Method of making nanocrystalline cellulose

Patent metadata

Field	Value
Publication number	US-2017291962-A1
Application number	US-201615092589-A
Country	US
Kind code	A1
Filing date	Apr 6, 2016
Priority date	Apr 6, 2016
Publication date	Oct 12, 2017
Grant date	—

Abstract

The method of making nanocrystalline cellulose is a flash lyophilized-acidic hydrolysis method for converting cellulosic fibers into nanocrystalline cellulose. Cellulosic fibers are initially ground in a high-speed, rotary grinder to produce ground cellulose fiber. The ground cellulose fiber is then dried to produce dried, ground cellulose, which is then freeze-dried to yield lyophilized cellulose. Pure concentrated sulfuric acid is then added to the lyophilized cellulose at a liquid/solid ratio of 1:1 (vol/wt) to form a cellulosic paste. The cellulosic paste is diluted in either water or absolute ethanol at a liquid/solid ratio of 1:1 (vol/wt) to form a cellulosic solution, which is then filtered under cooling by liquid nitrogen-vapor. The nanocrystalline cellulose precipitate is then washed until neutralization and dried to yield nanocrystalline cellulose.

First claim

We claim:

1 . A method of making nanocrystalline cellulose, comprising the steps of:
grinding cellulosic fibers to produce ground cellulose fiber; drying the ground cellulose fiber to produce dried, ground cellulose; freeze-drying the dried, ground cellulose to produce lyophilized cellulose; adding sulfuric acid to the lyophilized cellulose at a liquid/solid ratio of 1:1 (vol/wt) to form a cellulosic paste; diluting the cellulose paste in a cold liquid at a liquid/solid ratio of 1:1 (vol/wt) to form a cellulosic solution, wherein the cold liquid is selected from the group consisting of water and absolute ethanol; filtering the cellulosic solution under cooling by liquid nitrogen-vapor to produce a nanocrystalline cellulose precipitate; washing the nanocrystalline cellulose precipitate until neutralization, wherein the washing is performed in a liquid selected from the group consisting of cold water and ethanol; and drying the washed nanocrystalline cellulose precipitate to yield a nanocrystalline cellulose product.

2 . The method of making nanocrystalline cellulose as recited in claim 1 , wherein the step of drying the ground cellulose fiber comprises oven drying the ground cellulose fiber at a temperature of between approximately 100° C. and approximately 110° C. for approximately two hours.

3 . The method of making nanocrystalline cellulose as recited in claim 2 , wherein the step of drying the ground cellulose fiber further comprises desiccating the ground cellulose fiber.

4 . The method of making nanocrystalline cellulose as recited in claim 1 , wherein the step of freeze-drying the dried, ground cellulose comprises pouring liquid nitrogen over the dried, ground cellulose.

5 . The method of making nanocrystalline cellulose as recited in claim 4 , wherein the step of freeze-drying the dried, ground cellulose further comprises exposing the dried, ground cellulose to liquid nitrogen-vapor for approximately five minutes.

6 . The method of making nanocrystalline cellulose as recited in claim 1 , further comprising the step of stirring the sulfuric acid and the lyophilized cellulose following the step of adding the sulfuric acid to the lyophilized cellulose.

7 . The method of making nanocrystalline cellulose as recited in claim 1 , wherein the step of drying the washed nanocrystalline cellulose precipitate comprises air drying the washed nanocrystalline cellulose precipitate.

8 . A method of making nanocrystalline cellulose, comprising the steps of:
grinding cellulosic fibers to produce ground cellulose fiber; drying the ground cellulose fiber at a temperature of between approximately 100° C. and approximately 110° C. to produce dried, ground cellulose; freeze-drying the dried, ground cellulose to produce lyophilized cellulose; adding sulfuric acid to the lyophilized cellulose at a liquid/solid ratio of 1:1 (vol/wt) to form a cellulosic paste; diluting the cellulose paste in a liquid at a liquid/solid ratio of 1:1 (vol/wt) to form a cellulosic solution, wherein the liquid is selected from the group consisting of water and absolute ethanol; filtering the cellulosic solution under cooling by liquid nitrogen-vapor to produce a nanocrystalline cellulose precipitate; washing the nanocrystalline cellulose precipitate until neutralization, wherein the washing is performed in a liquid selected from the group consisting of cold water and ethanol; and drying the washed nanocrystalline cellulose precipitate to yield a nanocrystalline cellulose product.

9 . The method of making nanocrystalline cellulose as recited in claim 8 , wherein the step of drying the ground cellulose fiber comprises oven drying the ground cellulose fiber at a temperature of between approximately 100° C. and approximately 110° C. for approximately two hours.

10 . The method of making nanocrystalline cellulose as recited in claim 9 , wherein the step of drying the ground cellulose fiber further comprises desiccating the ground cellulose fiber.

11 . The method of making nanocrystalline cellulose as recited in claim 8 , wherein the step of freeze-drying the dried, ground cellulose comprises pouring liquid nitrogen over the dried, ground cellulose.

12 . The method of making nanocrystalline cellulose as recited in claim 11 , wherein the step of freeze-drying the dried, ground cellulose further comprises exposing the dried, ground cellulose to liquid nitrogen-vapor for approximately five minutes.

13 . The method of making nanocrystalline cellulose as recited in claim 8 , further comprising the step of stirring the sulfuric acid and the lyophilized cellulose following the step of adding the sulfuric acid to the lyophilized cellulose.

14 . The method of making nanocrystalline cellulose as recited in claim 8 , wherein the step of drying the washed nanocrystalline cellulose precipitate comprises air drying the washed nanocrystalline cellulose precipitate.

15 . A method of making nanocrystalline cellulose, comprising the steps of:
grinding cellulosic fibers to produce ground cellulose fiber; drying the ground cellulose fiber to produce dried, ground cellulose; freeze-drying the dried, ground cellulose by pouring liquid nitrogen over the dried, ground cellulose to produce lyophilized cellulose; adding sulfuric acid to the lyophilized cellulose at a liquid/solid ratio of 1:1 (vol/wt) to form a cellulosic paste; diluting the cellulose paste in a liquid at a liquid/solid ratio of 1:1 (vol/wt) to form a cellulosic solution, wherein the liquid is selected from the group consisting of water and absolute ethanol; filtering the cellulosic solution under cooling by liquid nitrogen-vapor to produce a nanocrystalline cellulose precipitate; washing the nanocrystalline cellulose precipitate until neutralization; and drying the washed nanocrystalline cellulose precipitate to yield a nanocrystalline cellulose product.

16 . The method of making nanocrystalline cellulose as recited in claim 15 , wherein the step of drying the ground cellulose fiber comprises oven drying the ground cellulose fiber at a temperature of approximately 100° C. and approximately 110° C. C for approximately two hours.

17 . The method of making nanocrystalline cellulose as recited in claim 16 , wherein the step of drying the ground cellulose fiber further comprises desiccating the ground cellulose fiber.

18 . The method of making nanocrystalline cellulose as recited in claim 15 , wherein the step of freeze-drying the dried, ground cellulose further comprises exposing the dried, ground cellulose to liquid nitrogen-vapor for approximately five minutes.

19 . The method of making nanocrystalline cellulose as recited in claim 15 , further comprising the step of stirring the sulfuric acid and the lyophilized cellulose following the step of adding the sulfuric acid to the lyophilized cellulose.

20 . The method of making nanocrystalline cellulose as recited in claim 15 , wherein the step of drying the washed nanocrystalline cellulose comprises air drying the washed nanocrystalline cellulose.

Assignees

• Univ King Abdulaziz

Inventors

• Hindi Sherif Shawki Zaki
• Abohassan Refaat Atalla

Classifications

• C08B15/00 Primary

  Preparation of other cellulose derivatives or modified cellulose {, e.g. complexes} · CPC title

• C08L1/02

  Cellulose; Modified cellulose · CPC title

• B05D3/00

  Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials (successively applying liquids or other fluent materials B05D1/36; drying ovens F26B) · CPC title

• C08B1/00

  Preparatory treatment of cellulose for making derivatives thereof {, e.g. pre-treatment, pre-soaking, activation} · CPC title

• C08B15/02

  Oxycellulose; Hydrocellulose; {Cellulosehydrate, e.g. microcrystalline cellulose} · CPC title