Application of a super-high cross-linking adsorption resin in adsorbing ferulic acid

Abstract

This invention provides the application of a highly cross-linked adsorption resin in the adsorption of ferulic acid. The preparation method of the highly cross-linked adsorption resin includes the following steps: In a protective gas atmosphere, a mixture of hydrophilic network monomers, hydrophobic network monomers, and a reaction solvent undergoes a free radical polymerization reaction under the action of an initiator; wherein the hydrophilic network monomer is one or more of N,N-4,4′-diphenylmethane-bismaleimide, N,N′-4-methyl-1,3-phenylene-bismaleimide, and N,N′-(4,4′-methylenediphenyl)bismaleimide; the hydrophobic network monomer is one or more of styrene or divinylbenzene; the molar ratio of the hydrophilic network monomer to the hydrophobic network monomer is 1:1 to 1:5; the reaction temperature is 25–85℃, and the reaction time is 18–48 h. The highly cross-linked adsorption resin exhibits excellent adsorption effect for ferulic acid, with short adsorption time, high adsorption rate, good stability, and good repeatability.

Description

Technical Field

[0001] This invention belongs to the field of ferulic acid separation technology. More specifically, it relates to the application of an ultra-high cross-linked adsorption resin in the adsorption of ferulic acid. Background Technology

[0002] Ferulic acid is an internationally recognized antioxidant with strong biological activity and numerous pharmacological properties. It is found in lignocellulosic biomass resources and is one of the chemicals used in biorefining. Ferulic acid can be obtained from various agricultural and industrial byproducts (such as corn bran and sugarcane bagasse) through alkaline or enzymatic hydrolysis. However, the purity of the initially extracted ferulic acid is insufficient for its applications, necessitating the continuous search for better separation methods to further purify it and obtain economically viable, high-value products.

[0003] Currently, many scholars both domestically and internationally have conducted research on the separation and purification of ferulic acid using methods such as solvent extraction, membrane separation, activated carbon adsorption, macroporous resin adsorption, and ion exchange adsorption. Solvent extraction requires multiple extraction transfers, which can easily lead to product loss, and the extraction solvent is generally an organic solution, which can cause environmental pollution. Membrane separation is still in the exploratory stage, requiring high costs, and the technology is not yet mature; furthermore, the membrane is prone to fouling. Activated carbon lacks selectivity, and regeneration and reuse are relatively difficult. Macroporous resins easily leave organic solvent residues. Ion exchange resin regeneration requires large amounts of acid and alkali, easily generating large amounts of acidic and alkaline wastewater, which is environmentally unfriendly.

[0004] In 2017, Dupoiron S. et al. reported (Industrial Crops & Products, 2017, 105: 148-155.) the recovery and purification of ferulic acid from hydrolysates containing ferulic acid (concentration 0.22 g / L), chloride, sulfate and phosphate using a weak anion exchange resin, but the adsorption efficiency was only 67%. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of the existing technology in the adsorption and separation of ferulic acid, and to provide an application of ultra-high cross-linked adsorption resin in the adsorption of ferulic acid.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] This invention seeks protection for the application of a highly cross-linked adsorption resin in the adsorption of ferulic acid, wherein the preparation method of the highly cross-linked adsorption resin includes the following steps:

[0008] In a protective gas atmosphere, a mixture of hydrophilic network monomers, hydrophobic network monomers, and a reaction solvent undergoes free radical polymerization under the action of an initiator to obtain an ultra-high crosslinking adsorption resin. The hydrophilic network monomer is one or more of N,N′-4,4′-diphenylmethane-bismaleimide, N,N′-4-methyl-1,3-phenylene-bismaleimide, and N,N′-(4,4′-methylenediphenyl)bismaleimide; the hydrophobic network monomer is one or two of styrene or divinylbenzene; the molar ratio of the hydrophilic network monomer to the hydrophobic network monomer is 1:1 to 1:5; the reaction temperature of the free radical polymerization reaction is 25–85°C, and the reaction time is 18–48 h.

[0009] The ultra-highly cross-linked adsorption resin provided by this invention achieves highly efficient and selective adsorption of ferulic acid through hydrogen bonding and hydrophobic interactions due to its surface rich in hydroxyl functional groups. Ferulic acid molecules contain phenolic hydroxyl and carboxyl groups, exhibiting significant polarity and aromaticity. The hydroxyl groups on the resin surface can form stable hydrogen bonds with the hydroxyl and carboxyl groups in the ferulic acid molecule. Simultaneously, the aromatic ring structure of ferulic acid interacts with the hydrophobic groups of the resin through hydrophobic interactions. The synergistic effect of these intermolecular interactions significantly improves the selective adsorption performance of the ultra-highly cross-linked adsorption resin for ferulic acid in complex systems.

[0010] In addition, the ultra-high cross-linked adsorption resin provided by the present invention has excellent stability and repeatability for ferulic acid. It can maintain its excellent adsorption performance even after multiple cycles of use, and it also has an extremely fast adsorption rate, which can be nearly saturated in about 1 minute.

[0011] The ultra-high cross-linking adsorption resin provided by this invention is easy to use in ferulic acid adsorption applications. It is a cost-effective and industrially promising solution for the separation, purification and extraction of ferulic acid, thereby improving the adsorption and separation efficiency of ferulic acid.

[0012] Preferably, the adsorption separation temperature is 280–315 K. More preferably, the adsorption separation temperature is 288–298 K.

[0013] Specifically, the ferulic acid is a ferulic acid solution. The ferulic acid solution can be an aqueous solution of ferulic acid or a ferulic acid solution in other solvent systems.

[0014] Preferably, the concentration of the ferulic acid solution is 0.01–0.16 g / L.

[0015] Preferably, the solid-liquid ratio of the ultra-high cross-linked adsorption resin to the ferulic acid solution is 1:50 to 500 g / mL. More preferably, the solid-liquid ratio of the ultra-high cross-linked adsorption resin to the ferulic acid solution is 1:80 to 150 g / mL.

[0016] Preferably, the free radical polymerization reaction is carried out at a temperature of 50–80°C for 20–30 h. More preferably, the free radical polymerization reaction is carried out at a temperature of 65–75°C for 24–28 h.

[0017] Preferably, the molar ratio of the hydrophilic network monomer to the hydrophobic network monomer is 1:1 to 1:2.

[0018] Preferably, the initiator is one or both of azo initiators and organic acyl peroxide initiators. Specifically, the azo initiator includes, but is not limited to, azobisisobutyronitrile (AIBN). The organic acyl peroxide initiator includes, but is not limited to, benzoyl peroxide (BPO) and dodecyl peroxide (DOC). More preferably, the initiator is AIBN.

[0019] Specifically, the specific surface area of ​​the ultra-high cross-linked adsorption resin is 110–710 m². 2 / g, pore volume 0.07~0.6cm 3 The resin has a surface area of ​​600–710 m² / g and an average pore size of 3–4 nm. The specific pore size distribution imparted by the highly cross-linked adsorption resin structure forms a good spatial match with the molecular size of ferulic acid, further enhancing the adsorption selectivity of the highly cross-linked adsorption resin for ferulic acid. Preferably, the specific surface area of ​​the highly cross-linked adsorption resin is 600–710 m² / g. 2 / g; pore volume is 0.4~0.6cm 3 / g; average pore size is 3.61–3.72 nm.

[0020] Specifically, the molar ratio of the hydrophilic network monomer to the initiator is 1:0.005 to 0.01.

[0021] Preferably, the hydrophilic network monomer is N,N′-(4,4′-methylenediphenyl)bismaleimide.

[0022] Preferably, the hydrophobic network monomer is divinylbenzene.

[0023] Preferably, the product after the reaction is complete can be purified, washed, or dried.

[0024] Specifically, the purification is a Soxhlet extraction. More specifically, the Soxhlet extraction time is 12–24 hours, and the solvent used for the Soxhlet extraction is one or more of anhydrous ethanol or tetrahydrofuran.

[0025] Specifically, the drying is vacuum drying. More specifically, the vacuum drying temperature is 30–60°C, and the vacuum drying time is 24–48 hours.

[0026] Preferably, the protective gas can be an inert gas conventionally used in the preparation of crosslinked resins.

[0027] The present invention has the following beneficial effects:

[0028] This invention provides the application of highly cross-linked adsorption resin in the adsorption of ferulic acid. Due to its surface rich in hydroxyl functional groups, the highly cross-linked adsorption resin achieves efficient and selective adsorption of ferulic acid through hydrogen bonding and hydrophobic interactions. The resin exhibits excellent adsorption performance for ferulic acid, with short adsorption time, high adsorption rate, and good stability and repeatability. The adsorption and separation operation of the highly cross-linked adsorption resin provided by this invention is simple, offering a cost-effective and industrially promising solution for the separation, purification, and extraction of ferulic acid, thereby improving the adsorption and separation efficiency of ferulic acid. Attached Figure Description

[0029] Figure 1 Infrared characterization spectra of ultra-high cross-linked adsorption resin.

[0030] Figure 2 The static equilibrium adsorption diagrams of ferulic acid on the ultra-high cross-linked adsorption resin at temperatures of 288K, 298K, and 308K are shown.

[0031] Figure 3 The figures show nonlinear simulations of the adsorption kinetics of the ultra-high cross-linked adsorption resin at 288 K for ferulic acid solutions of different initial concentrations, using quasi-first-order and quasi-second-order kinetic models. Detailed Implementation

[0032] The present invention is further illustrated below with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions in the art or as recommended by the manufacturer; the raw materials and reagents used, unless otherwise specified, are all commercially available from the conventional market. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention are within the scope of protection claimed by the present invention.

[0033] Example 1: Preparation of Ultra-Highly Crosslinked Adsorption Resin

[0034] (1) Synthesis steps:

[0035] Add 40 mmol of the hydrophilic network monomer N,N'-(4,4'-methylenediphenyl)bismaleimide and the hydrophobic network monomer divinylbenzene to a 150 mL three-necked flask, followed by 0.2 mmol of the initiator azobisisobutyronitrile. Add 100 mL of dimethylformamide to dissolve the mixture, stir at room temperature, and purge with N2 to remove oxygen for 0.5 h. Raise the temperature to 80 °C, continue purging with N2 until the solution solidifies, and maintain the reaction for 24 h.

[0036] (2) Post-processing steps:

[0037] After the reaction was completed, Soxhlet extraction was performed using tetrahydrofuran for 24 hours to remove unreacted substances. After extraction, the resin was rinsed with water until odorless, dried in a vacuum drying oven for 48 hours, pulverized, and set aside for later use to prepare the ultra-high crosslinking adsorption resin.

[0038] The ultra-high cross-linked adsorption resin prepared by the above method has a BET specific surface area of ​​709 m². 2 / g; pore volume is 0.55cm³ 3 / g; average pore size is 3.72nm.

[0039] Example 2: Application of ultra-high cross-linked adsorption resin in the adsorption of ferulic acid

[0040] 0.1 g of the ultra-high cross-linked adsorption resin prepared in Example 1 was added to 10 mL of ferulic acid solution with different initial concentrations (0.02, 0.04, 0.06, 0.08, 0.10, 0.12 and 0.14 g / L), and placed in a shaker at 288 K and a rotation speed of 120 r / min for 240 min to fully adsorb the resin.

[0041] Example 3: Application of ultra-high cross-linked adsorption resin in the adsorption of ferulic acid

[0042] The difference between this embodiment and Embodiment 2 is that the adsorption temperature is 298K.

[0043] Example 4: Application of ultra-high cross-linked adsorption resin in the adsorption of ferulic acid

[0044] The difference between this embodiment and Embodiment 2 is that the adsorption temperature is 308K.

[0045] Example 5: Application of ultra-high cross-linked adsorption resin in the adsorption of ferulic acid

[0046] Prepare a ferulic acid solution with an initial concentration of 0.015 g / L and a volume of 250 mL. Add 2.5 g of the ultra-high cross-linked adsorption resin prepared in Example 1 to the 250 mL ferulic acid solution. Place the solution at 288 K and turn on the stirrer with a speed of 120 rpm. Take samples using a 1 mL syringe at the set time points (0, 1, 3, 6, 9, 12, 15, 20, 30, 60 and 120 min).

[0047] Example 6: Application of ultra-high cross-linked adsorption resin in the adsorption of ferulic acid

[0048] The difference between this embodiment and Embodiment 5 is that the initial concentration of the ferulic acid solution is 0.109 g / L.

[0049] Example 7: Application of ultra-high cross-linked adsorption resin in the adsorption of ferulic acid

[0050] The difference between this embodiment and Embodiment 5 is that the initial concentration of the ferulic acid solution is 0.159 g / L.

[0051] Test case

[0052] (1) Infrared testing

[0053] The ultra-highly cross-linked adsorption resin prepared in this invention was characterized. Figure 1 It can be seen that the range is 3087-3105cm. -1 The =CH absorption peak appears at 1601-1629 cm⁻¹ -1 The C=C absorption peak appearing at 2926 cm⁻¹ is relatively weak in the resin spectrum. This is because N,N′-4,4′-diphenylmethane-bismaleimide and divinylbenzene were successfully crosslinked via alternating free radical polymerization, consuming the double bond. -1 An absorption peak appeared at 1711 cm⁻¹, but this peak was not observed in the spectrum of the monomer N,N′-4,4′-diphenylmethane-bismaleimide. This is mainly because the CH group in divinylbenzene extends to -CH₂-. At 1711 cm⁻¹... -1 and 1384cm -1 Absorption peaks were observed at all locations, which is attributed to the stretching vibrations of the C=O and CNC bonds in the bismaleimide monomer. In summary, this indicates that the bismaleimide monomer and divinylbenzene monomer were successfully linked via a one-step polymerization process to generate a highly crosslinked adsorption resin.

[0054] (2) Adsorption equilibrium test

[0055] Figure 2 The static equilibrium adsorption diagrams of ferulic acid on the ultra-high cross-linked adsorption resin at temperatures of 288, 298, and 308 K are shown. Figure 2 The data show that both decreasing temperature and increasing equilibrium concentration contribute to improving the equilibrium adsorption capacity of ferulic acid on ultra-highly cross-linked adsorption resins. Lower temperatures favor the adsorption process, possibly suggesting that adsorption is an exothermic reaction, while higher equilibrium concentrations increase the contact opportunities between ferulic acid molecules and adsorption sites. This conclusion provides an important theoretical basis for optimizing ferulic acid adsorption through temperature and concentration control, and has guiding significance for the design and optimization of adsorption processes in industrial applications.

[0056] Figure 3Nonlinear simulations of the adsorption kinetics of ferulic acid solutions with different initial concentrations on a highly cross-linked adsorption resin at 288 K using quasi-first-order and quasi-second-order kinetic models are shown. The adsorption of ferulic acid by the highly cross-linked adsorption resin is rapid in the first 12 minutes, then gradually slows down, reaching adsorption equilibrium at approximately 30 minutes. This phenomenon can be explained by the fact that the highly cross-linked adsorption resin has vacant adsorption sites in the first 12 minutes, and as the number of adsorption sites decreases, the repulsive force between ferulic acid molecules in the solid and liquid phases gradually increases, making it increasingly difficult for the remaining ferulic acid molecules in the solution to be adsorbed by the highly cross-linked adsorption resin. When the adsorption time is 30 minutes, the equilibrium adsorption capacities corresponding to ferulic acid solutions with initial concentrations of 0.015, 0.109, and 0.159 g / L are 1.10, 9.44, and 13.70 mg / g, respectively. Similarly, from... Figure 3 It can be seen that the adsorption capacity of the ultra-highly cross-linked adsorption resin for ferulic acid increases with the increase of the initial concentration of the ferulic acid solution. This is mainly because a higher concentration of ferulic acid solution can have a higher contact probability with the ultra-highly cross-linked adsorption resin, and a higher initial concentration can serve as an important driving force to overcome mass transfer resistance, resulting in a higher adsorption capacity.

[0057] (4) Adsorption performance test

[0058] Adsorption kinetic data were measured at different adsorption temperatures in Examples 2–4. Adsorption kinetic data were measured at different initial concentrations of ferulic acid in Examples 5–7. Stability tests were conducted under the conditions of an adsorption temperature of 288 K, an initial concentration of ferulic acid solution of 0.109 g / L, and an adsorption time of 15 min, i.e., adsorption kinetic data of repeated experiments were measured.

[0059] The experimental results are shown below:

[0060] Table 1 Adsorption kinetic data at different initial concentrations

[0061]

[0062] As can be seen from the adsorption kinetic data in Table 1, Example 1 at a temperature of 288 K exhibited the highest adsorption efficiency at all initial concentrations, indicating that lower temperatures contribute to enhanced adsorption of ferulic acid on the hypercrosslinked adsorption resin. This phenomenon supports the hypothesis that the adsorption process is an exothermic reaction. Furthermore, the adsorption efficiency of each example increased with increasing initial concentration, especially at higher concentrations where the adsorption effect was more significant.

[0063] Table 2 Adsorption kinetic data at different adsorption times

[0064]

[0065]

[0066] Table 2 shows that the adsorption process of ferulic acid by the ultra-high cross-linked adsorption resin exhibits significant rapid kinetic characteristics. In the initial few minutes of adsorption, the adsorption efficiency rapidly increases and approaches saturation. Adsorption nears saturation occurs within approximately 1 minute; after 12 minutes, the adsorption process essentially reaches equilibrium, and further extending the adsorption time has limited effect on improving efficiency. The optimal adsorption conditions occur when the ferulic acid concentration is 0.109 g / L and the adsorption time is 30 minutes, at which point the adsorption efficiency reaches its highest value of 98.99%.

[0067] Table 3 Adsorption kinetic data from repeated experiments

[0068] Number of repeated experiments Adsorption efficiency 1 98.38％ 2 98.59％ 3 98.71％ 4 98.83％ 5 98.99％ 6 98.59％ 7 98.71％ 8 98.83％ 9 98.38％ 10 98.59％ 11 98.71％ 12 98.83％

[0069] The data in Table 3 show that, under the conditions of an adsorption temperature of 288 K, an initial ferulic acid concentration of 0.109 g / L, and an adsorption time of 15 min, the ultra-high cross-linked adsorption resin maintained an adsorption efficiency of over 98% after 12 repeated experiments, with minimal fluctuation. This result demonstrates that the adsorption resin possesses extremely high stability and repeatability, maintaining its excellent adsorption performance even after multiple cycles of use.

[0070] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. The application of a highly cross-linked adsorption resin in the adsorption of ferulic acid, characterized in that, The preparation method of the ultra-high cross-linked adsorption resin includes the following steps: In a protective gas atmosphere, a mixture of hydrophilic network monomers, hydrophobic network monomers and reaction solvents undergoes free radical polymerization under the action of an initiator to obtain an ultra-high crosslinking adsorption resin. The hydrophilic network monomer is one or more of N,N′-4,4′-diphenylmethane-bismaleimide, N,N′-4-methyl-1,3-phenylene-bismaleimide, and N,N′-(4,4′-methylenediphenyl)bismaleimide; the hydrophobic network monomer is one or two of styrene or divinylbenzene. The molar ratio of the hydrophilic network monomer to the hydrophobic network monomer is 1:1 to 1:5; The free radical polymerization reaction is carried out at a temperature of 25–85°C for 18–48 hours.

2. The application according to claim 1, characterized in that, The adsorption temperature is 280–315 K.

3. The application according to claim 2, characterized in that, The adsorption temperature is 288–298 K.

4. The application according to claim 1, characterized in that, The ferulic acid is a ferulic acid solution; the concentration of the ferulic acid solution is 0.01–0.16 g / L.

5. The application according to claim 1, characterized in that, The solid-liquid ratio of the ultra-high cross-linked adsorption resin to the ferulic acid solution is 1:50-500 g / mL.

6. The application according to claim 5, characterized in that, The solid-liquid ratio of the ultra-high cross-linked adsorption resin to the ferulic acid solution is 1:80-150 g / mL.

7. The application according to claim 1, characterized in that, The free radical polymerization reaction is carried out at a temperature of 50–80°C for 20–30 h.

8. The application according to claim 1, characterized in that, The molar ratio of the hydrophilic network monomer to the hydrophobic network monomer is 1:1 to 1:

2.

9. The application according to claim 1, characterized in that, The initiator is one or two of azo initiators and organic acyl peroxide initiators.

10. The application according to claim 1, characterized in that, The specific surface area of ​​the ultra-high cross-linked adsorption resin is 600–710 m². 2 / g, pore volume 0.4~0.6cm 3 / g, with an average pore size of 3.61–3.72 nm.

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