# US 6,294,047 B1 · Methods for reducing fluorescence in paper-containing samples

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- Number: US 6,294,047 B1
- Document ID: US6294047B1
- Status: Granted
- Kind: B1
- Application number: 09/364,459
- Filed: 1999-07-30
- Granted: 2001-09-25
- Earliest claimed: 1999-07-30
- Assignees: Institute of Paper; Science and Technology Corporation
- Inventors: Fadi Selim Chakar; Arthur Jonas Ragauskas
- Web page: https://patentgrep.com/patent/US6294047B1

## CPC

- D21C 5/02: Working-up waste paper (mechanical part D21B1/08, D21B1/32)
- D21C 5/005: {Treatment of cellulose-containing material with microorganisms or enzymes}
- Y02W 30/64: Paper recycling
- D21C: PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT

## Abstract

The present invention provides methods for reducing fluorescence in a paper-containing sample. Methods for destroying fluorescent whitening agents in a paper-containing sample are also provided.

## Claims

### Claim 1

A method of reducing fluorescence in a paper-containing sample comprising the step of incubating a mixture comprising the paper-containing sample, an oxidoreductase, a mediator, and oxygen.

### Claim 2 (depends on 1)

The method of claim 1 further comprising the step of forming a paper.

### Claim 3 (depends on 1)

The method of claim 1 wherein the fluorescence of the paper-containing sample is reduced by up to about 50%.

### Claim 4 (depends on 1)

The method of claim 1 wherein the fluorescence of the paper-containing sample is reduced by up to about 85%.

### Claim 5 (depends on 1)

The method of claim 1 wherein the fluorescence of the paper-containing sample is reduced by up to about 100%.

### Claim 6 (depends on 1)

The method of claim 1 wherein said paper-containing sample comprises flourescent whitening agents.

### Claim 7 (depends on 1)

The method of claim 1 wherein said paper-containing sample comprises pulp.

### Claim 8 (depends on 7)

The method of claim 7 wherein said pulp comprises recycled paper.

### Claim 9 (depends on 7)

The method of claim 7 wherein said pulp comprises non-recycled paper.

### Claim 10 (depends on 1)

The method of claim 1 wherein said oxidoreductase is at least one member selected from the group consisting of laccase, manganese peroxidase, lignin peroxidase, and chloroperoxidase.

### Claim 11 (depends on 10)

The method of claim 10 wherein said oxidoreductase is at least two members selected from the group consisting of laccase, manganese peroxidase, lignin peroxidase, and chloroperoxidase.

### Claim 12 (depends on 10)

The method of claim 10 wherein one of said oxidoreductases is laccase.

### Claim 13 (depends on 12)

The method of claim 12 wherein said laccase is present in the mixture at a concentration from about 20,000 U per gram of O.D. pulp to about 560,000 U per gram of O.D. pulp.

### Claim 14 (depends on 1)

The method of claim 1 wherein said mediator is a N—OH compound.

### Claim 15 (depends on 14)

The method of claim 14 wherein said N—OH compound is at least one member selected from the group consisting of 1-OH-Benzotriazole, N—OH-acetanilide, violuric acid,2-2″ azinobis (3-ethylbenzthiazoline-6-sulfate) and N-hydroxyphtalimide.

### Claim 16 (depends on 15)

The method of claim 15 wherein said mediator is 1-OH-benzotriazole.

### Claim 17 (depends on 16)

The method of claim 16 wherein said 1-OH-benzotriazole is present in the mixture at a concentration from about 1% to about 4%.

### Claim 18 (depends on 15)

The method of claim 15 wherein said mediator is at least two N—OH compounds.

### Claim 19 (depends on 1)

The method of claim 1 wherein said oxygen is added to the paper-containing sample as a gas.

### Claim 20 (depends on 19)

The method of claim 19 wherein said oxygen is added to the paper-containing sample at a pressure from about 5 bars to about 10 bars.

### Claim 21 (depends on 1)

The method of claim 1 wherein said mixture is incubated at a temperature in the range from about 35° C. to about 60° C.

### Claim 22 (depends on 21)

The method of claim 21 wherein said mixture is incubated at a temperature of about 45° C.

### Claim 23 (depends on 1)

The method of claim 1 wherein said paper-containing sample is dried prior to combining the oxidoreductase, the mediator, and the oxygen with the sample.

### Claim 24 (depends on 1)

The method of claim 1 wherein the mixture has a pH in a range from about 4.0 to about 5.0.

### Claim 25 (depends on 24)

The method of claim 24 wherein the mixture has a pH of about 4.5.

### Claim 26 (depends on 1)

The method of claim 1 wherein the mixture comprises laccase at a concentration of about 24,000 U per gram of O.D. pulp, and 1-OH-benzotriazole at a concentration of about 2%, wherein the mixture is incubated for about 2 hours at a temperature of about 45° C., at a pH of about pH 4.5, and wherein the oxygen is added at a pressure of about 10 bars.

### Claim 27 (depends on 1)

The method of claim 1 further comprising the step of washing the mixture following incubation.

### Claim 28 (depends on 1)

The method of claim 1 further comprising the steps of washing and bleaching the mixture following incubation.

### Claim 29 (depends on 28)

The method of claim 28 further comprising the step of forming a paper.