How to obtain nanocellulose solid from aqueous solution

Nanocellulose (NFC) is a high-performance material derived from natural plants. Because of its high strength, good biodegradability and environmental protection, it is widely used in food packaging, textiles, coatings and other fields. Nanocellulose is usually obtained through the dispersion state in aqueous solution, but how to efficiently obtain nanocellulose solid materials from aqueous solution is a key issue in the production process. This article will introduce several commonly used methods, basic steps and precautions for obtaining nanocellulose solids from aqueous solutions.

What is nanocellulose?

Nanocellulose is nanoscale cellulose extracted from plants and its size is usually within the nanoscale (1-100 nanometers). Due to its unique microstructure, nanocellulose has excellent mechanical properties, transparency, thermal stability and biodegradability. Nanocellulose has good dispersion in water, but for further processing and application, it is necessary to extract the solid form of nanocellulose from the aqueous solution.。

How to obtain nanocellulose solid from aqueous solution?

Ultrafiltration method

Ultrafiltration is a commonly used separation method, mainly removing impurities, salts and small molecules from water through semipermeable membranes. This method can effectively extract nanocellulose from aqueous solution and retain its original structure.

Operating principle: When the aqueous solution passes through the semipermeable membrane, the nanocellulose cannot penetrate the membrane pores due to its large size, thereby achieving concentration and separation.

step:

1. Place the aqueous solution in the ultrafiltration device.

2. Use pressure to push water through the filter membrane to separate out moisture and other dissolved substances.

3. The filtered concentrate is a nanocellulose suspension.

4. Remove excess water by evaporation or freeze-drying to obtain nanocellulose solid.

Advantages: This method can efficiently remove impurities and moisture from the solution while retaining the nanocellulose structure without damage.

Freeze-drying

Freeze-drying is a commonly used drying technology, especially suitable for heat-sensitive substances. By this method, the moisture in the aqueous solution can be removed to obtain a solid of nanocellulose .

Operating principle: After the aqueous solution is frozen into a solid, the moisture is directly converted into a gas through sublimation, avoiding the damage to the nanocellulose structure by high temperature.

step:

1. Freeze the nanocellulose aqueous solution to low temperature.

2. Put the frozen sample into a vacuum freeze dryer.

3. Remove moisture through sublimation.

4. Obtain dried nanocellulose solids

It can maintain the structure and function of nanocellulose and is suitable for the extraction of high-quality nanocellulose.

Evaporation method

Evaporation is a simple and economical method for extracting nanocellulose solids. By evaporating the moisture in the aqueous solution, the remaining nanocellulose will form a solid.

Operating principle: The solution is concentrated by heating or natural evaporation of water in the aqueous solution to obtain a solid form of nanocellulose.

step:

1. Place the nanocellulose aqueous solution in a flat bottom container.

2. Naturally evaporate moisture by heating or in a ventilated environment.

3. After the moisture evaporates, the remaining substance is nanocellulose solid.

4. The required nanocellulose powder can be obtained by further drying or pulverizing treatment.

Advantages: Easy to operate, suitable for small-scale production, and low cost.

Centrifugation

Centrifugation is a technique that uses centrifugal force to separate different components in a solution. By rotating at high speed, the moisture and impurities in the aqueous solution are separated, and finally the concentrated nanocellulose is obtained.

Operating principle: Use centrifugal force to accumulate nanocellulose in larger particles to the bottom, thereby separating moisture and impurities.

step:

1. Add the aqueous solution to the centrifuge tube.

2. Use a high-speed centrifuge for centrifugation.

3. Separate the nanocellulose by precipitation to remove moisture and other impurities in the solution.

4. Through further drying treatment, a nanocellulose solid was obtained.

Advantages: This method is suitable for the separation of nanocellulose at high concentrations, and can be quickly separated and purified.

Different extraction methods are suitable for production and applications of different scales. Ultrafiltration and freeze-drying methods are suitable for the extraction of high-quality and high-purity nanocellulose solids, while evaporation and centrifugal methods are more suitable for small-scale or low-cost production.

The acquisition of nanocellulose solids from aqueous solutions is a critical step in its wide application. Ultrafiltration, freeze-drying, evaporation and centrifugation are the most commonly used extraction technologies at present. Choosing a suitable extraction method can effectively improve the quality and production efficiency of nanocellulose. With the continuous development of technology, more efficient and environmentally friendly extraction methods will emerge in the future, providing better solutions for the application of nanocellulose.