High-efficiency preparation of nanocellulose based on process parameters optimization

To improve the preparation method of nanocellulose (NFC or CNC) requires systematic optimization from multiple aspects such as raw material selection, preparation process, equipment optimization, surface modification, characterization means, environmental protection and sustainability. The following is a detailed explanation:

1. Raw material selection and pretreatment

The performance of nanocellulose depends to a large extent on the quality of the raw materials and the pretreatment method.

Raw material selection:

Choose high-purity and high crystallinity cellulose sources, such as cotton, wood pulp, hemp, sugar cane bagasse, etc.

Agricultural waste (such as straw, corn stalk) and industrial by-products (such as pulp waste) are low-cost, sustainable sources of raw materials.

Preprocessing:

Deligin: Use alkaline treatment (such as NaOH) or organic solvents to remove lignin to improve cellulose purity.

Dehemicellulose: Remove hemicellulose by acid treatment or enzyme treatment to reduce impurity interference.

Bleaching: Use hydrogen peroxide or chlorine to further improve the purity of the cellulose.

2. Optimization of preparation method

The preparation methods of nanocellulose mainly include mechanical methods, chemical methods and biological methods. Each method has its advantages and disadvantages, and optimizing process parameters is the key.

Mechanical method

High pressure homogenization method:

The cellulose suspension is forced through the tiny pores by high pressure, dissociating the fibers into nanofibers.

Optimization parameters: pressure (usually 500-1500 bar), cycle times (3-10 times), suspension concentration (1-2%).

Advantages: No chemical reagents required, environmentally friendly; Disadvantages: High energy consumption and uneven fiber length.

Ball grinding method:

The cellulose fibers are nano-nanized by mechanical shear force of the ball mill.

Optimized parameters: ball milling time (several hours to dozens of hours), rotation speed, ball material ratio.

Advantages: Simple operation; Disadvantages: Inefficient and may introduce impurities.

Ultrasonic treatment:

The cavitation of ultrasonic waves is used to destroy the fiber structure.

Optimization parameters: ultrasonic power (100-1000 W), processing time (minutes to hours).

Advantages: Fast and efficient; Disadvantages: May damage the crystallinity of the fiber.

Chemical method

Acid hydrolysis:

The amorphous region of cellulose hydrolyzed using strong acids such as sulfuric acid and hydrochloric acid, and retained the crystalline region to obtain nanocellulose crystals (CNC).

Optimized parameters: acid concentration (usually 60-65% sulfuric acid), temperature (45-60°C), time (30 minutes to several hours).

Advantages: The product has high crystallinity; Disadvantages: The acidic waste liquid is produced and needs to be processed later.

Oxidation method:

The TEMPO oxidation system is used to oxidize the hydroxyl groups on the surface of cellulose to carboxy groups to improve dispersion.

Optimization parameters: oxidant dosage, pH value, reaction time.

Advantages: Good product dispersibility; Disadvantages: High cost.

Biological method

Enzyme hydrolysis:

Amorphous regions of cellulose are selectively hydrolyzed using cellulase.

Optimization parameters: type, dosage, reaction temperature and time of enzyme.

Advantages: mild conditions and environmentally friendly; Disadvantages: low efficiency.

Microbial Synthesis:

Nanocellulose is synthesized using microorganisms such as Acetobacterium leukococcus.

Optimized parameters: medium composition, culture conditions (temperature, pH, ventilation volume).

Advantages: High purity of the product; Disadvantages: Long production cycle.

3. Process parameter optimization

Reaction conditions:

Control parameters such as temperature, pH, and reaction time to ensure efficient and stable reaction.

For example, excessive temperatures during acid hydrolysis may lead to excessive degradation of cellulose.

Equipment improvements:

Use high-efficiency equipment, such as high-pressure homogenizers, ultrasonic crushers, high shear mixers, etc. to improve preparation efficiency.

Develop new equipment, such as microfluidic reactors, to achieve continuous production.

4. Surface modification

The surface properties of nanocellulose directly affect their dispersion and application performance.

Chemical modification:

Esterification: Introduce hydrophobic groups to improve compatibility with hydrophobic materials.

Etherification: Improve the solubility and stability of nanocellulose.

Graft polymerization: Graft polymer chains on the surface to enhance functionality.

Physical modification:

Plasma treatment: Change surface energy and improve dispersion.

Irradiation treatment: Introduce active groups by igmoid ray or electron beam irradiation.

5. Characterization and Quality Control

Characterization means:

Topomorphology analysis: Transmission electron microscopy (TEM) and atomic force microscopy (AFM) were used to observe the morphology and size of nanocellulose.

Structural analysis: Crystallization degree was analyzed using X-ray diffraction (XRD) and chemical structures were analyzed using infrared spectroscopy (FTIR).

Performance testing: Test mechanical properties, thermal stability, dispersion, etc.

Quality Control:

Establish a strict quality control system to ensure the consistency and stability of products.

Develop standardized preparation procedures to reduce batch differences.

6. Environmental protection and sustainability

Green Chemistry:

Use environmentally friendly solvents and reagents to reduce environmental pollution.

Develop preparation processes with low energy consumption and low waste liquid emissions.

Resource Utilization:

Use agricultural waste and industrial by-products as raw materials to reduce production costs.

Develop a circular economy model to realize the resource utilization of waste liquids and by-products.

7. Application-oriented customized preparation

Adjust the preparation process to optimize the performance of nanocellulose according to specific application needs (such as composite materials, biomedicine, energy storage, etc.).

For example:

When used to enhance composite materials, the mechanical properties and dispersion of nanocellulose need to be improved.

When used in biomedical science, it is necessary to ensure the non-toxicity and biocompatibility of nanocellulose.

8. Cooperation and innovation

Interdisciplinary collaboration:

Combining knowledge in materials science, chemical engineering, biotechnology and other fields will promote technological innovation.

Continuous research and development:

Pay attention to the latest research results and explore new preparation methods (such as ionic liquid treatment, supercritical fluid technology, etc.).

Develop intelligent and automated production lines to improve production efficiency and product consistency.

Summarize

The preparation method of improving nanocellulose needs to be systematically optimized from multiple aspects such as raw materials, processes, equipment, characterization, and environmental protection. Through continuous improvement and innovation, high-performance and low-cost nanocellulose can be prepared, promoting its widespread application in composite materials, biomedical, energy storage and other fields. Nanjing Tianlu Nano Technology Co., Ltd. is specialized in the production of nanocellulose , cellulose nanofiber filaments, vitamin nanocrystals, bacterial cellulose, cellulose nanofiber filaments (CNF), cellulose nanocrystals (CNC), bacterial cellulose ( BC) manufacturer.