Construction And Application Of Functional Polyphenol Meterials

Polyphenols as secondary metabolite of organisms are natural product that exist in various natural plants.They are renewable,cheap,green,abundant reserves and have good biocompatibility.The structure of the phenolic hydroxyl group allows polyphenols to construct various functional polyphenol materials through covalent,hydrogen bonding,coordination etc.Compared with the original polyphenol materials,these functional polyphenol materials often retain the original excellent physical and chemical properties of polyphenols.In addition,the modified polyphenol materials realize the heterogeneity of polyphenols and a series of specific functionalization,that is why these can be applied to various branches of chemical engineering.However,current polyphenol materials often have some disadvantages such as complex synthesis and high raw material costs.Constructing green and environmentally friendly polyphenol materials is a big problem.Thence,this paper aims to construct green and environmentally friendly heterogeneous polyphenol materials.Based on the high designability of polyphenols,a variety of heterogeneous polyphenol materials are designed and prepared from the molecular level by a variety of physical and chemical effects.We have studied its catalytic performance in the Meerwein-Ponndorf-Verley reduction reaction and its adsorption performance in the waste liquid of heavy metal ions.(1)The Metal-Polyphenol Network Zr-tannin was prepared by a simple one-step hydrothermal method using tannin as building blocks.Zr-tannin was characterized by FT-IR,UV-vis,CO₂-TPD,NH₃-TPD,Pyridine-IR,SEM,EDS,XPS and N₂ adsorption-desorption.The results show that Zr-tannin is a stable and amorphous porous structure.What's more,Zr-tannin also contains abundant Lewis acid-base sites.Using the reduction of furfural as a probe reaction,at 80 ^oC,the conversion rate of furfural is as high as 96.2%,which is better than other zirconium-based catalysts.In additions,no active metals from Zr-tannin has dissolve in the reaction system.After separation,no significant decrease in catalytic activity after five reactions.The reason for the excellent catalytic performance of Zr-tannin is proposed:the porous structure with high specific surface area(162 m²/g)which is formed during the assembly process,abundant and stable Lewis acid-base sites(-Ar-O₂-Zr-O₂-Ar)are abundant and stable.),and its good wettability to the reaction substrate.(2)We select aluminum as the metal source and ethylenediamine as the auxiliary crosslinking agent to synthesize the double crosslinked polyphenol polymer network TN-EDA-Al by a simple hydrothermal method,and the comparative adsorbent TN-Al and TN-FA-Al.The adsorption performance of Pb(?)under different p H value,temperature and initial concentration were investigated.TN-EDA-Al has the best adsorption performance among the three polyphenol polymerization networks.The adsorption isotherm data accords with the Langmuir adsorption isotherm model.At p H=5,303K,the maximum adsorption capacity of TN-EDA-Al(Q_max)is 177.58 mg/g;The adsorption kinetics data follows the pseudo-second-order reaction kinetic model and Weber-Morris model;Van't Hoff equation model fitting results show that the adsorption process is endothermic,entropy increasing and spontaneous process.A series of characterizations such as FT-IR,Zeta potential,SEM,and N₂adsorption-desorption were used to characterize three types of polyphenol polymerization networks.Systematic investigation reveals that aluminum-based double-cross-inked polyphenol network TN-EDA-Al has a higher specific surface area and lower surface potential than TN-Al and TN-FA-Al,which is the reason for its high adsorption performance.In this paper,the use of small molecule-assisted cross-linking strategy provides a new idea for the construction of Polyphenol-Metal materials with high specific surface area.(3)Based on the research in the previous chapter,from the perspective of not consuming the adsorption site Ar-OH and improving the stability of the adsorbent,we directly use hexamethylenetetramine(HMT)as the cross-linking agent to synthesis a novel polyphenol microsphere TN-HMT.The obtained microstructure of TN-HMT was fully characterized by SEM,EDS,FT-IR and ¹³C MAS NMR,etc.In addition,its polymerization mechanism was systematic proposed:hydrogen bond induced self-assembly;hydrogen bond destruction/HMT decomposition;nucleophilic addition and self-polymerization into microspheres.TN-HMT was used in the batch adsorption experiment of Cr(?).The research results show that the removal rate of TN-HMT is as high as 99%under the conditions of 30 ^oC,p H 2.0 and Cr(?)initial concentration of 250 mg/L.Under the same conditions,the adsorption performance of TN-HMT is much higher than other tannin acid-based adsorbents.In addition,TN-HMT also has good universality and reusability.Combining macroscopic adsorption experiments and microscopic characterization to clarify the adsorption mechanism:A small amount of HCr O₄^-binds to the protonated phenolic hydroxyl and amine groups in an ionic interaction under acidic conditions.Whlie,most of the HCr O₄^-is reduced to Cr(?)in situ by TN-HMT and combine with Ar-OH in TN-HMT in a complex manner.