CN111437880B - Ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material and preparation method and application thereof - Google Patents

Abstract

The invention provides a ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material and a preparation method and application thereof, belonging to the technical field of photocatalytic materials. The preparation method provided by the invention comprises the following steps: microfibrillated cellulose of ramie bone and TiO₂Dispersing the nano particles in water to obtain a mixed dispersion liquid; and sequentially coating an adhesive and the mixed dispersion liquid on one surface of the plastic film, and drying to obtain the ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material. The invention uses ramie bone microfibrillated cellulose to disperse TiO₂Nanoparticles, reduced TiO₂Agglomeration effect of nano particles to make TiO₂The nano particles are uniformly dispersed, the specific surface area of the material is increased, and the ramie bone microfibrillated cellulose has a large number of microporous structures and net structures, so that the ramie bone microfibrillated cellulose has strong adsorption capacity on the dye, and the photocatalytic effect of the composite photocatalytic material is greatly enhanced; in addition, the method provided by the invention is simple to operate and low in cost.

Description

A kind of ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material and its preparation method and application

technical field

The invention relates to the technical field of photocatalytic materials, in particular to a ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material and a preparation method and application thereof.

Background technique

_TiO2 nanoparticles are a commonly used photocatalytic material, but the agglomeration effect of nanoparticles affects its photocatalytic effect, and individual _TiO2 nanoparticles are difficult to recycle after being used as photocatalytic materials. In response to this problem, patent CN106732812A discloses a new method for preparing high catalytic TiO ₂ /cotton cellulose composite material, specifically using butyl titanate as raw material, synthesizing nano-titania microspheres by hydrothermal method, and calcining at high temperature to form hollow Titanium dioxide microspheres and absorbent cotton are used as raw materials to synthesize hydroxymethyl cellulose, and finally titanium dioxide is chloropropylated to make titanium dioxide supported on cellulose. However, this method is complicated in operation and high in cost, and the photocatalytic performance of the obtained _TiO2 /cotton cellulose composite still needs to be improved. Patent CN109277097A discloses a TiO ₂ /cotton-based carbon fiber photocatalyst and its preparation method, specifically using the fibrous carbon obtained after carbonization of cotton fibers as a carrier to support nano-TiO ₂ on the surface. The photocatalytic performance of the obtained _TiO2 /cotton-based carbon fiber photocatalyst still needs to be improved.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material and a preparation method and application thereof. The method provided by the present invention has simple operation, low cost, and the prepared ramie bone microfibrillated cellulose - Titanium dioxide composite photocatalytic material has good photocatalytic effect.

In order to achieve the above-mentioned purpose of the invention, the present invention provides the following technical solutions:

A preparation method of ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material, comprising the following steps:

Dispersing ramie bone microfibrillated cellulose and TiO ₂ nanoparticles in water to obtain a mixed dispersion;

The adhesive and the mixed dispersion liquid are sequentially coated on one side of the plastic film, and after drying, the ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material is obtained.

Preferably, the particle size of the TiO ₂ nanoparticles is 20-30 nm.

Preferably, the ramie bone microfibrillated cellulose has a specific surface area of 20-100 m ² /g, a diameter of 100-1000 nm, and a porosity of 90-95%.

Preferably, the concentration of ramie bone microfibrillated cellulose in the mixed dispersion liquid is 0.3-2 mg/mL, and the concentration of TiO ₂ nanoparticles is 6-27 mg/mL.

Preferably, the coating amount of the mixed dispersion liquid is 0.01-0.03 mL/cm ² .

Preferably, the plastic film includes one of polyester film, nylon film, polypropylene film and polyvinyl chloride film.

Preferably, the drying includes a first drying and a second drying performed in sequence, the temperature of the first drying is room temperature, and the time is 2-3 hours; the temperature of the second drying is 50-60° C., and the time is 18 ~22h.

The present invention provides the ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material prepared by the preparation method described in the above technical solution, comprising a plastic film and a ramie bone microfibrillated cellulose- Titanium dioxide composite film.

The invention provides the application of the ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material according to the above technical solution in the field of printing and dyeing wastewater treatment.

The invention provides a preparation method of a ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material, comprising the following steps: dispersing the ramie bone microfibrillated cellulose and _TiO2 nanoparticles in water to obtain a mixed dispersion; One side of the plastic film is sequentially coated with the adhesive and the mixed dispersion, and after drying, the ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material is obtained. The invention utilizes the ramie bone microfibrillated cellulose to disperse the _TiO2 nanoparticles, reduces the agglomeration effect of the _TiO2 nanoparticles, makes the _TiO2 nanoparticles evenly dispersed, increases the specific surface area of the material, and the ramie bone microfibrillated cellulose itself It has a large number of microporous structures and network structures, and has strong adsorption capacity for dyes, which greatly enhances the photocatalytic effect of composite photocatalytic materials. The application example results show that compared with the pure TiO ₂ photocatalytic film, the degradation rate of methyl blue dye of the ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material in the present invention is increased by 78.8%.

The preparation method provided by the invention is simple and easy to implement, has few processes, low energy consumption, low cost, and is easy for industrialized production.

In addition, the ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material provided by the present invention is in the form of a film, which is easy to recycle and regenerate, and has high reuse efficiency.

Description of drawings

Fig. 1 is the SEM image of the ramie bone microfibrillated cellulose prepared in Example 1;

Fig. 2 is the FT-IR absorption spectrogram of ramie bone cellulose and ramie bone microfibrillated cellulose prepared in Example 1;

FIG. 3 is a SEM image of the ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material prepared in Example 1. FIG.

Detailed ways

The invention provides a preparation method of a ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material, comprising the following steps:

Dispersing ramie bone microfibrillated cellulose and TiO ₂ nanoparticles in water to obtain a mixed dispersion;

The adhesive and the mixed dispersion liquid are sequentially coated on one side of the plastic film, and after drying, the ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material is obtained.

The invention utilizes the ramie bone microfibrillated cellulose to disperse the _TiO2 nanoparticles, reduces the agglomeration effect of the _TiO2 nanoparticles, makes the _TiO2 nanoparticles evenly dispersed, increases the specific surface area of the material, and the ramie bone microfibrillated cellulose itself It has a large number of microporous structures and network structures, and has strong adsorption capacity for dyes, which greatly enhances the photocatalytic effect of composite photocatalytic materials. In the present invention, the preparation method of the ramie bone microfibrillated cellulose preferably comprises the following steps:

(1) carrying out steam explosion pretreatment after mixing the ramie bone meal with water to obtain the pretreated ramie bone meal;

(2) carrying out alkali treatment after mixing the pretreated ramie bone powder and sodium hydroxide solution in the described step (1) to obtain the crude ramie bone cellulose;

(3) performing bleaching after mixing the crude ramie bone cellulose, acetic acid buffer and sodium hypochlorite aqueous solution in the step (2) to obtain the ramie bone cellulose;

(4) mixing the ramie bone cellulose and water in the step (3) to obtain a ramie bone cellulose suspension, subjecting the ramie bone cellulose suspension to a homogenization treatment, and subjecting the obtained system to solidification after the homogenization treatment. The liquid is separated, and the obtained solid material is freeze-dried to obtain ramie bone microfibrillated cellulose.

In the invention, the ramie bone powder is mixed with water and then subjected to steam explosion pretreatment to obtain the pretreated ramie bone powder. In the present invention, the particle size of the ramie bone powder is preferably 20-40 meshes, and the ramie bone powder is preferably obtained by crushing the ramie bone. The invention uses the ramie bone as the raw material to prepare the ramie bone microfibrillated cellulose as the adsorbent, has rich raw material resources and low cost, not only solves the problem of environmental pollution by burning the ramie bone, but also improves the comprehensive utilization value of the ramie resource.

In the present invention, the mass ratio of the ramie bone meal to water is preferably 1:4-6, more preferably 1:5; the temperature of the steam explosion pretreatment is preferably 110-130°C, more preferably 115-125°C °C, more preferably 121 °C; the time of steam explosion pretreatment is preferably 20-30 min. The invention utilizes steam explosion pretreatment to keratinize and rearrange the cellulose in the ramie bone powder, partially degrade the hemicellulose and lignin in the ramie bone, and soften the fibers, which is favorable for disintegrating into microfibers after subsequent homogenization treatment. chemical fiber. In the present invention, after the steam explosion pretreatment is completed, the present invention preferably filters the obtained system, and the obtained solid material (ie, pretreated ramie bone powder) is directly mixed with sodium hydroxide solution for subsequent alkali treatment.

After the pretreated ramie bone powder is obtained, in the present invention, the pretreated ramie bone powder is mixed with a sodium hydroxide solution and then subjected to alkali treatment to obtain crude ramie bone cellulose. In the present invention, the number of times of the alkali treatment is preferably 2 to 3 times, the concentration of the sodium hydroxide solution is preferably 5 to 8 wt.%, and the ratio of the amount of solid material to the sodium hydroxide solution in the system when the alkali treatment is performed Preferably, it is 1 g: 10-15 mL; the temperature of the alkali treatment is preferably 75-85° C., and the time of a single alkali treatment is preferably 1.5-2.5 h. In the present invention, the alkali treatment is preferably performed under stirring conditions, and the rotational speed of the stirring is preferably 100 to 150 rpm. In the present invention, preferably, alkali treatment and filtration are carried out after mixing the pretreated ramie bone powder with sodium hydroxide solution, the obtained filter residue is mixed with sodium hydroxide solution, and alkali treatment and filtration are carried out again, wherein, with sodium hydroxide The operation of solution mixing-alkali treatment-filtration is carried out 2 to 3 times in total; after each alkali treatment is completed, the present invention preferably allows the obtained system to stand for 50 to 70 minutes, more preferably for 60 minutes, and then filter to increase the pretreatment. The contact time between the ramie bone meal and the sodium hydroxide solution makes the lignin in it fully degrade and dissolve in the sodium hydroxide solution. After the last filtration is completed, in the present invention, the obtained filter residue is preferably dried to obtain crude ramie bone cellulose.

The invention destroys the primary wall of fibers by alkali treatment, depolymerizes cellulose macromolecules, and at the same time partially dissolves cellulose with a low degree of polymerization; uses NaOH to interact with lignin to make lignin in a three-dimensional cross-linked network structure The chemical bonds of ramie are broken, and the lignin macromolecules are degraded to form a number of fragments or even low-molecular substances, which are dissolved in the lye, thereby obtaining crude ramie bone cellulose.

After the crude ramie bone cellulose is obtained, the present invention mixes the crude ramie bone cellulose, an acetic acid buffer and an aqueous sodium hypochlorite solution, and then performs bleaching treatment to obtain the ramie bone cellulose. In the present invention, the acetate buffer is preferably prepared by mixing sodium hydroxide, glacial acetic acid and water, the dosage of sodium hydroxide in the acetate buffer is preferably 30 g/L, and the dosage of glacial acetic acid is preferably 70 mL/L L, specifically mix 30g sodium hydroxide with 70mL glacial acetic acid, and dilute to 1L with water; the concentration of the sodium hypochlorite aqueous solution is preferably 1～2wt.%; the solid material in the system, the acetic acid buffer, and the sodium hypochlorite aqueous solution during bleaching treatment The dosage ratio is preferably 1g:5-10mL:5-10mL; the temperature of the bleaching treatment is preferably 75-85°C, more preferably 80°C; the time of a single bleaching treatment is preferably 0.5-1.5h, more preferably 1h . In the present invention, the bleaching treatment is preferably performed under stirring conditions, and the rotational speed of the stirring is preferably 100-150 rpm. In the present invention, preferably, the crude ramie bone cellulose, acetic acid buffer and sodium hypochlorite aqueous solution are mixed and then subjected to bleaching treatment and filtration in turn, the obtained filter residue is mixed with acetic acid buffer and sodium hypochlorite aqueous solution, and bleaching treatment and filtration are performed again, Wherein, the operations of mixing with acetate buffer and sodium hypochlorite aqueous solution-bleaching-filtering are carried out 2 to 3 times in total; after the last filtration is completed, the present invention preferably washes the obtained filter residue with water, and then performs drying to obtain ramie bone cellulose. In the present invention, the water consumption for the washing is preferably 8 to 10 times the mass of the filter residue, and the number of washings is preferably 3 to 5 times.

In the bleaching treatment process of the present invention, sodium hypochlorite can remove residual lignin and other components attached to the ramie bone cellulose. Specifically, the residual lignin undergoes oxidation reaction with sodium hypochlorite, and is fragmented to form soluble components that dissolve in the solvent It is removed, and sodium hypochlorite will also oxidize the ramie bone cellulose, thereby reducing the strength of the ramie bone cellulose to a certain extent. The function of the acetic acid buffer is to soften the pH value of the system and prevent the pH value during the bleaching process. Lead to an impact on the properties of ramie bone cellulose; the present invention adopts a relatively mild bleaching system (ie sodium hypochlorite aqueous solution and acetic acid buffer), which is conducive to the subsequent homogenization of the obtained ramie bone cellulose to form ramie bone with a loose porous network structure. Microfibrillated cellulose.

After the ramie bone cellulose is obtained, the present invention mixes the ramie bone cellulose with water to obtain a ramie bone cellulose suspension, the ramie bone cellulose suspension is subjected to homogenization treatment, and the obtained system after the homogenization treatment is subjected to homogenization treatment. The solid-liquid separation is performed, and the obtained solid material is freeze-dried to obtain ramie bone microfibrillated cellulose. In the present invention, the solid content of the system is preferably 4-6 wt.% during the homogenization treatment, the rotation speed of the homogenization treatment is preferably 20000-25000 rpm, and the time of a single homogenization treatment is preferably 5-8 min. In the present invention, preferably, the ramie bone cellulose is mixed with water to obtain a ramie bone cellulose suspension, the ramie bone cellulose suspension is subjected to homogenization treatment and filtration, the obtained filter residue is mixed with water, and the Homogenization treatment and filtration are carried out, wherein the operations of mixing with water - homogenization treatment and filtration are carried out for 8 to 10 times, and finally the obtained filter residue is freeze-dried to obtain ramie bone microfibrillated cellulose. The present invention has no special limitation on the freeze-drying, and a method well known to those skilled in the art can be used.

In the present invention, the ramie bone cellulose is treated by homogenization, and the fibers are broken and decomposed to form the ramie bone microfibrillated cellulose with a loose porous network structure, which has a large specific surface area, a large number of polar hydroxyl groups exposed on the surface, and has strong adsorption. dye ability; and no chemical reagents are used, the problem of environmental pollution is avoided, the production process is simplified, the efficiency is high, and the production cost is low.

After the ramie bone microfibrillated cellulose is obtained, the present invention disperses the ramie bone microfibrillated cellulose and TiO ₂ nanoparticles in water to obtain a mixed dispersion liquid. In the present invention, the concentration of ramie bone microfibrillated cellulose in the mixed dispersion is preferably 0.3-2 mg/mL, more preferably 0.5-1 mg/mL; the concentration of _TiO nanoparticles is preferably 6-27 mg/mL , more preferably 10 to 15 mg/mL.

In the present invention, the particle size of the TiO ₂ nanoparticles is preferably 20-30 nm; the specific surface area of the ramie bone microfibrillated cellulose is preferably 20-100 m ² /g, the diameter is preferably 100-1000 nm, and the porosity is preferably 100-1000 nm. It is preferably 90 to 95%.

In the present invention, the preparation method of the mixed dispersion is preferably as follows: mixing ramie bone microfibrillated cellulose with water, stirring and dispersing to obtain a ramie bone microfibrillating cellulose dispersion; mixing _TiO2 nanoparticles with water , stirring and dispersing to obtain a _TiO2 nanoparticle dispersion; mixing the ramie bone microfibrillated cellulose dispersion and the _TiO2 nanoparticle dispersion, stirring and then ultrasonically treating to obtain a mixed dispersion. In the present invention, the concentration of the ramie bone microfibrillated cellulose dispersion liquid is preferably 1-3 mg/mL, and the concentration of the TiO ₂ nanoparticle dispersion liquid is preferably 20-40 mg/mL. The present invention does not specifically limit the parameters of stirring and ultrasonic in the process of preparing the mixed dispersion liquid, as long as the ramie bone microfibrillated cellulose and the TiO ₂ nanoparticles are uniformly dispersed.

After the mixed dispersion liquid is obtained, the present invention sequentially coats the adhesive and the mixed dispersion liquid on one side of the plastic film, and after drying, the ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material is obtained. In the present invention, the plastic film preferably includes one of polyester film, nylon film, polypropylene film and polyvinyl chloride (PVC) film, more preferably PVC film; the present invention has no effect on the size of the plastic film There is a special limitation, specifically, length×width=(3±2)cm×(3±2)cm, and the thickness is not particularly limited.

The present invention does not specifically limit the type of the adhesive, and conventional commercially available adhesive sprays are sufficient; in the embodiment of the present invention, the model of the adhesive spray used is specifically 3M super 77, which is purchased from 3M Spray Mount company. The present invention does not limit the coating amount of the adhesive, as long as the plastic film can be firmly adhered to the ramie bone microfibrillated cellulose-titanium dioxide composite film formed by subsequent coating; in the embodiment of the present invention, Based on the plastic film of length×width=(3±2)cm×(3±2)cm, use 3M super 77 adhesive spraying agent to spray on one side of the plastic film for 3-6s.

In the present invention, after the adhesive is coated, it is preferable to immediately coat the surface of the adhesive with the mixed dispersion liquid, and after drying, the ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material is obtained. In the present invention, the coating amount of the mixed dispersion liquid is preferably 0.01 to 0.03 mL/cm ² , more preferably 0.01 to 0.02 mL/cm ² . In the present invention, the coating method of the mixed dispersion liquid is not particularly limited, and spraying can be used. In the present invention, the drying preferably includes the first drying and the second drying performed in sequence, the temperature of the first drying is preferably room temperature, and the time is preferably 2-3 hours; the temperature of the second drying is preferably 50- 60° C., the time is preferably 18-22 h, and the second drying is preferably performed in an oven. In the present invention, the above drying method is beneficial to ensure the integrity of the finally obtained ramie bone microfibrillated cellulose-titanium dioxide composite film.

The present invention provides the ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material prepared by the preparation method described in the above technical solution, comprising a plastic film and a ramie bone microfibrillated cellulose- Titanium dioxide composite film.

The invention provides the application of the ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material according to the above technical solution in the field of printing and dyeing wastewater treatment. The present invention does not specifically limit the specific use method of the ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material; in the embodiments of the present invention, taking the treatment of methyl blue solution as an example, the concentration of the methyl blue solution For 10-50 mg/L, the ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material with the size of length × width = (3 ± 2) cm × (3 ± 2) cm was immersed in 10 mL of methyl blue solution. Under the conditions of room temperature, ultraviolet lamp irradiation and 50-100 rpm photocatalytic degradation treatment for 30-60 min, the degradation rate of methyl blue was 93.5%.

The ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material provided by the present invention can be regenerated after use, and the obtained regenerated ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material still has a good photocatalytic effect; The regeneration method is not particularly limited. The used ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material is immersed in water, and the regeneration treatment is carried out under the conditions of room temperature, ultraviolet lamp irradiation and 50-100rpm for 1.5-2h, and then Washing and drying are enough; in the regeneration process, the photocatalytic properties of TiO ₂ are used to degrade the adsorbed dyes, and then washing to remove impurities, so that the obtained regenerated composite photocatalytic material has the ability to absorb dyes and degrade dyes again.

The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1

Mix 100 g of ramie bone powder (granularity of 20-40 mesh) with 500 mL of water, carry out steam explosion treatment at 121 ° C for 20 min, take 50 g of ramie bone powder after steam explosion treatment, add 500 mL of NaOH solution with a concentration of 5wt.%, Alkali treatment was carried out at 80°C and 100rpm for 2h, then left standing for 1h, the obtained system was suction filtered, and the obtained filter residue was repeatedly subjected to the alkali treatment-standing-suction filtration operation twice, and the final obtained filter residue was dried to obtain 19.62g ramie bone crude cellulose;

Mix 30 g of NaOH with 70 mL of glacial acetic acid, and dilute to 1 L with water to obtain acetate buffer; 10 g of ramie bone crude cellulose, 50 mL of acetic acid buffer and 50 mL of sodium hypochlorite aqueous solution with a concentration of 2 wt.% are mixed at 80 ° C and 100 rpm. Bleaching treatment was carried out for 1 h, the obtained system was suction filtered, the obtained filter residue was repeatedly subjected to the bleaching treatment-suction filtration operation 2 times, the final obtained filter residue was washed 3 times with 10 times the mass of water, and 8.62g of ramie bone cellulose was obtained after drying. ;

The ramie bone cellulose is mixed with water to prepare a ramie bone cellulose dispersion liquid with a concentration of 4 wt.%, the ramie bone cellulose dispersion liquid is homogenized for 5 minutes under the condition of 20000 rpm, and the obtained system is filtered, The obtained filter residue is repeatedly subjected to homogenization treatment-filtration operation 9 times, and a white gelatinous substance is obtained after the last filtration, and after vacuum freeze-drying, powdery ramie bone microfibrillated cellulose is obtained;

Mix ₂ g of TiO nanoparticles (20-30 nm in diameter) with 100 mL of distilled water, and stir for 10 min at 200 rpm to obtain a dispersion of _TiO nanoparticles; 0.1 g of ramie bone microfibrillated cellulose is mixed with 100 mL of distilled water, Under the condition of 600rpm, stir for 15min to obtain the ramie bone microfibrillated cellulose dispersion; under the condition of 600rpm, take 10mL of _TiO2 nanoparticle dispersion and add it to 10mL of the ramie bone microfibrillated cellulose dispersion, continue stirring for 15min and then ultrasonically treat 30min to obtain mixed dispersion;

Scrub the PVC film (length×width=3cm×5cm) with methanol, dry it naturally, spray 3M super 77 adhesive spraying agent on one side of the PVC film evenly for 5s, and then apply the 3M adhesive spraying agent on the surface of the 3M adhesive spraying agent. Immediately and uniformly, 0.2 mL of the mixed dispersion was sprayed on the surface, dried at room temperature for 2 hours, and then transferred to an oven for drying at 60° C. for 20 hours to obtain a ramie bone microfibrillated cellulose-TiO ₂ composite photocatalytic material.

FIG. 1 is a SEM image of the ramie bone microfibrillated cellulose prepared in Example 1. It can be seen from FIG. 1 that the ramie bone microfibrillated cellulose has a loose and porous network structure. The average diameter of the ramie bone microfibrillated cellulose measured by Nano Measurer was 112 nm. The average specific surface area of ramie bone microfibrillated cellulose measured by BET method was 32 m ² /g, and the average porosity was 92.32%.

Figure 2 is the FT-IR absorption spectrum of the ramie bone cellulose and the ramie bone microfibrillated cellulose prepared in Example 1. It can be seen from Figure 2 that the peak positions of the ramie bone cellulose and the ramie bone microfibrillated cellulose are basically Consistent, but the characteristic peaks of ramie bone microfibrillated cellulose are more obvious, in which the absorption peaks at 1048 cm ^-1 and 896 cm ^-1 are derived from the CH deformation of the glycosidic bond caused by ring vibration and OH bending vibration, which are the glucose β-glycosides in cellulose. Bonded characteristic absorption peaks; and no characteristic peaks (1509 cm ^-1 and 1426 cm ^-1 ) of lignin benzene ring skeleton were seen in the spectrum, indicating that lignin was removed during cellulose separation.

Figure 3 is the SEM image of the ramie bone microfibrillated cellulose-TiO ₂ composite photocatalytic material prepared in Example 1. It can be seen from Figure 3 that the TiO ₂ nanoparticles are combined with the ramie bone microfibrillated cellulose, and the TiO ₂ nanoparticles With less agglomeration and agglomeration, the ramie bone microfibrillated cellulose not only provides a larger surface area for _TiO2 nanoparticles, but also promotes the dispersion of _TiO2 nanoparticles and reduces their agglomeration.

Application example

Take the ramie bone microfibrillated cellulose-TiO ₂ composite photocatalytic material prepared in Example 1 and immerse it in 10 mL of methyl blue aqueous solution with a concentration of 10 mg/L, and carry out photocatalytic degradation under the conditions of room temperature, ultraviolet lamp irradiation and 50 rpm stirring. After treatment for 30 min, the degradation rate of methyl blue was obtained by colorimetric determination and calculation.

The ramie bone microfibrillated cellulose-TiO ₂ composite photocatalytic material used in Example 1 was immersed in 20 mL of distilled water, treated with ultraviolet light for 2 hours, taken out and dried at room temperature for 2 hours, and then transferred to an oven for drying at 60°C. 20h, the regenerated ramie bone microfibrillated cellulose-TiO ₂ composite photocatalytic material was obtained.

Newly prepared ramie bone microfibrillated cellulose- _TiO composite photocatalytic material, _TiO photocatalytic film (ie, photocatalytic film without ramie bone microfibrillated cellulose), and ramie bone microfibrillated fibers with different regeneration times The degradation rate data of methyl blue by plain- _TiO composite photocatalytic materials are shown in Table 1. It can be seen from Table 1 that the methyl blue dye is treated with the ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material in the present invention, and the degradation rate of the methyl blue dye is improved compared with the simple TiO ₂ photocatalytic film treatment. 78.8%; and, after the ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material provided by the present invention is regenerated after use, the regenerated ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material still has a good photocatalytic effect. .

Table 1 Degradation rate of methyl blue by different photocatalytic materials

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made. It should be regarded as the protection scope of the present invention.

Claims (6)

1. a preparation method of ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material, is characterized in that, comprises the following steps: The ramie bone microfibrillated cellulose and TiO ₂ nanoparticles are dispersed in water to obtain a mixed dispersion; the ramie bone microfibrillated cellulose has a specific surface area of 20-100 m ² /g, a diameter of 100-1000 nm, and a porosity of 100-1000 nm. 90-95%; the concentration of ramie bone microfibrillated cellulose in the mixed dispersion liquid is 0.3-2 mg/mL, and the concentration of TiO ₂ nanoparticles is 6-27 mg/mL; the particle size of the TiO ₂ nanoparticles is 20～30nm; One side of the plastic film is sequentially coated with the adhesive and the mixed dispersion, and after drying, the ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material is obtained; The preparation method of the ramie bone microfibrillated cellulose comprises the following steps: (1) carrying out steam explosion pretreatment after mixing the ramie bone meal with water to obtain the pretreated ramie bone meal; (2) carrying out alkali treatment after mixing the pretreated ramie bone powder and sodium hydroxide solution in the described step (1) to obtain the crude ramie bone cellulose; (3) performing bleaching after mixing the crude ramie bone cellulose, acetic acid buffer and sodium hypochlorite aqueous solution in the step (2) to obtain the ramie bone cellulose; (4) mixing the ramie bone cellulose and water in the step (3) to obtain a ramie bone cellulose suspension, subjecting the ramie bone cellulose suspension to a homogenization treatment, and subjecting the obtained system to solidification after the homogenization treatment. The liquid is separated, and the obtained solid material is freeze-dried to obtain ramie bone microfibrillated cellulose. 2 . The preparation method according to claim 1 , wherein the coating amount of the mixed dispersion liquid is 0.01-0.03 mL/cm ² . 3 . 3. The preparation method according to claim 1, wherein the plastic film comprises one of polyester film, nylon film, polypropylene film and polyvinyl chloride film. 4 . The preparation method according to claim 1 , wherein the drying comprises a first drying and a second drying performed in sequence, the temperature of the first drying is room temperature, and the time is 2-3 hours; Two drying temperature is 50～60 ℃, time is 18～22h. 5. The ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material prepared by the preparation method according to any one of claims 1 to 4, comprising a plastic film and a ramie bone microfibrillation adhered to one side of the plastic film Cellulose-titanium dioxide composite film. 6. The application of the ramie bone microfibrillated cellulose-titanium dioxide composite photocatalytic material according to claim 5 in the field of printing and dyeing wastewater treatment.

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