Titanium modified calcium aluminum compound and preparation method thereof, chlorine removal method of chlorine-containing industrial wastewater and regeneration application of chlorine removal product

Abstract

The invention relates to the technical field of wastewater dechlorination and resource utilization, in particular to a titanium-modified calcium-aluminum compound and a preparation method thereof, a dechlorination method of chlorine-containing industrial wastewater and regeneration application of a dechlorination product, and specifically, a calcium-containing raw material, an aluminum-containing raw material and a titanium-containing raw material are uniformly mixed and calcined to obtain the titanium-modified calcium-aluminum compound; the titanium modified calcium aluminum compound is low in raw material price, simple to prepare, clean and environment-friendly, and has a good dechlorination effect when being used for removing chloride ions in industrial wastewater, and the obtained dechlorination product can be subjected to dechlorination regeneration, can be used for dechlorination of industrial wastewater in a follow-up cycle for many times, and has a good recycling value.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater dechlorination and resource utilization, and specifically relates to titanium-modified calcium aluminate compounds and their preparation methods, a method for dechlorinating chlorine-containing industrial wastewater, and the recycling application of dechlorination products. Background Art

[0002] Desulfurization wastewater from industries such as coal-fired power plants and iron and steel smelting has become a difficult area in industrial pollution control due to its extremely high chloride concentration. Excessive chlorides entering the water can cause serious erosion, corrode metal pipes and buildings, and entering the soil can cause soil compaction, leading to salinization, and is more likely to cause poisoning of organisms and humans. Therefore, it is extremely important to effectively treat chlorine-containing wastewater.

[0003] In the chemical precipitation method, the ettringite method has more convenient operability and higher cost-effectiveness compared to other methods because its preparation raw materials are widely available, the cost is low, and the obtained dechlorination agent can effectively react with chloride ions to form insoluble Friedel's salt precipitates. Therefore, the ettringite method has strong applicability and a broader application prospect for removing chloride ions from industrial cooling water, rare earth smelting, and flue gas desulfurization wastewater. The large amount of sludge produced by the ettringite method, and the effective treatment and resource recycling of the main phase Friedel's salt in it are of great significance for the wide application of the Friedel's salt precipitation dechlorination method.

[0004] Ettringite (Ca 12 A1 14 0 33 ) is a functional material with a cage-like crystal structure and great application prospects in the CaO-A12O3 binary system. It has good room temperature stability, is easy to dope with various metal ions, and can realize the transformation from insulator to conductor, and has important application prospects in many fields such as electronic devices, electrochemistry, catalysis, and sensing elements. Porous bulk materials have been widely used in fields such as filtration, separation, adsorption, electrochemistry, and optoelectronic devices due to their unique pore structures. However, there are still problems of large addition amount and low efficiency in using ettringite to treat chloride ions in industrial wastewater. Summary of the Invention

[0005] In order to improve the efficiency of using ettringite to treat chloride ions in desulfurization wastewater and reduce the dosage of ettringite at the same time, the present invention provides titanium-modified calcium aluminate compounds and their preparation methods, a method for dechlorinating chlorine-containing industrial wastewater, and the application of dechlorination products. The present invention introduces titanium into calcium aluminate compounds and uses this material for dechlorination treatment of chlorine-containing desulfurization wastewater, which can not only greatly improve the degradation efficiency, but also reduce the material usage, lower the cost, and at the same time, the dechlorination products can be dechlorinated and regenerated for cyclic dechlorination.

[0006] To achieve the above objectives, the present invention is realized through the following technical solutions:

[0007] The first aspect of the present invention provides a method for preparing a titanium-modified calcium-aluminum compound, comprising the following steps:

[0008] Mix a calcium-containing raw material, an aluminum-containing raw material and a titanium-containing raw material evenly and then calcine to obtain a titanium-modified calcium-aluminum compound;

[0009] Wherein, the calcium-containing raw material and the aluminum-containing raw material are mixed in a ratio of the molar ratio of element Ca:Al of (1 - 1.3):1; the mass proportion of element titanium in the titanium-containing raw material in the titanium-modified calcium-aluminum compound is in the range of 0% - 20%.

[0010] Further, the calcium-containing raw material is selected from one or more of calcium oxide, calcium hydroxide, calcium chloride, limestone, dolomite, steel slag, and gypsum;

[0011] The aluminum-containing raw material is selected from one or more of aluminum oxide, aluminum hydroxide, polyaluminum chloride, aluminum nitrate, alunite, and fly ash;

[0012] The titanium-containing raw material is selected from one or more of titanium dioxide, titanium sesquioxide, titanium tetraisopropoxide, titanium tetrachloride, and titanium tetrabromide.

[0013] Further, the calcination is carried out by heating to 800 - 1400°C at a heating rate of 3 - 5°C / min and holding at this temperature for 2 - 6 h.

[0014] Further, the mixing of the calcium-containing raw material, the aluminum-containing raw material and the titanium-containing raw material is dry mixing and / or wet mixing. During mixing, stirring is carried out, the temperature during mixing is 20 - 60°C, and the total mixing time is 1 - 5 h.

[0015] The second aspect of the present invention provides a titanium-modified calcium-aluminum compound prepared by the above preparation method.

[0016] The third aspect of the present invention provides a method for removing chlorine from industrial wastewater containing chlorine. The titanium-modified calcium-aluminum compound prepared by any of the above methods is used as a chlorine remover and put into industrial wastewater containing chlorine with a chloride ion content of at least 3000 mg / L, and stirring reaction is carried out to remove chloride ions in the wastewater.

[0017] Further, the dosage of the titanium-modified calcium-aluminum compound in the industrial wastewater containing chlorine is 0.1 - 200 g / L; the temperature of the stirring reaction is from normal temperature to 80°C, and the reaction time is 1 - 12 h. The industrial wastewater is chlorine-containing desulfurization wastewater.

[0018] The fourth aspect of the present invention provides a regenerative application of the dechlorination product. After the titanium-modified calcium-aluminum compound prepared by any of the above methods is used for dechlorinating industrial wastewater containing chlorine, the solid part is dried and ground to obtain a dechlorination product;

[0019] Water is added to the dechlorinated product, and photocatalytic dechlorination is carried out under stirring at room temperature with light irradiation. After drying, it is calcined and regenerated to obtain titanium-modified calcium aluminate compounds, which are used for dechlorination of industrial wastewater containing chlorine for multiple cycles.

[0020] Furthermore, the time for photocatalytic dechlorination is 1 - 5 h; ultraviolet light is used for photocatalytic irradiation, and the wavelength range is 200 - 400 nm; the stirring speed during photocatalysis is 400 - 600 rpm;

[0021] The temperature for calcination and regeneration is 200 - 600 °C, and the time is 1 - 3 h;

[0022] The number of times of recycling use is 5 - 10 times.

[0023] Beneficial technical effects:

[0024] In the present invention, titanium-modified calcium aluminate compounds are obtained by using titanium to modify calcium aluminate compounds. The process is simple and the operation is convenient. The obtained titanium-modified calcium aluminate compounds are compatible with titanium compounds, improving the reactivity of ettringite to chlorine, having a good ability to remove chloride ions in industrial wastewater, and the dechlorination efficiency can reach 64.4% - 89.9%; in the titanium-modified calcium aluminate compounds of the present invention, the titanium dioxide generated by calcination can absorb ultraviolet light to form highly active electron-hole pairs, and these carriers can react with substances such as water and oxygen to generate strongly oxidizing free radicals, thereby degrading chloride ions in water to achieve the purpose of wastewater dechlorination; and the obtained dechlorinated products can be recycled and regenerated for multiple cycles of dechlorination;

[0025] The method of the present invention can significantly reduce the operating cost. The regeneration process can reuse the existing dechlorinating agent, reducing the consumption of new materials; cyclic dechlorination helps to reduce waste generation and environmental impact, conforms to the principle of sustainable development, and the dechlorination efficiency can reach 7.1% - 74.8%. Description of the Drawings

[0026] Figure 1 It is the XRD pattern of the titanium-modified calcium aluminate compound prepared in Example 1;

[0027] Figure 2 It is the SEM image of the titanium-modified calcium aluminate compound prepared in Example 1;

[0028] Figure 3 It is the SEM image of the dechlorinated product obtained by dechlorinating industrial wastewater with the titanium-modified calcium aluminate compound prepared in Example 1. Detailed Embodiments

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments and drawings of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way limits the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0030] Unless otherwise specifically stated, the numerical values set forth in these embodiments do not limit the scope of the present invention. Technologies and methods known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such technologies and methods should be regarded as part of the specification. In all examples shown and discussed herein, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0031] For the experimental methods without specific conditions noted in the following embodiments, they are generally determined according to national standards; if there are no corresponding national standards, they are carried out according to general standard requirements or general methods.

[0032] The following content percentages represent mass percentages (i.e., mass percentage content wt%).

[0033] Example 1

[0034] (1) Preparation of titanium-modified calcium aluminate compound:

[0035] Take 56 g of calcium oxide and 102 g of aluminum oxide in a container according to the molar ratio of element Ca:Al of 1:1, and then add 0 g, 1.7 g, 5.2 g, 8.7 g, 17.3 g, and 26 g of titanium tetraisopropoxide (TTIP) respectively. Stir at room temperature for 4 h. After mixing evenly, heat it in a muffle furnace at a heating rate of 5 °C / min to 1200 °C and keep it at this temperature for 4 hours, and then cool it at a cooling rate of 5 °C / min to 1000 °C. Take it out and grind it to obtain a series of titanium-modified calcium aluminate compounds with titanium element content percentages of 0%, 1%, 3%, 5%, 10%, and 15%.

[0036] The XRD patterns of the above series of titanium-modified calcium aluminate compounds with different titanium element content percentages are as Figure 1 shown. It can be seen from Figure 1 that as the amount of titanium added continuously increases, the titanium dioxide peak also gradually strengthens, proving that titanium elements have been successfully doped into the ettringite.

[0037] The SEM image of the titanium-modified calcium aluminate compound with a titanium element content percentage of 3% is as Figure 2 shown. It can be seen from Figure 2It can be seen that there are particulate matters loaded on the material surface.

[0038] (II) Chlorine removal method for industrial wastewater containing chlorine

[0039] Take 1 g of the above series of titanium-modified calcium aluminate compounds with titanium element content ratios of 0%, 1%, 3%, 5%, 10%, and 15% respectively, and add them to 20 mL of industrial wastewater with a chlorine ion concentration of 5000 mg / L. Stir and react at room temperature for 4 hours at a rotation speed of 500 rpm for chlorine removal. Then, use potentiometric titration to measure the remaining chlorine ion content in the liquid, and the results are shown in Table 1.

[0040] Table 1 Chlorine removal effect of titanium-modified calcium aluminate compounds with different titanium element content ratios on industrial wastewater

[0041]

[0042] As can be seen from Table 1, when the titanium element content ratio is 3%, the chlorine removal effect reaches 89.9%. When the dosage of the titanium-modified calcium aluminate compound is small, the chlorine ion removal efficiency has been greatly improved.

[0043] (III) Chlorine removal product

[0044] In the reaction of (II): After removing chlorine from industrial wastewater with the titanium-modified calcium aluminate compound with a titanium element content ratio of 3%, filter out the solid part of the precipitate and place it in an oven to dry at a temperature of 80 °C, and grind to obtain the chlorine removal product. The SEM diagram of this chlorine removal product is as Figure 3 shown, and it can be seen that it has a flaky structure. The chlorine removal product is reserved for subsequent regeneration.

[0045] Example 2

[0046] (I) Preparation of titanium-modified calcium aluminate compound:

[0047] Take 74 g of calcium hydroxide and 131 g of ferric aluminate in a container according to the molar ratio of element Ca:Al of 1:1, and then add 0 g and 17.1 g of titanium dioxide respectively. Stir at room temperature for 1 h, mix evenly, then heat in a muffle furnace at a heating rate of 5 °C / min to 800 °C and keep it at this temperature for 6 hours, and then cool at a cooling rate of 5 °C / min to 600 °C, take out, and grind to obtain titanium-modified calcium aluminate compounds with titanium element content ratios of 0% and 5%.

[0048] (II) Chlorine removal method for industrial wastewater containing chlorine

[0049] 0.6 g of the above-mentioned titanium-modified calcium aluminate compounds with a titanium element content ratio of 0% and 5% were respectively added to 20 mL of industrial wastewater with a chloride ion concentration of 10,000 mg / L, and stirred at a rotation speed of 500 rpm at room temperature for 3 hours for chlorine removal. Then, the remaining chloride ion content in the liquid was measured by potentiometric titration, and the results are shown in Table 2.

[0050] Table 2 Chlorine removal effect of titanium-modified calcium aluminate compounds with different titanium element content ratios on industrial wastewater

[0051]

[0052] As can be seen from Table 2, when the titanium element content ratio is 5%, the chlorine removal effect reaches 71.4%. When the dosage of the titanium-modified calcium aluminate compound is small, the chlorine ion removal efficiency has been greatly improved.

[0053] (III) Chlorine removal product

[0054] In the reaction of (II): After the industrial wastewater is dechlorinated with the titanium-modified calcium aluminate compound with a titanium element content ratio of 5%, the solid part is filtered out by precipitation and placed in an oven to be dried at a temperature of 50 °C, and then ground to obtain the chlorine removal product. The chlorine removal product is reserved for subsequent regeneration.

[0055] Example 3

[0056] (I) Preparation of titanium-modified calcium aluminate compound:

[0057] 100 g of calcium carbonate and 117 g of aluminum carbonate were taken in a container according to the molar ratio of element Ca:Al of 1.2:1, and 0 g and 10.9 g of the titanium-containing raw material titanium dioxide were respectively added. After stirring at room temperature for 12 h and mixing evenly, it was heated in a muffle furnace to 1000 °C at a heating rate of 5 °C / min and held at this temperature for 5 hours, and then cooled to 900 °C at a cooling rate of 5 °C / min, taken out, and ground to obtain titanium-modified calcium aluminate compounds with a titanium element content ratio of 0% and 5%.

[0058] (II) Chlorine removal method for chlorine-containing industrial wastewater

[0059] 2 g of the above-mentioned titanium-modified calcium aluminate compounds with a titanium element content ratio of 0% and 5% were respectively added to 20 mL of industrial wastewater with a chloride ion concentration of 3000 mg / L, and stirred at a rotation speed of 500 rpm at room temperature for 2 hours for chlorine removal. Then, the remaining chloride ion content in the liquid was measured by potentiometric titration, and the results are shown in Table 3.

[0060] Table 3 Chlorine removal effect of titanium-modified calcium aluminate compounds with different titanium element content ratios on industrial wastewater

[0061]

[0062]

[0063] As can be seen from Table 3, when the proportion of titanium element is 5%, the chlorine removal effect reaches 64.4%. When the amount of titanium-modified calcium aluminate compound is small, the removal efficiency of chloride ions has been greatly improved.

[0064] (III) Chlorine removal product

[0065] In the reaction of (II): After using the titanium-modified calcium aluminate compound with 5% titanium element content to remove chlorine from industrial wastewater, the solid part of the precipitate is filtered out and placed in an oven to be dried at a temperature of 100 °C, and then ground to obtain the chlorine removal product. The chlorine removal product is reserved for subsequent regeneration.

[0066] Example 4

[0067] (I) Preparation of titanium-modified calcium aluminate compound:

[0068] Take 164 g of calcium nitrate and 81 g of aluminosilicate according to the molar ratio of element Ca:Al of 1.3:1 and place them in a container. Then add 0 g and 24.5 g of titanium-containing raw material titanium tetrachloride respectively, stir at room temperature for 8 h, mix evenly, then heat up to 1300 °C at a heating rate of 5 °C / min in a muffle furnace and keep it at this temperature for 3 hours, and then cool down to 1100 °C at a cooling rate of 5 °C / min, take out and grind to obtain titanium-modified calcium aluminate compounds with titanium element contents of 0% and 10%.

[0069] (II) Chlorine removal method for chlorine-containing industrial wastewater

[0070] Take 3 g of the above titanium-modified calcium aluminate compounds with titanium element contents of 0% and 10% respectively, add them to 20 mL of industrial wastewater with a chloride ion concentration of 8000 mg / L, stir and react at room temperature for 5 hours at a rotation speed of 500 rpm for chlorine removal, and then use potentiometric titration to measure the remaining chloride ion content in the liquid. The results are shown in Table 4.

[0071] Table 4 Chlorine removal effect of titanium-modified calcium aluminate compounds with different titanium element contents on industrial wastewater

[0072]

[0073] As can be seen from Table 4, when the proportion of titanium element is 10%, the chlorine removal effect reaches 73.1%. When the amount of titanium-modified calcium aluminate compound is small, the removal efficiency of chloride ions has been greatly improved.

[0074] (III) Chlorine removal product

[0075] In reaction (2): After removing chlorine from industrial wastewater using a titanium-modified calcium-aluminum compound with a titanium element content of 10%, the solid part is precipitated and filtered out, placed in an oven, dried at a temperature of 70 °C, and ground to obtain a chlorine-removing product. The chlorine-removing product is reserved for subsequent regeneration.

[0076] Example 5

[0077] (1) Preparation of titanium-modified calcium-aluminum compound:

[0078] Take 162 g of calcium bicarbonate and 171 g of aluminum sulfate according to the molar ratio of element Ca:Al of 1:1 and place them in a container. Then, add 0 g and 383.4 g of titanium-containing raw material titanium tetrabromide respectively, stir at room temperature for 10 h, mix evenly, heat in a muffle furnace at a heating rate of 5 °C / min to 1000 °C, hold at this temperature for 5 hours, then cool at a cooling rate of 5 °C / min to 900 °C, take out, and grind to obtain titanium-modified calcium-aluminum compounds with a titanium element content of 0% and 15%.

[0079] (2) Method for removing chlorine from industrial wastewater containing chlorine

[0080] Take 4 g of the above-mentioned titanium-modified calcium-aluminum compounds with a titanium element content of 0% and 15% respectively, add them to 20 mL of industrial wastewater with a chloride ion concentration of 15000 mg / L, heat to 50 °C, stir and react for 6 hours at a rotation speed of 500 rpm to remove chlorine. Then, use potentiometric titration to measure the remaining chloride ion content in the liquid. The results are shown in Table 5.

[0081] Table 5 Chlorine removal effect of titanium-modified calcium-aluminum compounds with different titanium element content ratios on industrial wastewater

[0082]

[0083] As can be seen from Table 5, when the titanium element content ratio is 15%, the chlorine removal effect reaches 67.5%. When the dosage of the titanium-modified calcium-aluminum compound is small, the chloride ion removal efficiency has been greatly improved.

[0084] (3) Chlorine-removing product

[0085] In reaction (2): After removing chlorine from industrial wastewater using a titanium-modified calcium-aluminum compound with a titanium element content of 15%, the solid part is precipitated and filtered out, placed in an oven, dried at a temperature of 110 °C, and ground to obtain a chlorine-removing product. The chlorine-removing product is reserved for subsequent regeneration.

[0086] The titanium-modified calcium aluminate compound obtained by the present invention above can improve the removal efficiency of chloride ions in desulfurized wastewater. The reasons are as follows: After titanium modification, the specific surface area of the calcium aluminate compound material increases, a large number of Ti-OH groups are introduced, the active sites on the material surface are increased, inner-sphere complexes are formed with chloride ions, and the adsorption performance of the material for chloride ions is improved. In addition, titanium modification can also introduce negative charges. The strong polarization ability of titanium ions increases the interlayer charge density, enhances the ion exchange ability and ion selectivity of the material surface, and improves the adsorption selectivity for chloride ions.

[0087] Example 6

[0088] The regeneration application of the dechlorination product is as follows:

[0089] Take 2 g of the dechlorination product obtained in Example 1 (III) (the dechlorination product with a titanium element content ratio of 3%) and add it to 20 mL of deionized water. Set two parallel portions and perform the following treatments respectively. Treatment 1: Stir and react for dechlorination at normal temperature and normal state and a rotation speed of 500 rpm for 2 h. Treatment 2: Under stirring at normal temperature and a rotation speed of 500 rpm, control the mercury lamp to emit light with a wavelength of 200 - 360 nm for photocatalytic dechlorination for 2 h. After the reaction, place the precipitate part in an oven to dry, put it into a muffle furnace, heat it to 600 °C at a heating rate of 5 °C / min for roasting for 2 hours, then cool it to 50 °C at a cooling rate of 5 °C / min and take it out, and grind it to obtain the dechlorination and regeneration product again.

[0090] Take 1 g of the dechlorination and regeneration product and put it into 5 mL of industrial wastewater with a chloride ion concentration of 10000 mg / L, and stir and react at a rotation speed of 500 rpm at normal temperature for 4 hours. Use potentiometric titration to measure the remaining chloride ion content in the liquid.

[0091] Perform this cyclic operation 5 times. The results are shown in Table 6.

[0092] Table 6 Recycling application effect of the dechlorination and regeneration product

[0093]

[0094] It can be seen from the data in Table 6 that light can significantly improve the chloride ion removal efficiency of titanium-modified ettringite.

[0095] Example 7

[0096] The regeneration application of the dechlorination product is as follows:

[0097] Take 4 g of the dechlorinated product obtained in Example 2 (III) (the dechlorinated product with a titanium element content ratio of 5%) and add it to 10 mL of deionized water. Set two parallel samples and perform the following treatments respectively. Treatment 1: Stir and react for dechlorination at normal temperature and normal state and a rotation speed of 500 rpm for 1 h. Treatment 2: Under stirring at normal temperature and a rotation speed of 500 rpm, control the mercury lamp to emit light with a wavelength of 250 - 300 nm for photocatalytic dechlorination for 1 h. After the reaction, dry the precipitated part in an oven, put it into a muffle furnace, heat it to 200 °C at a heating rate of 5 °C / min for roasting for 2 hours, then cool it to 50 °C at a cooling rate of 5 °C / min and take it out, and grind it to obtain the dechlorinated and recycled product again.

[0098] Take 0.5 g of the dechlorinated and recycled product and put it into 5 mL of industrial wastewater with a chloride ion concentration of 10000 mg / L, and stir and react at normal temperature and a rotation speed of 500 rpm for 3 hours. Use potentiometric titration to measure the remaining chloride ion content in the liquid.

[0099] Perform this cyclic operation 5 times. The results are shown in Table 7.

[0100] Table 7 Recycling application effect of the dechlorinated and recycled product

[0101]

[0102]

[0103] As can be seen from the data in Table 7, light can significantly improve the chloride ion removal efficiency of titanium-modified ettringite.

[0104] Example 8

[0105] The recycling application of the dechlorinated product is as follows:

[0106] Take 6 g of the dechlorinated product obtained in Example 3 (III) (the dechlorinated product with a titanium element content ratio of 5%) and add it to 30 mL of deionized water. Set two parallel samples and perform the following treatments respectively. Treatment 1: Stir and react for dechlorination at normal temperature and normal state and a rotation speed of 400 rpm for 3 h. Treatment 2: Under stirring at normal temperature and a rotation speed of 400 rpm, control the mercury lamp to emit light with a wavelength of 280 - 400 nm for photocatalytic dechlorination for 3 h. After the reaction, dry the precipitated part in an oven, put it into a muffle furnace, heat it to 300 °C at a heating rate of 5 °C / min for roasting for 1 hour, then cool it to 50 °C at a cooling rate of 5 °C / min and take it out, and grind it to obtain the dechlorinated and recycled product again.

[0107] Take 1.5 g of the dechlorinated and recycled product and put it into 5 mL of industrial wastewater with a chloride ion concentration of 3000 mg / L, and stir and react at normal temperature and a rotation speed of 500 rpm for 3 hours. Use potentiometric titration to measure the remaining chloride ion content in the liquid.

[0108] Perform this cyclic operation 9 times. The results are shown in Table 8.

[0109] Table 8 Recycling application effect of dechlorination product

[0110]

[0111] As can be seen from the data in Table 8, light can significantly improve the chloride ion removal efficiency of titanium-modified calcium aluminate.

[0112] Example 9

[0113] The recycling application of the dechlorination product is as follows:

[0114] Take 8 g of the dechlorination product obtained in Example 4 (III) (the dechlorination product with a titanium element content ratio of 10%) and 40 mL of deionized water, and set two samples in parallel for the following treatments respectively. Treatment 1: React for 4 h under normal temperature and normal state and stirring at a speed of 600 rpm for dechlorination. Treatment 2: Under normal temperature and stirring at a speed of 600 rpm, control the mercury lamp to emit light with a wavelength of 300 - 400 nm for photocatalytic dechlorination for 4 h. After the reaction, dry the precipitate part in an oven, put it into a muffle furnace, heat it to 400 °C at a heating rate of 5 °C / min for roasting for 1 hour, then cool it to 50 °C at a cooling rate of 5 °C / min and take it out, and grind it to obtain the recycled dechlorination product again.

[0115] Take 2 g of the recycled dechlorination product and put it into 5 mL of industrial wastewater with a chloride ion concentration of 8000 mg / L, and stir and react at a speed of 500 rpm at normal temperature for 3 hours. Use potentiometric titration to measure the remaining chloride ion content in the liquid.

[0116] Perform this cyclic operation 10 times. The results are shown in Table 9.

[0117] Table 9 Recycling application effect of dechlorination product

[0118]

[0119] As can be seen from the data in Table 9, light can significantly improve the chloride ion removal efficiency of titanium-modified calcium aluminate.

[0120] Example 10

[0121] The recycling application of the dechlorination product is as follows:

[0122] Take 10 g of the dechlorinated product obtained in Example 5 (III) (the dechlorinated product with a titanium element content ratio of 15%), and 50 mL of deionized water. Set two samples in parallel and perform the following treatments respectively. Treatment 1: React and dechlorinate for 5 h under normal temperature and normal state and stirring at a speed of 600 rpm. Treatment 2: Under normal temperature and stirring at a speed of 600 rpm, control the mercury lamp to emit light with a wavelength of 200 - 400 nm for photocatalytic dechlorination for 5 h. After the reaction, dry the precipitated part in an oven, put it into a muffle furnace, heat it to 500 °C at a heating rate of 5 °C / min for roasting for 5 hours, then cool it to 50 °C at a cooling rate of 5 °C / min and take it out, and grind it to obtain the dechlorinated and reproduced product again.

[0123] Put 3 g of the dechlorinated and reproduced product into 5 mL of industrial wastewater with a chloride ion concentration of 15000 mg / L, and stir and react at a speed of 500 rpm at normal temperature for 3 hours. Use potentiometric titration to measure the remaining chloride ion content in the liquid.

[0124] Perform this cyclic operation 8 times. The results are shown in Table 10.

[0125] Table 10 Recycling application effect of the dechlorinated and reproduced product

[0126]

[0127] It can be seen from the data in Table 10 that light can greatly improve the chloride ion removal efficiency of titanium-modified ettringite.

[0128] As can be seen from the above Examples 6 - 10, the samples after dechlorination and regeneration have certain reuse value after roasting treatment, realizing the rational utilization of resources.

[0129] As described above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a titanium-modified calcium-aluminum compound, characterized in that, It includes the following steps: Mix the calcium-containing raw material, aluminum-containing raw material and titanium-containing raw material evenly and then calcine to obtain a titanium-modified calcium aluminate compound; Among them, the calcium-containing raw material and the aluminum-containing raw material are mixed in a ratio of the molar ratio of element Ca:Al of (1 - 1.3):1; the mass proportion of element titanium in the titanium-containing raw material in the titanium-modified calcium aluminate compound is in the range of 0% - 20%.

2. The preparation method of the titanium-modified calcium aluminate compound according to claim 1, wherein The calcium-containing raw material is selected from one or more of calcium oxide, calcium hydroxide, calcium chloride, limestone, dolomite, steel slag, and gypsum; The aluminum-containing raw material is selected from one or more of aluminum oxide, aluminum hydroxide, polyaluminum chloride, aluminum nitrate, alunite, and fly ash; The titanium-containing raw material is selected from one or more of titanium dioxide, titanium sesquioxide, titanium tetraisopropoxide, titanium tetrachloride, and titanium tetrabromide.

3. The preparation method of the titanium-modified calcium aluminate compound according to claim 1, characterized in that, The calcination is carried out by heating to 800 - 1400°C at a heating rate of 3 - 5°C / min and holding at this temperature for 2 - 6 h.

4. The preparation method of the titanium-modified calcium aluminate compound according to claim 1, characterized in that, The mixing of the calcium-containing raw material, the aluminum-containing raw material and the titanium-containing raw material is dry mixing and / or wet mixing. Stir during mixing, the temperature during mixing is 20 - 60°C, and the total mixing time is 1 - 5 h.

5. Titanium-modified calcium-aluminum compound, characterized in that, It is prepared by using the preparation method according to any one of claims 1 - 4.

6. Method for removing chlorine from industrial wastewater containing chlorine, characterized in that, Put the titanium-modified calcium aluminate compound prepared by using the preparation method according to any one of claims 1 - 4 as a dechlorination agent into the chlorine-containing industrial wastewater with a chloride ion content of at least 3000 mg / L, and stir and react to remove chloride ions in the wastewater.

7. The chlorine removal method for chlorine-containing industrial wastewater according to claim 6, characterized in that, The dosage of the titanium-modified calcium aluminate compound in the chlorine-containing industrial wastewater is 0.1 - 200 g / L; the temperature of the stirring reaction is from normal temperature to 80°C, and the reaction time is 1 - 12 h.

8. Regenerative application of chlorine removal product, characterized in that, After using the titanium-modified calcium aluminate compound prepared by using the preparation method according to any one of claims 1 - 4 for dechlorination of chlorine-containing industrial wastewater, dry the solid part and grind it to obtain a dechlorination product; Add water to the dechlorination product, and carry out photocatalytic dechlorination under illumination under normal temperature stirring conditions. After drying, calcine and regenerate to obtain a titanium-modified calcium aluminate compound, and recycle it multiple times for dechlorination of chlorine-containing industrial wastewater.

9. The regenerative application of the dechlorinated product according to claim 8, wherein, The time of the photocatalytic dechlorination is 1 - 5 h; ultraviolet light is used for photocatalytic illumination, and the wavelength range is 200 - 400 nm; The temperature of the calcination regeneration is 200 - 600°C and the time is 1 - 3 h; The number of recycling times is 5 - 10 times.

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