Preparation And Application Of Chitin Functional Materials Activated By Poly(dopamine)

Chitin,a natural polysaccharide rich in marine,shows excellent advantages such as non-toxic,biocompatibility,bio-degradability and high strength,which render it an ideal candidate for the construction of novel biomaterials.However,the chemical inert of chitin results in its poor bioactivity,which greatly confine the further development of chitin biomaterials.To this end,this report is aiming at utilize polydopamine biomass materials to activation chitin-based materials which has different structures.polydopamine coated on the surface of chitin-based materials,which will increasing the activity of the chitin,such as hydrophilicity,reductive properties.The activated chitin-based materials was secondary modifiction,which increased the application values of chitin.Firstly,chitin was pretreated in Li OH/ urea system,and then regenerated chitin hydrogels by ethanol,which has biocompatibility,excellent mechanical properties.Dopamine can be self-polymerization and formed the polydopamine layer on the surface of chitin aerogels.Because of the high reactivity and the diversity of the reaction of polydopamine,the disadvantages of inert surface can be solved while preserving the excellent properties of chitin.The activated chitin aerogels was secondary modifiction,polydopamine can adsorption of noble metal ions(such as Au³⁺,Ag+,Pt4+)in Wastewater,and then reduced noble metal nanoparticles.The young's modulus of DCh48-Ag was 420.9MPa,and the specific surface area was 292.1m2/g,and the loading capacity of the aerogel was as high as 95.3mg/g in the secondery modification.In the process of photocatalytic degradation of organic dyes,composite aerogel showed excellent catalytic properties,the reaction rate constant reached 4.0×10-5mol?L-1?min-1.Based on the physical and chemical properties of the secondery modification chitin composite,it was also used in studied on antibacterial property and the preliminary filtration for organic dye as a filter membrane.Secondly,chitin nanocrystals were prepared by sulfuric acid hydrolysis method,and for the further studies.The chitin nanocrystals were prepared by the hydrolysis of sulfuric acid in the amorphous region of chitin powder.The yield and the ratio of length to diameter were calculated by adjusting the concentration of sulfuric acid and reaction time.The optimum condition of hydrolysis chitin was: Sulfuric acid with mass fraction of 30%,90°C and reaction 6h.The stable chitin nanocrystals solution with high yield and large diameter was selected.chitin nanocrystals were secondary modified by the same way,the chitin nanocrystals composite formed nanofiltration membranes by a simple filtration process.And study on the applications of nanofiltration membranes in catalytic organic dyes,rejection of different sizes of nanoparticles and selective filtration of different metal ions.The results showed that Ag nanoparticles load capacity reached 57.2%,the water flux of 13400L·m-2·h-1·bar-1,nanoparticles can be successfully retained above dimensions of 3nm,the rejcetion rate of Au³⁺ higher than 90%.