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Energy efficient process for preparing nanocellulose fibers

Through the combined method of ozone oxidation treatment and cellulase, the environmental pollution of chlorine-containing bleaching and the high energy consumption of oxygen-based compounds in cellulose pulp processing are solved, the efficient release of nanocellulose fibers is achieved, and the performance of paper products is improved. .

Active Publication Date: 2015-04-29
UNIV OF MAINE SYST BOARD OF GOVERNORS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This creates two additional problems: (1) chemical modification of cellulose can hinder approval by regulatory agencies, such as FDA, on products so regulated; and (2) high negative charge can affect handling and compatibility with paper and other manufacturing Interactions with other materials commonly used in the process and may require neutralization with cations, adding unnecessary processing and cost
In addition, the use of ozone or chemical agents as bleaching pretreatments followed by mechanical refining methods to release nanofibrils entails very high energy costs, which are not sustainable on a commercial level

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0084] Embodiment 1: prepare comparative sample

[0085] A sample of bleached hardwood kraft craft pulp (Domtar Aspen) was prepared and treated by the various methods described in this example.

[0086] Table 1: Sample preparation

[0087]

[0088] Two samples (Samples 1 and 4) were unrefined pulp samples as purchased and had no treatment or refining. Sample 2 was refined without pretreatment. All refined samples were processed in Valley beaters according to Tappi standard T200. According to Pergalase TM Recommended procedure for sample 3 with enzyme (Pergalase TM A40 enzyme blend) pretreatment. Sample 5 was pretreated with ozone at a relatively high incorporation level of 2% and peroxide at an incorporation level of 5% (both based on dry fiber weight) for 15 minutes at a temperature of about 50°C and a pH of about 7. Ozone was bubbled into the reactor. Samples 6 and 7 were pretreated with 2,2,6,6-tetramethylpiperidin-1-oxyl ("TEMPO") according to the procedure of I...

Embodiment 2

[0089] Example 2: Charge and conductivity test

[0090] The charge and conductivity of each sample was measured using a Mütek PCD-03 instrument according to its standard instructions. The results are in Table 2 below.

[0091] Table 2: Charge and Conductivity

[0092]

[0093] This data demonstrates the aforementioned problem associated with TEMPO treatment, namely the high negative charge associated with chemically modified cellulose (which also leads to high conductivity). All other samples, including those ozone-treated according to the invention, had much less negative charge and conductivity.

Embodiment 3

[0094] Embodiment 3: energy consumption test

[0095] The energy expended to refine each MFC was monitored along with % fineness and average fibril length when comminution was performed. An electric meter connected to the motor-driven Valley beater provides power measurement for energy consumption, and a TechPap Morphi Fiber Length Analyzer provides continuous measurement of % fineness and fiber length as end point results. As seen in Table 1, Sample Nos. 2, 3, 5 and 7 were refined. This experiment allows the calculation of the energy efficiency of each of several treatment processes - ie the amount of energy required to reach a defined endpoint, or conversely the endpoint achievable with a fixed amount of consumed energy. exist Figure 3-4 The data are listed in .

[0096] image 3 The decrease in fiber length as a function of the total energy expended is illustrated. From the graph, it can be seen that both the enzyme treatment (#3) and the ozone treatment (#5) are more...

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PUM

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Abstract

A scalable, energy efficient process for preparing cellulose nanofibers is disclosed. The process employs a depolymerizing treatment with one or both of: (a) a relatively high charge of ozone under conditions that promote the formation of free radicals to chemically depolymerize the cellulose fiber cell wall and interfiber bonds; or (b) a cellulase enzyme. Depolymerization may be estimated by pulp viscosity changes. The depolymerizing treatment is followed by or concurrent with mechanical comminution of the treated fibers, the comminution being done in any of several mechanical comminuting devices, the amount of energy savings varying depending on the type of comminuting system and the treatment conditions. Comminution may be carried out to any of several endpoint measures such as fiber length, % fines or slurry viscosity.

Description

[0001] related application [0002] This application claims priority to US Provisional Application Serial No. 61 / 659,082, filed June 13, 2012, and is incorporated herein by reference. Background of the invention [0003] The present invention relates generally to the field of cellulose pulp processing, and more particularly to the processing of cellulose pulp to produce nanocellulose fibers, also referred to in this document as microfibrillated fibers, microfibrils and nanofibrils. Despite this variation in the literature, the present invention is applicable to microfibrillated fibers, microfibrils and nanofibrils, regardless of the actual physical size. [0004] Conventionally, chemical pulp produced using kraft, soda or sulfite cooking processes is bleached with chlorine bleach. Although chlorine gas is a very effective bleaching agent, effluents from chlorine bleaching processes contain significant amounts of chloride produced as a by-product of these processes. These ch...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): D21H17/25D21H17/01D21H21/00
CPCD21C5/005D21C9/00D21C9/002D21C9/004D21C9/007D21H11/18D21H17/005D21H17/63
Owner UNIV OF MAINE SYST BOARD OF GOVERNORS
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