# US 11,306,434 B2 · Method for separating lignin from ligno-cellulosic material

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- Number: US 11,306,434 B2
- Document ID: US11306434B2
- Status: Granted
- Kind: B2
- Application number: 17/407,663
- Filed: 2021-08-20
- Published: 2021-12-09
- Granted: 2022-04-19
- Earliest claimed: 2018-09-21
- Assignees: King Abdulaziz University
- Applicants: King Abdulaziz University
- Inventors: Sherif Shawki Zaki Hindi
- Web page: https://patentgrep.com/patent/US11306434B2

## CPC

- D21C 9/163: {with peroxides}
- D21C 1/04: with acid reacting compounds
- D21C 3/04: with acids, acid salts or acid anhydrides {(D21C3/003 and D21C3/222 take precedence)}
- D21C 5/022: {Chemicals therefor}
- D21C 9/16: with per compounds
- D21C 7/00: Digesters
- 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 involves an environmentally friendly process and apparatus for the delignification of lignin-containing materials, such as cardboard newspaper or agricultural or tree pruning wastes. This process produces cellulose using low temperatures and low concentrations of hydrogen peroxide. It can be performed using a column fitted with a semipermeable gasket that pressurizes the column by retaining oxygen released by action of the hydrogen peroxide on a lignin-containing material.

## Claims

### Claim 1

A method for forming cellulosic material from a ligno-cellulosic material, comprising:
blending the ligno-cellulosic material with water to form an aqueous liquor,
contacting the aqueous liquor with hydrogen peroxide under non-alkaline conditions in a reaction column to delignify the ligno-cellulosic material and form a mixture comprising dissolved lignin and cellulose, wherein oxygen generated during said contacting increases internal pressure relative to ambient atmospheric pressure, or increases partial internal O2 pressure relative to ambient partial O2 pressure during said contacting,
removing the dissolved lignin by filtering or centrifugation, and
recovering the cellulose;
wherein a top of the column is closed to atmospheric pressure by a gasket, which gasket retains sufficient oxygen in the column to maintain a higher than atmospheric pressure in the column during said contacting; and
wherein the gasket comprises a fiber plug or membrane which fits over an open top of the reaction column and prevents escape of sufficient oxygen molecules and oxygen radicals produced by said hydrogen peroxide treatment to enhance efficiency of delignification compared to an otherwise identical method that does not comprise the gasket.

### Claim 2 (depends on 1)

The method of claim 1, wherein the ligno-cellulosic material is paper.

### Claim 3 (depends on 1)

The method of claim 1, wherein the ligno-cellulosic material is cardboard.

### Claim 4 (depends on 1)

The method of claim 1, wherein said contacting occurs in the absence of NaOH or aqueous ammonia.

### Claim 5 (depends on 1)

The method of claim 1, wherein said contacting occurs in the absence of chlorine dioxide; or in the absence of methanol, hydrochloric acid and sulfuric acid.

### Claim 6 (depends on 1)

The method of claim 1, wherein the aqueous liquor contains 0.5 to 2 wt % hydrogen peroxide at a liquid to solid ratio of 10:1 to 20:1.

### Claim 7 (depends on 1)

The method of claim 1, wherein said oxygen increases the pressure at which said contacting occurs at least 5% above ambient atmospheric pressure.

### Claim 8 (depends on 1)

The method of claim 1, wherein said contacting occurs at a temperature ranging from 20 to 100° C.

### Claim 9 (depends on 1)

The method of claim 1, wherein said contacting occurs at a temperature ranging from 60 to 80° C.

### Claim 10 (depends on 1)

The method of claim 1, wherein said gasket comprises compressed cotton.

### Claim 11 (depends on 1)

The method of claim 1, wherein the gasket comprises a woven or nonwoven fiber.