Polaris Water Treatment Network News: Nanocellulose is a new type of nanomaterial, which is derived from natural cellulose materials, including trees, cotton, straw, grass, etc., and is formed after chemical and mechanical treatment. In 2007, Professor Akira Isogai of the University of Tokyo in Japan prepared cellulose fibers with a diameter of 4-5 nanometers and a length of up to 500-1000 nanometers. Since then, the preparation and application of nano-cellulose have been greatly developed, and they have gradually moved to industrial applications. .
The birth of nanocellulose Nanocellulose can be roughly divided into cellulose nanowebs, cellulose nanocrystals or cellulose nanowhiskers, and cellulose nanofibers based on its length and diameter.
Nanocellulose was recognized and separated as early as decades ago. At that time, its name was cellulose microfibrils. It was usually composed of chemically pretreated cellulose raw materials, frozen and mechanically processed. It is directly prepared by the grinding method. The obtained cellulose fibers have a relatively large diameter (about 10-100 nm) but the fibers are very long and have a network structure.
Later, cellulose nanocrystals were prepared by the sulfuric acid hydrolysis method, and nano-fibers with a diameter of 3-5 nanometers but an aspect ratio of only about 20 were obtained after mild ultrasonic treatment. Such nanofibers are easily dispersed in water because they have negatively charged functional groups on the surface.
In 2007, Professor Akira Isogai of the University of Tokyo in Japan first proposed the concept of cellulose nanofibers, and used a mild aqueous oxidation system TEMPO / NaBr / NaClO and mild mechanical treatment to prepare a diameter of 4-5 nanometers and a length of up to 500- 1000 nanometer cellulose fibers. Since then, the preparation and application of nano-cellulose has been greatly developed, and it is gradually moving towards industrial application. The excellent properties of nanocellulose The excellent properties of nanocellulose are mainly reflected in the following aspects:
(1) Nanocellulose is derived from natural cellulose and retains the crystalline structure of natural cellulose. Therefore, nanocellulose has excellent mechanical strength, solvent resistance, and thermal stability of natural cellulose.
(2) Nanofibers are new materials obtained by chemical treatment of cellulose materials such as oxidation or hydrolysis. In addition to the hydroxyl groups on the surface of cellulose, carboxyl groups, aldehyde groups, and sulfonic acid groups are attached to the surface. Hydrophilic functional groups, the presence of these functional groups heralds a wide range of applications.
(3) Nanocellulose can be stably dispersed in aqueous solution or other polar organic solvents (except cellulose nanonets), so it is easy to process and apply, and has good composite properties with other materials.
(4) Nanocellulose is derived from cellulose, the most renewable biomass material on the earth, and the preparation and separation method is relatively environmentally friendly and green (using water as the medium). Therefore, it has not only cheap advantages over other nanomaterials, but also degradable. Recycle.
Application of nano cellulose
Nanocellulose's excellent properties make it more and more concerned and favored by researchers. Nanocellulose applications are mainly concentrated in various fields such as biomedicine and tissue engineering, nanocomposite and reinforcement materials, gas sensing and separation, air filtration and water purification. Among them, the field of tissue engineering mainly applies its good biocompatibility and biodegradability; nanocomposites mainly apply its excellent mechanical properties and strength, as well as good solvent dispersibility, etc .; gas sensing and separation mainly apply its surface Polyfunctional groups and chemically modifiable properties; and the field of air and water purification combines the various excellent properties of nanocellulose and is compounded with other nanomaterials such as electrospun nanofibers, giving birth to a new type of nanocomposite separation materials . The following will focus on the application of nanocellulose in the fields of drinking water purification, sewage purification, seawater desalination, precious metal recovery, air purification and other fields.