Calcium silicate hydrate film with intrinsic photocatalytic capability as well as preparation method and application of calcium silicate hydrate film

Abstract

The invention relates to a hydrated calcium silicate film with intrinsic photocatalytic capacity and a preparation method and application thereof. The hydrated calcium silicate film is a composite film of hydrated calcium silicate and cellulose. The raw materials comprise the following components in parts by mass: 25-75 parts of a siliceous material; 25 to 75 parts of a calcium material; 5-20 parts of a cellulose material; 0-5 parts of a pH modifier; and 400 to 800 parts of water. The preparation method comprises the following steps: uniformly mixing a siliceous material, a calcareous material, a cellulose material and water in parts by mass, adjusting the pH value, heating in a water bath, and carrying out suction filtration and drying to obtain the hydrated calcium silicate film. Compared with the prior art, the raw materials adopted by the invention are widely available, green, pollution-free and degradable, and under the radiation of a light source with the wavelength of 200-400nm, the surface of the composite film is excited to generate photochemical reaction to generate hydroxyl radicals with strong oxidizing property. The free radicals can efficiently degrade typical organic pollutants in water, such as Congo red, methylene blue, crystal violet and sarranine.

Description

Technical Field

[0001] The present invention relates to the field of preparation of photocatalytic materials, and in particular to a calcium silicate hydrate thin film with intrinsic photocatalytic ability, a preparation method thereof, and an application thereof. Background Art

[0002] Hydroxyl radicals (·OH) have become an important tool for pollutant degradation due to their strong oxidation ability and diverse generation methods. With the increasing environmental pollution problems, the application potential of hydroxyl radicals in water treatment, air purification, and waste degradation has become more and more significant. Currently, common methods for generating hydroxyl radicals include the Fenton reaction, the electrochemical method, the ultraviolet light / hydrogen peroxide method, and the photocatalytic method, etc. However, these methods generally have certain technical bottlenecks that affect their wide application. First of all, most methods have poor adaptability to environmental conditions. For example, the Fenton reaction is sensitive to pH value changes, and too low or too high pH values will significantly reduce the reaction efficiency; changes in temperature and solution concentration may also be unfavorable for the generation of hydroxyl radicals; secondly, the electrochemical method and the ultraviolet light method have high operating costs due to high energy consumption and complex equipment, which limits their application in large-scale industries; in addition, the stability and recyclability problems of the catalyst are also important factors affecting the generation efficiency of hydroxyl radicals. The catalyst may be deactivated or difficult to recycle during long-term use, thereby reducing the reaction efficiency and increasing the maintenance cost.

[0003] Therefore, the existing methods for generating hydroxyl radicals generally have problems such as many side reactions, complex operations, large environmental pollution, and poor economy. The existing photocatalysts mainly rely on semiconductor materials and precious metals. Although these materials have good performance in photocatalytic reactions, there are still certain defects. Precious metal catalysts face challenges of high cost, scarce resources, and potential environmental impacts, while semiconductor materials are often limited by problems such as electron-hole pair recombination and photocorrosion, resulting in a decrease in catalytic activity.

[0004] Therefore, developing new photocatalysts with low cost, environmental friendliness, high stability, and applicable under a wider range of conditions has become an important research direction. How to achieve efficient and stable generation of hydroxyl radicals under various environmental conditions is the key challenge to improving their application effects. Developing efficient, low-cost, and environmentally friendly photocatalytic materials and their preparation methods is the core to promote the application of hydroxyl radicals in environmental governance. Summary of the Invention

[0005] The purpose of the present invention is to provide a calcium silicate hydrate thin film with intrinsic photocatalytic ability, a preparation method thereof, and an application thereof. The prepared calcium silicate hydrate thin film has excellent photocatalytic performance, is green and pollution-free, can achieve efficient and stable generation of hydroxyl radicals, and can efficiently degrade organic pollutants in water.

[0006] The object of the present invention can be achieved by the following technical solutions:

[0007] On the one hand, the present invention provides a calcium silicate hydrate film with intrinsic photocatalytic ability, and the calcium silicate hydrate film is a composite film of calcium silicate hydrate and cellulose.

[0008] Preferably, the raw materials of the calcium silicate hydrate film include the following components in parts by mass:

[0009]

[0010] Preferably, the mass ratio of the calcareous material to the siliceous material is 1:3 - 3:1.

[0011] More preferably, the mass ratio of the calcareous material to the siliceous material is 1:1.

[0012] Preferably, the percentage of cellulose in the sum of the masses of the calcareous material and the siliceous material is 10 - 20%.

[0013] More preferably, the percentage of cellulose in the sum of the masses of the calcareous material and the siliceous material is 15%.

[0014] Preferably, the calcareous material is selected from any one or more of calcium chloride, calcium nitrate, quicklime, and calcium hydroxide.

[0015] Preferably, the siliceous material is selected from any one or more of silica fume, fly ash, rice husk ash, and sodium silicate.

[0016] Preferably, the cellulose material is selected from any one or more of natural cellulose, microcrystalline cellulose, cellulose nanocrystals, and nanofibrillated cellulose.

[0017] Preferably, the pH modifier is selected from any one or both of sodium hydroxide and dilute hydrochloric acid.

[0018] On the second hand, the present invention provides a preparation method of the calcium silicate hydrate film with intrinsic photocatalytic ability as described above, including the following steps:

[0019] S1. Mix the siliceous material, calcareous material, cellulose material, and water in parts by mass, and stir evenly to obtain suspension A;

[0020] S2. Adjust the pH value of suspension A using a pH modifier, and stir evenly to obtain suspension B;

[0021] S3. Heat and stir suspension B in a water bath to obtain suspension C;

[0022] S4. Perform suction filtration on suspension C to obtain film material D;

[0023] S5. Dry the thin film material D to obtain the hydrated calcium silicate thin film E with intrinsic photocatalytic ability.

[0024] Preferably, in steps S1 and S2, the rotation speed of the stirring is 100 - 1000 r / min, and the time is 3 - 60 min for both.

[0025] More preferably, in steps S1 and S2, the rotation speed of the stirring is 200 r / min, and the time is 5 min for both.

[0026] Preferably, in step S2, the pH value of the suspension A after adjustment ranges from 11 to 11.5.

[0027] Preferably, in step S3, the temperature of the water bath heating is 30 - 70 °C, the rotation speed of the stirring is 300 - 1000 r / min, and the time is 20 - 28 h.

[0028] More preferably, in step S3, the temperature of the water bath heating is 40 °C, the rotation speed of the stirring is 400 r / min, and the time is 24 h.

[0029] Preferably, in step S4, the suction filtration treatment means using a vacuum filter to perform suction filtration on the suspension C.

[0030] Preferably, in step S5, the temperature of the drying is 40 - 70 °C, and the time is 20 - 28 h.

[0031] More preferably, in step S5, the temperature of the drying is 45 °C, and the time is 24 h.

[0032] More preferably, in step S5, the drying is carried out in a vacuum drying oven.

[0033] Preferably, the preparation method of the hydrated calcium silicate thin film with intrinsic photocatalytic ability includes the following steps:

[0034] S1. Mix the siliceous material, calcareous material, cellulose material and water in proportion, and stir at a rotation speed of 200 r / min for 5 min to obtain the suspension A;

[0035] S2. Measure the pH value of the suspension A, use a pH modifier to adjust the pH value of the suspension A to a suitable range, and continue to stir at a rotation speed of 200 r / min for 5 min to obtain the suspension B;

[0036] S3. Place the suspension B in a 40 - degree water bath pot, and magnetically stir at a rotation speed of 400 r / min for 24 h to obtain the suspension C;

[0037] S4. Use a vacuum filter to perform suction filtration on the suspension C to obtain a thin film material D;

[0038] S5. Place the suction-filtered thin film material D in a vacuum oven at 45 °C and dry it for 24 h to obtain a hydrated calcium silicate thin film E with intrinsic photocatalytic ability.

[0039] In a third aspect, the present invention provides an application of the hydrated calcium silicate thin film with intrinsic photocatalytic ability as described above in the degradation of organic pollutants, including the following steps:

[0040] a. Place the hydrated calcium silicate thin film with intrinsic photocatalytic ability in the organic pollutant liquid;

[0041] b. Use the hydrated calcium silicate thin film with intrinsic photocatalytic ability as a photocatalytic material and irradiate it with a light source having a wavelength of 200 - 400 nm to cause the hydrated calcium silicate thin film with intrinsic photocatalytic ability to react and generate hydroxyl radicals;

[0042] c. Utilize the generated hydroxyl radicals to degrade the organic pollutants.

[0043] Preferably, the organic pollutants include methylene blue, congo red, crystal violet, and safranin.

[0044] In the synthesis process of hydrated calcium silicate of the present invention, a green, pollution-free, and degradable cellulose material is introduced. The hydrated calcium silicate is modified by the cellulose material, and a hydrated calcium silicate thin film with intrinsic photocatalytic ability is obtained by compounding. Through the interaction between the two, hydroxyl radicals are generated under the light source to achieve the purpose of degrading organic pollutants. The present invention has the characteristics of being adjustable, low preparation cost, degradable, safe and pollution-free, simple process, easy to operate, and high degradation efficiency, and can well degrade organic pollutants such as methylene blue, congo red, crystal violet, and safranin in water.

[0045] The present invention breaks through the dependence on semiconductors and precious metals of traditional photocatalysts, discovers that the composite material of hydrated calcium silicate and cellulose can be used as a green material, and at the same time has the excellent performance of commercial titanium dioxide photocatalysts, which conforms to the concept of sustainable development. Hydrated calcium silicate can be used as the main component of cement, and cellulose can be extracted from green plants. The combination of the two not only improves the photocatalytic performance, but also provides a new idea for the development of environmentally friendly materials. In the comparison of the photocatalytic performance of the hydrated calcium silicate composite material proposed by the present invention with that of commercial titanium dioxide, although its photocatalytic activity is slightly lower than that of commercial titanium dioxide, the photocatalytic activity has been significantly improved compared with the unmodified material, showing good application prospects.

[0046] According to existing theories, both calcium silicate hydrate and cellulose are insulators and are difficult to generate photoexcited electrons and holes under light conditions in the traditional sense. Therefore, they cannot be effectively used for the degradation of organic substances. However, in this invention, a composite material of calcium silicate hydrate and cellulose is used as a photocatalyst, and the composite material is rich in a large number of Ca-OH, Si-OH, and C-OH functional groups. Under humid and aerobic conditions, cellulose degrades under the action of light, generating carbonyl and carboxyl compounds. At the same time, the alkaline solution environment provided by calcium silicate hydrate can continuously release hydroxide ions, and these hydroxide ions attack the glycosidic bonds in cellulose molecules, resulting in the cleavage of glycosidic bonds and the formation of smaller sugar units (such as glucose or short-chain oligosaccharides). During this process, the structural breakage of cellulose molecules is accompanied by the generation of hydroxyl radicals, especially when the concentration of hydroxide ions is high and the light conditions are sufficient. In addition, the Ca-OH and Si-OH functional groups in calcium silicate hydrate are converted into hydroxyl radicals during the cellulose oxidation reaction, further promoting the generation of hydroxyl radicals. The generation of highly efficient and stable hydroxyl radicals can be effectively used for the degradation of organic substances.

[0047] At the same time, as a natural polymer material, cellulose itself has many hydrophilic groups, such as hydroxyl groups, carboxyl groups, etc. During the synthesis of calcium silicate hydrate, when cellulose materials are introduced, through metal coordination, the cellulose chains will become entangled, and these chains interpenetrate and crosslink between the calcium silicate hydrate nanoparticles, making the formed composite calcium silicate hydrate material have a certain toughness, and this characteristic is convenient for practical applications and material replacement.

[0048] This invention proposes an application of the calcium silicate hydrate thin film with intrinsic photocatalytic ability in the degradation of organic pollutants, specifically a novel method for generating hydroxyl radicals based on a composite material of cellulose and industrial solid waste and removing organic pollutants in water. This method uses the composite material of the classical product calcium silicate hydrate generated by cement hydration and cellulose as a photocatalyst, and under light with a wavelength of 200 - 400 nm, a photochemical reaction occurs on the surface of the composite material, generating highly oxidizing hydroxyl radicals. These radicals can efficiently degrade typical organic pollutants in water, such as congo red, methylene blue, crystal violet, and safranin. Compared with traditional water treatment methods, this invention has the advantages of simple operation, low cost, and high efficiency; the reaction occurs on the surface of the solid-phase thin film, without the need to add hydroxyl radical precursors, avoiding secondary pollution.

[0049] In addition, this invention innovatively realizes the photocatalytic efficiency of calcium silicate hydrate, breaking through the application boundary of traditional cement-based materials. By making full use of cellulose and industrial solid waste (silica fume, fly ash, rice husk ash, sodium silicate), this invention provides a green and environmentally friendly wastewater treatment solution with broad application prospects, especially suitable for large-scale wastewater treatment.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] (1) The present invention provides a calcium silicate hydrate film with intrinsic photocatalytic ability. The film is a composite film of calcium silicate hydrate and cellulose. The prepared calcium silicate hydrate film has excellent photocatalytic performance, is green and pollution-free, can achieve efficient and stable generation of hydroxyl radicals, and can efficiently degrade organic pollutants in water.

[0052] (2) The calcium silicate hydrate film of the present invention uses widely available, green, pollution-free and degradable raw materials, including cellulose and industrial solid wastes (silica fume, fly ash, rice husk ash, sodium silicate). The preparation process is simple and easy to operate.

[0053] (3) In the present invention, hydroxyl radicals are generated through the interaction between calcium silicate hydrate and cellulose materials. The alkaline environment provided by calcium silicate hydrate accelerates the structural destruction of cellulose chains, thereby enhancing its ability to generate photocatalytic hydroxyl radicals. The film exhibits excellent performance in organic matter degradation.

[0054] (4) The present invention can generate hydroxyl radicals under the radiation of a light source with a wavelength of 200 - 400 nm, and can also play a photocatalytic role under sunlight, reducing the sewage treatment cost and having strong application potential.

[0055] (5) In the present invention, the cellulose material not only endows the composite material with film-forming ability, but also enhances its mechanical properties, expanding the application scenarios.

[0056] (6) Compared with traditional commercial titanium dioxide catalysts, the material of the present invention (the composite system of calcium silicate hydrate and cellulose) has low cost and similar photocatalytic degradation effect, is suitable for large-scale application, and reduces the dependence on semiconductor materials.

[0057] (7) The photochemical reaction of the present invention occurs on the surface of the solid film, without the need to additionally add hydroxyl radical precursors, avoiding secondary pollution.

[0058] (8) The calcium silicate hydrate film of the present invention has excellent repeated degradation ability and can be recycled and degraded 5 times. At the same time, the film form effectively solves the problem of difficult recovery of photocatalytic materials. Description of the Drawings

[0059] Figure 1 Photocurrent data for Examples 1 - 2 and Comparative Examples 3 - 4.

[0060] Figure 2 Degradation time of organic dyes for Examples 1 - 2 and Comparative Examples 3 - 4.

[0061] Figure 3 Repeated degradation ability of Example 2. Detailed implementation mode

[0062] This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0063] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0064] A hydrated calcium silicate film with intrinsic photocatalytic ability, the hydrated calcium silicate film is a composite film of hydrated calcium silicate and cellulose, and the raw materials of the hydrated calcium silicate film include the following components in parts by mass:

[0065]

[0066] Its preparation method includes the following steps:

[0067] S1. Mix the siliceous material, calcareous material, cellulose material and water according to the parts by mass, and stir evenly to obtain suspension A;

[0068] S2. Use a pH modifier to adjust the pH value of suspension A, and stir evenly to obtain suspension B;

[0069] S3. Heat and stir suspension B in a water bath to obtain suspension C;

[0070] S4. Perform suction filtration on suspension C to obtain film material D;

[0071] S5. Dry the film material D to obtain a hydrated calcium silicate film E with intrinsic photocatalytic ability.

[0072] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0073] Example 1:

[0074] A hydrated calcium silicate film with intrinsic photocatalytic ability, the raw materials include the following components in parts by mass:

[0075]

[0076] In this embodiment, the composition of the calcium material is as follows: calcium chloride 50wt%, calcium nitrate 20wt%, quicklime 10wt%, calcium hydroxide 20wt%; the composition of the silicon material is as follows: silica fume 10wt%, fly ash 20wt%, rice husk ash 10wt%, sodium silicate 60wt%; the composition of the cellulose material is as follows: natural cellulose 10wt%, microcrystalline cellulose 10wt%, cellulose nanocrystals 30wt%, nanofibrillated cellulose 50wt%; the pH modifier is sodium hydroxide and dilute hydrochloric acid.

[0077] The preparation method is as follows: First, 50 parts of the silicon material, 50 parts of the calcium material, 10 parts of the cellulose material and 800 parts of water are mixed in proportion, and stirred at a speed of 200 r / min for 5 min to obtain suspension A; 2 parts of the pH modifier are used to adjust the pH value of suspension A to the range of 11 - 11.5, and continue to stir at a speed of 200 r / min for 5 min to obtain suspension B; suspension B is placed in a water bath at 40°C and magnetically stirred at a speed of 400 r / min for 24 h to obtain suspension C; suspension C is subjected to vacuum filtration to obtain the thin film material D; the filtered thin film material D is placed in a vacuum oven at 45°C and dried for 24 h to obtain the calcium silicate hydrate thin film E with intrinsic photocatalytic ability.

[0078] Example 2:

[0079] A calcium silicate hydrate thin film with intrinsic photocatalytic ability, the raw materials include the following components in parts by mass:

[0080]

[0081] In this embodiment, the composition of the calcium material is as follows: calcium chloride 50wt%, calcium nitrate 20wt%, quicklime 10wt%, calcium hydroxide 20wt%; the composition of the silicon material is as follows: silica fume 10wt%, fly ash 20wt%, rice husk ash 10wt%, sodium silicate 60wt%; the composition of the cellulose material is as follows: natural cellulose 10wt%, microcrystalline cellulose 10wt%, cellulose nanocrystals 30wt%, nanofibrillated cellulose 50wt%; the pH modifier is sodium hydroxide and dilute hydrochloric acid.

[0082] The preparation method is as follows: First, 50 parts of siliceous material, 50 parts of calcareous material, 15 parts of cellulose material and 800 parts of water are mixed in proportion and stirred at a speed of 200 r / min for 5 min to obtain suspension A; 2 parts are used to adjust the pH value of suspension A to the range of 11 - 11.5, and stirring is continued at a speed of 200 r / min for 5 min to obtain suspension B; suspension B is placed in a water bath at 40 °C and magnetically stirred at a speed of 400 r / min for 24 h to obtain suspension C; suspension C is subjected to vacuum filtration to obtain film material D; the filtered film material D is placed in a vacuum oven at 45 °C and dried for 24 h to obtain hydrated calcium silicate film E with intrinsic photocatalytic ability.

[0083] Example 3:

[0084] A hydrated calcium silicate film with intrinsic photocatalytic ability, the raw materials include the following components in parts by mass:

[0085]

[0086] In this example, the composition of the calcareous material is as follows: 50 wt% calcium chloride, 20 wt% calcium nitrate, 10 wt% quicklime, 20 wt% calcium hydroxide; the composition of the siliceous material is as follows: 10 wt% silica fume, 20 wt% fly ash, 10 wt% rice husk ash, 60 wt% sodium silicate; the composition of the cellulose material is as follows: 10 wt% natural cellulose, 10 wt% microcrystalline cellulose, 30 wt% cellulose nanocrystals, 50 wt% nanofibrillated cellulose; the pH modifier is sodium hydroxide and dilute hydrochloric acid.

[0087] The preparation method is as follows: First, 50 parts of siliceous material, 50 parts of calcareous material, 20 parts of cellulose material and 800 parts of water are mixed in proportion and stirred at a speed of 200 r / min for 5 min to obtain suspension A; 3 parts of pH modifier are used to adjust the pH value of suspension A to the range of 11 - 11.5, and stirring is continued at a speed of 200 r / min for 5 min to obtain suspension B; suspension B is placed in a water bath at 40 °C and magnetically stirred at a speed of 400 r / min for 24 h to obtain suspension C; suspension C is subjected to vacuum filtration to obtain film material D; the filtered film material D is placed in a vacuum oven at 45 °C and dried for 24 h to obtain hydrated calcium silicate film E with intrinsic photocatalytic ability.

[0088] Comparative Example 1

[0089] Compared with Example 2, the ratio of calcareous material to siliceous material is changed to 3:1, and the dosage of pH modifier is changed to 5.

[0090] A hydrated calcium silicate film, the raw materials include the following components in parts by mass:

[0091]

[0092] In this embodiment, the composition of the calcium material is as follows: calcium chloride 50 wt%, calcium nitrate 20 wt%, quicklime 10 wt%, calcium hydroxide 20 wt%; the composition of the silicon material is as follows: silica fume 10 wt%, fly ash 20 wt%, rice husk ash 10 wt%, sodium silicate 60 wt%; the composition of the cellulose material is as follows: natural cellulose 10 wt%, microcrystalline cellulose 10 wt%, cellulose nanocrystals 30 wt%, nanofibrillated cellulose 50 wt%; the pH modifiers are sodium hydroxide and dilute hydrochloric acid.

[0093] First, 25 parts of the silicon material, 75 parts of the calcium material, 20 parts of the cellulose material and 800 parts of water are mixed in proportion, and stirred at a speed of 200 r / min for 5 min to obtain suspension A; 3 parts of the pH modifier are used to adjust the pH value of suspension A to the range of 11 - 11.5, and continue to stir at a speed of 200 r / min for 5 min to obtain suspension B; suspension B is placed in a water bath at 40 °C and magnetically stirred at a speed of 400 r / min for 24 h to obtain suspension C; suspension C is subjected to vacuum filtration to obtain the film material D; the filtered film material D is placed in a vacuum oven at 45 °C and dried for 24 h to obtain the calcium silicate hydrate film E.

[0094] Comparative Example 2

[0095] Compared with Comparative Example 1, in this comparative example, the dosages of the silicon material and the calcium material are changed to 75 parts and 25 parts respectively, and the dosage of the pH modifier is 4 parts, and the rest are the same.

[0096] A calcium silicate hydrate film, the raw materials include the following components in parts by mass:

[0097]

[0098] In this embodiment, the composition of the calcium material is as follows: calcium chloride 50 wt%, calcium nitrate 20 wt%, quicklime 10 wt%, calcium hydroxide 20 wt%; the composition of the silicon material is as follows: silica fume 10 wt%, fly ash 20 wt%, rice husk ash 10 wt%, sodium silicate 60 wt%; the composition of the cellulose material is as follows: natural cellulose 10 wt%, microcrystalline cellulose 10 wt%, cellulose nanocrystals 30 wt%, nanofibrillated cellulose 50 wt%; the pH modifiers are sodium hydroxide and dilute hydrochloric acid.

[0099] First, 75 parts of siliceous material, 25 parts of calcareous material, 20 parts of cellulose material and 800 parts of water were mixed in proportion and stirred at a speed of 200 r / min for 5 min to obtain suspension A; 4 parts of pH modifier were used to adjust the pH value of suspension A to the range of 11 - 11.5, and stirring was continued at a speed of 200 r / min for 5 min to obtain suspension B; suspension B was placed in a water bath at 40 °C and magnetically stirred at a speed of 400 r / min for 24 h to obtain suspension C; suspension C was subjected to vacuum filtration to obtain film material D; the filtered film material D was placed in a vacuum oven at 45 °C and dried for 24 h to obtain calcium silicate hydrate film E.

[0100] Comparative Example 3

[0101] Commercial nano-titanium dioxide particles were used as the photocatalyst.

[0102] Comparative Example 4:

[0103] A calcium silicate hydrate film, the raw materials include the following components in parts by mass:

[0104]

[0105] In this example, the composition of the calcareous material is as follows: 50 wt% calcium chloride, 20 wt% calcium nitrate, 10 wt% quicklime, 20 wt% calcium hydroxide; the composition of the siliceous material is as follows: 10 wt% silica fume, 20 wt% fly ash, 10 wt% rice husk ash, 60 wt% sodium silicate; the pH modifier is sodium hydroxide and dilute hydrochloric acid.

[0106] The preparation method is as follows: First, 50 parts of the above-mentioned siliceous material, 50 parts of calcareous material, 5 parts of cellulose material and 800 parts of water were mixed in proportion and stirred at a speed of 200 r / min for 5 min to obtain suspension A; 1 part of pH modifier was used to adjust the pH value of suspension A to the range of 11 - 11.5, and stirring was continued at a speed of 200 r / min for 5 min to obtain suspension B; suspension B was placed in a water bath at 40 °C and magnetically stirred at a speed of 400 r / min for 24 h to obtain suspension C; suspension C was subjected to vacuum filtration to obtain film material D; the filtered film material D was placed in a vacuum oven at 45 °C and dried for 24 h to obtain calcium silicate hydrate film E.

[0107] The prepared calcium silicate hydrate film was fixed on the conductive glass, and the photocurrent data of the calcium silicate hydrate film were measured using a three-electrode system (Ag / AgCl as the reference electrode, platinum sheet as the counter electrode, conductive glass @ calcium silicate hydrate film as the working electrode). The light source used was a xenon lamp with a wavelength of 200 nm to 400 nm, and the constant voltage was set at 0.2 V. The test results are as Figure 1 shown.

[0108] From Figure 1 It can be seen that for the calcium silicate hydrate film containing 5 parts of cellulose material in Comparative Example 4, no photocurrent generation was observed, indicating that under the excitation of a light source with a wavelength range of 200 nm to 400 nm, it does not have the function of generating photoinduced electrons. In Examples 1 and 2, due to the incorporation of a larger mass fraction of cellulose material, obvious photocurrent signals were observed. Under light source irradiation, the cellulose-modified calcium silicate hydrate film has the ability to generate hydroxyl radicals, and then generates a current signal, which indicates that the cellulose-modified calcium silicate hydrate film has a certain photocatalytic effect. Among them, the photocurrent signal of Example 2 is better, similar to the photocurrent signal of the calcium silicate hydrate film using commercial titanium dioxide (Comparative Example 3).

[0109] The present invention evaluated the ability of the prepared calcium silicate hydrate film to degrade organic dyes (such as methylene blue, congo red, crystal violet, and safranin). The results are as Figure 2 shown. The calcium silicate hydrate film incorporating 5 parts of cellulose material in Comparative Example 4 did not show degradation ability, indicating that it does not have photocatalytic function. In Examples 1-2, by incorporating a larger mass fraction of cellulose material, the calcium silicate hydrate film was successfully endowed with the ability to photocatalytically degrade organic dyes, and this degradation ability is positively correlated with the cellulose content. Comparative Example 3 (using commercial titanium dioxide) showed the best photocatalytic degradation performance, while the cellulose-modified calcium silicate hydrate film with a cellulose material content of 15% (the percentage of cellulose modification in the total mass of calcium and silicon raw materials) showed sub-optimal photocatalytic degradation performance. By adjusting the proportion of cellulose in the present invention, precise regulation of the interfacial interaction was achieved, so that the non-semiconductor composite material has photocatalytic performance comparable to that of semiconductors, realizing the "photoinduced electricity" effect of insulators under light irradiation.

[0110] Regarding the excellent photocatalytic degradation ability of the cellulose-modified calcium silicate hydrate film in Example 2, we tested its ability to repeatedly degrade organic dyes (methylene blue, congo red, crystal violet, and safranin). Five cycles were tested respectively, and its degradation ability was determined by ultraviolet light testing method. The results show that( Figure 3 ) the cellulose-modified calcium silicate hydrate film in Example 2 has the ability to repeatedly degrade organic dyes.

[0111] Referring to the national standard "Textiles - Tensile properties of fabrics - Part 1: Determination of maximum force and elongation at break (strip method)" (GB / T 3923.1-2013), the tensile strength tests were carried out on the above Examples 1-3 and Comparative Examples 1, 2, 4. The test instrument is an electronic universal testing machine.

[0112] Table 1 Physical properties of Examples 1-3 and Comparative Examples 1-2, 4.

[0113] Sample number Example 1 Example 2 Example 3 Comparative example 1 Comparative example 2 Comparative example 4 Tensile strength (MPa) 1.1 6.8 4.1 3.9 4.7 0

[0114] Table 1 shows the results of physical property tests, namely the tensile strength test results. Examples 1-3 and Comparative Example 4 evaluated the effect of the cellulose material content on the tensile strength of the calcium silicate hydrate film. The results showed that the calcium silicate hydrate film with 5 parts of cellulose material had no tensile ability. As the cellulose material content increased, the tensile strength gradually increased. In Example 2, when the cellulose material content was 15%, the calcium silicate hydrate film had the optimal tensile strength. When the cellulose content was further increased to 20%, the agglomeration of the cellulose material would be aggravated, resulting in a decrease in the tensile strength. Comparative Examples 1-2 evaluated the effect of the calcium-silicon ratio in the calcium silicate hydrate film with 15% cellulose material content on the performance. The results showed that when the content of the calcareous material and the siliceous material was 1:1, the calcium silicate hydrate film had the optimal tensile strength.

[0115] Traditional calcium silicate hydrate materials are brittle solid particles, and there are problems such as inconvenient use and difficult replacement in practical applications. Through the modification of cellulose, not only has a breakthrough in photocatalytic ability been achieved, but also excellent toughness has been imparted to the calcium silicate hydrate composite material. Thanks to this, the composite calcium silicate hydrate film of the present invention can be applied in more complex scenarios and is convenient to replace.

[0116] In summary, the present invention prepares a calcium silicate hydrate film with excellent photocatalytic performance, green and pollution-free, and having intrinsic photocatalytic ability, which can achieve the degradation of organic pollutants in water.

[0117] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. Those skilled in the art can obviously make various modifications to these embodiments easily and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A calcium silicate hydrate film with intrinsic photocatalytic ability, characterized in that: The calcium silicate hydrate film is a composite film of calcium silicate hydrate and cellulose.

2. The calcium silicate hydrate film with intrinsic photocatalytic ability according to claim 1, characterized in that: The raw materials include the following components by mass:

3. The calcium silicate hydrate film with intrinsic photocatalytic ability according to claim 2, characterized in that: The calcareous material is selected from any one or more of calcium chloride, calcium nitrate, quicklime, and calcium hydroxide; the siliceous material is selected from any one or more of silica ash, fly ash, rice husk ash, and sodium silicate.

4. The calcium silicate hydrate film with intrinsic photocatalytic ability according to claim 2, characterized in that: The cellulose material is selected from any one or more of natural cellulose, microcrystalline cellulose, cellulose nanocrystals, and nanocellulose.

5. The calcium silicate hydrate film with intrinsic photocatalytic ability according to claim 2, characterized in that: The pH regulator is selected from any one or both of sodium hydroxide and dilute hydrochloric acid.

6. A method for preparing a calcium silicate hydrate film having intrinsic photocatalytic ability according to any one of claims 1 to 5, characterized in that: The steps include: S1. Mix the siliceous material, the calcareous material, the cellulose material and water according to their weight proportions, and stir them evenly to obtain a suspension A; S2. Use a pH modifier to adjust the pH value of suspension A, stir evenly, and obtain suspension B; S3, heating the suspension B in a water bath with stirring to obtain a suspension C; S4, filtering the suspension C to obtain a film material D; S5. Dry the film material D to obtain a calcium silicate hydrate film E with intrinsic photocatalytic ability.

7. The method for preparing a calcium silicate hydrate film having intrinsic photocatalytic ability according to claim 6, characterized in that: In steps S1 and S2, the stirring speed is 100-1000 r / min and the stirring time is 3-60 min; In step S2, the pH value of the suspension A is adjusted to a range of 11-11.

5.

8. The method for preparing a calcium silicate hydrate film having intrinsic photocatalytic ability according to claim 6, characterized in that: In step S3, the water bath heating temperature is 30-70°C, the stirring speed is 300-1000r / min, and the time is 20-28h; In step S5, the drying temperature is 40-70°C and the drying time is 20-28 hours.

9. Use of the calcium silicate hydrate film with intrinsic photocatalytic ability as claimed in any one of claims 1 to 5 in degrading organic pollutants, characterized in that: The following steps are involved: a. placing a calcium silicate hydrate film having intrinsic photocatalytic ability in an aqueous solution of organic pollutants; b. Using a calcium silicate hydrate film with intrinsic photocatalytic ability as a photocatalytic material, irradiating it with a light source with a wavelength of 200-400 nm, so that the calcium silicate hydrate film with intrinsic photocatalytic ability reacts to generate hydroxyl radicals; c. Use the generated hydroxyl free radicals to degrade organic pollutants.

10. The use of a calcium silicate hydrate film with intrinsic photocatalytic ability in degrading organic pollutants according to claim 9, characterized in that: The organic contaminants include methylene blue, Congo red, crystal violet and safranin.

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