1. The preparation method of the multifunctional titanium-containing solid waste source cement-based material is characterized by comprising the following steps:

step one, mixing industrial solid waste and titanium white solid waste to obtain a mixture, and then drying, crushing and sieving to obtain mixed powder;

step two, placing the mixed powder in a high-temperature muffle furnace for heating and heat preservation, taking out the mixed powder and quenching the mixed powder in the air to obtain the TiO-doped material₂The solid waste source sulphoaluminate cement clinker;

step three, doping TiO₂The solid waste source sulphoaluminate cement clinker is respectively high in polycarboxylic acid contentAnd mixing the effect water reducing agent and the deionized water, uniformly stirring, pouring into a mold for molding, and then placing into a standard curing room for curing to obtain the titanium-containing solid waste source cement-based material.

2. The preparation method of the multifunctional titanium-containing solid waste source cement-based material according to claim 1, characterized in that: in the mixture obtained in the first step, the mass fraction of the titanium white solid waste is 4-48%.

3. The preparation method of the multifunctional titanium-containing solid waste source cement-based material according to claim 1 or 2, characterized in that: the industrial solid waste comprises the following components in percentage by weight: 15-17% of aluminum powder, 21-23% of desulfurized gypsum, 32-35% of carbide slag and 26-29% of red mud.

4. The preparation method of the multifunctional titanium-containing solid waste source cement-based material according to claim 1 or 2, characterized in that: the titanium dioxide solid waste comprises the following components in percentage by weight: 25-28% of CaO and 21-25% of SiO₂10 to 15% of Al₂O₃10 to 13% of TiO₂11 to 13% of ZrO₂5 to 7% of a sulfate phase, and 6 to 9% of sulfur oxide.

5. The preparation method of the multifunctional titanium-containing solid waste source cement-based material according to claim 1, characterized in that: in the first step, the drying temperature is 100-110 ℃, and the sieved screen is 150-250 meshes.

6. The preparation method of the multifunctional titanium-containing solid waste source cement-based material according to claim 1, characterized in that: in the second step, the heating temperature is 1250-1300 ℃, the heating rate is 5-8 ℃/min, the ambient atmosphere is air, and the heat preservation time is 0.5-1 h.

7. The preparation method of the multifunctional titanium-containing solid waste source cement-based material according to claim 1, characterized in that: in the second step, TiO₂The blending amount of the sulfur accounts for the solid waste source sulfur0.5-5% of the total mass of the aluminate cement clinker.

8. The preparation method of the multifunctional titanium-containing solid waste source cement-based material according to claim 1, characterized in that: in the third step, TiO is doped₂The mass ratio of the solid waste source sulphoaluminate cement clinker to the polycarboxylic acid high-efficiency water reducing agent to the deionized water is 100: 0.2: 40.

9. the preparation method of the multifunctional titanium-containing solid waste source cement-based material according to claim 1, characterized in that: in the third step, the stirring speed is 300-600 rpm, and the stirring time is 3-5 min.

10. The preparation method of the multifunctional titanium-containing solid waste source cement-based material according to claim 1, characterized in that: in the third step, the standard curing room is at a temperature of 20-25 ℃, a relative humidity of 90-95% and a curing time of 1-7 days.

Background

The sulphoaluminate cement-based material is mainly composed of tetracalcium sulphoaluminate (C)₄A₃$), dicalcium silicate (C)₂S) and tetracalcium aluminoferrite (C)₄AF), has a series of advantages of quick solidification time, high early-age strength, large compensation shrinkage and the like, and is very suitable for roadbed materials. But one of the raw materials of the conventional sulphoaluminate cement-based material is Al₂O₃But is expensive and has a certain demand competition with the traditional aluminum industry, which limits the large-scale use of the aluminum.

The traditional general industry is very easy to generate a large amount of industrial waste in the technical production process, such as Al production by Bayer process₂O₃In the process of (1) ton of Al is produced₂O₃1-2 tons of red mud is generated, and in the process of generating acetylene gas by adding water into calcium carbide, 10 tons of calcium carbide slurry with the solid content of about 12 percent can be generated when 1 ton of calcium carbide is consumed. Most of industrial wastes are idle in a damming and accumulating mode in the treatment process, so that a large amount of manpower and material resources are consumed, and certain damage is caused to the ecological environment. Therefore, the design concept of utilizing the urban industrial solid waste components to prepare the sulphoaluminate cementing material in a synergic and complementary manner is provided, the problem of high cost of the sulphoaluminate cement-based material is solved, the problem of urban industrial solid waste treatment is solved, and the 'waste is turned into wealth' is really realized.

The common solid waste source sulphoaluminate cement base can easily obtain higher compressive strength due to the early rapid hydration characteristic, but also causes quite irregular development of the pore structure. This can severely affect the carbon capture of the cement-based material, resulting in a decrease in its carbon sequestration efficiency. The use of nano SiO has been proposed in the existing research₂To modify and refine the pore structure, but with nano-SiO₂Calcium silicate gel formed with calcium hydroxide may also fill the pores, resulting in excessive reduction of the pores. Therefore, how to improve the solid waste source sulphoaluminate cementThe internal pore structure improves the utilization efficiency of solid waste resources, so that the preparation of multifunctional self-cleaning cement-based materials becomes a problem to be solved urgently.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to provide a preparation method of a multifunctional titanium-containing solid waste source cement-based material with carbon capture and photocatalytic pollutant degradation.

The technical scheme is as follows: the invention relates to a preparation method of a multifunctional titanium-containing solid waste source cement-based material, which comprises the following steps:

step one, mixing industrial solid waste and titanium white solid waste to obtain a mixture, and then drying, crushing and sieving to obtain mixed powder;

step two, placing the mixed powder in a high-temperature muffle furnace for heating and heat preservation, taking out the mixed powder and quenching the mixed powder in the air to obtain the TiO-doped material₂The solid waste source sulphoaluminate cement clinker;

step three, doping TiO₂The solid waste source sulphoaluminate cement clinker is respectively mixed with a polycarboxylic acid high-efficiency water reducing agent and deionized water, the mixture is poured into a mould for forming after being uniformly stirred, and then the mould is placed in a standard curing room for curing to obtain the titanium-containing solid waste source cement-based material.

Further, in the mixture obtained in the first step, the mass fraction of the titanium white solid waste is 4-48%; the industrial solid waste comprises the following components in percentage by weight: 15-17% of aluminum powder, 21-23% of desulfurized gypsum, 32-35% of carbide slag and 26-29% of red mud; the titanium dioxide solid waste comprises the following components in percentage by weight: 25-28% of CaO and 21-25% of SiO₂10 to 15% of Al₂O₃10 to 13% of TiO₂11 to 13% of ZrO₂5 to 7% of a sulfate phase, and 6 to 9% of sulfur oxide.

Further, in the first step, the drying temperature is 100-110 ℃, and the sieved screen is 150-250 meshes.

Further, in the second step, the heating temperature is 1250-1300 ℃, the heating rate is 5-8 ℃/min, the ambient atmosphere is air,the heat preservation time is 0.5-1 h; in the second step, TiO₂The mixing amount of the solid waste source sulphoaluminate cement clinker is 0.5-5% of the total mass of the solid waste source sulphoaluminate cement clinker.

Further, in the third step, TiO is doped₂The mass ratio of the solid waste source sulphoaluminate cement clinker to the polycarboxylic acid high-efficiency water reducing agent to the deionized water is 100: 0.2: 40; in the third step, the stirring speed is 300-600 rpm, and the stirring time is 3-5 min; in the third step, the standard curing room is at a temperature of 20-25 ℃, a relative humidity of 90-95% and a curing time of 1-7 days.

The preparation principle of the invention is as follows: industrial waste and titanium white solid waste are mixed homogeneously in different proportion into cement raw material, and at 1250 deg.c, the titanium-containing solid waste source sulfoaluminate cement clinker is prepared, and through the mutual action of the components, tetracalcium sulfoaluminate (C) is produced gradually at high temperature₄A₃$), dicalcium silicate (C)₂S) and tetracalcium aluminoferrite (C)₄AF), and the like, while the titanium element in the titanium white solid waste is stabilized rutile TiO₂The form exists. In the subsequent cement hydration process, TiO₂As a material with better chemical stability, the material does not participate in hydration reaction, only provides nucleation sites for hydration products in the form of 'catalyst', reduces the potential barrier of the hydration reaction and then promotes the reaction process; simultaneous TiO 2₂Plays a role in filling in the aspect of physics, preferentially adsorbs at the irregular edges of macropores, reduces the pore volume of macropores, improves the pore volume of micropores, and leads the pore appearance to be more spherical. Introduction of TiO by using titanium dioxide solid waste₂The method has the advantages that the cost is reduced, the ecological environment is protected, meanwhile, the photocatalytic oxidation-reduction degradation performance is provided, the cement-based pore structure is regulated and controlled, the formation, filling and modification of pores inside cement and the crystallization, nucleation and growth of ettringite crystals are mainly involved, and finally, the photocatalytic/carbon capture performance of the titanium-containing solid waste source cement-based material is greatly improved.

Due to TiO₂When the cement matrix is exposed to strong ultraviolet radiation, the energy of photons can be absorbed by the energy band, and photogenerated holes can be generated on the valence bandAn electron pair (h +, e-) and causes the electron to move from the valence band towards the conduction band. Electrons and holes active in the conduction and valence bands are highly susceptible to free radicals (O) in the ambient environment₂OH-) to form a reactive radical (O) corresponding thereto^2-OH) which can then undergo a series of reactive oxidation and reduction chemical reactions with the reactants. Thus, nano TiO₂Can pass through active free radicals excited by ultraviolet light and adsorb on nano TiO₂The harmful pollutants on the surface react to degrade the organic pollutants.

Because the pore structure is more uniform, compact and spherical, the cement is more beneficial to carbon capture, and CO is generated in the reaction process₂Firstly, the water-soluble polymer is quickly dissolved in a pore solution of a cement-based material to form H₂CO₃. During hydration induction period, C₂S and C₄A₃Hydrolysis to produce Ca²⁺And H₂CO₃Combined neutralization to produce CaCO₃And (4) precipitating. Due to Ca in the solution²⁺Is rapidly consumed, resulting in C₂Further hydrolysis of S to make Ca²⁺A dynamic equilibrium process occurs in the concentration; during the hydration acceleration period, a large amount of hydration products such as ettringite, C-S-H gel, silicate phase and aluminate phase are generated, the decalcification phenomenon occurs in the carbon capture environment, and a large amount of Ca is also generated in the water environment²⁺With H in the pore liquid₂CO₃Combined formation of CaCO₃. The specific carbon capture equations for the two major carbon capture reactants, ettringite and C-S-H gel, are shown below: 3 CaO. Al₂O₃·3CaSO₄·32H₂O+3CO₂→3CaCO₃+3CaSO₄+Al₂O₃·XH₂O+(32-X)H₂O； (CaO)x(SiO₂)y(H₂O)z+XCO₂→XCaCO₃+y(SiO₂)(H₂O)t+(z-yt)H₂O。

Has the advantages that: compared with the prior art, the invention has the following remarkable advantages: the addition of a proper amount of titanium dioxide solid waste in the raw materials can be introduced into the obtained cement clinkerRutile type TiO₂The pore structure can be obviously regulated and controlled in the subsequent hydration process, so that the pore structure is more uniform, densified and spheroidized, the hydration of the solid waste source sulphoaluminate cement is promoted, and the further crystallization, nucleation and growth of the ettringite crystal are promoted. The titanium-containing solid waste source sulphoaluminate cement-based material has higher photocatalysis/carbon capture effect on organic matters and carbon oxides (COx), and has the advantages of low cost, simple operation, short flow and no secondary pollution.

Drawings

FIG. 1 is a graph comparing the specific surface areas of cement-based materials prepared in examples 1-4;

FIG. 2 shows different TiO examples 1 to 4₂Hydration heat test chart of the mixed amount cement clinker in the hydration process;

FIG. 3 is a graph comparing the compressive strength of cement-based materials prepared in examples 1-4 before and after carbonation;

FIG. 4 is a graph illustrating photocatalytic degradation testing of cement-based materials prepared in examples 3 and 4;

figure 5 is a comparison of the carbon capture test for cement-based materials prepared in examples 1-4.

Detailed Description

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

In the following examples, the cement-based material raw meal mainly comprises the following components in percentage by mass:

general industrial solid waste: 15-17% of aluminum powder, 21-23% of desulfurized gypsum, 32-35% of carbide slag and 26-29% of red mud;

titanium white solid waste: 25-28% CaO, 21-25% SiO₂、10～15％Al₂O₃、10～13％TiO₂11 to 13% of ZrO₂5 to 7% of a sulfate phase, and 6 to 9% of sulfur oxide.

The used desulfurized gypsum is provided by chatting a coal-fired power plant, the red mud and the aluminum powder are provided by a new group, the carbide slag is provided by chatting acetylene company, and the titanium white solid waste (titanium extraction tailings) is provided by a certain titanium industry company Limited in Panzhihua city.

Example 1

(1) Mixing industrial solid waste and titanium white solid waste, wherein the mass fraction of the titanium white solid waste in the mixture is 4.68%, respectively, then drying at 105 ℃ until a constant mass is observed, and then crushing the mixture to pass through a 200-mesh sieve to obtain mixed powder;

(2) heating the mixed powder in a high-temperature muffle furnace to 1250 ℃, wherein the heating rate is 5 ℃/min, the ambient atmosphere is air, and keeping the temperature for 0.5h to obtain the product doped with 0.5 wt% of TiO₂The titanium-containing solid waste source sulphoaluminate cement clinker;

(3) mixing 100g of titanium-containing solid waste source sulphoaluminate cement clinker, 0.2g of polycarboxylic acid high-efficiency water reducing agent and 40g of deionized water, immediately starting stirring, wherein the stirring speed is 300rpm, the stirring time is 3min, uniformly stirring, pouring into a mold with the size of 20mm multiplied by 20mm for molding, then placing in a standard curing room, and curing for 1 day under the conditions of 20 ℃ and relative humidity of 90% to obtain the titanium-containing solid waste source cement-based material.

Example 2

(1) Mixing industrial solid waste and titanium white solid waste, wherein the mass fraction of the titanium white solid waste in the mixture is respectively 9.35%, then drying at 100 ℃ until constant mass is observed, and then crushing the mixture to pass through a 200-mesh sieve to obtain mixed powder;

(2) heating the mixed powder in a high-temperature muffle furnace to 1300 ℃, wherein the heating rate is 8 ℃/min, the ambient atmosphere is air, and keeping the temperature for 1h to obtain the product doped with 1 wt% of TiO₂The titanium-containing solid waste source sulphoaluminate cement clinker;

(3) mixing 100g of titanium-containing solid waste source sulphoaluminate cement clinker, 0.2g of polycarboxylic acid high-efficiency water reducing agent and 40g of deionized water, immediately starting stirring at the stirring speed of 600rpm for 5min, uniformly stirring, pouring into a mold with the size of 20mm multiplied by 20mm for molding, then placing into a standard curing room, and curing for 1 day at the temperature of 25 ℃ and the relative humidity of 95% to obtain the titanium-containing solid waste source cement-based material.

Example 3

(1) Mixing industrial solid waste and titanium white solid waste, wherein the mass fraction of the titanium white solid waste in the mixture is 46.8%, respectively, then drying at 100 ℃ until a constant mass is observed, and then crushing the mixture to pass through a 200-mesh sieve to obtain mixed powder;

(2) placing the mixed powder in a high-temperature muffle furnace to heat to 1250 ℃, wherein the heating rate is 5 ℃/min, the ambient atmosphere is air, and the temperature is kept for 0.5h to obtain the product doped with 5 wt% of TiO₂The titanium-containing solid waste source sulphoaluminate cement clinker;

(3) mixing 100g of titanium-containing solid waste source sulphoaluminate cement clinker, 0.2g of polycarboxylic acid high-efficiency water reducing agent and 40g of deionized water, immediately starting stirring, wherein the stirring speed is 450rpm, the stirring time is 3min, uniformly stirring, pouring into a mold with the size of 20mm multiplied by 20mm for molding, then placing into a standard curing room, and curing for 1 day under the conditions of 20 ℃ and relative humidity of 90% to obtain the titanium-containing solid waste source cement-based material.

Example 4

The specific preparation scheme is the same as that of example 1, except that only industrial solid waste is used, and titanium dioxide solid waste is not added, so that 0 wt% TiO is doped₂The solid waste source sulphoaluminate cement clinker is cured under the same conditions to obtain a solid waste source cement-based material for comparison.

Example 5

Taking the cement-based material in the embodiment 1-4, removing the mold, and continuously maintaining until the hydration day 7, taking the particles with the diameter of about 2-3 mm at the center of the cube sample test block for counting. Testing the specific surface area of the sample by using a full-automatic micropore physical adsorption analyzer to detect that the environmental atmosphere is N₂The test pore diameter range is 0-50 nm. Referring to fig. 1, the introduction of titanium white solid waste reduces the specific surface area of the sample, wherein the titanium-containing solid waste source is sulphoaluminate cement (1% TiO)₂) The sample is reduced by only 23.5 percent relative to the rest doping amount, and still maintains larger specific surface area, while TiO₂The samples with the content of 0.5 percent and 5 percent respectively reduce the corresponding specific surface area by 38.8 percent and 38.6 percent, the reduction range is larger than one third, which indicates that the TiO₂The introduction of (b) will reduce the specific surface area of the sample to a certain extent, i.e. the porosity of the sample is reducedSmall but due to TiO₂At 1%, the component (b) is more preferentially adsorbed at irregular corners of large pores, so that the specific surface area of the component (b) is still higher than that of other doped samples.

Example 6

Doping of different TiO's to examples 1-4₂Carrying out hydration heat test on the cement clinker with the content according to the ratio of 100: 0.2: and 40, mixing the cement clinker, the polycarboxylic acid high-efficiency water reducing agent and the deionized water, immediately starting stirring at the stirring speed of 300rpm for 1min, then quickly pouring into a container corresponding to the isothermal calorimeter, pouring 8-10 g of slurry, screwing a cover cap, quickly placing the container into the isothermal calorimeter, detecting the temperature at 20 ℃, and detecting the environment atmosphere to be air. Referring to fig. 2, the results show that the introduction of titanium dioxide solid waste promotes the early hydration process, the forward movement of the thermal peak and the increase of the corresponding peak. And with TiO₂The doping amount is increased, the forward span of the peak value is enlarged, the corresponding peak value is enlarged, and 5 percent of TiO₂The mixing amount is 186min earlier than the heat release peak of the control group, and the peak value is increased by 36 percent. This indicates that TiO₂The addition of the composite can promote the hydration process of cement, improve the hydration rate and increase the amount of hydration products, which is beneficial to carbon fixation and photocatalysis.

Example 7

The cement-based materials obtained in examples 1-4 were divided into two groups, one group was naturally cured for 3 days (20 ℃ C., relative humidity 70%); the other group was maintained in a carbon trap box for 3 days (20 ℃, relative humidity 70%, CO2 concentration 20%), and the two groups of samples were subjected to compressive strength tests. See FIG. 3, and TiO-free₂Comparison of samples of (1%) titanium-containing solid waste source sulphoaluminate cement₂) The compressive strength of the sample which is not carbonized for 7 days is obviously improved, the compressive strength is improved by 8.2 percent, and the compressive strength of the sample which is 7 days after carbon capture is still the highest in all the samples with the doping amount. This suggests that the carbonization process is via hydration products such as ettringite, calcium silicate hydrate gel and CO₂A chemical reaction occurs which generally results in the breakdown of the hydration products, which in turn reduces the compressive strength of the cement. But due to 1% TiO₂Promoting early hydrationThe process, which produces a large amount of hydration products, allows the sample to retain a high compressive strength after carbonization.

Example 8

The cement-based materials obtained in the examples 3 and 4 are demolded and maintained until the hydration day 7, and square titanium-containing solid waste source sulphoaluminate cement-based material sheets with the size of 20mm multiplied by 3mm are prepared. Adding the slices into a RhB solution with the volume of 50mL and the concentration of 20mg/L, adsorbing for 40min under the dark condition, then opening a 250w mercury ultraviolet lamp for photocatalytic degradation, wherein the illumination time is 4h, sampling every 0.5h, centrifuging, taking a supernatant, centrifuging at the rotation speed of 10000rpm for 6min, placing the supernatant into a purple light spectrometer for detecting the RhB concentration, and taking a peak value at 554nm to draw a degradation degree time-dependent graph. Referring to FIG. 4, a titanium-containing solid waste source sulphoaluminate cement (5% TiO) is compared to the sample of example 4₂) The removal rate of the sample to the waste organic matters such as RhB and the like within 4h reaches 80.27 percent, which is 2.54 times of that of pure solid waste source sulphoaluminate cement (the removal rate to the waste organic matters such as RhB and the like within 4h is only 31.6 percent). Description of TiO₂The doping of the organic compound is excited by light to generate a photoproduction electron-vacancy pair, so that the degradation efficiency of the organic compound is effectively improved.

Example 9

The cement-based material obtained in examples 1 to 4 was demolded and maintained until the 3 rd day of hydration, and the sample was placed in a carbon trap box and maintained for 3 days (20 ℃, relative humidity 70%, CO)₂Concentration of 20%), drying and grinding the sample, sieving with a 60-mesh sieve, taking 10mg of the sample, and performing thermogravimetric analysis to detect ettringite and CaCO₃Content, detection environment condition is N₂The temperature range of the atmosphere is 25-1000 ℃, the heating rate is 10 ℃/min, and the cooling rate is 5 ℃/min. Referring to FIG. 5, the titanium-containing solid waste source sulphoaluminate cement (1% TiO) is compared with the control group₂) The carbon capture rate of the sample is obviously improved, CaCO₃The content, namely the carbon capture rate is improved by 34 percent. This illustrates TiO₂The doping can obviously improve the carbon fixation effect of the cement sample, and greatly reduce CO₂In which TiO is discharged₂When the content of (A) is 1%, the pore structure and pores are alignedReasonable optimization is carried out, and in the early hydration process, hydration active sites are provided, the hydration reaction rate is promoted, and more hydration products are generated in the early stage. This allows for better carbon sequestration efficiency than other spiked samples.

In conclusion, the titanium-containing solid waste source sulphoaluminate cement is prepared by utilizing industrial solid waste and titanium white solid waste according to different proportions, and the way of photocatalysis/degradation of organic matters and carbon oxides (COx) is carried out, so that the removal effect of the organic matters and the carbon oxides (COx) in the automobile exhaust is more outstanding, and higher compressive strength is still maintained: 3 days later, the titanium-containing solid waste source sulphoaluminate cement (1% TiO)₂) Compared with pure solid waste source sulphoaluminate cement (0 percent TiO)₂) The carbon trapping degree is improved by 34%; titanium-containing solid waste source sulphoaluminate cement (5% TiO) within 4h₂) The removal rate of the organic matters such as RhB reaches 80.27 percent, and the removal effect is pure solid waste source sulphoaluminate cement (0 percent TiO)₂) The removal rate of organic matters such as RhB and the like in 4h is only 31.6 percent, which is 2.54 times that of the prior art; compared with a control group when hydrated for 7 days, the titanium-containing solid waste source sulphoaluminate cement (1 percent TiO)₂) The compressive strength of the sample is improved by 8.2%, and the compressive strength after carbon capture is still the highest in all the doped samples. The titanium-containing solid waste source sulphoaluminate cement becomes a novel photocatalysis/carbon capture material which is environment-friendly, simple in treatment process and low in cost benefit, and is suitable for popularization and application.