High-efficiency and low-energy-loss nanocellulose preparation method

Abstract

The invention discloses a high-efficiency and low-energy-loss nanocellulose preparation method, and belongs to the technical field of nanometer material preparation. The method includes the steps of firstly, preprocessing cellulosic materials; secondly, conducting washing and filter-press concentration till the concentration is 6% or above, pumping a high-concentration sizing agent into a grinding and smashing machine through a vertical screw pump, and grinding the cellulosic materials multiple times in a circulating mode under certain pumping pressure and certain grinding process conditions, and obtaining nanocellulose. Compared with the prior art, high-concentration nanocellulose gel can be continuously and rapidly prepared, the unit product preparation energy consumption is greatly lowered, the production cost is reduced, and the production efficiency is improved. The method is simple in process step and capable of being easily implemented in an industrialized mode.

Description

technical field

[0001] The invention belongs to the technical field of nanomaterial preparation, in particular to a method for preparing nanocellulose with high efficiency and low energy consumption. Background technique

[0002] Nanocellulose is a natural biomass nanomaterial that can be completely degraded. Its diameter is less than 100 nanometers, and its length is several microns to hundreds of microns. It has a large specific surface area and unique physical and chemical properties. It is used in barrier coatings, food, Cosmetics, papermaking and biomedical materials, energy storage materials, filter media, high-performance composite materials and other industrial fields have broad application prospects.

[0003] The preparation of nanocellulose can be roughly divided into physical mechanical methods, chemical methods and biological methods, among which chemical methods (such as strong acid hydrolysis to prepare nanocellulose crystals) and chemical pretreatment combined...

Examples

Embodiment 1

[0022] 1) Cellulose pretreatment: refer to the method introduced in the non-patent literature "TEMPO-mediated surface oxidation of cellulose whiskers. Youssef Habibietal. Cellolose, 2006, 13: 679-687." to perform TEMPO-induced oxidation pretreatment on cellulose, specifically: equivalent to absolute dry weight 1000g of bleached hardwood kraft pulp fiber is wet dissociated, then diluted with water to a concentration of 1%, to which TEMPO (15.6g), NaBr (206g) and NaClO solution (available chlorine content 12%, 3725ml), use 0.5M NaOH solution to control the pH value of the reaction system to be 10.5, after reacting for 90min, add 450ml ethanol to terminate the reaction, neutralize the slurry solution with 0.5M dilute hydrochloric acid until the pH value is neutral. The carboxyl group content of measuring this oxidized slurry is 0.85mmol / g, and the hydroxyl substitution degree is 0.05. 2) Washing and concentrating: the slurry after oxidation is all transferred to a centrifugal dehy...

Embodiment 2

[0024] Except that the concentration of the concentrated slurry is 8.45% and the pump outlet pressure is 0.35MPa, the rest of the implementation process is the same as that of Example 1. Final preparation concentration is the high-concentration nanocellulose of 8.66%, and nanocellulose is gelatinous, and its transmission scanning electron microscope (TEM) photograph sees image 3 , Fiber diameter 20 ~ 50nm. The power consumption during the record grinding process is 0.65kWh, and the power consumption per unit product is calculated as 650kWh / t (dry pulp). The yield of nanocellulose was 84%.

Embodiment 3

[0026] Except that the concentration of the concentrated slurry is 10.12% and the pump outlet pressure is 0.45MPa, the rest of the implementation process is the same as that of Example 1. Final preparation concentration is the high-concentration nanocellulose of 10.37%, and nanocellulose is gelatinous, and its transmission scanning electron microscope (TEM) photograph sees Figure 4 , Fiber diameter 20 ~ 50nm. The power consumption during the record grinding process is 0.53kWh, and the power consumption per unit product is calculated as 530kWh / t (dry pulp). The yield of nanocellulose was 86%.

technical field

[0001] The invention belongs to the technical field of nanomaterial preparation, in particular to a method for preparing nanocellulose with high efficiency and low energy consumption. Background technique

[0002] Nanocellulose is a natural biomass nanomaterial that can be completely degraded. Its diameter is less than 100 nanometers, and its length is several microns to hundreds of microns. It has a large specific surface area and unique physical and chemical properties. It is used in barrier coatings, food, Cosmetics, papermaking and biomedical materials, energy storage materials, filter media, high-performance composite materials and other industrial fields have broad application prospects.

[0003] The preparation of nanocellulose can be roughly divided into physical mechanical methods, chemical methods and biological methods, among which chemical methods (such as strong acid hydrolysis to prepare nanocellulose crystals) and chemical pretreatment combined...

Examples

Embodiment 1

[0022] 1) Cellulose pretreatment: refer to the method introduced in the non-patent literature "TEMPO-mediated surface oxidation of cellulose whiskers. Youssef Habibietal. Cellolose, 2006, 13: 679-687." to perform TEMPO-induced oxidation pretreatment on cellulose, specifically: equivalent to absolute dry weight 1000g of bleached hardwood kraft pulp fiber is wet dissociated, then diluted with water to a concentration of 1%, to which TEMPO (15.6g), NaBr (206g) and NaClO solution (available chlorine content 12%, 3725ml), use 0.5M NaOH solution to control the pH value of the reaction system to be 10.5, after reacting for 90min, add 450ml ethanol to terminate the reaction, neutralize the slurry solution with 0.5M dilute hydrochloric acid until the pH value is neutral. The carboxyl group content of measuring this oxidized slurry is 0.85mmol / g, and the hydroxyl substitution degree is 0.05. 2) Washing and concentrating: the slurry after oxidation is all transferred to a centrifugal dehy...

Embodiment 2

[0024] Except that the concentration of the concentrated slurry is 8.45% and the pump outlet pressure is 0.35MPa, the rest of the implementation process is the same as that of Example 1. Final preparation concentration is the high-concentration nanocellulose of 8.66%, and nanocellulose is gelatinous, and its transmission scanning electron microscope (TEM) photograph sees image 3 , Fiber diameter 20 ~ 50nm. The power consumption during the record grinding process is 0.65kWh, and the power consumption per unit product is calculated as 650kWh / t (dry pulp). The yield of nanocellulose was 84%.

Embodiment 3

[0026] Except that the concentration of the concentrated slurry is 10.12% and the pump outlet pressure is 0.45MPa, the rest of the implementation process is the same as that of Example 1. Final preparation concentration is the high-concentration nanocellulose of 10.37%, and nanocellulose is gelatinous, and its transmission scanning electron microscope (TEM) photograph sees Figure 4 , Fiber diameter 20 ~ 50nm. The power consumption during the record grinding process is 0.53kWh, and the power consumption per unit product is calculated as 530kWh / t (dry pulp). The yield of nanocellulose was 86%.

Images