A modified titanium gypsum wastewater purifying agent and its preparation method

Abstract

The present invention discloses a modified titanium gypsum industrial wastewater purifying agent, which comprises the following raw materials in parts by mass: 30 - 45 parts of porous modified titanium gypsum, 5 - 9 parts of reducing bacteria, 1 - 3 parts of surfactant, and 5 - 10 parts of water; the porous modified titanium gypsum is obtained through a preparation method including the following steps: after the nano-SiO2 microsphere dispersion liquid and titanium gypsum are fully mixed, they are dried, ground, etched with alkali solution, washed, and dried. The modified titanium gypsum obtained by the present invention has a porous structure and has a good adsorption effect. The present invention uses industrial solid waste titanium gypsum to prepare an industrial wastewater purifying agent, realizing the high-value utilization of titanium gypsum. The modified titanium gypsum industrial wastewater purifying agent provided by the present invention has a good adsorption and removal effect on heavy metals in industrial wastewater.

Description

Technical Field

[0001] The present invention belongs to the technical field of resource utilization of industrial solid waste, and relates to a modified titanium gypsum wastewater purifying agent and a preparation method thereof. Background Art

[0002] Titanium gypsum is an industrial by-product gypsum obtained in the process of producing titanium dioxide by the sulfuric acid method. Titanium dioxide is a commonly used industrial material and has been widely promoted in fields such as rubber materials, paper, beauty makeup, and coatings. With the continuous development of fields such as materials and construction, the demand for titanium dioxide is increasing year by year, resulting in an increase in the stockpile of industrial solid waste titanium gypsum generated during its production process. According to incomplete statistics, 41 domestic titanium dioxide enterprises emit approximately 22 Mt of titanium gypsum, but its comprehensive utilization efficiency is only about 10%, far less than 38% of phosphogypsum, and its cumulative total stockpile has reached 130 Mt. Therefore, the large-scale comprehensive utilization of titanium gypsum urgently needs to be solved.

[0003] Titanium gypsum has characteristics such as high water content, many impurities, and high viscosity. Although there are currently some studies on the comprehensive utilization of titanium gypsum, at present, the only practical application is to use it as a cement retarder, and there are also some studies on using it to prepare composite cementitious materials and other materials. To achieve large-scale utilization of titanium gypsum, further exploration is still needed. In addition, limited by defects such as low quality, poor stability, and insignificant economic benefits of titanium gypsum and its related products, there are few titanium gypsum and its related products on the current market, which will have an adverse impact on its large-scale comprehensive utilization. Currently, there is no reasonable way for the high-value utilization of titanium gypsum. Therefore, a method for the high-value utilization of titanium gypsum is needed.

[0004] Industrial wastewater mainly comes from enterprises such as smelting, electrolysis, pesticides, pharmaceuticals, paints, and pigments. The types, contents, and existing forms of heavy metals in the wastewater vary with different production enterprises. Since heavy metals cannot be decomposed and destroyed, but can only transfer their existing positions and transform their physical and chemical forms. Therefore, it is necessary to add an industrial wastewater purifying agent to treat heavy metals in industrial wastewater.

[0005] Publication No. CN114602435A proposes an efficient biomass sewage purifying agent and a preparation method thereof. The method includes the following steps: taking modified biochar, sodium carboxymethylcellulose, potassium permanganate, nonylphenol polyoxyethylene ether, polyepoxysuccinic acid, and sodium lipoate, stirring for 40 - 60 min, adding ethanol, mixing evenly, and granulating to obtain the efficient biomass sewage purifying agent. This modified biochar has a three-dimensional porous structure that is easy to separate and recycle, endows the purifying agent with bactericidal properties, and has an adsorption effect on heavy metal ions in sewage. However, it only performs physical adsorption and does not treat heavy metal ions through chemical reactions, and the adsorption effect on heavy metal ions is not ideal. Summary of the Invention

[0006] In view of the above problems, the present invention provides a method for preparing an industrial wastewater purifying agent from modified titanium gypsum. By modifying titanium gypsum, heavy metal ions in industrial wastewater can be adsorbed and removed, realizing the high-value utilization of titanium gypsum.

[0007] To achieve the above object, the present invention provides a modified titanium gypsum industrial wastewater purifying agent, which comprises the following raw materials in parts by mass: 30-45 parts of porous modified titanium gypsum, 5-9 parts of reducing bacteria, 1-3 parts of surfactant, and 5-10 parts of water; the porous modified titanium gypsum is obtained by a preparation method including the following steps: after the nano-SiO2 microsphere dispersion liquid and titanium gypsum are fully mixed, they are dried, ground, etched with alkali solution, washed, and dried.

[0008] Further, in the preparation of nano-SiO2 modified titanium gypsum, the mass ratio of nano-SiO2 microspheres to titanium gypsum is 3-5:1.

[0009] Further, the particle size of the nano-SiO2 microspheres is 100-500 nm; preferably 200-400 nm.

[0010] Further, the specific surface area of the titanium gypsum is ≥400 m 2 / kg.

[0011] Further, the nano-SiO2 modified titanium gypsum is obtained by a preparation method including the following steps: adding titanium gypsum to the aqueous dispersion liquid of nano-SiO2 microspheres, ultrasonically dispersing evenly to obtain a solution, evaporating the solution to dryness, drying, grinding, fully mixing the obtained powdery solid with the alkali solution, ultrasonically dispersing, stirring and etching at 70-90 °C for 10-15 h, centrifuging, washing, and drying after the etching is completed to obtain modified titanium gypsum.

[0012] Furthermore, the mass concentration of the aqueous dispersion liquid of nano-SiO2 microspheres is 30-50 wt%, and there is no particular limitation on the method of evaporating the solution to dryness. For example, rotary evaporation can be used, specifically spinning dry at 70-90 °C; there is no particular limitation on the drying method, as long as it can ensure complete evaporation of water, such as a blast drying oven, vacuum drying, etc. In an embodiment of the present invention, it is dried in a blast drying oven at 60-80 °C for 24-48 h; the alkali solution is a 2-3 mol / L NaOH and / or KOH solution. The amount of the alkali solution can fully submerge the powdery solid and ensure smooth etching under stirring conditions; for example, in a specific embodiment of the present invention, the amount of the alkali solution is 7-10 times the mass of the powdery solid. The washing is carried out by washing with deionized water and absolute ethanol in sequence.

[0013] The preparation of nano-SiO2 microspheres is well-known in the art. In a specific embodiment of the present invention, it is obtained by a preparation method including the following steps: An alcohol solvent, dehydrated water, and ammonia water are mixed in a beaker, and then tetraethoxysilane is dropped into the mixture. After sealing, it is stirred at room temperature for 8-12 h by a magnetic stirrer; The milky white suspension obtained after stirring is centrifuged by a centrifuge to collect the sample, and the collected sample is washed with absolute ethanol to obtain nano-SiO2 microspheres, which are dried in a vacuum drying oven at 60 °C for later use.

[0014] The mass parts of raw materials in the preparation of nano-SiO2 microspheres are as follows: 5-10 parts of ammonia water, 80-100 parts of alcohol solvent, 5-10 parts of tetraethoxysilane, and 20-30 parts of water; The alcohol solvent is one or more of methanol, ethanol, n-propanol, and isopropanol.

[0015] The modified titanium gypsum obtained by the above method is titanium gypsum wrapped with SiO2 spheres. The SiO2 spheres are etched by NaOH to obtain modified titanium gypsum with a porous structure. The modified titanium gypsum has a larger surface area and better adsorption capacity. The main role of the nano-silica microspheres is to act as a template. The etching makes the silica microspheres fully react so that the original position of the silica spheres becomes pores, and finally modified titanium gypsum with a porous structure is formed.

[0016] Further, the reducing bacteria are a compound of sulfate-reducing bacteria and iron-reducing bacteria in a mass ratio of 1:1-5:1.

[0017] Furthermore, the sulfate-reducing bacteria are selected from one or more of the genera Desulfovibrio, Desulfomonas, Desulfobulbus, and Desulfotomaculum, and the iron-reducing bacteria are selected from one or more of the genera Geococcus, Anaeromyxobacter, Geobacter arcticus, and Geobacter.

[0018] Further, the surfactant is selected from at least one of glycine salts, phosphate surfactants, and long-chain alkyl sulfonate anionic surfactants; preferably, it is a compound of glycine salts, phosphate surfactants, and long-chain alkyl sulfonate anionic surfactants in a mass ratio of 3-5:1-2:1-2; The glycine salts are selected from at least one of sodium glycinate and potassium glycinate; The phosphate surfactants are selected from lauryl polyoxyethylene ether phosphate, C12-18 alkanol polyoxyethylene ether phosphate (such as cetyl polyoxyethylene ether phosphate, octadecyl polyoxyethylene ether phosphate), and cetearyl alcohol polyoxyethylene ether phosphate; The long-chain alkyl sulfonate anionic surfactants are selected from at least one of sodium dodecylbenzenesulfonate, sodium tetradecylbenzenesulfonate, and sodium hexadecylbenzenesulfonate.

[0019] The above-mentioned surfactant mixture can not only play a role in stabilizing the mixture, but also promote the growth and metabolism of reducing bacteria, further improving the purification efficiency of the purifying agent of the present invention. The possible reason is that the above substances can provide some nutrients for reducing bacteria, including amino acids and phosphate groups, providing the necessary material conditions for the growth and reproduction of reducing bacteria and promoting bacterial metabolism; at the same time, the presence of the surfactant mixture may also improve the living environment of reducing bacteria, increasing the survival rate and production efficiency of reducing bacteria.

[0020] Figure 1 It is a process schematic diagram of the method for preparing an industrial wastewater purifying agent with modified titanium gypsum of the present invention.

[0021] The second object of the present invention is to provide a preparation method of the above-mentioned modified titanium gypsum industrial wastewater purifying agent, including the following steps: taking modified titanium gypsum, reducing bacteria, surfactant and deionized water, stirring and mixing evenly, and granulating to obtain an industrial wastewater purifying agent.

[0022] The third object of the present invention is to provide the use of the above-mentioned modified titanium gypsum industrial wastewater purifying agent in the purification of industrial wastewater, and the industrial wastewater contains heavy metal ions, such as Pb(II), Cd(II), Cr(VI), As(V).

[0023] The beneficial effects of the present invention are:

[0024] (1) The present invention uses SiO2 spheres to modify titanium gypsum, adds titanium gypsum to wrap the SiO2 spheres, and etches the SiO2 spheres with NaOH to obtain modified titanium gypsum with a porous structure. The modified titanium gypsum has a larger surface area and better adsorption capacity.

[0025] (2) The present invention adds sulfate-reducing bacteria and iron-reducing bacteria to reduce sulfates and iron oxides in titanium gypsum to Fe 2+ and S 2- , which combines with heavy metal ions in industrial wastewater to form precipitates, showing good treatment effects on heavy metal ions in industrial wastewater.

[0026] (3) The present invention uses a surfactant mixture, which can not only play a role in stabilizing the mixture, but also promote the growth and metabolism of reducing bacteria, further improving the purification efficiency of the purifying agent. Description of the Drawings

[0027] Figure 1 It is a process schematic diagram of the method for preparing an industrial wastewater purifying agent with modified titanium gypsum of the present invention.

[0028] Figure 2 It is a SEM micrograph of the microscopic morphology of the SiO2 spheres prepared in the preparation example.

[0029] Figure 3This is a SEM photograph of the modified titanium gypsum obtained in Example 1. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The titanium gypsum described in the embodiments of the present invention comes from an environmental protection company in Chongqing, and the other reagents, drugs, etc. are purchased from the market.

[0032] Desulfovibrio was purchased from China Center for Type Culture Collection: CCTCC ZB 2008249; Geococcus was purchased from National Microbial Resources Platform ACCC 01035.

[0033] Preparation Example

[0034] Take 100 parts of isopropanol, 20 parts of deionized water, and 5 parts of ammonia water and mix them in a beaker, then add 5 parts of tetraoxysilane to the mixture, seal it, and stir it at room temperature for 10 hours with a magnetic stirrer. The resulting milky white suspension is centrifuged to collect the sample, and the collected sample is passed through anhydrous ethanol to obtain pure nano-SiO2 microspheres, which are placed in a vacuum drying oven at 60°C and fully dried for standby use. Figure 2 This is the SEM photo of the obtained nano-SiO2 microspheres.

[0035] Example 1

[0036] (S1) The nano-SiO2 microspheres prepared in Preparation Example 1 were dispersed in deionized water under ultrasonic conditions to obtain a 40wt% nano-SiO2 dispersion, and the ground titanium gypsum was added and ultrasonic dispersion was continued for 1min until there was no suspended matter, and the mass ratio of nano-SiO2 microspheres to titanium gypsum was 3:1; the solution was dried at 70°C and 120r / min on a rotary evaporation dryer until the water in the solution was completely evaporated, and then transferred to a 60°C blast drying oven for drying for 24h to ensure complete evaporation of the water, and the obtained sample was fully ground; the ground sample was fully mixed with a 2.5mol / L NaOH solution of 7 times the mass of the sample, and after ultrasonic dispersion, it was stirred and etched at a rate of 400r / min in an 80°C oil bath. After etching, the sample was collected by centrifugation, and the obtained sample was washed with deionized water and anhydrous ethanol, and the modified titanium gypsum was obtained after drying. Figure 3 This is a SEM photo of the modified titanium gypsum. It can be seen that the modified titanium gypsum has a loose and porous structure. The large number of pores and large specific surface area can better adsorb heavy metal ions and provide more attachment sites for reducing bacteria.

[0037] (S2) Take 40 parts of modified titanium gypsum, 8 parts of reducing bacteria (a compound of Desulfovibrio and Geococcus in a mass ratio of 2:1), 3 parts of surfactant (a compound of sodium glycinate, cetyl polyoxyethylene ether phosphate ester and sodium dodecylbenzenesulfonate in a mass ratio of 3:1:1), and 7 parts of deionized water. Stir and mix evenly, and granulate to obtain an industrial wastewater purifying agent.

[0038] Example 2

[0039] Other conditions, operations and Example 1 are the same, except that in step (S1), the mass ratio of nano-SiO₂ microspheres to titanium gypsum is 5:1.

[0040] In step (S2), the industrial wastewater purifying agent includes the following raw materials in parts by mass: 30 parts of modified titanium gypsum, 5 parts of reducing bacteria, 2.5 parts of surfactant (a compound of potassium glycinate, octadecyl polyoxyethylene ether phosphate ester and sodium dodecylbenzenesulfonate in a mass ratio of 5:1:2), and 5 parts of deionized water.

[0041] Example 3

[0042] Other conditions, operations and Example 1 are the same, except that the industrial wastewater purifying agent is made of the following raw materials in parts by mass: 40 parts of modified titanium gypsum, 5 parts of reducing bacteria, 1 part of surfactant, and 8 parts of deionized water.

[0043] Example 4

[0044] Other conditions, operations and Example 1 are the same, except that in step (S1), the mass ratio of nano-SiO₂ microspheres to titanium gypsum is 1:1.

[0045] Example 5

[0046] Other conditions, operations and Example 1 are the same, except that in step (S1), the mass ratio of nano-SiO₂ microspheres to titanium gypsum is 8:1.

[0047] Example 6

[0048] Other conditions, operations and Example 1 are the same, except that the surfactant is a compound of sodium glycinate and sodium dodecylbenzenesulfonate in a mass ratio of 3:1.

[0049] Example 7

[0050] Other conditions, operations and Example 1 are the same, except that the surfactant is a compound of sodium glycinate and cetyl polyoxyethylene ether phosphate ester in a mass ratio of 3:1.

[0051] Example 8

[0052] Other conditions were the same as those in Operation and Example 1, except that the surfactant was a compound of cetyl polyoxyethylene ether phosphate and sodium cetylbenzenesulfonate at a mass ratio of 1:1.

[0053] Comparative Example 1

[0054] Other conditions were the same as those in Operation and Example 1, except that titanium gypsum was used to replace an equal mass of modified titanium gypsum.

[0055] Application Example

[0056] Weigh the industrial wastewater purifying agents prepared in Examples 1 to 5, conduct simulated industrial wastewater treatment. The dosage of the industrial wastewater purifying agent was 0.5 g / L, which was added to the industrial wastewater and treated at room temperature for 30 min. The content of heavy metal ions in the treated wastewater was measured, and the results are shown in Table 1 below. Among them, the concentrations of Pb(II), Cd(II), Cr(VI), and As(V) in the simulated industrial wastewater were all 500 mg / L.

[0057] Table 1 Treatment Effect of Heavy Metal Wastewater

[0058] Heavy metal ion type Pb(II) / ppm Cd(II) / ppm Cr(VI) / ppm As(V) / ppm Example 1 0.32 0.36 0.38 0.31 Example 2 0.40 0.42 0.44 0.39 Example 3 0.72 0.66 0.61 0.58 Example 4 0.83 0.75 0.85 0.78 Example 5 1.12 0.95 0.81 0.92 Example 6 0.63 0.62 0.75 0.83 Example 7 0.78 1.13 0.85 1.52 Example 8 1.53 1.82 1.27 2.46 Comparative Example 1 5.28 3.84 8.76 2.45

[0059] It can be seen from the data in Table 1 that the industrial wastewater purifying agent prepared from the modified titanium gypsum of the present invention can effectively remove heavy metal ions from industrial wastewater. By comparing Examples 1 and 4, 5, it can be seen that when modifying titanium gypsum, the ratio of nano-SiO2 microspheres to titanium gypsum should be within a reasonable range to achieve the best water purification effect. By comparing Examples 1 and 6 - 8, it can be seen that the surfactant compounded with glycinate, phosphate surfactant, and long-chain alkyl sulfonate anionic surfactant can achieve the best treatment effect. The possible reason is that the compounded surfactant can not only stabilize the mixing task but also has a certain protective or promoting effect on the activity of bacteria.

Claims

1. A modified titanium gypsum industrial wastewater purifying agent, characterized in that, It comprises raw materials in the following parts by mass: 30 - 45 parts of porous modified titanium gypsum, 5 - 9 parts of reducing bacteria, 1 - 3 parts of surfactant, 5 - 10 parts of water. The reducing bacteria are a compound of sulfate-reducing bacteria and iron-reducing bacteria in a mass ratio of 1:1 - 5:

1. The porous modified titanium gypsum is obtained by a preparation method including the following steps: after the nano-SiO2 microsphere dispersion liquid and titanium gypsum are fully mixed, they are dried, ground, etched with alkali solution, washed, and then dried. The particle size of the nano-SiO2 microspheres is 100 - 500 nm. The specific surface area of the titanium gypsum is ≥400 m 2 / kg.

2. The modified titanium gypsum industrial wastewater purifying agent according to claim 1, characterized in that, In the preparation of porous modified titanium gypsum, the mass ratio of nano-SiO₂ microspheres to titanium gypsum is 3 - 5:

1.

3. The modified titanium gypsum industrial wastewater purifying agent according to claim 1, characterized in that, The particle size of the nano-SiO₂ microspheres is 200 - 400 nm.

4. The modified titanium gypsum industrial wastewater purifying agent according to claim 1, characterized in that, The porous modified titanium gypsum is obtained by a preparation method including the following steps: adding titanium gypsum into an aqueous dispersion of nano-SiO₂ microspheres, ultrasonically dispersing evenly to obtain a solution, evaporating the solution to dryness, drying, grinding, fully mixing the obtained powdery solid after grinding with an alkali solution, ultrasonically dispersing, etching by stirring at 70 - 90 °C for 10 - 15 h, centrifuging, washing, and drying after the etching ends to obtain the porous modified titanium gypsum.

5. The modified titanium gypsum industrial wastewater purifying agent according to claim 4, characterized in that, The mass concentration of the aqueous dispersion of nano-SiO₂ microspheres is 30 - 50 wt%, and the alkali solution is a 2 - 3 mol / L NaOH and / or KOH solution.

6. The modified titanium gypsum industrial wastewater purifying agent according to claim 1, characterized in that, The sulfate-reducing bacteria are selected from one or more of the genera Desulfovibrio, Desulfomonas, Desulfobulbus, and Desulfotomaculum, and the iron-reducing bacteria are selected from one or more of the genera Geococcus, Anaeromyxobacter, Geopsychrobacter, and Geobacter.

7. The modified titanium gypsum industrial wastewater purifying agent according to claim 1, characterized in that, The surfactant is selected from at least one of glycine salts, phosphate surfactants, and long-chain alkyl sulfonate anionic surfactants; the phosphate surfactant is selected from lauryl alcohol polyoxyethylene ether phosphate, C12 - 18 alkanol polyoxyethylene ether phosphate, and cetearyl alcohol polyoxyethylene ether phosphate; the long-chain alkyl sulfonate anionic surfactant is selected from at least one of sodium dodecylbenzenesulfonate, sodium tetradecylbenzenesulfonate, and sodium hexadecylbenzenesulfonate.

8. The modified titanium gypsum industrial wastewater purifying agent according to claim 7, characterized in that, The glycine salt is selected from at least one of sodium glycinate and potassium glycinate.

9. The modified titanium gypsum industrial wastewater purifying agent according to claim 7, characterized in that, The C12 - 18 alkanol polyoxyethylene ether phosphate is selected from hexadecyl polyoxyethylene ether phosphate and octadecyl polyoxyethylene ether phosphate.

10. The modified titanium gypsum industrial wastewater purifying agent according to claim 7, characterized in that, The surfactant is a compound mixture of glycine salts, phosphate surfactants, and long-chain alkyl sulfonate anionic surfactants in a mass ratio of 3 - 5:1 - 2:1 - 2.

11. A preparation method of the modified titanium gypsum industrial wastewater purifying agent according to any one of claims 1 - 10, comprising the following steps: taking porous modified titanium gypsum, reducing bacteria, surfactant and deionized water, stirring and mixing evenly, and granulating to obtain the industrial wastewater purifying agent.

12. Use of the modified titanium gypsum industrial wastewater purifying agent according to any one of claims 1 - 10 in removing heavy metal ions from industrial wastewater.

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