Method for recycling hydrotalcite production wastewater

Abstract

The invention relates to the technical field of fine chemical engineering, in particular to a method for recycling hydrotalcite production wastewater. The method comprises the following steps: carrying out filtration and synthetic reaction conversion on wastewater generated in hydrotalcite production, and carrying out heating reaction, filtration and drying to obtain the finished product hydrotalcite. According to the method provided by the invention, the wastewater generated in the hydrotalcite production process can be converted into the finished product hydrotalcite again, the reduction rate of OH <-> in the wastewater reaches 90% or above, the reduction rate of CO3 < 2-> reaches 82% or above, and material waste and environmental pollution are reduced; the method provided by the invention is low in production wastewater treatment cost and convenient to operate.

Description

Technical Field

[0001] This application relates to the field of fine chemical technology, and in particular to a method for recycling and reusing wastewater from hydrotalcite production. Background Technology

[0002] With the acceleration of industrialization, the adverse impacts of human activities on the ecological environment are becoming increasingly prominent, with water pollution being a particularly serious problem. Industrial wastewater that is not treated according to environmental standards and is directly discharged into natural water bodies not only disrupts the ecological balance of aquatic bodies and pollutes soil and groundwater, but also, due to the various harmful organic pollutants it contains (such as persistent organic pollutants and other pollutants), accumulates through the food chain and endangers human health. In recent years, these pollutants have been frequently detected in various types of water bodies, including surface water and wastewater treatment plant effluent, posing a dual threat to the ecological environment and public health.

[0003] Among industrial wastewater pollution, the hazards of hydrotalcite production wastewater are particularly prominent: this type of wastewater is highly alkaline, and direct discharge will cause a severe imbalance in the pH value of the receiving water body, damaging the living environment of aquatic organisms. At the same time, the residual raw materials and reaction byproducts contained in the wastewater will further aggravate the pollution load of the water body. Traditional treatment processes usually adopt the process of "acid neutralization → COD oxidation → alkaline incineration", which is not only cumbersome and complicated to operate, but also has many drawbacks: the acid neutralization process is prone to generating secondary pollutants such as salts, and the subsequent oxidation and incineration processes consume a lot of energy and emit a large amount of greenhouse gases such as carbon dioxide. This increases the treatment costs of enterprises (including reagent costs, energy consumption costs, equipment operation and maintenance costs, etc.) and contradicts the concept of low-carbon and environmental protection, making it difficult to meet the requirements of current green development.

[0004] With increasingly stringent environmental regulations and the growing acceptance of green production concepts, efficient and environmentally friendly industrial wastewater treatment technologies are receiving increasing attention. Addressing the challenges in treating wastewater from hydrotalcite production, there is an urgent need to develop a new treatment technology that simplifies the process, enables resource recovery (such as recovering effective components from wastewater to prepare finished products or byproducts), has low treatment costs, high treatment efficiency, and eliminates secondary pollution. This technology can not only completely solve the wastewater pollution problem but also achieve resource recycling. Summary of the Invention

[0005] This application provides a method for recycling and reusing wastewater from hydrotalcite production, in order to solve the problems of complex and costly existing wastewater treatment processes in hydrotalcite production.

[0006] In a first aspect, this application provides a method for recycling and reusing wastewater from hydrotalcite production, comprising the following steps: Step S101: Obtain the wastewater from the production of hydrotalcite and filter it using a filter screen to remove mechanical impurities from the wastewater. Step S102: Thoroughly stir and circulate the filtered hydrotalcite production wastewater until uniform, and test the OH content in the wastewater. - and CO3 2- mass concentration; Step S103, based on the OH in the production wastewater - and CO3 2- Based on the mass concentration and total amount of production wastewater, calculate the theoretical amounts of magnesium and aluminum sources needed, assuming a reaction conversion rate of 95%-98%, and then calculate based on CO3²⁻. - Calculate the theoretical amount of carbonate source at 1.02-1.05 times the amount of the deficit. Then add magnesium source, aluminum source and carbonate source according to the theoretical amount, stir, add carbon dioxide and heat to react. Step S104: Add stearic acid to the reaction system of step S103, stir, cool to room temperature, filter, wash the obtained filter cake until the pH of the filtrate is alkaline, and dry to obtain the finished hydrotalcite.

[0007] In some embodiments, the magnesium source is selected from one or more of magnesium hydroxide, magnesium nitrate, magnesium chloride, and magnesium sulfate; the aluminum source is selected from one or more of aluminum hydroxide, aluminum nitrate, aluminum chloride, and aluminum sulfate; and the carbonate source is selected from sodium bicarbonate or sodium carbonate.

[0008] In some embodiments, in step S102, the stirring speed is 200-400 rpm.

[0009] In some embodiments, in step S103, magnesium hydroxide and aluminum hydroxide are pulverized into 200-300 mesh powder.

[0010] In some embodiments, in step S103, the stirring speed is 200-300 rpm.

[0011] In some embodiments, in step S103, the temperature of the heating reaction is 150-200°C, and the reaction time is 3-10 hours.

[0012] In some embodiments, in step S104, the drying temperature is 60-100°C and the drying time is 4-6 hours.

[0013] The beneficial effects of the technical solution provided in this application include: the method provided in this application can convert wastewater generated during the production of hydrotalcite back into finished hydrotalcite, and the OH- in the wastewater... - The reduction rate reached over 90%, CO3 2- The reduction rate reaches over 82%, reducing material waste and environmental pollution; the method provided in this application has low cost and is easy to operate for treating production wastewater. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the process for recycling and reusing wastewater from hydrotalcite production provided in Embodiment 1 of this application. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0017] This application provides a method for recycling and reusing wastewater from hydrotalcite production, which can solve the problems of complex and costly wastewater treatment processes in the prior art.

[0018] Example 1: Step S101: Obtain the wastewater from the production of hydrotalcite and filter it using a filter screen to remove mechanical impurities from the wastewater. Step S102: The filtered hydrotalcite production wastewater is thoroughly stirred and circulated at 300 rpm until homogeneous, and the OH content is measured. - and CO3 2- The mass percentage concentration of [OH] - ] = 0.03%, [CO3 2- =2.69%; Step S103, based on the OH in the production wastewater - and CO3 2- Based on the mass concentration and total amount of production wastewater, calculate the theoretical dosage of magnesium hydroxide and aluminum hydroxide according to a reaction conversion rate of 95%-98%, and then calculate based on CO3²⁻. - Calculate the theoretical amount of sodium bicarbonate to 1.02-1.05 times the shortfall amount. Then, according to the theoretical amount, add 1950g of wastewater, 120g of magnesium hydroxide powder pulverized to 200 mesh, 80g of aluminum hydroxide powder pulverized to 200 mesh, and 40g of sodium bicarbonate to a 5L heatable reactor. Stir at 200rpm, introduce 9g of carbon dioxide, heat to 150℃ and keep the reaction at that temperature for 3 hours. Step S104: Add 2.5g of stearic acid to the reaction system, stir for 10 minutes, cool to room temperature, filter, and wash the filter cake with tap water until pH=8.1; place the filter cake in an oven at 100℃ and dry for 4 hours to obtain 236g of the finished product, hydrotalcite, with a magnesium-aluminum ratio of 3.95:1. The wastewater contains [OH-]. - ] = 0.003%, [CO3 2- =0.39%.

[0019] The above process flow diagram is shown below. Figure 1 .

[0020] Example 2: Step S101: Obtain the wastewater from the production of hydrotalcite and filter it using a filter screen to remove mechanical impurities from the wastewater. Step S102: The filtered hydrotalcite production wastewater is thoroughly stirred and circulated at 400 rpm until homogeneous, and the OH content is measured. - and CO3 2- The mass percentage concentration of [OH] - ] = 0.05%, [CO3 2- =3.33%; Step S103, based on the OH in the production wastewater - and CO3 2- Based on the mass concentration and total amount of production wastewater, calculate the theoretical dosage of magnesium sulfate and aluminum nitrate according to a reaction conversion rate of 95%-98%, and then calculate based on CO3²⁻. - Calculate the theoretical amount of sodium bicarbonate to 1.02-1.05 times the shortfall amount. Then, according to the theoretical amount, add 1950g of wastewater, 247g of magnesium sulfate powder pulverized to 300 mesh, 219.4g of aluminum nitrate powder pulverized to 300 mesh, and 19g of sodium bicarbonate to a 5L heatable reactor. Stir at 300rpm, introduce 15g of carbon dioxide, heat to 165℃ and keep the reaction at that temperature for 5 hours. Step S104: Add 2.5g of stearic acid to the reaction system, stir for 10 minutes, cool to room temperature, filter, and wash the filter cake with tap water until pH=8.9; dry the filter cake in an oven at 100℃ for 4 hours to obtain 238.4g of the finished hydrotalcite product, with a magnesium-aluminum ratio of 3.97:1. The wastewater [OH-] - ] = 0.004%, [CO3 2- =0.42%.

[0021] Example 3: Step S101: Obtain the wastewater from the production of hydrotalcite and filter it using a filter screen to remove mechanical impurities from the wastewater. Step S102: The filtered hydrotalcite production wastewater is thoroughly stirred and circulated at 400 rpm until homogeneous, and the OH content is measured.- and CO3 2- The mass percentage concentration of [OH] - ] = 0.01%, [CO3 2- =2.94%; Step S103, based on the OH in the production wastewater - and CO3 2- Based on the mass concentration and total amount of production wastewater, calculate the theoretical dosage of magnesium chloride and aluminum sulfate according to a reaction conversion rate of 95%-98%, and then calculate based on CO3²⁻. - Calculate the theoretical amount of sodium bicarbonate to 1.02-1.05 times the shortfall amount. Then, according to the theoretical amount, add 1950g of wastewater, 196g of magnesium chloride powder pulverized to 300 mesh, 352.3g of aluminum sulfate powder pulverized to 200 mesh, and 33g of sodium bicarbonate to a 5L heatable reactor. Stir at 300rpm, introduce 11g of carbon dioxide, heat to 170℃ and keep the reaction at that temperature for 7 hours. Step S104: Add 2.5g of stearic acid to the reaction system, stir for 10 minutes, cool to room temperature, filter, and wash the filter cake with tap water until pH=10; dry the filter cake in an oven at 80℃ for 4 hours to obtain 237.6g of the finished hydrotalcite product. The magnesium-aluminum ratio was measured to be 4.01:1. The [OH-] in the wastewater... - ]=0%, [CO3 2- =0.49%.

[0022] Example 4: Step S101: Obtain the wastewater from the production of hydrotalcite and filter it using a filter screen to remove mechanical impurities from the wastewater. Step S102: The filtered hydrotalcite production wastewater is thoroughly stirred and circulated at 300 rpm until homogeneous, and the OH content is measured. - and CO3 2- The mass percentage concentration of [OH] - ] = 0.03%, [CO3 2- =3.01%; Step S103, based on the OH in the production wastewater - and CO3 2- Based on the mass concentration and total amount of production wastewater, calculate the theoretical dosage of magnesium hydroxide and aluminum hydroxide according to a reaction conversion rate of 95%-98%, and then calculate based on CO3²⁻. -Calculate the theoretical amount of sodium bicarbonate to 1.02-1.05 times the shortfall amount. Then, according to the theoretical amount, add 1950g of wastewater, 120g of magnesium hydroxide powder pulverized to 200 mesh, 80g of aluminum hydroxide powder pulverized to 200 mesh, and 30g of sodium bicarbonate to a 5L heatable reactor. Stir at 200rpm, introduce 12g of carbon dioxide, heat to 185℃ and keep the reaction at that temperature for 8 hours. Step S104: Add 2.5g of stearic acid to the reaction system, cool to room temperature, filter, and wash the filter cake with tap water until pH=8.5; place the filter cake in an oven at 100℃ and dry for 4 hours to obtain 239.7g of the finished hydrotalcite product. The magnesium-aluminum ratio was measured to be 4.06:1. The [OH-] in the wastewater... - ] = 0.002%, [CO3 2- =0.52%; Example 5: Step S101: Obtain the wastewater from the production of hydrotalcite and filter it using a filter screen to remove mechanical impurities from the wastewater. Step S102: The filtered hydrotalcite production wastewater is thoroughly stirred and circulated at 300 rpm until homogeneous, and the OH content is measured. - and CO3 2- The mass percentage concentration of [OH] - ] = 0.02%, [CO3 2- =3.17%; Step S103, based on the OH in the production wastewater - and CO3 2- Based on the mass concentration and total amount of production wastewater, calculate the theoretical dosage of magnesium nitrate and aluminum chloride according to a reaction conversion rate of 95%-98%, and then calculate based on CO3²⁻. - Calculate the theoretical amount of sodium carbonate to be 1.02-1.05 times the shortfall amount. Then, according to the theoretical amount, add 1950g of wastewater, 305g of magnesium nitrate (crushed to 300 mesh), 137.5g of aluminum chloride powder (crushed to 300 mesh), and 32.9g of sodium carbonate to a 5L heatable reactor. Stir at 200rpm, introduce 13g of carbon dioxide, heat to 200℃ and keep the reaction at that temperature for 10 hours. Step S104: Add 2.5g of stearic acid to the reaction system, cool to room temperature, filter, and wash the filter cake with tap water until pH=9.4; place the filter cake in a 90℃ oven and dry for 4 hours to obtain 239.1g of the finished hydrotalcite product. The magnesium-aluminum ratio was measured to be 3.98:1. The [OH-] in the wastewater... - ] = 0.002%, [CO3 2- =0.5%.

[0023] The finished hydrotalcites obtained in Examples 1 and 4 were tested: 1. According to the test formula (SG-5) for hydrotalcite, use 100g of PVC resin powder, 50g of plasticizer, 0.1g of zinc stearate, 0.2g of calcium stearate, and 0.3g of hydrotalcite sample (Example 1 / Example 4). Plasticize the sample for 3 minutes on a two-roll mill and stretch it into sheets. The temperature of the two-roll mill is 180℃ and the front and rear roll speed ratio is 1:1. 2. Cut the sample into small pieces of 2cm*3cm, take 10 pieces and place them in a constant temperature 190℃ rotating oven for high-temperature aging, taking one piece every 5 minutes; 3. After the samples aged and faded, the yellowness values ​​of samples taken at the same time period were compared. The results are shown in Table 1.

[0024] Table 1: Comparison of Yellowness Values Color value chart (Type: HP200, Light source: D65) ; In Table 1, the smaller the B value, the lighter the yellow color, the slower the color change, and the better the stability. As can be seen from Table 1, the hydrotalcite treated by wastewater recycling exhibits excellent stability.

[0025] Examples 1-5: OH in production wastewater - The concentration changes are shown in Table 2.

[0026] Table 2: OH- in the production wastewater of Examples 1-5 - Concentration change ; CO3 in production wastewater from Examples 1-5 2- The concentration changes are shown in Table 3.

[0027] Table 3: CO3 in the production wastewater of Examples 1-5 2- Concentration change ; As can be seen from Tables 2 and 3, after treatment, the OH- in the production wastewater... - and CO3 2- Greatly reduced.

[0028] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0029] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. In this application, "a plurality of" means at least two, such as two, three, etc., unless otherwise expressly specified.

[0030] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for recycling and reusing wastewater from hydrotalcite production, characterized in that, Includes the following steps: S101, Obtain the wastewater from the production of hydrotalcite, and use a filter screen to remove mechanical impurities from the wastewater; S102, thoroughly stir and circulate the filtered hydrotalcite production wastewater until uniform, and test the OH content in the wastewater. - and CO3 2- mass concentration; S103, based on the OH in the production wastewater - and CO3 2- Based on the mass concentration and total amount of production wastewater, calculate the theoretical amounts of magnesium and aluminum sources needed, assuming a reaction conversion rate of 95%-98%, and then calculate based on CO3²⁻. - Calculate the theoretical amount of carbonate source at 1.02-1.05 times the amount of the deficit. Then add magnesium source, aluminum source and carbonate source according to the theoretical amount, stir, add carbon dioxide and heat to react. S104. Stearic acid is added to the reaction system of step S103, stirred, cooled to room temperature, filtered, and the resulting filter cake is washed until the pH of the filtrate is alkaline. The filtrate is then dried to obtain the finished hydrotalcite.

2. The method for recycling and reusing wastewater from hydrotalcite production according to claim 1, characterized in that, The magnesium source is selected from one or more of magnesium hydroxide, magnesium nitrate, magnesium chloride, and magnesium sulfate; the aluminum source is selected from one or more of aluminum hydroxide, aluminum nitrate, aluminum chloride, and aluminum sulfate; and the carbonate source is selected from sodium bicarbonate or sodium carbonate.

3. The method for recycling and reusing wastewater from hydrotalcite production according to claim 1, characterized in that, In step S102, the stirring speed is 200-400 rpm.

4. The method for recycling and reusing wastewater from hydrotalcite production according to claim 1, characterized in that, In step S103, the magnesium source and aluminum source are pulverized into 200-300 mesh powder.

5. The method for recycling and reusing wastewater from hydrotalcite production according to claim 1, characterized in that, In step S103, the stirring speed is 200-300 rpm.

6. The method for recycling and reusing wastewater from hydrotalcite production according to claim 1, characterized in that, In step S103, the temperature of the heating reaction is 150-200℃, and the reaction time is 3-10h.

7. The method for recycling and reusing wastewater from hydrotalcite production according to claim 1, characterized in that, In step S104, the drying temperature is 60-100℃ and the drying time is 4-6 hours.

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