Efficient modified resin for epicatechin adsorption

Abstract

The invention relates to efficient modified resin for adsorbing epicatechin. According to the method, alkalescent resin D301G is taken as a raw material, and chloromethylation is carried out to prepare the D301G-Cl resin. The preparation method comprises the following steps: adding D301G-Cl resin and N, N-dimethylformamide into a three-necked flask with a stirrer and a thermometer, sealing a cover, soaking, and adding NaCl, p-aminobenzene sulfonic acid and NaOH into the flask; stirring the mixed solution by using a stirrer, and reacting for a period of time at constant temperature; and after the reaction is finished, filtering by adopting a filter screen with a certain mesh number, and recycling filtrate. Repeatedly washing the resin with ethanol and distilled water until the added AgNO3 solution does not precipitate; the modified resin (D301G-SO3 <->) with the sulfonic acid group is obtained. The macroporous resin contains amino groups and sulfonic acid groups, so that the adsorption of epicatechin hydroxyl groups is further enhanced on the basis of benzene ring pi-pi adsorption. The adsorption capacity of the D301G-SO3-resin is larger than that of AB-8 under the condition that the pore volume is small, the adsorption effect of the D301G-SO3-resin on epicatechin is remarkably improved, the maximum adsorption capacity is improved by one time, the maximum adsorption capacity is kept within the PH range of 7-9, and the adsorption efficiency on the epicatechin is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of natural product processing and relates to materials and methods for efficiently adsorbing epicatechin. Background Technology

[0002] Current macroporous resins, with their polystyrene framework, suffer from relatively weak technology regarding structure-activity relationships and separation mechanisms with target molecules. This makes it difficult to achieve targeted resin design and preparation, resulting in poor selectivity and specificity, and low adsorption and separation efficiency. Epicatechin, a typical polyphenol, is readily soluble in water and widely found in natural products. Highly efficient enrichment is needed during extraction and separation to improve extraction efficiency and reduce costs. Currently, AB-8 macroporous resins are commonly used for epicatechin adsorption in natural product purification, but their adsorption efficiency is limited. Therefore, developing macroporous resins with improved adsorption efficiency is of great practical significance. Summary of the Invention

[0003] Currently, taking advantage of the structural characteristics of epicatechin with multiple hydroxyl groups, macroporous resins are modified to enhance the adsorption efficiency of hydroxyl groups, thereby improving the adsorption performance of epicatechin.

[0004] D301G-Cl resin was prepared by chloromethylation of the weakly basic resin D301G. In a three-necked flask equipped with a stirrer and thermometer, D301G-Cl resin and N,N-dimethylformamide were added, the flask was sealed, and after soaking, NaCl, p-aminobenzenesulfonic acid, and NaOH were added. The mixture was then stirred and reacted at a constant temperature for a period of time. After the reaction was complete, the solution was filtered through a fine-mesh filter, and the filtrate was recovered and reused. The resin was repeatedly washed with ethanol and distilled water until AgNO3 solution was added without precipitation. The modified resin with sulfonic acid groups (D301G-SO3-) was obtained.

[0005] Beneficial effects: 1) The macroporous resin prepared using weakly basic resin D301G as raw material contains amino and sulfonic acid groups, which further enhances the adsorption of epicatechin hydroxyl groups on the basis of benzene ring pi-pi adsorption.

[0006] 2) The adsorption effect is significantly greater than that of AB-8 macroporous resin, and the efficiency is improved.

[0007] 3) The preparation method is simple and the conditions are mild. The reaction solution can be filtered, recycled and reused, which can save raw materials and reduce the discharge of pollutants, thus helping to protect the environment. Attached Figure Description

[0008] Figure 1 Simplified diagram of the sulfonation reaction process; Figure 2 Infrared spectrum; Figure 3 Surface adsorption, (A) pore volume; (B) adsorption capacity; Figure 4 Adsorption capacity of epicatechin at different pH values. Detailed Implementation

[0009] Resin D301G-Cl was obtained by chloromethylation of weakly basic resin D301G, followed by sulfonation. 12.0 g of the chloromethylated resin D301G-Cl was introduced into a 250 mL three-necked flask equipped with a stirrer and thermometer, and 150.0 mL of DMF (N,N-dimethylformamide) was added; then, the lid was sealed. After soaking for 6 hours, 30.0 g of NaCl, 24.0 g of p-aminobenzenesulfonic acid, and 6.0 g of NaOH were added to the flask. The mixture was then stirred with a stirrer and reacted at a constant temperature of 60 °C for 48 h (e.g., ...). Figure 1 (As shown). After the reaction, the mixture was filtered through a filter with a certain mesh size, and the filtrate was recovered and reused. The product was repeatedly washed with ethanol and distilled water until no precipitation occurred upon addition of AgNO3 solution. The modified D301G-SO3- (D301G-S) was obtained. The performance of the obtained modified macroporous resin D301G-SO3- was compared with that of the raw material D301G and the commonly used AB-8 resin, as well as their adsorption capacity for epicatechin. Figure 2 Infrared spectra show that D301G-S is located at 1113 cm⁻¹. −1 and 1025 cm −1 The presence of a stretching vibration peak of SO3- indicates successful insertion of the sulfonic acid group. Figure 3 The surface adsorption test results for nitrogen gas showed that the pore volume and adsorption capacity of D301G-S were increased compared to D301G, but lower than AB-8. The adsorption results of epicatechin on the three resins at different pH values ​​were also presented. Figure 4 It was found that D301G-S significantly enhanced the adsorption capacity of epicatechin, with the maximum adsorption value being twice that of the commonly used resin AB-8, indicating that it improved the adsorption efficiency of epicatechin.

Claims

1. A highly efficient modified resin for the adsorption of epicatechin, characterized in that: D301G-Cl resin was prepared by chloromethylation of the weakly basic resin D301G. In a three-necked flask equipped with a stirrer and thermometer, D301G-Cl resin and N,N-dimethylformamide were added, the flask was sealed, and after soaking, NaCl, p-aminobenzenesulfonic acid, and NaOH were added. The mixture was then stirred and reacted at a constant temperature for a period of time. After the reaction was complete, the solution was filtered through a fine-mesh filter, and the filtrate was recovered and reused. The resin was repeatedly washed with ethanol and distilled water until AgNO3 solution was added without precipitation. The modified resin with sulfonic acid groups (D301G-SO3-) was obtained.

2. A highly efficient modified resin for epicatechin adsorption, characterized in that: the macroporous resin prepared using weakly basic resin D301G as raw material contains amino and sulfonic acid groups, which further enhances the adsorption of epicatechin hydroxyl groups on the basis of benzene ring pi-pi adsorption. This results in the D301G-SO3- resin having a greater adsorption capacity than AB-8 with a smaller pore volume, significantly improving the adsorption effect on epicatechin, doubling the maximum adsorption capacity, and maintaining the maximum adsorption capacity in the pH range of 7-9.

3. A highly efficient modified resin for adsorption of epicatechin, characterized in that: a modified macroporous resin with amino and sulfonic acid groups is constructed using weakly basic resin D301G as raw material.

4. A highly efficient modified resin for adsorption of epicatechin, characterized in that: the D301G-SO3- resin is prepared by a simple and mild method, and the reaction solution can be filtered, recycled, and reused, which can save raw materials and reduce the discharge of polluting liquid, thus benefiting environmental protection.

5. A highly efficient modified resin for adsorption of epicatechin, characterized in that: the D301G-SO3- resin is suitable for adsorption of polyphenolic substances with parent structures containing hydroxyl groups.

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