| Macroporous adsorption resin(MAR)is a kind of macromolecule separation material which integrates adsorption and separation.Because of its large specific surface area,excellent adsorption performance,simple operation and easy regeneration,MAR is widely used in medicine,medical treatment,sewage treatment and other fields.At present,the structure of macroporous adsorbent resin is relatively single,and it has no screening ability for the target components.Therefore,in order to improve the adsorption performance and selectivity of macroporous adsorbent resin,surface modification of its functional groups is the focus of current research.The components of natural products are complex,and most of the existing macroporous adsorbent resins are hydrophobic,which can not achieve the purpose of high efficiency separation and purification.According to the structural characteristics of specific active components in natural products,the design and preparation of functional modification materials may be the way to solve this bottleneck problem,but there are few related studies,and the surface chemical properties of macroporous adsorbent resins.The research on the structure-activity relationship and separation law of macroporous adsorbent resins with respect to their surface chemical properties is very weak.Therefore,according to the active components in natural products,directional design and preparation of functional modified adsorbent materials,changing the adsorptive driving force of adsorbent materials,improving the separation and purification efficiency and selectivity of effective active components in natural products is a new direction in the separation and purification of active components in natural products.In this paper,matrine and oxymatrine were used as research objects.The commercially available D101 macroporous adsorption resin was used as the substrate to obtain D101-Br macroporous adsorption resin by Blanc bromination methylation reaction;based on matrine and oxymatrine The structural characteristics of the base were designed to prepare 4-vinyl pyridine(VP),4-Ethenylphenol acetate(EP),Methylstyrenepvinyltoluene(MP),1-Allylpiperazine(TC)is a functional group-modifiedadsorbent and an adsorbent containing carboxyl,nitro and amino groups by oxidation reaction and nitration reaction;by analyzing the analytical behavior of the target component,The structure-activity relationship between modified macroporous adsorption resin and the adsorption properties of matrine and oxymatrine was investigated.The effect of hydrophobic interaction,hydrogen bonding and π-π interaction on adsorption performance and its separation were investigated.And its adsorption mechanism was discussed in depth.The main research contents and results are as follows:(1)Based on D101 macroporous resin and D101-Br macroporous resin,a series of modified macroporous resin were designed and prepared.The structure of modified resin was characterized by Fourier transform infrared spectroscopy(FTIR),specific surface area analyzer(BET),organic element analysis,X-ray photoelectron spectroscopy(XPS),thermogravimetric analysis(TG)and differential scanning calorimetry(DSC).The results showed that the corresponding groups were successfully grafted onto the resin surface by Blanc bromomethylation,SI-ATRP and nitration.Compared with D101 macroporous resin,the specific surface area of the modified resin decreased and the pore size increased,and with the increase of reaction time,the specific surface area,pore size,N and O elements of the modified resin presented.The trend increases first and then decreases.(2)The effects of grafting reaction time,initial concentration,adsorption temperature and adsorption time on the adsorption of matrine and oxymatrine by modified resin were discussed by static adsorption.The results showed that the modified resin prepared by SI-ATRP method had the best adsorption effect,and the D101-COOH-6 resin prepared by oxidation reaction for 6 hours had better adsorption effect.The adsorption amounts of D101-EP-12,D101-MP-12,D101-VP-12,D101-TC-12,D101-COOH-6,D101-NO2 and D101-NH2 to oxymatrine were 50.15 mg,respectively./g,32.5mg/g,12.25mg/g,25.03mg/g,101mg/g,80.2mg/g and 61.2mg/g,the adsorption amount of matrine is 37.89mg/g,50.57mg/g 23.58mg/g,31.04mg/g,114.72mg/g,86.22mg/g and102.33mg/g,all lower than D101 macroporous adsorption resin for matrine(116.15mg/g)and oxymatrine(The saturated adsorption amount of 103.06 mg/g)may be caused by the decrease of the specific surface area of the modified resin and the partial pore collapsereconstruction,which reduces the adsorption active sites.(3)The adsorption mechanism of matrine and oxymatrine on the modified resin was systematically analyzed.The results showed that the hydrophobicity,hydrophobic-hydrogen bond,π-π action,geometry between functional group and adsorbate of the modified resin The matching is beneficial to the selective adsorption of matrine and oxymatrine,and the Freundlich and Langmuir isotherm adsorption model of the adsorption process indicate that the adsorption process is a preferential adsorption process of the multi-molecular layer.The fitting of the experimental data by quasi-first-order kinetic model,quasi-secondary kinetic model,intragranular diffusion model and liquid membrane diffusion model shows that the adsorption process conforms to the quasi-second-order kinetic model and the activation of the adsorption process The energy Ea<40kJ/mol indicates that the adsorption process is a common controlled physical adsorption of multiple processes.By thermodynamic calculation of matrine and oxymatrine in the modified resin,the results show that △H<0,△G<0 and △S>0,indicating that the adsorption process is a spontaneous exothermic process,and solid-liquid The degree of chaos at the interface increases,and there is a synergy between hydrogen bonding and other forces(van der Waals force,π-π force,etc.).(4)The dynamic competition of the modified resin for matrine and oxymatrine was investigated by dynamic column layer method,and the dynamic adsorption mechanism was further studied.Studies have shown that the binding ability of matrine and modified resin is stronger than that of oxymatrine,and it is easy to wash and elute in the concentration of 20~40% ethanol solution,showing a certain adsorption selectivity.The Biot criterion is less than 1,indicating that the adsorption process is controlled by liquid film diffusion and particle diffusion. |
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