As a natural green energy widely existing in nature, cellulose has the advantages of large output, stable performance and recyclability. Among them, from the molecular structure of cellulose, it is formed by D-glucopyranose rings connected by β-1,4 glycosidic bonds, in which there are C-2, 3, and 6 positions on each glucose unit, respectively. Hydroxyl group, this structural particularity enables cellulose to be chemically modified to generate a variety of cellulose derivatives, such as cellulose esters, cellulose ethers and mixed ether esters.

      In recent years, scientists have successfully prepared this material into products such as microspheres, membranes, fibers, hydrogels, and aerogels using layer-by-layer self-assembly, phase inversion, electrospinning technology, etc., which have been used in many applications. A high value-added technology field [2].

      Membrane science and technology is a high-tech developed successfully in this century, and it is one of the effective means to solve the three major problems of energy, resources and environment faced by human beings. Cellulose materials have been used in this technical field for hundreds of years. However, the traditional method of preparing cellulose separation membrane materials mostly adopts the phase inversion method, which dissolves the polymer in a certain solvent and introduces it into the casting liquid after molding. The gelling agent excludes the solvent, and the desired membrane material is formed by mass transfer exchange between the solvent and the gelling agent. Although this process is widely used in membrane technology, the disadvantage is that it will lead to poor distribution uniformity of membrane pore structure and small specific surface area, thus affecting the separation efficiency.

      In recent years, scientists have combined the phase inversion method with new technologies to prepare some novel membrane materials. Centering on membrane technology, this paper reviews the recent research progress of cellulose and derivative materials in this field.

2 Application of cellulose and derivatives in membrane technology

2.1 Specific selection separation

      The molecular structure of cellulose contains a large number of hydroxyl groups, which is conducive to chemical modification. After its access to functional groups, the cellulose separation membrane has a specific adsorption function for the separated substances, and then the captured purified substances are eluted to achieve For separation and purification purposes, this functionalized cellulose separation membrane can be used in many fields such as biomedicine, food processing, and water treatment.

      Adikane et al. reported that the chemically modified methylcellulose membrane successfully adsorbed human immunoglobulin and human serum albumin. The process is based on 5% methylcellulose film (48% methyl content, 300 cP viscosity), first treated with 2M hydrochloric acid, 1% polyethyleneimine, 1% glutaraldehyde for 24 h, and then washed To equilibrium, the protein A component was adsorbed and immobilized under mild conditions. Finally, the protein A component/methylcellulose composite membrane was immersed in the buffer containing human immunoglobulin and human serum albumin for adsorption, and the concentration could reach 318.5 μgcm- 2, and has lower nonspecific adsorption parameters.

      Barroso et al. used ionic liquid [BMIM]Cl to dissolve cellulose and prepared a 10% regenerated cellulose membrane. Subsequently, the regenerated cellulose-based affinity membrane was prepared by the successful introduction of 22/8 synthetic ligands after epoxy activation and amination treatment of the base membrane. The membrane selectively separates immunoglobulin G from bovine serum albumin.

      Lu et al. spun cellulose acetate nanofiber mats by electrospinning technology, and then used layer-by-layer self-assembly technology to deposit multiple layers of F3GA/Candida wrinkle enzyme (monolayer thickness 11 nm, number of layers) on the nanofiber mats. 5 layers), the cellulose-based nanofiber mat can not only efficiently and selectively separate enzyme substrates, but also has high resolution selectivity for specific proteins.

2.2 Charge modification

      In addition to introducing specific ligands into cellulose-based membranes to make the membranes have a targeted separation effect, another research hotspot is to effectively combine the electrostatic interaction between charges with the cellulose membranes to improve the membrane's ability to separate specific substances. .

In the membrane separation process, substances with large molecular weight differences are usually separated and purified by following the sieving mechanism; however, when the molecular weight difference between the two-component or even multi-component substances in the mixed raw solution is small, it is impossible to determine the specific molecular weight. Substances are efficiently purified. However, electrostatic repulsion is used to charge the cellulose separation membrane through physical blending, chemical modification, etc., and then the isoelectric points of different substances are used to change the pH value of the buffer solution, ionic strength and other conditions to make the separation substances contain charges. In this way, the cellulose separation membrane has a selective separation effect, and can also effectively reduce the pollution in the separation process.

      Zydney et al. introduced ammonium ions into cellulose acetate to make it functional. This membrane material contains positive charges, prepared a functional ion exchange charged ultrafiltration membrane, and studied the separation of cytochrome C and lysozyme by the membrane. and analyzed the influence of the surface charge distribution of the membrane on the protein ultrafiltration process.

      Watadta[7] used the layer-by-layer deposition method to deposit different layers of chitosan/sodium alginate, chitosan/polysulfonated styrene on cellulose acetate fiber non-woven fabric, and successfully prepared cellulose acetate /Polyelectrolyte composite separation membrane, analyzed the effect of the number of deposited layers on membrane permeation and desalination, and found that the polyelectrolyte layer played an effective separation role, but the retention rate of NaCl was not obvious.

      Taha et al. chemically modified cellulose acetate, introduced amino functional groups, used it as a precursor, and incorporated silica by sol-gel method to prepare a silica/functionalized cellulose acetate nanofiber composite membrane, which is used to absorb