Preparation Of New Boronic Acid Resins And Adsorption Of Polyhydroxyl Compounds

High boiling point and strong hydrophilicity make it more difficult to separate and purify polyhydroxyl compounds from solvent system.Traditional distillation and membrane separation methods can't achieve better separation.Adsorption technology stands out with advantages of green economy and high separation efficiency.At present,adsorption resins with adjustable structure and high specific surface area are widely used.The physical structure of styrene-divinylbenzene crosslinked resin relies on?-?conjugated physical adsorption force to achieve the separation of phenol and other substances,but the molecular size matching in the process of polyhydroxyl compounds separation has not been systematically reported.The chemical modified resins by different functional group monomers also lack literature support.In this study,chloromethyl was used as the active site,and the physical structure of resins was accurately regulated by changing the reaction temperature and time.The chemical structure of resins was optimized by modifying the active sites of chloromethyl,carboxyl and amine groups.The adsorption behavior of polyhydroxyl compounds by modified resins was studied,and the detailed conclusions were as follows:(1)In Friedel-Crafts reaction with CMPS resin as precursor and Al Cl₃ as catalyst,10kinds of physical structure regulated resins with high specific surface area and pore structure were successfully prepared by adjusting reaction temperature and time.The specific surface areas of PS-W100 and PS-W120 were as high as 1382 and 1336 m²/g.By static adsorption,it was found that the adsorption of polyhydroxyl compounds by specific surface area,size matching regulated and other physical forces was comparable to the commercial resin CHA-111.Nitrogen and oxygen modified resins DCE-NH₂ and PS-GA were prepared by using chloromethyl as active site,amine group and gallic acid as the functional group.The results showed that the contribution of the resins to 1,3-propanediol was limited.36 kinds of PS-SBT series modified resins were prepared by modification of functional monomers such as 4-carboxyphenylboronic acid with CMPS as the precursor.24 kinds of ZXD series modified resins were prepared by modification of 3-carboxyphenylboronic acid and other functional group monomers with ZXD-39 resin as precursors.Through the determination of boronic acid functional group,the optimal resin was PS-SBT,with a loading capacity of 1.220 mmol/g and adsorption capacity was 17.23mg/g,which was 35%higher than that of CHA-111.(2)Adsorption behaviors of 1,3-propanediol in water medium were studied.The adsorption capacity of PS-SBT and PS-3NB resin was 35%and 22%higher than that of CHA-111 commercial resin by static adsorption screening.The influence of resin dosage,initial concentration,adsorption time,p H and temperature on the adsorption performance was systematically investigated.It was found that PS-SBT resin had the best adsorption effect in the system with initial concentration of 2 g/L and p H=10 for 16 h,and the adsorption capacity was 17.23 mg/g.The whole adsorption process was endothermic.The two-component competitive experiment of 1,3-propanediol showed that PS-SBT can specifically adsorb compounds with the structure similar to diol and had a good selection performance.The resin was recycled for 6 times and the adsorption capacity was about 17mg/g.The regeneration performance was good.By thermogravimetric characterization,it was found that the resin still had no obvious weight loss at 573 K and had good thermal stability.The adsorption mechanism was further explained by FT-IR,XPS and DFT theory optimization,the chemical adsorption force of boronic acid-diol specific binding was increased in the alkaline system.(3)Organic solvents have considerable value in effective enrichment of polyhydroxy compounds(such as extraction of natural products),and organic systems have research significance in the separation of polyhydroxy compounds.In order to further investigate the selective binding effect between boronic acid and polyhydroxyl compounds,the best adsorption medium,adsorbent and resin were ethanol,1,3-butanediol and PS-SBT through static adsorption experiment,and the adsorption capacity was 0.9470 mmol/g.The adsorption kinetics of 1,3-butanediol showed that the adsorption process was more consistent with the pseudo-second-order kinetic model.The adsorption thermodynamics experiment indicated that the adsorption process was spontaneous and endothermic in accordance with the Langmuir model.The dynamic adsorption-desorption data found that the resin PS-SBT has the application value of separation and concentration.The experimental data were combined with DFT theory to optimize the energy difference between boronic acid monomer,glucose and gastrodin at different sites,indicating that the borate ester structure formed between the resin PS-SBT and polyhydroxyl compounds is beneficial to enhance the selective adsorption.In this paper,the design and preparation of the adsorption materials,the study of adsorption behavior and the analysis of its mechanism were described in detail,indicating that boronic acid resin has the development potential of specific binding of polyhydroxyl compounds.