CN111559923A

CN111559923A - Preparation method of cement-based material with photocatalytic performance

Info

Publication number: CN111559923A
Application number: CN202010389988.0A
Authority: CN
Inventors: 万克树; 陈悦
Original assignee: Southeast University
Current assignee: Southeast University
Priority date: 2020-05-09
Filing date: 2020-05-09
Publication date: 2020-08-21

Abstract

The invention discloses a preparation method of a cement-based material with photocatalytic performance, which comprises the steps of loading titanium dioxide sol obtained by a sol-gel method on the surface of a cement test block, putting the cement test block into a steam curing box, and obtaining titanium dioxide crystals with anatase structures on the surface of the cement test block after steam curing; the temperature of steam curing is 50-100 ℃, and the time of steam curing is 2-48 h. Compared with the existing internal doping, external doping and coating processes, the method disclosed by the invention has the advantages of saving raw materials of titanium dioxide and good durability, realizes crystallization of titanium dioxide during steam curing of cement, and has certain energy-saving and environment-friendly properties.

Description

Preparation method of cement-based material with photocatalytic performance

Technical Field

The invention relates to a preparation method of a cement-based material with photocatalytic performance, belonging to the technical field of building materials.

Background

While the economy of China is rapidly developed, environmental pollution causes a series of problems. A large amount of pollution media exist in the air, including powder particles in the urban construction process, tail gas discharged by automobiles, oily smoke discharged by industries and kitchens and the like, and the pollution media can not only cause harm to human health, but also be easily adsorbed on the outer wall of a building, thereby greatly influencing the aesthetic property of the building. The most common practice at present is to clean the outer wall of the building periodically, which consumes a lot of manpower and material resources.

Titanium dioxide is a common photocatalyst, and can perform oxidation-reduction reaction with organic pollutants contacting with the surface under illumination, so that the effect of degrading the pollutants is achieved. Therefore, the inventor proposes to combine titanium dioxide with cement-based materials to develop photocatalytic cement-based materials with self-cleaning effect. The common preparation methods of the photocatalytic cement-based material mainly comprise three methods, namely an internal doping method, an external doping method and a loading method. The internal doping method is that titanium dioxide is directly mixed or replaces part of cement and then is directly used in engineering; the external doping method is to coat titanium dioxide suspension on the finished cement-based material; the loading method is to wrap a layer of photocatalytic film outside aggregate and then insert the photocatalytic film on the surface layer of mortar to prepare the concrete. However, these three methods all have certain limitations: the internal mixing method requires the use of a large amount of titanium dioxide powder, waste is easily caused, titanium dioxide in cement is easily wrapped, the photocatalytic efficiency is low, and the durability of the cement is greatly reduced due to hydration and carbonization of the cement; although the photocatalytic efficiency of the photocatalytic cement-based material prepared by the external doping method is higher, the durability of the photocatalytic cement-based material is poor under natural conditions, and titanium dioxide particles are easy to fall off; the loading method is similar to the internal mixing method, and the influence of hydration and carbonization on the photocatalytic effect is large.

The sol-gel method is a common method for preparing titanium dioxide, the reaction process of the method is easy to control, the side reaction is less, the equipment and the process are simple to operate, and the prepared nano titanium dioxide has high purity, good dispersibility, small particle size and uniform distribution. The traditional sol-gel method needs to be roasted at a high temperature of about 500 ℃ at the later stage so as to obtain the titanium dioxide with the anatase crystal form. However, the application of high temperature treatment to the surface of a substrate with poor heat resistance is limited, for example, a common cement-based material cannot withstand high temperature of more than 500 ℃.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a preparation method of a cement-based material with photocatalytic performance, and the method completes the crystallization of titanium dioxide sol on a cement matrix while cement steam curing is carried out, so that the cement-based material has certain photocatalytic performance.

The technical scheme of the invention is as follows:

a preparation method of a cement-based material with photocatalytic performance comprises the steps of loading titanium dioxide sol obtained by a sol-gel method on the surface of a cement test block, putting the cement test block into a steam curing box, and obtaining titanium dioxide crystals with anatase structures on the surface of the cement test block after steam curing; wherein the steam curing temperature is 50-100 ℃, and the steam curing time is 2-48 h.

The titanium dioxide sol on the surface of the cement test block is converted from an amorphous structure into an anatase structure under the action of steam curing.

Wherein the loading thickness of the titanium dioxide sol on the surface of the cement test block is 0.1 mm-1 mm.

Wherein, the loading mode of loading the titanium dioxide sol on the surface of the cement test block is coating, spraying or soaking.

The cement test block is prepared by the following method: mixing and stirring raw materials for preparing a cement matrix to obtain cement paste, pouring and molding, and demolding after cement is hardened to obtain a cement test block.

Wherein the time for loading the titanium dioxide sol on the surface of the cement test block is as follows: and pouring and forming the cement paste for 4-24 hours.

Has the advantages that: compared with the existing internal doping process, the method has the advantage of saving raw materials of titanium dioxide, and compared with the existing external doping and coating processes, the cement-based material with photocatalytic performance prepared by the method has the advantage of good durability; the method is low in cost and environment-friendly, and the problem that the cement-based material cannot bear high-temperature roasting is effectively solved by effectively combining the maintenance of the cement test block and the crystallization of the titanium dioxide sol, namely, the crystallization of the titanium dioxide sol is completed while the steam maintenance of the cement is carried out; finally, the cement-based material obtained by the invention can effectively degrade organic pollutants adsorbed on the surface of cement.

Drawings

FIG. 1 is an XRD spectrum of titanium dioxide sol after being steamed at 80 ℃ for 4 h;

FIG. 2 is a diagram of the photocatalytic degradation of methylene blue by the cement-based material of the present invention under UV irradiation.

Detailed Description

The technical solution of the present invention is described in detail below with reference to the accompanying drawings and examples.

Example 1

The titanium dioxide sol is obtained by the following method: mixing 15mL of absolute ethyl alcohol and 5mL of tetrabutyl titanate to obtain solution A; mixing 5mL of absolute ethyl alcohol, 4mL of acetylacetone and 3mL of deionized water to obtain solution B; adjusting the pH value of the solution B by ammonia water to enable the pH value of the solution B to be 11; slowly pouring the solution B into the solution A, and stirring at constant temperature of 30 ℃ for 1200min to obtain transparent titanium dioxide sol.

Loading titanium dioxide sol on a glass substrate in a coating mode, wherein the coating thickness is 0.5mm, and then placing the glass substrate in a steam curing box for steam curing, wherein the steam curing temperature is 75 ℃, and the steam curing time is 10 h.

Example 1 the crystalline form of titanium dioxide obtained on the glass substrate is anatase, and the XRD pattern is shown in fig. 1, which shows that the steam curing technique can crystallize amorphous titanium dioxide sol to obtain anatase crystalline titanium dioxide.

Example 2

The cement-based material with photocatalytic performance is prepared by the following method: firstly, preparing a cement test block: selecting 100 parts of white portland cement, sieving the white portland cement with a 0.3mm sieve and 35 parts of water according to the mass parts, mixing and stirring the white portland cement and the water to form cement slurry, injecting the cement slurry into a mold, and removing the mold to obtain a cement test block; preparing titanium dioxide sol: mixing 18mL of absolute ethyl alcohol and 6mL of tetrabutyl titanate to obtain solution A; mixing 6mL of absolute ethyl alcohol, 5mL of acetylacetone and 4mL of deionized water to obtain solution B; regulating pH of solution B to 11 with calcium hydroxide solution, slowly dropping solution B into solution A, stirring at constant temperature of 30 deg.C for 1200min to obtain transparent titanium dioxide sol with certain viscosity; and (3) loading the titanium dioxide sol on the cement test block which is 4 hours after the mould is removed in a coating mode, and then putting the cement test block into a steam curing box for steam curing at the steam curing temperature of 80 ℃ for 4 hours to obtain the cement-based material with photocatalytic performance, wherein the surface of the cement test block has anatase-structure titanium dioxide crystals.

The cement-based material with photocatalytic performance prepared in example 2 was used to degrade rhodamine B solution with an initial concentration of 10 mg/L.

Coating the surface layer part of the cement-based material with photocatalytic performance in a scraping way, and grinding into powder; respectively weighing 0.1g of cement powder without titanium dioxide and 0.1g of powder scraped from the surface layer part of the material, respectively putting the powder into two rhodamine B solutions with the initial concentration of 10mg/L, performing ultrasonic dispersion for 10min, stirring the mixture in a dark environment for 30min to achieve adsorption-desorption balance, then taking an ultraviolet lamp as a light source, taking an ultraviolet spectrophotometer as a test instrument, testing the absorbance once every 1h, and testing for 7 h.

As shown in figure 2, compared with cement powder without titanium dioxide, the cement-based material has good photocatalytic degradation capability under ultraviolet light, and the photocatalytic degradation efficiency reaches 97% after 7 hours of ultraviolet irradiation.

Claims

1. A preparation method of a cement-based material with photocatalytic performance is characterized by comprising the following steps: loading titanium dioxide sol obtained by a sol-gel method on the surface of a cement test block, putting the cement test block into a steam curing box, and performing steam curing to obtain titanium dioxide crystals with an anatase structure on the surface of the cement test block; the temperature of steam curing is 50-100 ℃, and the time of steam curing is 2-48 h.

2. The method for preparing a cementitious material with photocatalytic properties according to claim 1, characterized in that: the loading thickness of the titanium dioxide sol on the surface of the cement test block is 0.1 mm-1 mm.

3. The method for preparing a cementitious material with photocatalytic properties according to claim 1, characterized in that: the loading mode of loading the titanium dioxide sol on the surface of the cement test block is coating, spraying or soaking.

4. The method for preparing a cementitious material with photocatalytic properties according to claim 1, characterized in that: the cement test block is prepared by the following method: mixing and stirring raw materials for preparing a cement matrix to obtain cement paste, pouring and molding, and demolding after cement is hardened to obtain a cement test block.

5. The method for preparing a cementitious material with photocatalytic properties according to claim 1, characterized in that: the time for loading the titanium dioxide sol on the surface of the cement test block is as follows: and pouring and forming the cement paste for 4-24 hours.