CN113600139B - Preparation method and application of cellulose biomass-based in-situ mesoporous composite material - Google Patents

Abstract

The invention discloses a method for preparing a cellulose biomass-based in-situ mesoporous composite material, which includes the steps of: immersing the cellulose biomass in an alkaline solution, and adopting a "cocondensation-induced in-situ generation" strategy to create a matrix of cellulose biomass in the biomass material matrix. A functionalized mesoporous silica composite material was prepared, and a hydroxyl-terminated hyperbranched polymer was used to enhance the function of the composite material. The mesoporous composite material provided by the invention has mild preparation conditions, simple process, short cycle, low cost, is easy to realize large-scale industrial production, and has broad application prospects; the mesoporous material on the surface of the product has high dispersion density, stable physical and chemical structure, and excellent adsorption performance. Strong, good mechanical recyclability, can be used in heavy metal and organic wastewater adsorption treatment and heavy metal recovery and other fields.

Description

Preparation method and application of cellulose biomass-based in-situ mesoporous composite material

Technical field

The invention relates to a preparation method and application of mesoporous composite materials, in particular to a preparation method and application of cellulose biomass-based in-situ mesoporous composite materials.

Background technique

Mesoporous silicon is a silicon-based porous material with a pore diameter between 2 and 50nm. It has the advantages of large specific surface area, good hydrothermal stability, high plasticity, and strong modifiability. It is widely used in adsorption, catalysis, sensing, separation and other fields. It has huge application potential. On this basis, micro-nano mesoporous silica spheres have high surface energy, high mass transfer rate, high density of functional sites and significant interface effects, and have efficient adsorption performance for organic wastewater and heavy metals. However, mesoporous silicon alone is used to adsorb heavy metal wastewater. Mesoporous silicon is dispersed in water and is not easy to recover, which may cause secondary pollution and affect the adsorption effect.

Contents of the invention

In view of the above-mentioned deficiencies in the prior art, the task of the present invention is to provide a method for preparing cellulose biomass-based in-situ mesoporous composite materials, with the purpose of solving the problem of recycling the mesoporous silicon composite materials so that they can be recycled and reused. The present invention also aims to provide an application of cellulose biomass-based in-situ mesoporous composite materials.

The technical solution of the present invention is as follows: a preparation method of cellulose biomass-based in-situ mesoporous composite material, including the following steps:

S1. Dip the cellulosic biomass material into an alkali solution with a concentration of 1 to 30 wt% for heat treatment, then filter the product, wash it thoroughly, and dry it to constant weight to obtain the activated biomass material;

S2. Dissolve the template agent, organic solvent and alkaline regulator in water, heat to 30~100℃, mix and stir for 10~120 minutes, control the molar ratio of the components to template agent: alkaline regulator: organic solvent: water, 0.05 ~5:0.05~5:0.5~60:100;

S3. Add the functional silane coupling agent and orthosilicate to the mixed system in step S2, continue stirring at 30-100°C for 10-120 minutes, and control the molar ratio of the components: functional silane coupling agent: orthosilicate to 0.01- 5:1, the mass volume ratio of the orthosilicate and the mixed system of step S2 is 2 to 10%;

S4. Add the activated biomass material into the mixed system obtained in S3, with a liquor ratio of 1:20~200, and let it stand at 30~100°C for 6~48 hours;

S5. Filter out the biomass material from the mixed system, wash, dry, place under protective gas and reflux with an organic solvent at 40°C to 120°C for 2 to 24 hours, filter, wash, and vacuum dry to obtain primary biomass-based mesopores. composite materials;

S6. Disperse the primary biomass-based mesoporous composite material in an organic solvent solution of 1 to 20 wt% hydroxyl-terminated hyperbranched polymer. The bath ratio is 1: 20 to 200. Stir and react at 30 to 100°C for 0.5 to 6 hours. , filter out the material, wash it, and dry it in a vacuum to obtain a cellulose biomass-based in-situ mesoporous composite material.

Further, in the step S1, the cellulosic biomass material is immersed in 2 to 5 alkaline solutions with a concentration of 1 to 30 wt% in order of increasing concentration for heat treatment. The concentration difference of the alkali solutions in two consecutive treatments is Greater than 5wt%.

Further, the cellulosic biomass is cotton, hemp, wheat straw, rice straw or sugarcane bagasse.

Further, the alkali solution is one or more of sodium hydroxide solution, sodium carbonate solution or sodium bicarbonate solution.

Further, the template agent is one or more of cetyltrimethylammonium chloride or cetyltrimethylammonium bromide.

Further, the alkaline regulator is one or more of ethanolamine, diethanolamine, triethanolamine, and ammonia.

Further, the functional silane coupling agent is 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropylmethyldimethoxysilane, One or more propyltriethoxysilane.

Further, the orthosilicate is one or more of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, and butyl orthosilicate.

Further, the organic solvent is one or more of methanol, absolute ethanol, acetone, toluene, cyclohexane, and isopropyl alcohol.

An application of cellulose biomass-based in-situ mesoporous composite materials, which are used to absorb organic pollutants and/or heavy metal ions that pollute water bodies.

The preparation method of the hydroxyl-terminated hyperbranched polymer described in the present invention refers to the literature Xu S, Chen S, Zhang F, et al. Preparation and controlled coating of hydroxyl-modified silvernanoparticles on silk fibers through intermolecular interaction-induced self-assembly[J ].Materials&Design, 2016: 107-118, it is obtained by the synthetic reaction of one of the monomers containing double bonds and carboxyl or aliphatic groups with polyhydroxy monomers and organic acids. The monomer containing double bonds and carboxyl or aliphatic groups is methyl acrylate, ethyl acrylate, methyl methacrylate, acrylic acid or methacrylic acid; the polyhydroxy monomer is iminodiethanol, trimethylol ethane or trimethylolpropane; the organic acid is dodecylbenzenesulfonic acid, m-toluenesulfonic acid, o-toluenesulfonic acid or p-toluenesulfonic acid.

The advantages of the present invention compared with the prior art are:

Adopting the "cocondensation-induced in-situ generation" strategy, the negatively charged cellulose biomass is used to induce the direct condensation of the silicon source on its surface to generate amino-functionalized mesoporous silicon, thereby obtaining a biomass-based mesoporous composite material with high dispersion density. It can give full play to the efficient adsorption performance of functional mesoporous silicon and utilize the recyclability performance of biomass carriers. The use of multi-concentration alkaline solutions to activate biomass materials can further open the hydrogen bonds within the macromolecular chain, fully swell the fiber bundles, increase the effective reaction space of the biomass, and enhance the reaction activity.

A hydroxyl-terminated hyperbranched polymer is introduced into the high specific surface structure of in-situ mesoporous silicon. The hydroxyl-terminated hyperbranched polymer has a spherical network branched molecular structure with high rheology, low viscosity and many active reaction sites, which is beneficial to its application in When modifying nanoporous materials, they are fully expanded and are not easy to block nanopores; the cavity structure containing a large number of active sites can effectively control nanomaterials, form electrostatic repulsion between particles, and prevent aggregation; hyperbranched polymers can be used to induce nanometers through electrostatic effects. The material is assembled on its surface. The high-density terminal active functional groups of the hyperbranched polymer easily form strong hydrogen bonds with the nanomaterials, which is conducive to building a stable structure. In addition, the rich functional groups of the hyperbranched polymer can capture pollution. material particles to participate in cooperative adsorption.

The mesoporous composite material of the present invention has mild preparation conditions, simple process, short cycle, rich sources of biomass materials and mesoporous silicon materials used, low cost, strong plasticity, easy to realize large-scale industrial production, and has broad application prospects; the surface mesoporous material of the product The porous material has high dispersion density, stable physical and chemical structure, strong adsorption performance, and good mechanical recyclability. It can be used in fields such as heavy metal and organic wastewater adsorption treatment and heavy metal recycling.

Description of the drawings

Figure 1 is the molecular structural formula of the hyperbranched polymer used in the cellulose biomass-based in-situ mesoporous composite material prepared in the embodiment of the present invention.

Figure 2 is a scanning electron microscope image of the cellulose biomass-based in-situ mesoporous composite material prepared in Example 2 of the present invention.

Figure 3 is a static adsorption kinetic curve chart of organic dyes and heavy metal ions adsorbed by the cellulose biomass-based in-situ mesoporous composite material prepared in Example 2 of the present invention.

Figure 4 is a line chart showing the regeneration adsorption performance of the cellulose biomass-based in-situ mesoporous composite material prepared in Example 2 of the present invention for organic dyes and heavy metal ions.

Detailed ways

The present invention will be further described below with reference to the examples, but they are not intended to limit the present invention.

Example 1:

The cotton fiber was immersed in a sodium hydroxide solution with a concentration of 5 wt% and subjected to heat treatment (100°C). The product was then filtered, washed thoroughly, and dried to constant weight to obtain activated cotton fiber.

Dissolve cetyltrimethylammonium chloride, absolute ethanol and diethanolamine in water, heat to 50°C, mix and stir for 30 minutes. Control the molar ratio of components cetyltrimethylammonium chloride:diethanolamine:anhydrous ethanol:water to be 0.3:1:5:100.

Add 3-aminopropyltrimethoxysilane and ethyl orthosilicate to the above mixed system, continue stirring at 50°C for 60 minutes, and control the molar ratio of the components 3-aminopropyltrimethoxysilane:ethyl orthosilicate to be 0.5:1, the mass volume ratio of ethyl orthosilicate and the mixed system is 8.4%.

Then add 5g of activated cotton fiber into the above mixed system, with a liquor ratio of 1:100, and let it stand at 50°C for 12 hours.

The cotton fiber was filtered out from the mixed system, washed, dried, placed under nitrogen and refluxed with absolute ethanol at 60°C for 6 hours, filtered, washed, and vacuum dried to obtain a primary biomass-based mesoporous composite material.

Disperse 5g of the primary composite material in an organic solvent solution of 5 wt% hydroxyl-terminated hyperbranched polymer. The liquor ratio is 1:100. Stir the reaction at 60°C for 2 hours. Filter out the material, wash it, and dry it in a vacuum to obtain cellulose. Biomass-based in situ mesoporous composites. The molecular structure of the hydroxyl-terminated hyperbranched polymer is shown in Figure 1. It has a highly branched cavity structure and abundant carbonyl, hydroxyl and other active groups, which can significantly enhance the functional activity of the composite material.

The cellulose biomass-based in-situ mesoporous composite material prepared above was put into simulated wastewater with a certain concentration and pH value of organic dye (methylene blue) and heavy metal ions (Cu ²⁺ ) to conduct oscillation adsorption experiments and adsorption-desorption experiments. The results of the recycling experiment are as follows:

After four adsorption-desorption cycles, the average adsorption capacity for the two pollutants can still remain above 73% of the first saturated adsorption capacity. Test results show that the composite material adopts the "cocondensation-induced in-situ generation" strategy to introduce mesoporous silicon. The surface adsorption structure has strong stability and good regeneration adsorption performance, and can be used as a highly sustainable biomass adsorption material. .

Example 2:

The cotton fiber is first immersed in a sodium hydroxide solution with a concentration of 2wt% for heat treatment (100°C). The product is filtered and then immersed in a sodium hydroxide solution with a concentration of 10wt% for heat treatment (50°C). The product is filtered, washed thoroughly, and dried to constant weight to obtain activated cotton fiber.

Dissolve cetyltrimethylammonium chloride, absolute ethanol and diethanolamine in water, heat to 50°C, mix and stir for 30 minutes. Control the molar ratio of components cetyltrimethylammonium chloride:diethanolamine:anhydrous ethanol:water to be 0.3:1:5:100.

Add 3-aminopropyltrimethoxysilane and ethyl orthosilicate to the above mixed system, continue stirring at 50°C for 60 minutes, and control the molar ratio of the components 3-aminopropyltrimethoxysilane:ethyl orthosilicate to be 0.6:1. The mass volume ratio of ethyl orthosilicate to the mixed system is 6.4%.

Then add 5g of activated cotton fiber into the above mixed system, with a liquor ratio of 1:100, and let it stand at 50°C for 12 hours.

The cotton fiber was filtered out from the mixed system, washed, dried, placed under nitrogen and refluxed with absolute ethanol at 60°C for 6 hours, filtered, washed, and vacuum dried to obtain a primary biomass-based mesoporous composite material.

Disperse 5g of the primary composite material in an organic solvent solution of 5 wt% hydroxyl-terminated hyperbranched polymer. The liquor ratio is 1:100. Stir the reaction at 60°C for 2 hours. Filter out the material, wash it, and dry it in a vacuum to obtain cellulose. Biomass-based in situ mesoporous composites. Figure 2 shows the scanning electron microscope image of the composite material. A large number of mesoporous silicon microspheres with a particle size of about 100 to 1000 nm are generated in situ on the biomass surface, and the surface is covered with hyperbranched polymers, which significantly increases the specific surface area and functionality of the material. Figure 3 shows the static adsorption kinetic curve of the composite material adsorbing organic dyes (methylene blue) and heavy metal ions (Cu ²⁺ ). The experimental results prove that the "mesoporous silicon-hyperbranched" adsorption structure of the composite material is effective for both pollutants. It has efficient adsorption performance, and the saturated adsorption capacity is 222mg/g and 124mg/g respectively. Figure 4 shows the regeneration adsorption performance line chart of composite materials for organic dyes and heavy metal ions. After four adsorption-desorption cycles, the average adsorption capacity of the two pollutants can still remain above 80% of the first saturated adsorption capacity.

Experimental results prove that multiple activation treatments with alkaline solutions of increasing concentrations can further open the internal hydrogen bonds of the macromolecular chain, fully swell the biomass surface, increase the effective reaction space of the biomass, enhance the reaction activity, thereby effectively improving the composite material Static saturated adsorption capacity and cyclic adsorption capacity of pollutants.

Example 3:

The hemp fiber is first immersed in a sodium carbonate solution with a concentration of 5wt% for heating treatment (120°C), the product is filtered and then immersed in a sodium carbonate solution with a concentration of 10wt% for heating treatment (40°C), and then the product is filtered The product is immersed in a sodium carbonate solution with a concentration of 25 wt% (40° C.) for heat treatment, and then the product is filtered, washed thoroughly, and dried to constant weight to obtain activated hemp fiber.

Dissolve cetyltrimethylammonium bromide, methanol and triethanolamine in water, heat to 50°C, mix and stir for 30 minutes. The molar ratio of the controlled components is cetyltrimethylammonium bromide: triethanolamine: methanol: water, which is 0.5: 2: 7: 100.

Add 3-aminopropyltriethoxysilane and methyl orthosilicate to the above mixed system, continue stirring at 60°C for 120 minutes, and control the molar ratio of the components 3-aminopropyltriethoxysilane:methyl orthosilicate The ester is 0.3:1, and the mass/volume ratio of methyl orthosilicate to the mixed system is 5.2%.

Add 10g of activated hemp fiber into the above mixed system, with a liquor ratio of 1:80, and let it stand at 80°C for 24 hours.

The hemp fiber was filtered out from the mixed system, washed, dried, refluxed with methanol at 60°C for 8 hours under nitrogen, filtered, washed, and vacuum dried to obtain a primary biomass-based mesoporous composite material.

Disperse 10g of the primary composite material in an organic solvent solution of 25wt% hydroxyl-terminated hyperbranched polymer. The liquor ratio is 1:80. The reaction is stirred at 60°C for 5 hours. The material is filtered out, washed, and dried in a vacuum to obtain cellulose. Biomass-based in situ mesoporous composites. This material was subjected to static adsorption experiments of organic dyes (methylene blue) and heavy metal ions (Cu ²⁺ ). The saturated adsorption capacity of methylene blue was 205 mg/g, and the saturated adsorption capacity of Cu ²⁺ was 116 mg/g. Adsorption-desorption recycling was carried out. Four times, the average adsorption amount of methylene blue was 166 mg/g, and the average adsorption amount of Cu ²⁺ was 99 mg/g.

Example 4:

The rice straw fiber is first immersed in a sodium bicarbonate solution with a concentration of 5wt% for heat treatment (100°C). The product is filtered and immersed in a sodium bicarbonate solution with a concentration of 20wt% for heat treatment (50°C). The product is filtered, washed thoroughly, and dried to constant weight to obtain activated rice straw fiber.

Dissolve cetyltrimethylammonium bromide, absolute ethanol and triethanolamine in water, heat to 60°C, mix and stir for 60 minutes. Control the molar ratio of components: cetyltrimethylammonium bromide: triethanolamine: absolute ethanol: water to be 0.5: 3: 5: 100.

Add 3-aminopropyltriethoxysilane and ethyl orthosilicate to the above mixed system, continue stirring at 50°C for 60 minutes, and control the molar ratio of the components 3-aminopropyltriethoxysilane:ethyl orthosilicate The ester is 0.4:1, and the mass/volume ratio of ethyl orthosilicate to the mixed system is 6.8%.

Add 5g of activated rice straw fiber to the above mixed system, with a liquor ratio of 1:100, and let it stand at 50°C for 12 hours.

The rice straw fibers were filtered out from the mixed system, washed, dried, placed under nitrogen and refluxed with absolute ethanol at 60°C for 6 hours, filtered, washed, and vacuum dried to obtain primary biomass-based mesoporous composite materials.

Disperse 5g of the primary composite material in an organic solvent solution of 5 wt% hydroxyl-terminated hyperbranched polymer. The liquor ratio is 1:100. Stir the reaction at 60°C for 2 hours. Filter out the material, wash it, and dry it in a vacuum to obtain cellulose. Biomass-based in situ mesoporous composites. This material was subjected to static adsorption experiments of organic dyes (methylene blue) and heavy metal ions (Cu ²⁺ ). The saturated adsorption capacity of methylene blue was 217 mg/g, and the saturated adsorption capacity of Cu ²⁺ was 109 mg/g. Adsorption-desorption recycling was carried out. Four times, the average adsorption amount of methylene blue was 153 mg/g, and the average adsorption amount of Cu ²⁺ was 85 mg/g.

Example 5:

The wheat straw fiber is first immersed in a sodium carbonate solution with a concentration of 5wt% for heat treatment (120°C), the product is filtered and then immersed in a sodium carbonate solution with a concentration of 10wt% for heat treatment (60°C), and then the product is filtered Then, it is immersed in a sodium carbonate solution with a concentration of 20wt% for heat treatment (40°C). Finally, the product is filtered and immersed in a sodium carbonate solution with a concentration of 25wt% for heat treatment (30°C). The product is then filtered and washed thoroughly. Dry to constant weight to obtain activated wheat straw fiber.

Dissolve cetyltrimethylammonium chloride, absolute ethanol and ethanolamine in water, heat to 65°C, mix and stir for 90 minutes. Control the molar ratio of components: cetyltrimethylammonium chloride: ethanolamine: absolute ethanol: water to be 0.3: 3: 6: 100.

Add 3-aminopropyltrimethoxysilane and methyl orthosilicate to the above mixed system, continue stirring at 65°C for 90 minutes, and control the molar ratio of the components 3-aminopropyltrimethoxysilane:methyl orthosilicate to be 0.25:1, the mass volume ratio of methyl orthosilicate to the mixed system is 5.6%.

Add 10g of activated wheat straw fiber to the above mixed system, with a liquor ratio of 1:50, and let it stand at 65°C for 9 hours.

The wheat straw fibers were filtered out from the mixed system, washed, dried, placed under nitrogen and refluxed with absolute ethanol at 60°C for 6 hours, filtered, washed, and vacuum dried to obtain primary biomass-based mesoporous composite materials.

Disperse 10g of the primary composite material in an organic solvent solution of 10wt% hydroxyl-terminated hyperbranched polymer. The liquor ratio is 1:50. Stir and react at 65°C for 4 hours. Filter out the material, wash it, and dry it in a vacuum to obtain cellulose. Biomass-based in situ mesoporous composites. This material was subjected to static adsorption experiments of organic dyes (methylene blue) and heavy metal ions (Cu ²⁺ ). The saturated adsorption capacity of methylene blue was 219 mg/g, and the saturated adsorption capacity of Cu ²⁺ was 118 mg/g. Adsorption-desorption recycling was carried out. Four times, the average adsorption amount of methylene blue was 179 mg/g, and the average adsorption amount of Cu ²⁺ was 90 mg/g.

Example 6:

The hemp fiber is first immersed in a sodium hydroxide solution with a concentration of 5wt% for heat treatment (100°C). The product is filtered and immersed in a sodium hydroxide solution with a concentration of 20wt% for heat treatment (60°C). The product is filtered, washed thoroughly, and dried to constant weight to obtain activated hemp fiber.

Dissolve cetyltrimethylammonium bromide, methanol and diethanolamine in water, heat to 60°C, mix and stir for 60 minutes. The molar ratio of the controlled components cetyltrimethylammonium bromide:diethanolamine:methanol:water is 0.5:5:10:100.

Add 3-aminopropyltriethoxysilane and propyl orthosilicate to the above mixed system, continue stirring at 60°C for 60 minutes, and control the molar ratio of the components: 3-aminopropyltriethoxysilane:propyl orthosilicate The ester is 0.6:1, and the mass and volume ratio of propyl orthosilicate to the mixed system is 7.1%.

Add 15g of activated hemp fiber to the above mixed system, with a liquor ratio of 1:60, and let it stand at 60°C for 12 hours.

The hemp fiber was filtered out from the mixed system, washed, dried, placed under nitrogen at 60°C and methanol refluxed for 12 hours, filtered, washed, and vacuum dried to obtain a primary biomass-based mesoporous composite material.

Disperse 15g of the primary composite material in an organic solvent solution of 8 wt% hydroxyl-terminated hyperbranched polymer. The liquor ratio is 1:60. Stir the reaction at 60°C for 6 hours. Filter out the material, wash it, and dry it in a vacuum to obtain cellulose. Biomass-based in situ mesoporous composites. This material was subjected to static adsorption experiments of organic dyes (methylene blue) and heavy metal ions (Cu ²⁺ ). The saturated adsorption capacity of methylene blue was 204 mg/g, and the saturated adsorption capacity of Cu ²⁺ was 102 mg/g. Adsorption-desorption recycling was carried out. Four times, the average adsorption amount of methylene blue was 152 mg/g, and the average adsorption amount of Cu ²⁺ was 74 mg/g.

Claims (9)

1. A method for preparing cellulosic biomass-based in-situ mesoporous composite materials, which is characterized by comprising the following steps: S1. Dip the cellulosic biomass material into an alkali solution with a concentration of 1 to 30 wt% for heat treatment, then filter the product, wash it thoroughly, and dry it to constant weight to obtain the activated biomass material; S2. Dissolve the template agent, organic solvent and alkaline regulator in water, heat to 30~100℃, mix and stir for 10~120 minutes, control the molar ratio of the components to template agent: alkaline regulator: organic solvent: water, 0.05 ~5:0.05~5:0.5~60:100; S3. Add the functional silane coupling agent and orthosilicate to the mixed system in step S2, continue stirring at 30-100°C for 10-120 minutes, and control the molar ratio of components orthosilicate:functional silane coupling agent to 0.01 ~5:1, the mass volume ratio of the mixed system of the orthosilicate and step S2 is 2~10%; the functional silane coupling agent is 3-aminopropyltrimethoxysilane, 3-aminopropyl One or more of methyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, and 3-aminopropyltriethoxysilane; S4. Add the activated biomass material into the mixed system obtained in S3, with a liquor ratio of 1:20~200, and let it stand at 30~100°C for 6~48 hours; S5. Filter out the biomass material from the mixed system, wash, dry, place under protective gas and reflux with an organic solvent at 40°C to 120°C for 2 to 24 hours, filter, wash, and vacuum dry to obtain primary biomass-based mesopores. composite materials; S6. Disperse the primary biomass-based mesoporous composite material in an organic solvent solution of 1 to 20 wt% hydroxyl-terminated hyperbranched polymer, with a liquor ratio of 1:20 to 200, and stir the reaction at 30 to 100°C for 0.5 to 6h, filter the material out, wash, and vacuum dry to obtain a cellulose biomass-based in-situ mesoporous composite material. The hydroxyl-terminated hyperbranched polymer is composed of one of the monomers containing double bonds and carboxyl or ester groups. species, obtained by a synthetic reaction with polyhydroxy monomers and organic acids, and the monomer containing a double bond and a carboxyl group or an ester group is methyl acrylate, ethyl acrylate, methyl methacrylate, acrylic acid or methacrylic acid; The polyhydroxy monomer is iminodiethanol, trimethylolethane or trimethylolpropane; the organic acid is dodecylbenzenesulfonic acid, m-toluenesulfonic acid, o-toluenesulfonic acid or p-toluenesulfonic acid acid. 2. The preparation method of cellulosic biomass-based in-situ mesoporous composite materials according to claim 1, characterized in that, in the step S1, the cellulosic biomass materials are immersed in 2 to 5 sulfate in order of increasing concentration. The heat treatment is carried out in an alkali solution with a concentration of 1 to 30 wt%, and the concentration difference of the alkali solutions in two consecutive treatments is greater than 5wt%. 3. The method for preparing cellulosic biomass-based in-situ mesoporous composite materials according to claim 1, characterized in that the cellulosic biomass is cotton, hemp, wheat straw, rice straw or sugarcane bagasse. 4. The preparation method of cellulosic biomass-based in-situ mesoporous composite materials according to claim 1, characterized in that the alkali solution is one of sodium hydroxide solution, sodium carbonate solution or sodium bicarbonate solution. or more. 5. The preparation method of cellulose biomass-based in-situ mesoporous composite material according to claim 1, characterized in that the template agent is cetyltrimethylammonium chloride or cetyltrimethylammonium chloride. One or more of the ammonium bromides. 6. The preparation method of cellulosic biomass-based in-situ mesoporous composite materials according to claim 1, characterized in that the alkaline regulator is one or more of ethanolamine, diethanolamine, triethanolamine, and ammonia. kind. 7. The preparation method of cellulose biomass-based in-situ mesoporous composite material according to claim 1, characterized in that the orthosilicate is methyl orthosilicate, ethyl orthosilicate, orthosilicate One or more of propyl ester and butyl orthosilicate. 8. The preparation method of cellulose biomass-based in-situ mesoporous composite material according to claim 1, characterized in that the organic solvent is methanol, absolute ethanol, acetone, toluene, cyclohexane, isopropyl alcohol one or more of them. 9. The application of a cellulose biomass-based in-situ mesoporous composite material, which is characterized in that it is made by the preparation method of the cellulose biomass-based in-situ mesoporous composite material according to any one of claims 1 to 8. The obtained cellulose biomass-based in-situ mesoporous composite material is used to adsorb organic pollutants and/or heavy metal ions that pollute water bodies.