A spherical lignin-phenol formaldehyde resin, a preparation method thereof and application thereof in adsorbing N-containing organic dyes

Abstract

The application provides a spherical lignin-phenolic resin and a preparation method and application thereof in adsorbing N-containing organic dyes, and belongs to the technical field of adsorbing materials. The lignin-phenolic resin with regular spherical morphology is prepared by one-step condensation polymerization reaction through the reverse suspension polymerization method under acid catalysis, wherein lignin, hydroquinone and trioxane are used as raw materials. The lignin belongs to renewable resources, has the characteristics of low cost and environmental friendliness, can replace phenol as the main phenol source, and the replacement rate can reach 75%. The yield of the synthesized phenolic resin is as high as 60-80%. In addition, the monomer type can be selected to introduce rich phenolic hydroxyl groups, sulfonic acid groups and other oxygen-containing groups in the resin, the monomer ratio is controlled to change the crosslinking structure of the resin, the adsorption capacity of the resin for N-containing organic dyes is effectively improved, and efficient adsorption of rhodamine B and methylene blue can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of adsorption materials, in particular to a spherical lignin-phenolic resin, a preparation method thereof and application thereof in adsorbing N-containing organic dyes. BACKGROUND

[0002] Dyes are widely used in the textile, printing and dyeing, and cosmetic industries, and are indispensable chemicals in the production process of many industries. However, organic dye molecules often have complex aromatic structures and strong biological toxicity, and are difficult to be naturally degraded. A large amount of dye wastewater generated in the production and use process will destroy the ecological environment of water bodies and pose a serious threat to the health of organisms and even humans. Rhodamine B (RhB) and methylene blue (MB) are typical N-containing dyes, which have high toxicity, carcinogenicity and persistence, and can cause harm to aquatic organisms even at low concentrations, and can be accumulated in the human body through the food chain, leading to damage to multiple organs and the occurrence of diseases.

[0003] Among the many wastewater treatment technologies, adsorption method has shown great application value in the field of dye wastewater treatment due to its simple operation, low cost, high efficiency and stability, and renewability. At present, the materials used for dye adsorption mainly include activated carbon, metal organic frameworks (MOFs), and high polymer materials. Activated carbon has a high specific surface area and can achieve a large adsorption capacity, but has the disadvantages of poor selectivity, easy interference by coexisting organic matters, and high regeneration cost; metal organic frameworks also have a high specific surface area and adjustable pore structure, but have high synthesis cost and are difficult to regenerate; high polymer materials such as resins have strong designability, and can be designed to have pore structure and surface functional groups by changing the crosslinking degree and monomer composition, so as to realize size matching and electrostatic / hydrogen bond synergistic effect on dye molecules, but often have high synthesis cost or require a complex post-processing process. Therefore, developing new adsorption materials with high efficiency, environmental friendliness, low cost and simple synthesis process has become a current research hotspot.

[0004] In recent years, biomass-based adsorbents have attracted attention due to their renewability and environmental friendliness, but their adsorption capacity is generally low, and they have insufficient mechanical strength and are difficult to recover. It is still a challenge to design biomass-based adsorbents with high adsorption capacity and good appearance. SUMMARY

[0005] In view of the above, the purpose of the present application is to provide a spherical lignin-phenolic resin, a preparation method thereof and application thereof in adsorbing N-containing organic dyes. The spherical lignin-phenolic resin provided by the present application has low cost and high N-containing organic dye adsorption capacity.

[0006] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical solutions:

[0007] The application provides a preparation method of spherical lignin-phenolic resin.

[0008] Mixing sodium lignosulfonate, phenolic substances, aldehyde substances, an aqueous solvent and an acid catalyst to obtain a reaction phase;

[0009] Mixing an oily dispersion medium and a dispersion stabilizer to obtain a continuous phase;

[0010] Mixing the reaction phase and the continuous phase, and performing suspension polymerization and thermal curing under stirring to obtain the spherical lignin-phenolic resin.

[0011] Preferably, the phenolic substances include hydroquinone;

[0012] The aldehyde substances include trioxane;

[0013] The molar ratio of the phenolic substances and the aldehyde substances is 1:2-4.

[0014] Preferably, the mass ratio of the phenolic substances and the sodium lignosulfonate is 1:0.5-3.

[0015] Preferably, the aqueous solvent is an aqueous solution of ethylene glycol; and the mass ratio of the total mass of the sodium lignosulfonate, the phenolic substances and the aldehyde substances to the aqueous solvent is 1:0.8-2.0.

[0016] The acid catalyst includes concentrated hydrochloric acid; and the pH value of the reaction phase is 1-2.

[0017] Preferably, the oily dispersion medium includes liquid paraffin;

[0018] The dispersion stabilizer includes compounded span-80 and tween-85, and the mass ratio of the span-80 and the tween-85 is 4-8:1.

[0019] Preferably, the mass of the dispersion stabilizer is 2-3‰ of the mass of the oily dispersion medium.

[0020] Preferably, the volume ratio of the continuous phase to the reaction phase is 3-5:1.

[0021] Preferably, the temperature of the suspension polymerization is 90-100 DEG C, and the holding time is 1-1.5 h.

[0022] The temperature of the thermal curing is 110-115 DEG C, and the holding time is 5-10 h.

[0023] The application further provides the spherical lignin-phenolic resin prepared by the above preparation method.

[0024] Preferably, the particle size of the spherical lignin-phenolic resin is 0.1-0.8 mm.

[0025] The application provides application of the spherical lignin-phenolic resin in adsorption of N-containing organic dyes.

[0026] The application provides a preparation method of a spherical lignin-phenolic resin, which comprises the following steps: mixing sodium lignosulfonate, a phenolic substance, an aldehyde substance, an aqueous solvent and an acid catalyst to obtain a reaction phase; mixing an oily dispersion medium and a dispersion stabilizer to obtain a continuous phase; mixing the reaction phase and the continuous phase, and performing suspension polymerization and thermal curing under stirring to obtain the spherical lignin-phenolic resin. The application adopts an acid catalytic condition, takes sodium lignosulfonate, hydroquinone and trioxane as raw materials, and adopts a reverse-phase suspension polymerization method, so that the lignin-phenolic resin (abbreviated as SLHF) with a regular spherical morphology can be prepared through only one step of condensation polymerization reaction. The sodium lignosulfonate is a renewable resource, and has the characteristics of low cost and environmental friendliness. In the application, the sodium lignosulfonate is used to replace the phenolic substance (hydroquinone) to become a main phenol source, and the replacement rate can reach 75%, and the yield of the synthesized phenolic resin can reach 60-80%. In addition, the application can introduce rich phenolic hydroxyl groups, sulfonic acid groups and other oxygen-containing groups into the resin through selection of monomer types, and the adsorption capacity of the lignin-phenolic resin for N-containing organic dyes can be effectively improved. The obtained spherical lignin-phenolic resin has high bio-based content, good spherical morphology and adjustable crosslinking density, and can realize efficient adsorption of rhodamine B and methylene blue. The adsorption capacity of the lignin-phenolic resin for 100-1000 mg / L rhodamine B solution can reach 558-2118 mg / g, and the adsorption capacity of the lignin-phenolic resin for 100-500 mg / L methylene blue solution can reach 248-334 mg / g.

[0027] The application adopts the suspension polymerization method to prepare the spherical lignin-phenolic resin. The good spherical appearance endows the material with good fluidity in actual operation and the characteristics of being beneficial to separation and recovery, facilitates filling of an adsorption column and a bed reactor, and has excellent industrial application potential. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The optical microscope pictures of the spherical lignin-phenolic resins of examples 1, 2 and 3;

[0029] Figure 2 The Fourier infrared spectrum of the lignin-phenolic resin of example 1;

[0030] Figure 3 The scanning electron microscope photos of the appearance and internal pore structure of the lignin-phenolic resin of example 1;

[0031] Figure 4 The adsorption kinetics curves of example 1 and the commercial macroporous sulfonic acid resin D072 (hydrogen type);

[0032] Figure 5 Optical microscope photos of resins obtained with different dispersion stabilizers. DETAILED DESCRIPTION

[0033] The application provides a preparation method of spherical lignin-phenolic resin, comprising the following steps:

[0034] Mixing sodium lignosulfonate, phenolic substances, aldehyde substances, aqueous solvent and acid catalyst to obtain a reaction phase;

[0035] Mixing the oily dispersion medium and the dispersion stabilizer to obtain a continuous phase;

[0036] Mixing the reaction phase and the continuous phase, and performing suspension polymerization and thermal curing under stirring to obtain the spherical lignin-phenolic resin.

[0037] Unless otherwise specified, the raw materials used in the application are commercially available.

[0038] The application mixes sodium lignosulfonate, phenolic substances, aldehyde substances, aqueous solvent and acid catalyst to obtain a reaction phase. In the application, the phenolic substances preferably include hydroquinone. In the application, the mass ratio of the phenolic substances to sodium lignosulfonate is preferably 1:0.5-3, more preferably 1:2-3, and most preferably 1:3. In the application, the aldehyde substances include trioxane. In the application, the molar ratio of the phenolic substances to aldehyde substances is preferably 1:2-4, and more preferably 1:2-3. By controlling the types and dosage ratio of monomers, the application can introduce abundant phenolic hydroxyl groups, sulfonic acid groups and other oxygen-containing groups into the resin, and can effectively control the adsorption capacity of the resin to rhodamine B by adjusting the crosslinking structure of the resin through monomer proportioning.

[0039] In the application, the aqueous solvent is preferably an aqueous solution of ethylene glycol. In the application, the mass concentration of ethylene glycol in the aqueous solution of ethylene glycol is preferably 80-85%, and more preferably 83%-84%. In the application, the mass ratio of the total mass of sodium lignosulfonate, phenolic substances and aldehyde substances to the aqueous solvent is preferably 1:0.8-2.0, more preferably 1:1.2-1.6, and further preferably 1:1.6.

[0040] In the application, the acid catalyst includes concentrated hydrochloric acid, and the amount of the acid catalyst is controlled to adjust the pH value of the reaction phase to 1-2.

[0041] In the application, the mixing mode is preferably as follows: sodium lignosulfonate, phenolic substances and aldehyde substances are first added to the aqueous solvent, and then the acid catalyst is added.

[0042] The present application mixes oily dispersion medium with dispersion stabilizer to obtain continuous phase. In the present application, the oily dispersion medium preferably comprises liquid paraffin. In the present application, the dispersion stabilizer preferably comprises compounded span-80 and tween-85, the mass ratio of which is preferably 4-8:1, more preferably 5-7:1. In the present application, the dispersion stabilizer preferably accounts for 2-3‰ of the mass of the oily dispersion medium. The present application can adjust the hydrophilic-lipophilic value of the system by controlling the type and amount of the oily dispersion medium and the dispersion stabilizer, which is conducive to the control of the sphericity during synthesis.

[0043] The present application does not have special requirements for the mixing method, and the mixing method known to those skilled in the art can be used.

[0044] The present application mixes the reaction phase and the continuous phase, and performs suspension polymerization reaction and thermal curing under stirring to obtain spherical lignin-phenolic resin. In the present application, the volume ratio of the continuous phase to the reaction phase is preferably 3-5:1, more preferably 4:1. In the present application, the stirring paddle used for stirring is preferably placed at the junction of the reaction phase and the continuous phase. In the present application, the stirring rate is preferably 150-230 rpm. The present application adjusts the appropriate stirring speed to disperse the reaction phase into small droplets with appropriate size and uniform size.

[0045] In the present application, the temperature of the suspension polymerization reaction is preferably 90-100℃, more preferably 95℃, and the holding time is preferably 1-1.5 h. In the present application, the reaction occurring during the suspension polymerization reaction is shown in formula A:

[0046]

[0047] After the suspension polymerization reaction, the present application preferably directly heats the obtained suspension polymerization reaction liquid to perform thermal curing. In the present application, the temperature of the thermal curing is preferably 110-115℃, and the holding time is preferably 5-10 h, more preferably 6-8 h. In the present application, the purpose of the thermal curing is to make the crosslinking of the resin more sufficient.

[0048] After the thermal curing, the reaction is stopped, and the solid spherical resin is obtained after cooling and filtration, and the following post-processing steps are performed on the solid spherical resin:

[0049] After reaction, the solid product is washed with ethanol for 4-5 times, and then washed with distilled water for 5-6 times until neutral. The resin is placed into a Soxhlet extractor, petroleum ether with a boiling range of 60-90℃ is used as the solvent, and heated to reflux extraction for 8 hours to remove the residual pore-forming agent and unreacted monomers in the resin. Then the resin is soaked in a 5% hydrochloric acid solution in a shaker, and the hydrochloric acid solution is replaced every half hour. The washing is repeated for 4-5 times until the resin is neutral. The product with a size of 0.1-0.8mm is obtained by screening, and is stored in a wet state to obtain the spherical lignin-phenolic resin.

[0050] The present application provides the spherical lignin-phenolic resin prepared by the above preparation method. In the present application, the particle size of the spherical lignin-phenolic resin is preferably 0.1-0.8mm.

[0051] The present application provides the application of the above spherical lignin-phenolic resin in adsorbing N-containing organic dyes. In the present application, the N-containing organic dyes preferably include rhodamine B and / or methylene blue. In the present application, the method of the application preferably includes the following steps:

[0052] The spherical lignin-phenolic resin is mixed with a solution containing N-containing organic dyes for adsorption, and the spherical lignin-phenolic resin is separated after adsorption.

[0053] In the present application, the solution containing N-containing organic dyes can be wastewater containing N-containing organic dyes. In the present application, when the N-containing organic dye is rhodamine B, the concentration of the N-containing organic dye in the solution containing N-containing organic dyes is preferably 100-1000mg / L, and more preferably 1000mg / L; when the N-containing organic dye is methylene blue, the concentration of the N-containing organic dye in the solution containing N-containing organic dyes is preferably 100-500mg / L. As a specific embodiment of the present application, the mass (dry weight) of the spherical lignin-phenolic resin to the volume of the solution containing N-containing organic dyes is preferably 10mg:100mL, the temperature of the adsorption is preferably 25℃(±0.5℃), and the time is preferably 40-48h.

[0054] The spherical lignin-phenolic resin, the preparation method thereof, and the application thereof in adsorbing N-containing organic dyes provided by the present application are described in detail below with reference to the examples, but they should not be understood as limiting the scope of protection of the present application.

[0055] Example 1

[0056] In this example, the monomers are sodium lignosulfonate, hydroquinone, and trioxane, the mass ratio of hydroquinone to sodium lignosulfonate is 1:3, the molar ratio of hydroquinone to trioxane is 1:2.1, and the amount of solvent is 1.6 times the total mass of the monomers.

[0057] Preparation of reaction phase: In a three-necked flask, add 9.02 g of sodium lignosulfonate, 3.01 g of hydroquinone, 1.72 g of trioxane, and 22.07 g of 83 wt% ethylene glycol aqueous solution as solvent. After fully dissolving under mechanical stirring, slowly add concentrated hydrochloric acid to adjust the pH to 1.

[0058] Preparation of continuous phase: Weigh span-800.2 g, tween-850.03 g, and liquid paraffin 104.92 g in a beaker, and mix uniformly under magnetic stirring.

[0059] Slowly add the prepared continuous phase to the three-necked flask containing the reaction phase, start stirring, and adjust the rotation speed to 225 rpm. After the reaction phase is dispersed into small droplets of appropriate size and uniformity, start heating to 95°C for polymerization, and keep the temperature for 1 h. Continue to heat to 110°C for solidification, and react for 5 h. After the reaction is completed, the spherical resin filtered after cooling is first washed with ethanol for 5 times, and then washed with distilled water for 5 times until neutral. The resin is then placed in a Soxhlet extractor, petroleum ether with a boiling range of 60-90°C is used as solvent, and heated to reflux for 7 hours to remove the pore-forming agent and unreacted monomers remaining in the resin. Then, the resin is soaked in 5% hydrochloric acid solution in a shaking bed, and the hydrochloric acid solution is replaced every half hour. The process is repeated for 4-5 times until the resin is neutral. The product with a size of 0.1-0.8 mm is obtained by sieving, and is stored in a wet state. The spherical lignin-phenolic resin is obtained.

[0060] The obtained product has good sphericity, and the yield is 74% and the water content is 73.8%.

[0061] Example 2

[0062] In this example, the monomers are sodium lignosulfonate, hydroquinone, and trioxane. The mass ratio of hydroquinone to sodium lignosulfonate is 1:3, the molar ratio of hydroquinone to trioxane is 1:4, and the amount of solvent is 1.6 times the total mass of monomers.

[0063] Preparation of reaction phase: In a three-necked flask, add 9.02 g of sodium lignosulfonate, 3.01 g of hydroquinone, 1.72 g of trioxane, and 22.07 g of 83 wt% ethylene glycol aqueous solution as solvent. After fully dissolving under mechanical stirring, slowly add concentrated hydrochloric acid to adjust the pH to 1.

[0064] Preparation of continuous phase: Weigh span-800.2 g, tween-850.03 g, and liquid paraffin 104.92 g in a beaker, and mix uniformly under magnetic stirring.

[0065] The prepared continuous phase was slowly added to the three-necked flask containing the reaction phase, the stirring was started, the rotating speed was adjusted to 165 rpm, the reaction phase was dispersed into small droplets with appropriate size and uniformity, then the heating was started to raise the temperature to 95℃ for polymerization, the temperature was kept for 1.5 h, then the temperature was raised to 110℃ for solidification, the reaction was carried out for 6 h. After the reaction, the solid product filtered after cooling was washed with ethanol for 4 times, then washed with distilled water for 6 times until neutral, then the resin was put into a Soxhlet extractor, petroleum ether with boiling range of 60-90℃ was used as solvent, the extraction was carried out for 8 hours under heating and reflux, the residual pore-forming agent and unreacted monomers in the resin were removed, then the resin was soaked in 5% hydrochloric acid solution in a shaking table, the hydrochloric acid solution was replaced every half hour, the washing was repeated for 4 times until neutral, then the product with size of 0.1-0.8 mm was obtained by screening, and the product was stored in wet state, thus spherical lignin-phenolic resin was obtained.

[0066] The obtained product was spherical, the yield was 62%, and the water content was 72.2%.

[0067] Example 3

[0068] In this example, the monomers were sodium lignosulfonate, hydroquinone and trioxane, the mass ratio of hydroquinone to sodium lignosulfonate was 1:3, the molar ratio of hydroquinone to trioxane was 1:2.1, and the amount of solvent was 0.8 times of the total mass of monomers.

[0069] Preparation of the reaction phase: sodium lignosulfonate 12.15 g, hydroquinone 4.05 g, trioxane 2.30 g, and 84 wt% ethylene glycol aqueous solution 14.94 g were added to a three-necked flask as solvent, after fully dissolved under mechanical stirring, concentrated hydrochloric acid was slowly added to adjust the pH to 1.

[0070] Preparation of the continuous phase: span-800.23 g, tween-850.03 g, and liquid paraffin 97.70 g were weighed in a beaker, and then magnetically stirred and mixed uniformly.

[0071] The prepared continuous phase was slowly added to the three-necked flask containing the reaction phase, the stirring was started, the rotating speed was adjusted to 165 rpm, the reaction phase was dispersed into small droplets with appropriate size and uniformity, then the heating was started to raise the temperature to 95℃ for polymerization, the temperature was kept for 1.5 h, then the temperature was raised to 110℃ for solidification, the reaction was carried out for 6 h. After the reaction, the solid product filtered after cooling was washed with ethanol for 4 times, then washed with distilled water for 6 times until neutral, then the resin was put into a Soxhlet extractor, petroleum ether with boiling range of 60-90℃ was used as solvent, the extraction was carried out for 8 hours under heating and reflux, the residual pore-forming agent and unreacted monomers in the resin were removed, then the resin was soaked in 5% hydrochloric acid solution in a shaking table, the hydrochloric acid solution was replaced every half hour, the washing was repeated for 4 times until neutral, then the product with size of 0.1-0.8 mm was obtained by screening, and the product was stored in wet state, thus spherical lignin-phenolic resin was obtained.

[0072] The product obtained is spherical, and the yield is 72%, and the water content is 58.1%.

[0073] Example 4

[0074] In this example, the monomers are sodium lignosulfonate, hydroquinone and trioxane, wherein the mass ratio of hydroquinone to sodium lignosulfonate is 1:3; the molar ratio of hydroquinone to trioxane is 1:3; and the amount of solvent is 1.2 times the total mass of the monomers.

[0075] Preparation of the reaction phase: sodium lignosulfonate 48.6 g, hydroquinone 16.2 g, and trioxane 13.25 g were added to a three-necked flask, 93.7 g of 83.5 wt% ethylene glycol aqueous solution was added as a solvent, and after being fully dissolved under mechanical stirring, concentrated hydrochloric acid was slowly added to adjust the pH to 1.

[0076] Preparation of the continuous phase: span-800.98 g, tween-850.14 g, and liquid paraffin 420.02 g were weighed into a beaker and mixed uniformly under magnetic stirring.

[0077] The prepared continuous phase was slowly added to the three-necked flask containing the reaction phase, and the stirring was started with a speed of 210 rpm. After the reaction phase was dispersed into small droplets of appropriate size and uniformity, the heating was started to raise the temperature to 95°C for polymerization, and the temperature was maintained for 1.2 h. Then the temperature was raised to 110°C for curing, and the reaction was continued for 7 h. After the reaction was completed, the solid product obtained after cooling and filtration was washed with ethanol for 5 times, and then washed with distilled water for 6 times until it was neutral. The resin was then placed into a Soxhlet extractor, and petroleum ether with a boiling range of 60-90°C was used as the solvent for extraction under heating and reflux for 6 hours to remove the pore-forming agent and unreacted monomers. Then the resin was soaked in a 5% hydrochloric acid solution in a shaking bed, and the hydrochloric acid solution was replaced every half hour. The above process was repeated for 4 times until the resin was neutral. The product with a size of 0.1-0.8 mm was obtained after screening, and was stored in a wet state. Thus, the spherical lignin-phenolic resin was obtained.

[0078] The product obtained is spherical, and the yield is 73%, and the water content is 64.9%.

[0079] Example 5

[0080] In this example, the monomers are sodium lignosulfonate, hydroquinone and trioxane, wherein the mass ratio of hydroquinone to sodium lignosulfonate is 1:3; the molar ratio of hydroquinone to trioxane is 1:2.5; and the amount of solvent is 1.6 times the total mass of the monomers.

[0081] Preparation of reaction phase: In a three-necked flask, add sodium lignosulfonate 90.2 g, hydroquinone 30.3 g, trioxane 17.23 g, add 83 wt% aqueous ethylene glycol 248.2 g as solvent, after fully dissolved under mechanical stirring, slowly add concentrated hydrochloric acid, adjust pH to 1.

[0082] Preparation of continuous phase: weigh span-80 2.20 g, tween-85 0.55 g, liquid paraffin 1250.50 g in a beaker, mix evenly under magnetic stirring.

[0083] Slowly add the prepared continuous phase to the three-necked flask containing the reaction phase, start stirring, adjust the speed to 200 rpm, disperse the reaction phase into small droplets of appropriate size and uniformity, then start heating to 95°C for polymerization, keep the temperature for 1.5 h, continue to heat to 110°C for curing, react for 6 h. After the reaction is completed, the solid product after cooling and filtration is first washed with ethanol 4 times, then washed with distilled water 6 times until neutral, then put the resin into a Soxhlet extractor, use petroleum ether with boiling range 60-90°C as solvent, heat and reflux for 8 hours to remove the residual pore-forming agent and unreacted monomers in the resin, then soak the resin in a 5% hydrochloric acid solution in a shaker, replace the hydrochloric acid solution every half hour, repeat 5 times until neutral, then sieve to get 0.1-0.8 mm product, store in wet state, and spherical lignin-phenolic resin is obtained.

[0084] The obtained product has good sphericity, the yield is 65%, and the water content is 71.2%.

[0085] Example 6

[0086] In this example, the monomers are sodium lignosulfonate, hydroquinone and trioxane, the mass ratio of hydroquinone to sodium lignosulfonate is 1:3, the molar ratio of hydroquinone to trioxane is 1:2.1, and the amount of solvent is 1.8 times the total mass of monomers.

[0087] Preparation of reaction phase: In a three-necked flask, add sodium lignosulfonate 90.2 g, hydroquinone 30.3 g, trioxane 17.23 g, add 83 wt% aqueous ethylene glycol 248.2 g as solvent, after fully dissolved under mechanical stirring, slowly add concentrated hydrochloric acid, adjust pH to 1.

[0088] Preparation of continuous phase: weigh span-80 2.20 g, tween-85 0.55 g, liquid paraffin 1250.50 g in a beaker, mix evenly under magnetic stirring.

[0089] The prepared continuous phase was slowly added to a three-necked flask containing the reaction phase. Stirring was started, and the speed was adjusted to 220 rpm to disperse the reaction phase into appropriately sized, uniform droplets. The temperature was then raised to 95°C for polymerization, held for 1.5 hours, and then further increased to 110°C for curing, with a reaction time of 8 hours. After the reaction, the cooled and filtered solid product was washed five times with ethanol, then six times with distilled water until neutral. The resin was then placed in a Soxhlet extractor and extracted under reflux for 6 hours using petroleum ether with a boiling range of 60–90°C as the solvent to remove residual porogens and unreacted monomers. The resin was then soaked in a 5% hydrochloric acid solution and shaken in a shaker, with the hydrochloric acid solution changed every half hour. This process was repeated five times until neutral. The product was then sieved to obtain a size of 0.1–0.8 mm and stored in a humid state to obtain spherical lignin-phenol resin.

[0090] The resulting product had good spherical shape, a yield of 71%, and a moisture content of 74.5%.

[0091] Structural characterization

[0092] (1) The spherical lignin-phenolic resins of Examples 1, 2, and 3 were characterized by optical microscopy, and the results are as follows: Figure 1 As shown, Figure 1 In the examples, (a) is the spherical lignin-phenolic resin of Example 1, (b) is the spherical lignin-phenolic resin of Example 2, and (c) is the spherical lignin-phenolic resin of Example 3. Figure 1 It can be seen that the product obtained by this invention is a spherical resin with a good appearance.

[0093] (2) The lignin-phenol resin of Example 1 was characterized by Fourier transform infrared spectroscopy, and the results are as follows: Figure 2 As shown. By Figure 2 It can be seen that sodium lignosulfonate was successfully introduced into the resin obtained by this invention.

[0094] (3) Figure 3 These are scanning electron microscope images showing the appearance and internal pore structure of the lignin-phenolic resin from Example 1. Figure 3 It can be seen that lignin-phenolic resin has a smooth spherical appearance and a rich internal pore structure.

[0095] Performance testing

[0096] (1) The lignin-phenol resin obtained in Examples 1 to 4 was used for the adsorption of Rhodamine B solution with a concentration of 100 to 1000 mg / L. The specific method is as follows: Weigh about 10 mg of resin (dry weight) into a brown conical flask, add 100 mL of adsorption solution, and perform static adsorption in a constant temperature shaker at 25°C for 48 h. The concentration of Rhodamine B solution before and after adsorption was measured by ultraviolet spectrophotometer and the adsorption amount was calculated. The results are listed in Table 1.

[0097] Table 1. Adsorption capacity of lignin-phenolic resins for Rhodamine B obtained in Examples 1-4

[0098]

[0099]

[0100] As can be seen from Table 1, the lignin-phenolic resin obtained in this invention has a high adsorption capacity for Rhodamine B. Its adsorption capacity for Rhodamine B solution of 100-1000 mg / L can reach 558-2118 mg / g, and its adsorption capacity for Rhodamine B solution of 1000 mg / L can reach 1714-2118 mg / g.

[0101] (2) The lignin-phenol resin obtained in Examples 5 and 6 was used for the adsorption of methylene blue solution. The specific method is as follows: 10 mg of resin (dry weight) was weighed into a brown conical flask, 100 mL of adsorption solution was added, and static adsorption was carried out in a constant temperature shaker at 25 °C for 48 h. The concentration of methylene blue solution before and after adsorption was measured by ultraviolet spectrophotometer and the adsorption amount was calculated. The results are listed in Table 2.

[0102] Table 2 shows the adsorption capacity of methylene blue by the lignin-phenolic resins obtained in Examples 5 and 6.

[0103] Example Methylene blue solution concentration (mg / L) Adsorbed amount of methylene blue (mg / g) Example 5 100 248 Example 6 500 334

[0104] As can be seen from Table 2, the lignin-phenol resin obtained in this invention has a high adsorption capacity for methylene blue, and its adsorption capacity for methylene blue solution of 100-500 mg / L can reach 248-334 mg / g.

[0105] (3) Following the adsorption method in (1), the adsorption kinetic curves of Example 1 and the commercial macroporous sulfonic acid resin D072 (hydrogen form) were compared under the same adsorption conditions. The results are as follows: Figure 4 As shown. By Figure 4 It can be seen that the equilibrium times of the two resins are not significantly different, but the adsorption capacity of the lignin-phenol resin in Example 1 has a significant advantage over that of the commercial resin.

[0106] Comparative Example 1

[0107] Comparing with Example 1, the difference is that the kind of raw material is changed, the preparation method is unchanged, the balling of the obtained resin is observed, and the obtained results are listed in Table 3.

[0108] Table 3 Balling of resin after changing the kind of raw material

[0109]

[0110]

[0111] It can be seen from Table 3 that the selection of monomer and catalyst is crucial to the balling effect. The commonly used monomers and catalysts in the synthesis of phenolic resin are screened, and the results show that the copolymerization of hydroquinone and trioxane under acidic conditions, with high reactivity, symmetrical tetrafunctionality and suitable molecular configuration, has the best balling effect.

[0112] Comparative Example 2

[0113] On the basis of Example 1, the kind of aqueous solvent is changed, and the dissolution and balling of the reaction monomer in different solvents are compared as shown in Table 4.

[0114] Table 4 Comparison of dissolution and balling of reaction monomer in different solvents

[0115]

[0116] It can be seen from Table 4 that the selection of solvent must meet the requirements of solubility and balling of monomer at the same time. Ethylene glycol has poor solubility for sodium lignosulfonate, and water is a good solvent, but in the polymerization process, the time of sticking together is long, and the block is sticky. After screening, 80wt%-85wt% ethylene glycol aqueous solution is finally selected as the solvent for better balling effect, and more preferably 83wt%-84wt%.

[0117] Comparative Example 3

[0118] On the basis of Example 1, the mass of dispersing stabilizer (complex span-80 and tween-85) is changed to 1.5‰ and 3.5‰ of the mass of liquid paraffin, respectively, and the optical microscope photos of the resins obtained by using different amounts of dispersing stabilizer are shown in Figure 5 The left photo is for the dispersing agent amount of 1.5‰, and the right photo is for the dispersing agent amount of 3.5‰.

[0119] It can be seen that when the amount of dispersing stabilizer is small (1.5‰), the dispersing effect is poor or the spheroids are difficult to maintain due to the increase of molecular weight at the time of phase separation, resulting in ellipsoidal and droplet sinking and coalescence. When the amount of dispersing stabilizer is large (3.5‰), the spheroids are small and the adhesion is serious.

[0120] The above merely describes the preferred embodiments of the present application, and it should be pointed out that, for those skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as falling within the protection scope of the present application.

Claims

1. A method for preparing spherical lignin-phenolic resin, characterized in that, Includes the following steps: Sodium lignosulfonate, phenolic substances, aldehydes, aqueous solvents, and acid catalysts are mixed to obtain the reaction phase; An oily dispersion medium is mixed with a dispersion stabilizer to obtain a continuous phase; The reactive phase and the continuous phase are mixed, and a suspension polymerization reaction and thermosetting are carried out under stirring conditions to obtain spherical lignin-phenolic resin. The phenolic substance is hydroquinone; The aldehyde is trioxymethylene; The molar ratio of the phenolic substances to the aldehydes is 1:2~4; the mass ratio of the phenolic substances to sodium lignosulfonate is 1:0.5~3. The acid catalyst is concentrated hydrochloric acid; the pH value of the reaction phase is 1~2; The aqueous solvent is an aqueous solution of ethylene glycol; the mass concentration of ethylene glycol in the aqueous solution is 80-85%; the total mass ratio of sodium lignosulfonate, phenolic substances, and aldehydes to the aqueous solvent is 1:0.8-2.

0. The oily dispersion medium is liquid paraffin; The dispersant stabilizer is a compound of span-80 and tween-85, and the mass ratio of span-80 to tween-85 is 4~8:1; The dispersant stabilizer is 2-3‰ of the mass of the oily dispersion medium; The volume ratio of the continuous phase to the reactive phase is 3~5:

1.

2. The preparation method according to claim 1, characterized in that, The suspension polymerization reaction is carried out at a temperature of 90~100℃ for 1~1.5h. The thermosetting temperature is 110~115℃, and the holding time is 5~10h.

3. The spherical lignin-phenolic resin prepared by the preparation method according to claim 1 or 2.

4. The spherical lignin-phenolic resin according to claim 3, characterized in that, The spherical lignin-phenol resin has a particle size of 0.1~0.8 mm.

5. The application of the spherical lignin-phenolic resin according to claim 3 or 4 in the adsorption of nitrogen-containing organic dyes.

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