A method for purifying gardenia yellow pigment

Abstract

The present invention belongs to the technical field of purification of gardenia yellow pigment, and particularly relates to a purification method of gardenia yellow pigment. In this method, Ag / Fe3O4-MCM-41 mesoporous molecular sieve is placed in the gardenia yellow pigment solution for adsorption to obtain a first solution. The first solution is subjected to magnetic separation to obtain a second solution and a solid. The second solution is filtered with an organic membrane, and the solid is washed with water. The washed solid is desorbed in ethanol to obtain a third solution. Finally, the third solution is subjected to magnetic separation, and the separated ethanol / gardenia yellow pigment solution is filtered, rotary evaporated, and dried to obtain the purified gardenia yellow pigment. The purification method provided by the present invention is efficient, simple, and stable, and can be well applied to the acquisition of high-purity gardenia yellow pigment and the industrial-scale production of pigment.

Description

Technical Field

[0001] The invention belongs to the technical field of gardenia yellow pigment purification, and particularly relates to a method for purifying gardenia yellow pigment. Background Art

[0002] Gardenia yellow pigment (GYP) is a water-soluble natural pigment mainly derived from the extract of gardenia fruit. Crocin and crocetin are the main components of gardenia yellow, which has pharmacological effects such as treating nervous system diseases, anti-tumor, and anti-cardiovascular diseases. Compared with synthetic pigments, gardenia yellow pigment has higher safety and certain nutritional and health functions. It has excellent coloring properties for proteins and starches, and can be widely used in various foods such as cakes, candies, flour, beverages, jellies, biscuits, and ice cream.

[0003] In the food industry, the crudely extracted Gardenia yellow pigment contains a large amount of Gardenia glycoside, which will be hydrolyzed by β-glucosidase, and the resulting aglycone will react with the same amino acid to form Gardenia blue. This reaction process will cause Gardenia yellow pigment to turn green, which makes it easy to fade and turn green in food applications. Therefore, it is necessary to study an effective method for purifying Gardenia yellow pigment. Summary of the invention

[0004] The purpose of the present invention is to solve the deficiencies in the prior art and provide a method for purifying gardenia yellow pigment, which specifically adopts the following technical scheme:

[0005] A method for purifying gardenia yellow pigment comprises the following steps:

[0006] Step 1: Ag / Fe 3 O 4 - MCM-41 mesoporous molecular sieve is placed in the gardenia yellow pigment solution, stirred, and then shaken in a constant temperature shaker to obtain a first solution;

[0007] Step 2: The first solution is subjected to magnetic separation to obtain a solid, and the solid is washed with water; the solid is Ag / Fe loaded with gardenia yellow pigment. 3 O 4 -MCM-41 mesoporous molecular sieve;

[0008] Step 3: The Ag / Fe 3 O 4 -MCM-41 mesoporous molecular sieve is placed in an ethanol desorption solution and then shaken in a constant temperature shaker to obtain a second solution;

[0009] Step 4: Magnetically separate the second solution to obtain the ethanol / gardenia yellow pigment solution. Then, filter the ethanol / gardenia yellow solution through an organic filter membrane, perform rotary evaporation, and drying to obtain purified gardenia yellow pigment.

[0010] The present invention innovatively adopts for the first time the principle of complexation reaction between silver ions and unsaturated C=C double bonds to use Ag / Fe 3 O 4 -MCM-41 mesoporous molecular sieve for the purification of gardenia yellow pigment, so as to achieve the purpose of purifying gardenia yellow pigment. The purification method provided by the present invention is efficient, simple, and stable, and can be well applied to the acquisition of high-purity gardenia yellow pigment and the industrial-scale production of pigments.

[0011] The above Ag / Fe 3 O 4 -MCM-41 mesoporous molecular sieve is prepared by the following steps:

[0012] Immerse Fe 3 O 4 -MCM-41 particles in silver nitrate solution, stir for 3 hours at room temperature after ultrasonic treatment for 30 min, perform magnetic separation, wash the collected precipitate with distilled water, dry at 60°C, and then calcine in a muffle furnace at 550°C for 6 h to obtain Ag / Fe 3 O 4 -MCM-41 mesoporous molecular sieve. Its Ag / Fe 3 O 4 -MCM-41 mesoporous molecular sieve has good mesoporous properties, such as a large specific surface area, uniform pore size distribution, and adjustable pore size.

[0013] As a further preferred embodiment, the mass concentration of the above gardenia yellow pigment solution is 1%; the dosage ratio of the gardenia yellow pigment solution to the Ag / Fe 3 O 4 -MCM-41 mesoporous molecular sieve is 15 mL: 1.5 g. When the initial concentration of gardenia yellow pigment is 15 mg / mL and the addition amount of Ag / Fe 3 O 4 -MCM-41 is 1.5 g, the corresponding adsorption rate and adsorption capacity reach the maximum value, and the purification effect is optimal.

[0014] As a further preferred embodiment, the temperature of oscillation in the constant temperature shaker in Step 1 is 30 °C, and the oscillation time is 30 min. When the temperature is 30 °C, the corresponding adsorption rate and adsorption capacity reach the maximum value and are significantly different from the adsorption rates and adsorption capacities at other temperatures; when the adsorption time is in the range of 20 min to 70 min, the adsorption rate shows a trend of first increasing and then stabilizing, and the adsorption rate and adsorption capacity reach the maximum value at 30 min. However, after 30 min, with the increase of time, the adsorption rate and adsorption capacity change little. Therefore, 30 min is the optimal purification time.

[0015] As a further preferred embodiment, the size of the organic filter membrane in Step 4 above is 0.45 μm.

[0016] As a further preferred embodiment, the concentration of the ethanol desorption solution in Step 3 above is 65%. In Step 3 above, the dosage ratio of Ag / Fe 3 O 4 -MCM-41 to the ethanol desorption solution is 1:10. When the solid-liquid ratio is 1:10, the maximum value of 87% is reached, indicating that the crocin dissolution amount is almost saturated at this time. It can be determined that when the solid-liquid ratio is 1:10, the desorption effect is the best.

[0017] As a further preferred embodiment, the temperature of oscillation in the constant temperature shaker in Step 3 above is 40 °C. The oscillation time in the constant temperature shaker in Step 3 above is 60 min. When the oscillation temperature is 40 °C, the desorption effect is the best; when the time is around 60 min to 65 min, the desorption rate of the pigment gradually stabilizes, and the desorption rate is about 88%. With the increase of time, the desorption rate of the pigment increases slightly, but there is no significant difference. Therefore, when the time is about 60 min, the desorption effect is the best.

[0018] As a further preferred embodiment, drying is carried out in an oven in Step 4 above, and the drying temperature is 65 °C.

[0019] The beneficial effects of the present invention are as follows: The present invention provides a purification method for gardenia yellow pigment, and for the first time, Ag / Fe 3 O 4 -MCM-41 mesoporous molecular sieve is used as an adsorbent for the purification of gardenia yellow pigment, and this purification method is efficient, simple, and stable, and can be well applied in the acquisition of high-purity gardenia yellow pigment and the industrial-scale production of pigments. Under the optimal process conditions for purifying gardenia yellow pigment with Ag / Fe 3 O 4 -MCM-41, Ag / Fe 3 O 4The adsorption rate of crocin by -MCM-41 was 85.7%. The color value of the purified gardenia yellow pigment was 1018, which was 3.8 times higher than that before purification. The OD value was 0.22, the absorption peak at 440 nm increased, and the absorption peaks at 235 nm and 338 nm decreased. Description of the Drawings

[0020] Figure 1 The figure shows the effect of the initial concentration of gardenia yellow on the adsorption effect;

[0021] Figure 2 The figure shows the effect of the addition amount of Ag / Fe 3 O 4 -MCM-41 on the adsorption effect;

[0022] Figure 3 The figure shows the effect of the volume of the gardenia yellow solution on the adsorption effect;

[0023] Figure 4 The figure shows the effect of the adsorption time on the adsorption effect;

[0024] Figure 5 The figure shows the effect of the adsorption temperature on the adsorption effect;

[0025] Figure 6 The figure shows the effect of the ethanol concentration on the desorption effect;

[0026] Figure 7 The figure shows the effect of the adsorption temperature on the desorption effect;

[0027] Figure 8 The figure shows the effect of the adsorption time on the desorption effect;

[0028] Figure 9 The figure shows the effect of the solid-liquid ratio on the desorption effect. Detailed Embodiments

[0029] The following will clearly and completely describe the concept, specific structure and technical effects of the present invention in combination with the embodiments and drawings, so as to fully understand the purpose, scheme and effects of the present invention. It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0030] The materials and instruments used in this embodiment are as follows:

[0031] Electronic balance of model AED110, rotary evaporator of model R201, constant temperature shaker of model SHZ-82A, etc. Crocin reference substance, methanol, ethanol, gardenia yellow pigment, Ag / Fe 3 O 4 -MCM-41 mesoporous molecular sieve.

[0032] Drawing of the standard working curve of crocin

[0033] Accurately weigh 2 mg of crocin reference substance, dissolve it with methanol solution, place it in a 10 mL volumetric flask, and make up the volume with 50% methanol solution to prepare a 200 μg / mL crocin reference substance solution. Take 5 dry 10 mL volumetric flasks, add 0.5 mL, 1.0 mL, 1.5 mL, 2.0 mL, and 2.5 mL of crocin standard solution to each, make up the volume with 50% methanol solution, mix well, and obtain crocin standard solutions with concentrations of 10 μg / mL, 20 μg / mL, 30 μg / mL, 40 μg / mL, and 50 μg / mL respectively. Use it as the abscissa. Using 50% methanol solution by volume as the blank control, take the prepared crocin standard solution, and draw the standard working curve of crocin with the absorbance measured at the maximum absorption wavelength of crocin at 440 nm as the ordinate; the regression equation of the standard working curve of crocin is y = 0.1974x + 0.0084, R2 = 0.9995.

[0034] Determination of the contents of crocin and geniposide in the sample solution: Add a certain amount of gardenia yellow sample solution to a 10 mL volumetric flask, make up the volume with 50% methanol solution, mix well, and measure the absorbance values at 238 nm and 440 nm. Using 50% methanol solution by volume as the blank control.

[0035] Example 1

[0036] A method for purifying gardenia yellow pigment, which specifically includes the following steps:

[0037] Step 1, Oscillating adsorption: Add 1.5 g of Ag / Fe 3 O 4 -MCM-41 mesoporous molecular sieve to 15 mL of gardenia yellow pigment solution with a mass concentration of 1%, stir well, and oscillate in a constant temperature shaker at 30 °C for 30 min;

[0038] Step 2, Magnetic separation: After the oscillation in Step 1 is completed, perform magnetic separation to obtain the Ag / Fe3O4-MCM-41 mesoporous molecular sieve loaded with gardenia yellow pigment, and then wash it with distilled water multiple times;

[0039] Step 3, Oscillating desorption: Place the Ag / Fe 3 O 4 -MCM-41 mesoporous molecular sieve loaded with gardenia yellow pigment after being washed with distilled water multiple times after magnetic separation in Step 2 into 10 times the volume of 65% ethanol solution, and oscillate in a constant temperature shaker at 40 °C for 60 min;

[0040] Step 4, magnetic separation: After the desorption in Step 3 is completed, magnetic separation is carried out, and the separated ethanol / gardenia yellow solution is filtered through a 0.45 μm organic filter membrane;

[0041] Step 5: Rotate and evaporate the solution obtained after the treatment in Step 4 to remove a large amount of ethanol, and then dry it in an oven at 65 °C to obtain purified gardenia yellow pigment.

[0042] Example 2

[0043] In this example, response surface design and experiments were carried out on the main influencing factors screened by partial factor design to obtain the optimal process conditions for the purification of gardenia yellow pigment.

[0044] Weigh 2.0 g of Ag / Fe 3 O 4 -MCM-41 mesoporous molecular sieve, add it to 30 mL of a 1% gardenia yellow pigment solution by mass fraction, stir well, oscillate in a constant temperature shaker for 2.5 h, set the temperature to 30 °C, carry out magnetic separation after oscillation, filter the separated solution through a 0.45 μm organic filter membrane, wash the solid with distilled water multiple times, and calculate its adsorption rate and equilibrium adsorption capacity according to the formula.

[0045] In the formula, Qe represents the total adsorption amount at equilibrium, mg / g; Ad: the adsorption rate of the adsorbent to crocin, %; C 0 is the initial concentration of crocin in the sample solution, mg / mL; Ce is the concentration of crocin at adsorption equilibrium, mg / mL; W: the mass of the adsorbent, g; V: the volume of the gardenia yellow solution, mL.

[0046] (1) Adsorption single factor experiment

[0047] a Investigation of the initial concentration of gardenia yellow pigment

[0048] Weigh 2 g of Ag / Fe 3 O 4 -MCM-41 adsorbent, add it to 20 mL of gardenia yellow pigment solutions with initial concentrations of 5 mg / mL, 10 mg / mL, 15 mg / mL, 20 mg / mL, and 25 mg / mL respectively, stir well, oscillate in a constant temperature shaker, and set the temperature to 25 °C. After magnetic separation, filter the solution through a 0.45 μm organic filter membrane, and measure the contents of crocin and geniposide in the solution. Calculate its adsorption rate and equilibrium adsorption capacity according to the formula.

[0049] When the initial concentration of gardenia yellow pigment is 15 mg / mL, the corresponding adsorption rate and adsorption capacity reach the maximum values of 63.28% and 53.34 mg / g respectively. Therefore, the initial concentration of gardenia yellow pigment is determined to be 15 mg / mL, and the results are as Figure 1 shown.

[0050] b Ag / Fe 3 O 4 Investigation on the addition amount of -MCM-41

[0051] Weigh 0.5 g, 1.0 g, 1.5 g, 2.0 g, and 2.5 g of Ag / Fe 3 O 4 -MCM-41 as adsorbent and conduct experiments according to a. When the addition amount of Ag / Fe 3 O 4 -MCM-41 is 1.5 g, the corresponding adsorption rate and adsorption capacity are 83.86% and 32.15 mg / g respectively. Therefore, the addition amount of Ag / Fe3O4-MCM-41 is determined to be 1.5 g; the results are as Figure 2 shown

[0052] c Investigation on the volume of gardenia yellow solution

[0053] Weigh 2.0 g of Ag / Fe 3 O 4 -MCM-41 as adsorbent and add it to 10 mL, 15 mL, 20 mL, 25 mL, and 30 mL of gardenia yellow pigment solution with an initial concentration of 15 mg / mL respectively, and conduct experiments according to a; when the volume of gardenia yellow solution is 15 mL, the corresponding adsorption rate and adsorption capacity are 64.10% and 29.86 mg / g respectively. Therefore, the volume of gardenia yellow solution is determined to be 15 mL, as Figure 3 shown

[0054] d Investigation on adsorption time

[0055] Conduct experiments according to a, and set the oscillation time to 20 min, 30 min, 40 min, 50 min, 60 min, and 70 min respectively; when the adsorption time is in the range of 20 min to 70 min, the adsorption rate shows a trend of increasing first and then stabilizing, and the adsorption rate and adsorption capacity reach the maximum at 30 min; after 30 min, with the increase of time, the adsorption rate and adsorption capacity change little and there is no significant difference from the results at 30 min; therefore, the adsorption time is determined to be 30 min, as Figure 4 shown

[0056] e Investigation on adsorption temperature

[0057] Conduct experiments according to a, set the temperature to 15 °C, 20 °C, 25 °C, 30 °C, and 35 °C respectively, and then conduct experiments respectively; when the temperature is 30 °C, the corresponding adsorption rate and adsorption capacity reach the maximum values of 65.84% and 30.67 mg / g respectively, and there are significant differences from the adsorption rates and adsorption capacities at other temperatures. Therefore, the adsorption temperature is determined to be 30 °C, asFigure 5 as shown

[0058] (2)Response surface test

[0059] Three main influencing factors screened by partial single-factor tests: the initial concentration, addition amount of gardenia yellow pigment, and temperature during the adsorption process were used as independent variables. The purification process of gardenia yellow pigment was optimized by response surface test. The experimental data were fitted and analyzed using Design expert software. The low, medium, and high levels of each factor were coded as -1, 0, and 1 respectively, with a total of 17 groups of tests, and each group of tests was repeated 3 times; the results are shown in Table 1-3

[0060] Table 1 Response surface factors and levels

[0061]

[0062] Table 2 Response surface test design and results

[0063]

[0064] Table 3 Variance analysis of the response surface model

[0065]

[0066] The 17 groups of test data were fitted and statistically analyzed to establish a regression equation model: Ad = 61.55 - 2.02A + 7.18B + 1.93C - 5.68AB + 5.78AC - 2.41BC + 5.52A 2 + 1.16B 2 + 3.80C 2 .

[0067] As can be seen from Table 3, the P value of the model is 0.0002 < 0.01, and the lack-of-fit term P = 0.2726 > 0.05, and R 2 = 0.9663, R Adj 2 = 0.9229. This model shows extremely high significance and a high degree of fitting effect, and can be used to predict the adsorption rate of crocin by Ag / Fe 3 O 4 -MCM-41 under different adsorption conditions. In addition, for the linear term B and the interaction terms AB, AC, and the quadratic terms A 2 and C 2 , their influence on the response value is extremely significant; while for the linear terms A and C, and the interaction term BC, their influence on the response value is also significant, indicating that the levels of these factors have a very significant influence on the response value. According to the F value, the order of the influence of each factor on the adsorption rate is: Ag / Fe 3 O4 The addition amount of Ag / Fe-MCM-41 > the initial concentration of gardenia yellow pigment > the adsorption temperature.

[0068] (3)Verification test of the optimal process conditions

[0069] Operate according to the optimal purification process conditions obtained from the response surface test model, and measure the best adsorption rate of Ag / Fe-MCM-41 for crocin. 3 O 4 -MCM-41. The best adsorption conditions for purifying gardenia yellow pigment with Ag / Fe-MCM-41 are as follows: the initial concentration of gardenia yellow pigment: 10.17 mg / mL; the addition amount of Ag / Fe-MCM-41: 1.49 g; the adsorption temperature: 27 °C. Under these conditions, the adsorption rate of the adsorbent for crocin is 85.66%. 3 O 4 -MCM-41: 1.49 g; adsorption temperature: 27 °C. Under these conditions, the adsorption rate of the adsorbent for crocin is 85.66%. 3 O 4 -MCM-41: 1.49 g; adsorption temperature: 27 °C. Under these conditions, the adsorption rate of the adsorbent for crocin is 85.66%.

[0070] (4)Single factor desorption test

[0071] a Influence of ethanol concentration on desorption rate

[0072] In this experiment, ethanol with a concentration of 50% - 95% was selected as the desorbent for the desorption experiment of gardenia yellow pigment. The specific experimental method is as follows: Place the Ag / Fe-MCM-41 adsorbent loaded with gardenia yellow pigment, which has been washed several times with distilled water after magnetic separation, into 30 mL of ethanol solutions with volume fractions of 55%, 65%, 75%, 85%, and 95% respectively, and perform the desorption experiment by shaking in a constant temperature shaker for 30 min. The temperature is set at 25 °C. After desorption, perform magnetic separation. The separated ethanol / gardenia yellow solution passes through a 0.45 μm organic filter membrane, and after a large amount of ethanol is removed by rotary evaporation, it is placed in an oven to dry; prepare a gardenia yellow pigment solution with a certain concentration and measure the absorbance at 440 nm, and calculate the content of crocin in it according to the standard working curve of crocin. Calculate the desorption rate according to the formula. 3 O 4 -MCM-41 adsorbent into 30 mL of ethanol solutions with volume fractions of 55%, 65%, 75%, 85%, and 95% respectively, and perform the desorption experiment by shaking in a constant temperature shaker for 30 min. The temperature is set at 25 °C. After desorption, perform magnetic separation. The separated ethanol / gardenia yellow solution passes through a 0.45 μm organic filter membrane, and after a large amount of ethanol is removed by rotary evaporation, it is placed in an oven to dry; prepare a gardenia yellow pigment solution with a certain concentration and measure the absorbance at 440 nm, and calculate the content of crocin in it according to the standard working curve of crocin. Calculate the desorption rate according to the formula.

[0073] Desorption rate: De = C d / (C 0 - Ce) × 100

[0074] In the formula, De is the desorption rate, %; C d is the concentration of crocin in the desorbing solution, mg / mL; C 0 is the initial concentration of crocin in the sample solution, mg / mL; Ce is the concentration of crocin at adsorption equilibrium.

[0075] When the ethanol concentration is 65%, the desorption rate of crocin is 60.70%. It can be determined that when the ethanol concentration is above 65%, the desorption effect is better, as Figure 6 shown.

[0076] b Investigation of temperature

[0077] The Ag / Fe 3 O 4 -MCM-41 adsorbent after adsorption was placed in 30 mL of ethanol solution with a volume fraction of 85%. The temperatures were set at 20 °C, 30 °C, 40 °C, 50 °C, and 60 °C respectively, and the desorption experiment was carried out according to step a; when the temperature was 40 °C, the desorption rate reached the maximum value of 88.85%. It can be determined that when the temperature is 40 °C, the desorption effect is better, as Figure 7 shown.

[0078] c Investigation of time

[0079] The Ag / Fe 3 O 4 -MCM-41 adsorbent after adsorption was placed in 30 mL of ethanol solution with a volume fraction of 85%, and the desorption experiment was carried out according to step a; when the time was around 60 min - 65 min, the desorption rate of the pigment gradually stabilized, and the desorption rate was about 88%. As the time increased, the desorption rate of the pigment increased slightly, but there was no significant difference. It can be determined that when the time is 60 min, the desorption effect is better, as Figure 8 shown.

[0080] d Investigation of solid-liquid ratio

[0081] The Ag / Fe 3 O 4 -MCM-41 adsorbent after adsorption was placed in 30 mL of ethanol solution with a volume fraction of 85%. The solid-liquid ratios were set at 1:5, 1:7.5, 1:10, 1:12.5, and 1:15 respectively, and the desorption experiment was carried out according to step a; when the solid-liquid ratio was 1:10, the maximum value of 87% was reached, indicating that the dissolution amount of crocin almost reached saturation at this time. It can be determined that when the solid-liquid ratio is 1:10, the desorption effect is better, as Figure 9 shown.

[0082] Although the description of the present invention has been quite detailed and particularly describes several of the described embodiments, it is not intended to be limited to any of these details or embodiments or any particular embodiment, but rather should be regarded as providing a broad interpretation of these claims in light of the prior art by reference to the appended claims, thereby effectively covering the intended scope of the present invention. In addition, the present invention is described above in terms of embodiments foreseeable by the inventors for the purpose of providing a useful description, and non-substantive modifications to the present invention that are not currently foreseeable may still represent equivalent modifications of the present invention.

Claims

1. A purification method of gardenia yellow pigment, characterized in that, it comprises the following steps: Step 1: Place the Ag / Fe 3 O 4 -MCM-41 mesoporous molecular sieve into the gardenia yellow pigment solution, stir, and then oscillate in a constant temperature shaker to obtain a first solution; Step 2: Magnetically separate the first solution to obtain a solid, and wash the solid with water; the solid is Ag / Fe 3 O 4 -MCM-41 mesoporous molecular sieve; Step 3: Place the Ag / Fe 3 O 4 -MCM-41 mesoporous molecular sieve loaded with gardenia yellow pigment into an ethanol desorption solution, and then oscillate it in a constant temperature shaker to obtain a second solution; Step 4: Magnetically separate the second solution to obtain the ethanol / gardenia yellow pigment solution, then filter the ethanol / gardenia yellow solution with an organic membrane, perform rotary evaporation, and dry it to obtain the purified gardenia yellow pigment; The Ag / Fe 3 O 4 -MCM-41 mesoporous molecular sieve is prepared by the following steps: Immerse the Fe 3 O 4 -MCM-41 particles in silver nitrate solution, stir for 3 hours at room temperature after ultrasonic treatment for 30 min, perform magnetic separation, wash the collected precipitate with distilled water, dry it at 60 °C, and then calcine it in a muffle furnace at 550 °C for 6 h to obtain Ag / Fe 3 O 4 -MCM-41 mesoporous molecular sieve.

2. The purification method according to claim 1, characterized in that, The mass concentration of the gardenia yellow pigment solution is 1%; the dosage ratio of the gardenia yellow pigment solution to the Ag / Fe 3 O 4 -MCM-41 mesoporous molecular sieve is 15 mL: 1.5 g.

3. The purification method according to claim 1, characterized in that, the temperature of oscillation in the constant temperature shaker in step 1 is 30 °C.

4. The purification method according to claim 1, characterized in that, the time of oscillation in the constant temperature shaker in step 1 is 30 min.

5. The purification method according to claim 1, characterized in that, the size of the organic membrane in step 4 is 0.45 μm.

6. The purification method according to claim 1, characterized in that, the concentration of the ethanol desorption solution in step 3 is 65%.

7. The purification method according to claim 1, characterized in that, Ag / Fe in step 3 3 O 4 The dosage ratio of -MCM-41 to the ethanol desorption solution is 1:

10.

8. The purification method according to claim 1, characterized in that, the temperature of oscillation in the constant temperature shaker in step 3 is 40 °C.

9. The purification method according to claim 1, characterized in that, the time of oscillation in the constant temperature shaker in step 3 is 60 min.

10. The purification method according to claim 1, characterized in that, drying is carried out in an oven in step 4, and the drying temperature is 65 °C.

Images