A low-concentration fluorine-containing wastewater deep removal zeolite-like adsorption material and a preparation method thereof

Abstract

This invention discloses a zeolite-like adsorbent material for deep removal of low-concentration fluoride-containing wastewater and its preparation method, belonging to the field of solid waste resource utilization and sewage treatment technology. The method includes the following steps: (1) grinding and sieving dried red mud to obtain 100-mesh powder material; immersing the powder material in dilute sulfuric acid for acid washing to partially remove alkali, and then drying to obtain partially dealkalized red mud material; (2) immersing the partially dealkalized red mud material in MnCl2 solution for metal salt activation treatment, and then drying at 105℃ to obtain activated red mud material; placing the activated red mud material in a muffle furnace at 500-800℃ for full calcination and activation, and cooling to obtain zeolite-like adsorbent material, which has a good effect on the treatment of low-concentration fluoride-containing wastewater. The preparation method of this invention is simple, has high adsorption capacity, and can meet the discharge concentration of low-concentration fluoride-containing wastewater at the end of industrial sewage treatment to reach the Class III standard of "GB3838-2002 Surface Water Environmental Quality Standard", that is, the fluoride content is less than 1 mg / L, and the preparation cost is low.

Description

Technical Field

[0001] This invention belongs to the field of solid waste resource utilization and wastewater treatment technology, specifically relating to a zeolite-like adsorbent material for deep removal of low-concentration fluoride-containing wastewater and its preparation method. Background Technology

[0002] In recent years, environmental pollution caused by fluoride and its compounds has attracted worldwide attention. In many industrial production processes, fluoride-containing wastewater is unavoidably generated due to the presence of fluoride in raw materials or the addition of fluoride-containing substances during processing. These industries include traditional industries such as fluoride mining, fluoride synthesis, rare earth and non-ferrous metal smelting, aluminum electrolytic refining, electroplating, coking, thermal power generation, glass, fluorosilicates, pesticides, cement, brick and tile production, stainless steel pickling, fertilizers, chlorofluorocarbons, ceramics, silicon-based electrical parts washing, and petrochemicals; as well as modern industries such as organic synthesis chemicals, electronic integrated circuits, and nuclear energy. The fluoride in this wastewater exists in the form of fluorosilicic acid, hydrofluoric acid, and other fluoride salts, and the fluoride content varies greatly among different types of wastewater. Furthermore, industrial fluoride-containing wastewater generally contains multiple pollutants, making removal extremely difficult. Fluorides are non-biodegradable, highly hazardous, and persistent pollutants, making fluoride pollution in water unavoidable. In the rapidly developing industrial sector, how to effectively treat fluoride-containing wastewater has become a hot issue. As environmental problems become increasingly prominent, new environmental protection policies are constantly being issued, and the enforcement of these policies is becoming increasingly stringent. my country stipulates that the maximum allowable emission concentration of inorganic fluoride compounds in industrial wastewater is 10 mg / L, as seen in standards such as the "Electroplating Pollutant Emission Standard," "Battery Industry Pollutant Emission Standard," and "Electronic Industry Pollutant Emission Standard." The "Aluminum Industry Pollutant Emission Standard" stipulates a fluoride limit of 5 mg / L for the total wastewater discharge outlet of newly built enterprises. Some local standards require wastewater fluoride levels to be treated to below 2 mg / L. Beijing's local standard, the "Integrated Discharge Standard for Water Pollutants," stipulates a fluoride limit of 1.5 mg / L for water discharged into surface water bodies. The fluoride concentration in coal mine water effluent must meet the Class III standard of the "GB3838-2002 Surface Water Environmental Quality Standard," meaning a fluoride concentration of less than 1 mg / L.

[0003] Currently, the main defluoridation methods used domestically and internationally include chemical precipitation, electrochemical methods, coagulation and sedimentation, ion exchange, and adsorption. However, simply using chemical precipitation to treat high-concentration fluoride wastewater can result in unstable fluoride ion concentrations in the effluent, sometimes even failing to meet standards. Therefore, further treatment of the effluent is necessary to achieve discharge standards. Electrochemical methods suffer from electrode passivation, requiring frequent replacement, and are affected by numerous factors. Coagulation and sedimentation methods produce large amounts of sludge, introducing inorganic salt ions into the effluent, and leaving fluoride complexes in the wastewater after the reaction, resulting in incomplete defluoridation. Ion exchange resins are expensive, with high costs and regeneration expenses, making them difficult to apply in industrial treatment. Adsorption methods offer advantages such as simple operation, no increase in water salinity, and excellent performance. Extensive research on adsorption for fluoride removal focuses on finding adsorption materials that are inexpensive, widely available, and produce stable effluent quality and excellent performance after defluorination treatment.

[0004] Red mud is a solid waste generated during the aluminum industry. Currently, my country has approximately 600 million tons of red mud stockpiled, with an annual new production exceeding 70 million tons, and a comprehensive utilization rate of only 5%. The ever-increasing discharge of red mud brings severe disposal and environmental problems, making its resource utilization an urgent global challenge. Red mud is rich in metallic minerals, has good particle dispersibility, a high specific surface area, and abundant lattice defects and adsorption sites, making it effective in wastewater treatment. However, for industrial wastewater containing fluoride ions, powdered red mud suffers from low adsorption capacity, high environmental sensitivity, poor material stability, difficulty in solid-liquid separation, and low recovery rate.

[0005] Therefore, how to make full use of red mud and carry out in-depth treatment of fluoride ions in wastewater is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a zeolite-like adsorbent material for deep removal of low-concentration fluoride-containing wastewater and its preparation method, which has good environmental, economic, and social benefits and broad application prospects.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for preparing a zeolite-like adsorbent for deep removal of low-concentration fluoride-containing wastewater includes the following steps:

[0009] (1) The dried red mud is ground into particles and then sieved to obtain red mud powder material.

[0010] (2) The red mud powder material is mixed with dilute sulfuric acid at a certain solid-liquid ratio, and then partially dealkalized. After drying, the partially dealkalized red mud material is obtained.

[0011] (3) The dealkalized red mud material is mixed with MnCl2 solution at a certain solid-liquid ratio, and then subjected to metal salt immersion activation treatment, and then dried to obtain activated red mud material;

[0012] (4) The activated red mud material is fully roasted and cooled to obtain the composite adsorbent material.

[0013] As a further explanation of the present invention, in step (4), the parameters of the roasting are set as follows: roasting temperature 500-800℃, heating rate 5-10℃ / min, roasting time 1-2h, and holding time 1.5h.

[0014] As a further explanation of the present invention, in step (2), the certain solid-liquid ratio is 0.1 to 1.0 g / mL, and the duration of the sulfuric acid impregnation modification treatment is 2 to 5 h.

[0015] As a further explanation of the present invention, in step (3), the certain solid-liquid ratio is 0.1 to 1.0 g / mL, and the duration of the metal salt immersion activation treatment is 2 to 5 h.

[0016] As a further explanation of the present invention, in steps (2) and (3), the drying temperature is 105°C.

[0017] As a further explanation of the present invention, in step 1, the mesh size of the sieve is 100 mesh.

[0018] The present invention also provides a zeolite-like adsorbent material for deep removal of low-concentration fluoride-containing wastewater, which is prepared by the above-described preparation method.

[0019] The present invention further explains that the zeolite-like adsorbent material for deep removal of low-concentration fluoride wastewater adopts the following specifications for its raw materials: the red mud is red mud with an average iron oxide content of 30-40%; the concentration of the dilute sulfuric acid is 0.1-0.2 mol / L; and the concentration of the MnCl2 solution is 0.5-1.0 mol / L.

[0020] The zeolite-like adsorbent material for deep removal of low-concentration fluoride wastewater of the present invention has a good adsorption effect when applied to the treatment of low-concentration fluoride wastewater. The adsorbent material is relatively stable and can be repeatedly used after regeneration without causing secondary pollution.

[0021] In this invention, red mud, a bulk solid waste, is used as the base material. The red mud contains an average iron oxide content of about 30-40%, as well as a large amount of metal oxides such as aluminum oxide and calcium oxide. These metal oxides can generate active hydroxyl sites after activation, which can achieve physical and chemical adsorption of fluoride ions. Dilute sulfuric acid is used as a dealkalizing agent, which can react with the strongly alkaline substances in the original red mud, change the pH of the red mud, and generate a porous structure on its surface. Manganese chloride, a metal salt, is used as an activator, which can combine with the metal oxides in the red mud and generate manganese aluminum iron minerals containing active hydroxyl groups after high-temperature calcination, forming a porous zeolite adsorbent material. This adsorbent material has a good treatment effect on low-concentration fluoride-containing wastewater.

[0022] Advantages of this invention:

[0023] 1. The preparation method proposed in this invention is simple, requires no complex technical equipment or high-pressure equipment, has low cost, and produces materials with good adsorption performance, making it suitable for industrial promotion and large-scale production.

[0024] 2. The material prepared by this invention has high stability, long service life, and good regeneration effect.

[0025] 3. The material prepared by this invention is suitable for the treatment of low-concentration fluoride-containing wastewater in the final stage of industrial wastewater treatment, with good results. The effluent can meet the Class III standard of "GB3838-2002 Surface Water Environmental Quality Standard", that is, the fluoride mass concentration is less than 1 mg / L. Attached Figure Description

[0026] Figure 1 This is a topographical image of the materials used in this application. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments.

[0028] The raw materials used in the following examples are: red mud from bulk industrial solid waste red mud, with an iron oxide content of 32%, a calcium oxide content of 19.4%, an aluminum oxide content of 18%, and a silicon dioxide content of 14.6%; dilute sulfuric acid and manganese chloride are both analytical chemical reagents.

[0029] Example 1:

[0030] A method for preparing a zeolite-like adsorbent for deep removal of low-concentration fluoride-containing wastewater includes the following steps:

[0031] (1) The dried red mud is ground into fine particles and passed through a 100-mesh sieve to obtain red mud powder material.

[0032] (2) The red mud powder material is mixed with dilute sulfuric acid (0.1 mol / L) at a solid-liquid ratio of 0.5 g / mL, and impregnated for 3 h. Then it is dried in an oven at 105 °C to obtain partially dealkalized red mud material.

[0033] (3) The dealkalized red mud material is mixed with MnCl2 solution (0.5mol / L) at a solid-liquid ratio of 0.5g / mL, and then impregnated and activated for 3h. After that, it is dried in an oven at 105℃ to obtain activated red mud material.

[0034] (4) The activated red mud material was placed in a muffle furnace for full roasting (roasting temperature 600℃, heating rate 7℃ / min, roasting time 1.5h, holding time 1.5h), and then cooled to room temperature to obtain zeolite-like adsorbent material.

[0035] Example 2:

[0036] A method for preparing a composite adsorbent material for the deep treatment of low-concentration fluoride-containing wastewater includes the following steps:

[0037] (1) The dried red mud is ground into fine particles and passed through a 100-mesh sieve to obtain the initial red mud raw material.

[0038] (2) The initial red mud raw material is mixed with dilute sulfuric acid (0.1 mol / L) at a solid-liquid ratio of 1.0 g / mL, and impregnated for 2 hours. Then it is dried in an oven at 105°C to obtain modified red mud material.

[0039] (3) The modified red mud material is mixed with MnCl2 solution (0.5mol / L) at a solid-liquid ratio of 1.0g / mL, and then impregnated and activated for 2.5h. The mixture is then dried in an oven at 105℃ to obtain activated red mud material.

[0040] (4) The activated red mud material was placed in a muffle furnace for full roasting (roasting temperature 700℃, heating rate 5℃ / min, roasting time 1h, holding time 1.5h), and then taken out and cooled to room temperature to obtain zeolite-like adsorbent material.

[0041] Example 3:

[0042] A method for preparing a composite adsorbent material for the deep treatment of low-concentration fluoride-containing wastewater includes the following steps:

[0043] (1) The dried red mud is ground into fine particles and passed through a 100-mesh sieve to obtain the initial red mud raw material.

[0044] (2) The initial red mud raw material is mixed with dilute sulfuric acid (0.2 mol / L) at a solid-liquid ratio of 0.5 g / mL, and impregnated for 2 hours. Then it is dried in an oven at 105°C to obtain modified red mud material.

[0045] (3) The modified red mud material is mixed with MnCl2 solution (1.0 mol / L) at a solid-liquid ratio of 0.5 g / mL, and then impregnated and activated for 3 h. After that, it is dried in an oven at 105 °C to obtain activated red mud material.

[0046] (4) The activated red mud material was placed in a muffle furnace for full roasting (roasting temperature 500℃, heating rate 10℃ / min, roasting time 3h, holding time 1.5h), and after being taken out and cooled to room temperature, zeolite-like adsorbent material was obtained.

[0047] Those skilled in the art will understand that the instruments or devices used in the different embodiments described above are merely illustrative and not intended to be limiting. Provided that the operating procedures are compliant, any other available instruments or devices can be used in the preparation method according to the present invention.

[0048] Comparative Example 1

[0049] A method for preparing an adsorbent material, which differs from Example 1, is to use only MnCl2 metal salt for activation, without using sulfuric acid for partial dealkalization.

[0050] Comparative Example 2

[0051] A method for preparing an adsorbent material differs from Example 1 in that only sulfuric acid is used to dealkalize red mud, without the use of MnCl2 metal salt for activation.

[0052] Implementation effect analysis:

[0053] The materials prepared in Examples 1-3 and Comparative Examples 1-2 were used to treat power plant desulfurization wastewater.

[0054] The treatment process was as follows: the initial concentration of fluoride ions in the power plant desulfurization wastewater was 16.7 mg / L. The initial pH value was adjusted to 4.5. Adsorption was carried out using a filter device with the adsorbents obtained in Examples 1-3 and Comparative Examples 1-2. Then, the maximum adsorption capacity of the zeolite-like adsorbent for fluoride ions was determined using the Langmuir model. The determination of fluoride ion concentration in the wastewater was based on the standard HJ488-2009 "Determination of Fluoride in Water - Fluoride Reagent Spectrophotometric Method". The results are shown in Table 1.

[0055] Table 1 Comparison of the treatment effects of Examples 1-2 and red mud raw materials on fluoride-containing wastewater

[0056]

[0057]

[0058] As shown in Table 1, the fluoride ion content in the wastewater treated by the material of this invention can meet the optimal requirements under the best conditions.

[0059] The Class III standard of the "GB3838-2002 Surface Water Environmental Quality Standard" means that the fluoride concentration is less than 1 mg / L.

[0060] Obviously, the above embodiments are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description; it is neither necessary nor possible to exhaustively list all possible implementations; however, obvious variations or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A method for preparing a zeolite-like adsorbent material for deep removal of low-concentration fluoride-containing wastewater, characterized in that: Includes the following steps: (1) The dried red mud is ground into granules and then sieved to obtain powder material; (2) The powder material is immersed in dilute sulfuric acid for acid washing and partial dealkalization. The powder material after partial dealkalization is dried to obtain partially dealkalized red mud material. (3) The dealkalized red mud material is immersed in MnCl2 solution for metal salt activation treatment, and then dried to obtain activated red mud material; (4) The activated red mud material is placed in a muffle furnace for full calcination, and after cooling, a zeolite-like adsorbent material is obtained; The red mud is red mud with an average iron oxide content of 30-40%; the concentration of the dilute sulfuric acid is 0.1-0.2 mol / L; the concentration of the MnCl2 solution is 0.5-1.0 mol / L; in step (4), the roasting parameters are set as follows: roasting temperature 500-800℃, heating rate 8-12℃ / min, roasting time 1-2h, and holding time 1.5h.

2. The preparation method of the zeolite-like adsorbent material for deep removal of low-concentration fluoride-containing wastewater according to claim 1, characterized in that: In step (2), the solid-liquid ratio of the powder material to dilute sulfuric acid is 0.1~1.0 g / mL, and the duration of the immersion modification treatment is 2~5 h.

3. The method of claim 1, wherein the low concentration fluorochemical wastewater is characterized by: In step (3), the solid-liquid ratio of the partially dealkalized red mud material to the MnCl2 solution is 0.1~1.0 g / mL, and the duration of the immersion activation treatment is 2~5 h.

4. The method of claim 1, wherein the low concentration fluorochemical wastewater is characterized by: In steps (2) and (3), the drying temperature is 105~150℃.

5. The method for preparing the zeolite-like adsorbent material for deep removal of low-concentration fluoride-containing wastewater according to claim 1, characterized in that: In step (1), the grinding is dry grinding, and the residue on a 100-mesh sieve is 1%.

6. A composite adsorbent material for deep treatment of low-concentration fluoride-containing wastewater, characterized in that, It is prepared by the preparation method described in any one of claims 1-5.

7. The application of the composite adsorbent material for deep treatment of low-concentration fluoride-containing wastewater according to claim 6 in the treatment of low-concentration fluoride-containing wastewater.

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