period of 15 mi- nutes up to 12 hours during which time it is con- stantly stirred. INTERNATIONAL SEARCH REPORT Internationat Application No PCT/EP 91/00540 I. CLASSIFICATION OF SUBJECT MATTER (If several classification symbols apply, Indicate all) According to International Patent Classification (IPC) or to both National Classification and IPC Int. C1. 5 D 21 C 9/10 II. FIELDS SEARCHED Minimum Documentation Searched 7 Classifcation System Classification Symbols Int. Cl. 5 D 21 C Locumentation Searched other than Minimum Documentation to the Extent that such Documents are Included In the Fields Searched W Ill. DOCUMENTS CONSIDERED TO BE RELEVANT' Category i Citation o ocument, I' with Indication, where appropriate, of the relevant passages 12 Relevant to Claim No, 1" X WO, A, 8803190 (CALL, 5 May 1988, see paqe 2, line 22 page 3, line 30, see page 4, line 7-15,23 33 page 5, line 3; claims 1-20 A EP, A, 345715 (INTERNATIONAL PAPER COMPANY) 1,3,5, 13 December 1989, see page 3, lines 20 40, 7-9 see page 5, line 51 page 6, line 50; 11-14, claims 1-i6 16,19,23,

25-27 P,A PAPIER DAS. volume 44, No. !0A, October 1990, 1,3,5, DARMSTAT DE pages V33 V41; Call. H.P. et al.: 8,9, "Einsatz von lignolytischen Enzymen bei der 11-14 Zellstoff- und Papierherstellung (Biopulping, Biobleaching)." see page V39 i Special categories of cited documentas: 1 later document published after the International filing date document defining the general state of the art which i not or priority date and not in conflict with the application but mnide i r t th a which pias not cited to understand the principle ot theory underlying the conidered to be or particular relevance Invention earlier document but published on or after the international "XII document of particular relevanc; the claimed Invention filng date cannot be considered novel or cannot be considered to document which may throw doubts on priority claim(s) or involve an inventive stap which is cited to establish the publication date of another document of particular relevance; the claimed Invention citation or other Ipeclal reason (as specified) cannot be considered to involve an inventive step when the document referrlng to an oral disclosure, use, exhibition or document Is combined with one or more other such docu. other means ments, such combination being obvious to a person silled document publiehed prior to the International filing date but in the art. later than the priority date claimed document member of the same patent family IV. CERTIFICATION____ Date of the Actual Completion of the International Search Date of Mailing of this Iritefnatlonai search Report 28 June 1991 (28.06.91) 10 July 1991 (10.07.91) International Searching Authority Signature of Authorized Offcer European Patent Office Form PCTIISA/210 e(econd sheet) (January 1985) ANNEX TO THE INTERNATIONAL SEARCH REPORT ON INTERNATIONAL PATENT APPLICATION NO. EP 9100540 SA 45712 This arnex lists the patent family members relating to the patent documents cited in the above-mentioned international search report. The members arc as contained in the European Patent Office EDP filec on The European Patent Office is in no way liahle for these particulars; which are merely given for purpose of information. 28/06/9 1 Patent ~Ocument Publicaio Patent family Publication cited in search report I ate memher(s) Idatec WO-A-8803 190 05-05-88 DE-A- AU-B- AU-A- EP-A- JP-T- 3636208 605215 8230387 '-327576 2500990 05-05-88 10-0 1-9 1 25-05-88 16-08-89 05-04-90 EP-A-345715 13-12-89 AU-A- 3604589 14-12-89 ~JP-A- 2080687 20-03-90 0 w For miore details about this annex 'see Official Jolarnal of the European Patent Office, No. 121112 INTCRNATION ALER RECHERCIIENBERICHT Intntionairs Ahlcieithert PCT/EP 91/00540 1. KLASSIFIKATION DES ANMELD UNGSG FG F.NSTANDS (bet nmehreren Kiassifikatinssyrnboen slpd atir anzugebei) Nach dk n rT ti' ae kisi~~n (1170 Hser ssach der nationsten Kliasikation iind dcr Ii'C Int.1. 5 021C9/10 11. RFCIIERCIi]FRTF SACITGEBIETE ftecherchieeter Nlindestprifsrsff 7 Klassifikationssyie KWassifikttionssymbrile Int.K1. 5 D21C Ttcvhorchirrip.sicht umn Mindesipr~)stoff Retdrende Verillfrntlichungen, sowelftheise tinter die retherchlerlen Sachpeblete fallen a Ill. IRINSUILAGE VFROFFENTLICIIUNCVN 9 Art.' Kentizelchnung der VertffentichuriRIt sowelt erfordetich ufliw' Aligabe der mtislgeblichel Teile n feir. Ansptuch Nt.11 3 xWO,A,8803190 (CALL, 05 Mai 1988 siehe Selte 2, Zeile 22 Seite 3, Z il~e 30 7-15, 23 siehe Seite 4, Zelle 33 Seite 5, Zeile 3; Anspriiche 1-20 A EP,A,345715 (INTERNATIONAL PAPER COMPANY) 1, 3, 13 Dezember 1989 7-9 siehe Seite 3, Zeilen 20 siehe Selte S, Zelle 51 -Seite 6, Zeile 50; 1 -4 Anspriche 1-16 16, 19, 23, 25-27 Ilesoridere KH.teeorien vnn arigegebertn Vertifrentlilhungen Vcrithfteitichung, die den aligemeinen Stand der Technik IT Spatsre V0?eitntCh!ung, itt nach den internationalen An- dlinlert, ahiet nichi als besonders bedeutsm anusehen Ist rnidedatumn oiler den H~orillisdatumn vertlfrentiicht wotden 1iteres Dotkument, us; ledocis erst ant oiler nach den itria- 1st tind mit der Anminidung n~cht koltidieri, sondern nur zumn tionalen Annmeidedaturn vftticht Twoden Ist Versigndnis des def,' Frfinidunki ulrundelegendeti rlps 'I,'Veriffntlchuitdiepee netIst tien rioittls~ispuchoder der lhr zogtuAdeleRenden Theorie angtegeben 1st 1, crtfentii echg, die gclgnet 1s, oene dutch ie sas pril Vertitfentiichung v'on besonderet Bedeutung die beansprach- zlfeihuaf frcennz asn drdthdedsvclf e Erfindung kann nicht als neu oder auf erfiriderls~cher Ttg- V.tlch ,,dzu= =te anderen imn Recherchtenbeftcht ge- keit xierithind betrachtr1 werden n~annten ettfnlcug beiet werden soil oer die am~. ein~m I'V~fnicugvnbeod~yHdau ,u 2 nderen hesrinderen Grund angegetten Ist (vile auite etifnlcun o esnee ed'au die beanru- 0 Vetifentlchug, de sch af ese ntinlich Ofenhaun~ IcErfindung kann nichl als auf erfinderischer Tgtfgk~t be- erilfetllhundiesic au ein modlihe frenaroit,1s0hend betrachNet werden, wenn die Vertiffentlchung mill vine flenusrung. tine Aussteiiung oder onilciC Mtinahmenf eiricr niler menreren anderen Vertiffentiichunre dieser Kate- kweicht gorle it Verbindurig gebracht wind und dimse V- ndung fdr PI Vertfrntichunit, die von dcm Internationatep Anmeldede- tinen Fahmn naheilegenid 1st ium,. abet nach derm heanispnuchm~ Prinritlsdatumn verdtflent- '3 Verliltfntilkhung, die Mitgiied dercelien Patentfamtiite 140. iirht warden ilo IV. flFSIF~INIGJNC Datum des Atichlussc der Internatlonaien Rechrche Absvesiedaturn des Intnatinuaien Rocherctscritrrchts

28. 1 JUNI 1991 10 J uL 1991 Internationale Rechenchenhelie Untetschrtft deq bevollm~chtlefen fledicleeen FUROPAISCIIES PATENTANIT1 BERNAROJ NORIEGA F raombilt PCII711A1210 INA' 2) (Jasuu 1945) PCT/EP 91/00540 Intern2tion2les Akfort0rhen rflIetnatIOfl2Ics Akten~Ie~hen PCT/EP 91/00540 fit. EIN.9CIILAGIGE VERO rrENTUCI IUNC Ir r (Ponlseitng von Blatt 1) Art Kentizeichnung dier Verd$ffcntlichum ioweil erfordrilci ,iN Ar ie BI i tsiefefrelctitrAgabde mechen Tet iu.Aepuh P,A PAPIER, DAS. 1, 3, vol. 44, no. 10A, Oktober 1990, DARMSTADT DE 8, 9, Seiten V33 V41; Call,H.P. et al.: 11-14 "Einsatz von lignolytischen Enzymen bei der Zelistoff- und Papierherstel lung (Biopulping, Biobleaching),' siehe Seite V139 Forivibirto PCTIISAIZIO E7.ssmlzbote"Y JusW 1409) ANHANG ZUM INTERNATION ALEN RECHERCHENBERICHT OBER DIE INTERNATIONALE PATENTANMELDUNG NR. EP 9100540 SA 45712 In diesemn Anhang wind die Mitgliedtr der Patentfamilien der im obengenannten internationalen Recherchenbericht angefOlirten Patentdolwmentc angogeben. Die Angaben Ober die Familienmitglieder entsprechen demn Stand der Datei des Europ~ischen ratentamnts am fliese Angaben dienen nur zur Untcrrichtung und erfolgen ohne Gewfihr. 28/06/9 1 Im Recherchenbericht I Datum der Mitglied(er) der Datum der anpgerdhrtes ratentdokument Veritifentlichung ratentfamilie T %erdffentlichung WO-A-8803190 05-05-88 DE-A- 3636208 05-05-88 AU-B- 605215 10-01-91 AU-A- 8230387 25-05-88 EP-A- 0327576 16-08-89 JP-T- 2500990 05-04-90 EP-A-345715 13-12-89 AU-A- 3604589 14-12-89 ~JP-A- 2080687 20-03-90 w FOr nflhere EUnzelheiten 7.u diesemn Anhoog slehe Amtblatt des IEuropisrehen Pntcntamts, Nr.12182