Crown ether-inorganic ion modified adsorption material as well as preparation method and application thereof

Abstract

The invention relates to a crown ether-inorganic ion modified adsorption material as well as a preparation method and application thereof, and belongs to the technical field of heavy metal wastewater treatment. The preparation method comprises the following steps: mixing a metal cation salt solution with an adsorption matrix material, carrying out ion exchange, and drying to obtain an ion exchange modified sample; and dipping the ion exchange modified sample in an organic solvent containing crown ether to obtain the crown ether-inorganic ion modified adsorption material. The preparation method provided by the invention has the advantages of mild reaction conditions, simple process, low equipment investment and operation cost and the like. Meanwhile, the crown ether-inorganic ion modified adsorption material provided by the invention can efficiently, quickly and selectively adsorb thallium ions in wastewater, so that the purpose of purifying water is achieved.

Description

Technical Field

[0001] The invention relates to a crown ether-inorganic ion modified adsorption material and a preparation method and application thereof, belonging to the technical field of heavy metal wastewater treatment. Background Art

[0002] Thallium is a widely distributed, rare and highly toxic heavy metal element, second only to methylmercury in toxicity. Thallium has two characteristics: lithophile and sulfophile. Lithophile is often present as a trace element in silicate minerals such as albite, potassium feldspar and mica, while sulfophile is often associated with sulfide minerals such as lead, zinc, copper and iron. The main cause of thallium pollution is not the use of thallium and its compounds, but the release of thallium into the environment as an impurity in raw materials in certain industrial activities. These pollution incidents are mainly caused by the mining and smelting of sulfur-containing ores (such as pyrite, galena, sphalerite, smithsonite and arsenite) and lithium ores. Due to the high toxicity of thallium, the current standards require that the total thallium concentration in industrial wastewater is less than 5μg / L. In recent years, thallium-related water pollution incidents have occurred frequently in many places across the country, including Jiangxi, Shaanxi, Yunnan, etc., posing a serious threat to the ecosystem and human health. Therefore, it is crucial to develop thallium wastewater treatment technology.

[0003] At present, the commonly used methods for removing thallium mainly include ion exchange, redox precipitation, solvent extraction and adsorption. Among them, the ion exchange method has high separation efficiency, non-toxicity and can be used renewable, but the operating conditions are strict, time-consuming, ion exchange resin is expensive, and the elution and regeneration process is complicated. The redox precipitation method has a simple process and low operating cost, but it also has many shortcomings, such as the need to invest a large amount of sulfiding agent to generate insoluble sulfide precipitates, and because sulfides are toxic, if the sulfide dosage is not strictly controlled, H2S gas will be generated, further polluting the environment and causing poisoning of operators. The solvent extraction method has fast reaction and high efficiency, but it has strict requirements on the system, the extractant and diluent have certain toxicity, and there is a problem of secondary pollution. The adsorption method is considered to be one of the best technologies for water treatment because of its convenience, easy operation, wide adaptability and high efficiency. The materials with good adsorption effect on thallium mainly include metal oxides such as Fe, Mn, Ti, Prussian blue and its analogs, and biochar.

[0004] Since the concentration of thallium in industrial thallium-containing wastewater is usually low and there are usually multiple heavy metal complex pollution, a thallium removal agent with good selectivity is needed. And since the amount of industrial thallium-containing wastewater is large, the cost of thallium removal treatment is required to be low in order to improve economic benefits. However, the current thallium wastewater treatment methods and principles are often relatively simple, and it is often difficult to achieve deep removal of trace thallium. The treatment of industrial thallium-containing wastewater still faces some challenges.

[0005] Therefore, it is necessary to develop economical, efficient and highly selective thallium pollution remediation materials to provide solutions and technical support for the treatment of thallium-containing wastewater. Summary of the invention

[0006] In view of the problems of poor selectivity, low efficiency, high cost and complicated preparation process of existing thallium removal agents, one of the objects of the present invention is to provide a method for preparing a crown ether-inorganic ion modified adsorption material, which has the advantages of mild reaction conditions, simple process, low equipment investment and operating costs, etc.

[0007] The second object of the present invention is to provide a crown ether-inorganic ion modified adsorption material, which improves the adsorption capacity of thallium through cation exchange. At the same time, the selective complexation between the crown ether and the thallium ion realizes the selective adsorption capacity of thallium. The material is used for the adsorption of thallium ions in water, has the characteristics of good selectivity and fast rate, and has good industrial application prospects.

[0008] The third object of the present invention is to provide the application of crown ether-inorganic ion modified adsorption material as thallium adsorption material, which can efficiently, quickly and selectively adsorb thallium ions in wastewater to achieve the purpose of purifying water quality.

[0009] In order to achieve the above object, the first aspect of the present invention is to provide a method for preparing a crown ether-inorganic ion modified adsorption material, the method comprising: (1) mixing a metal cation salt solution with an adsorption matrix material for ion exchange and then drying to obtain an ion exchange modified sample; the adsorption matrix material is selected from at least one of activated carbon, biochar, molecular sieve and carbon aerogel; (2) Immersing the ion exchange modified sample in an organic solvent containing crown ether to obtain a crown ether-inorganic ion modified adsorption material.

[0010] The innovative point of the present invention is that a specific adsorption matrix material is fully stirred and mixed with a cationic salt solution to cause ion exchange, and an ion exchange modified sample is obtained after drying, and then the ion exchange modified sample is further immersed in an organic solvent containing a crown ether to obtain a crown ether-inorganic ion modified adsorption material. The adsorption matrix material provided by the present invention has a stable structure, rich pore structure and a large specific surface area, and can provide adsorption sites and exchangeable cations. At the same time, the adsorption capacity of the crown ether-inorganic ion modified adsorption material and thallium is improved by cation exchange, and further, by immersing in an organic solvent containing a crown ether, the selective complexation of thallium ions is improved, and the selective adsorption capacity of thallium is achieved. The method provided by the present invention integrates inorganic modification and organic modification, comprehensively improves the performance of the adsorption matrix material, does not generate harmful waste, and has mild reaction conditions.

[0011] As a preferred embodiment, the metal cation salt is selected from at least one of lithium salt, potassium salt and sodium salt. + , K+ and Na + All are monovalent alkali metal cations, and Tl + Has similar properties and is easier to + Ion exchange occurs.

[0012] As a preferred solution, the concentration of the metal cation salt solution is 0.1-3 mol / L.

[0013] As a preferred embodiment, the metal cation salt is selected from at least one of lithium sulfate, lithium nitrate, lithium chloride, potassium sulfate, potassium nitrate, potassium chloride, sodium sulfate, sodium nitrate and sodium chloride.

[0014] As a preferred solution, the liquid-to-solid ratio of the metal cation salt solution to the adsorption matrix material is 20-100 ml / g.

[0015] As a preferred solution, the ion exchange conditions are: stirring speed of 100-500 rpm, reaction temperature of 25-95°C, reaction time of 1-8 h, and exchange times of at least 2 times. Under the preferred temperature and stirring rate conditions, the ion exchange rate can be accelerated. If the temperature is too high, it will affect the structure of the matrix material. Too few ion exchanges will result in too little exchange of metal cations, reducing Tl + removal rate.

[0016] As a more preferred solution, the number of exchanges is 1 to 5 times.

[0017] As a preferred solution, the drying treatment conditions are: temperature of 80-150° C. and time of 8-20 hours.

[0018] As a preferred solution, the method further comprises first centrifuging the product obtained after the ion exchange and then performing the drying treatment.

[0019] As a preferred embodiment, the crown ether is selected from at least one of 18-crown-6, aza-18-crown-6, thia-18-crown-6 and dibenzo-18-crown-6.

[0020] As a preferred solution, the concentration of the crown ether in the organic solution is 10-100 g / L.

[0021] As a preferred solution, the organic solvent is selected from at least one of N,N-dimethylformamide, dichloromethane, tetrahydrofuran, benzene and toluene. The solubility of the crown ether in the organic solvent under the preferred conditions is relatively large, and a crown ether solution with a higher concentration can be obtained, thereby increasing the loading rate of the crown ether on the material.

[0022] As a preferred solution, the liquid-to-solid ratio of the organic solvent containing the crown ether to the ion exchange modified sample is 20-100 ml / g.

[0023] As a preferred solution, the impregnation conditions are: reaction time is 1-24 h, and reaction temperature is 25-80° C. Impregnation under the preferred conditions can accelerate the loading of crown ether on the material, but too high a temperature will volatilize the organic solvent and crown ether, reducing the loading amount of crown ether.

[0024] As a preferred solution, the impregnation is carried out under stirring conditions.

[0025] It should be noted that the present invention has no special requirements for the stirring conditions of the immersion, and any conditions known in the art may be used.

[0026] As a preferred solution, the ion exchange modified sample is immersed in an organic solvent containing crown ether, and the sample obtained after the immersion is subjected to solid-liquid separation, washing and drying to obtain the crown ether-inorganic ion modified adsorption material.

[0027] As a preferred solution, it should be noted that the present invention has no special requirements for the conditions of solid-liquid separation, washing and drying, and those known in the art can be adopted.

[0028] The present invention also provides a crown ether-inorganic ion modified adsorption material prepared by the above-mentioned preparation method. The modified adsorption material can efficiently, quickly and selectively adsorb thallium ions in wastewater.

[0029] The present invention also provides the application of crown ether-inorganic ion modified adsorption material as thallium adsorption material. The modified adsorption material can efficiently, quickly and selectively adsorb thallium ions in wastewater to achieve the purpose of purifying water quality.

[0030] As a preferred solution, the concentration of the crown ether-inorganic ion modified adsorption material in the thallium-containing wastewater is no higher than 2 g / L, more preferably 0.05-1.5 g / L, and further preferably 0.5-1 g / L.

[0031] Compared with the prior art, the present invention has at least the following advantages: (1) The preparation process of the crown ether-inorganic ion modified adsorption material provided by the present invention is simple, integrating inorganic modification and organic modification, comprehensively improving the performance of the adsorption matrix material, generating no harmful waste, and using mild reaction conditions.

[0032] (2) The crown ether-inorganic ion modified adsorption material provided by the present invention has selectivity and a high adsorption capacity for thallium ions, and can selectively adsorb thallium pollution characteristics in wastewater. Even under the condition that other metal ions exist in large quantities, the modified adsorption material still has excellent selective adsorption performance for thallium ions.

[0033] (3) The crown ether-inorganic ion modified adsorption material provided by the present invention is simple to use, has a small amount added to thallium-contaminated wastewater, and has the potential for recycling and reuse. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The XRD spectra of the 4A molecular sieve before and after potassium ion exchange modification in Example 1; Figure 2 This is the Fourier infrared spectrum image of the 4A molecular sieve before modification in Example 1; Figure 3 This is the Fourier infrared spectrum image of the crown ether-potassium ion modified 4A type molecular sieve in Example 1; Figure 4 This is the SEM-EDS image of the clinoptilolite before modification in Example 2; Figure 5 This is the SEM-EDS image of the crown ether-potassium ion modified clinoptilolite in Example 2. DETAILED DESCRIPTION

[0035] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0036] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the following specific embodiments. Obviously, the embodiments described below are only a part of the embodiments, and all other embodiments obtained by professionals in this field without creative work still belong to the protection scope of the present invention.

[0037] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0038] Example 1 (1) Add 1.0 g of 4A molecular sieve to 50 mL of 1 mol / L potassium chloride solution, heat and stir at 80°C for 1 h, repeat the exchange twice, use fresh solution each time. Remove the supernatant by centrifugation, wash with deionized water 3 times, and dry in an oven at 105°C for 12 h. The resulting solid is the potassium ion exchange modified 4A molecular sieve.

[0039] (2) Weigh 1.0 g of 18-crown-6 and add it to 50 ml of N,N-dimethylformamide, then add 1.0 g of potassium ion exchange modified molecular sieve, and stir at room temperature for 12 h. Filter, then wash with deionized water and dry to obtain crown ether-potassium ion modified 4A molecular sieve.

[0040] The present invention exemplarily provides XRD spectra of 4A type molecular sieve before and after potassium ion exchange modification in this embodiment, see Figure 1 ,It can be seen from the figure that after potassium ion exchange modification, the sample still maintains the complete structural characteristics of 4A type molecular sieve.

[0041] The present invention exemplarily provides the Fourier transform infrared spectrum image of the 4A type molecular sieve before modification and the Fourier transform infrared spectrum image of the 4A type molecular sieve modified with crown ether-potassium ion in this embodiment, specifically see Figure 2 and Figure 3 ,from Figure 2 and Figure 3 It can be seen that the material is at 3446 cm -1 , 1010 cm -1 、667 cm -1 The peak intensity at changed and the peak position shifted significantly, confirming the successful loading of the crown ether.

[0042] Example 2 (1) Add 1.0 g of clinoptilolite to 50 mL of 1 mol / L potassium chloride solution, heat and stir at 80°C for 1 h, and repeat the exchange twice, using fresh solution each time. Remove the supernatant by centrifugation, wash with deionized water three times, and dry in an oven at 105°C for 12 h. The resulting solid is potassium ion exchange modified clinoptilolite.

[0043] (2) Weigh 1.0 g of 18-crown ether-6 and add it to 50 ml of N,N-dimethylformamide and stir until the solid is completely dissolved. Then add 1.0 g of ion exchange modified zeolite and stir at room temperature for 12 h. Filter, then wash with deionized water and dry to obtain crown ether-potassium ion modified clinoptilolite.

[0044] The present invention exemplarily provides the SEM-EDS image of the clinoptilolite before modification and the SEM-EDS image of the clinoptilolite modified by the crown ether-potassium ion in this embodiment, see respectively Figure 4 Hehe Figure 5 ,contrast Figure 4 and Figure 5 It can be seen that the potassium ion content of the modified sample increases significantly, and the modification does not affect the morphology of the sample.

[0045] Example 3 (1) Add 1.0 g of 4A molecular sieve to 50 mL of 1 mol / L sodium chloride solution, heat and stir at 80°C for 1 h, repeat the exchange twice, use fresh solution each time. Remove the supernatant by centrifugation, wash with deionized water three times, and dry in an oven at 105°C for 12 h. The resulting solid is the sodium ion exchange modified 4A molecular sieve.

[0046] (2) Weigh 1.0 g of 18-crown-6 and add it to 50 ml of N,N-dimethylformamide, then add 1.0 g of sodium ion exchange modified molecular sieve, and stir at room temperature for 12 h. Filter, then wash with deionized water and dry to obtain crown ether-sodium ion modified 4A molecular sieve.

[0047] Example 4 (1) Add 1.0 g of activated carbon to 50 mL of 1 mol / L sodium chloride solution, heat and stir at 80°C for 1 h, and repeat the exchange twice, using fresh solution each time. Remove the supernatant by centrifugation, wash with deionized water three times, and dry in an oven at 105°C for 12 h. The resulting solid is the sodium ion exchange modified activated carbon.

[0048] (2) Weigh 1.0 g of 18-crown ether-6 and add it to 50 ml of N,N-dimethylformamide, then add 1.0 g of sodium ion exchange modified activated carbon, and stir at room temperature for 12 h. Filter, then wash with deionized water and dry to obtain crown ether-sodium ion modified activated carbon.

[0049] Example 5 (1) Add 1.0 g of 4A molecular sieve to 30 mL of 1 mol / L potassium chloride solution, heat and stir at 50°C for 4 h, repeat the exchange twice, use fresh solution each time. Remove the supernatant by centrifugation, wash with deionized water three times, and dry in an oven at 105°C for 12 h. The resulting solid is the potassium ion exchange modified 4A molecular sieve.

[0050] (2) Weigh 1.0 g of aza-18-crown-6 and add it to 25 ml of N,N-dimethylformamide, then add 1.0 g of potassium ion exchange modified molecular sieve, and stir at 50°C for 8 h. Filter, then wash with deionized water and dry to obtain crown ether-potassium ion modified 4A molecular sieve.

[0051] Comparative Example 1 Weigh 1.0 g of 18-crown-6 and add it to 50 ml of N,N-dimethylformamide and stir until the solid is completely dissolved, then add 1.0 g of 4A molecular sieve and stir at room temperature for 12 h. Filter, then wash with deionized water and dry to obtain crown-4A molecular sieve.

[0052] Comparative Example 2 Add 1.0 g of 4A molecular sieve to 50 mL of 1 mol / L potassium chloride solution, heat and stir at 80°C for 1 h, repeat the exchange twice, use fresh solution each time. Centrifuge to remove the supernatant, wash with deionized water 3 times, and dry in an oven at 105°C for 12 h to obtain a solid, which is the potassium ion exchange modified 4A molecular sieve.

[0053] Comparative Example 3 Weigh 1.0 g of 18-crown-6 and add it to 50 ml of N,N-dimethylformamide and stir until the solid is completely dissolved, then add 1.0 g of clinoptilolite and stir at room temperature for 12 h. Filter, then wash with deionized water and dry to obtain crown-clinoptilolite.

[0054] Comparative Example 4 1.0 g of clinoptilolite was added to 50 mL of 1 mol / L potassium chloride solution, heated and stirred at 80°C for 1 h, and the exchange was repeated twice, using fresh solution each time. The supernatant was removed by centrifugation, washed with deionized water 3 times, and dried in an oven at 105°C for 12 h. The resulting solid was potassium ion exchange modified clinoptilolite.

[0055] Test Case Prepared with a concentration of 1.0 ppm Tl + The heavy metal solution was added to the adsorbent material prepared in the above example at an addition amount of 1.0 g / L, and adsorbed at 25°C and 200 r / min for 240 min. The water sample after adsorption was filtered with a 0.45 μm filter membrane, and the Tl content in the treated solution was determined by inductively coupled plasma mass spectrometry (ICP-MS). + The residual concentration of Tl + The removal rate of 2.5% and 2.5% of the total removal rate are shown in Table 1.

[0056]

[0057] It can be seen from Table 1 that the crown ether-inorganic ion modified adsorption material provided by the present invention has a beneficial adsorption effect on thallium and a high removal rate.

[0058] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing a crown ether-inorganic ion modified adsorbent material, characterized in that: The method includes: (1) mixing a metal cation salt solution with an adsorption matrix material for ion exchange and then drying to obtain an ion exchange modified sample; the adsorption matrix material is selected from at least one of activated carbon, biochar, molecular sieve and carbon aerogel; (2) Immersing the ion exchange modified sample in an organic solvent containing crown ether to obtain a crown ether-inorganic ion modified adsorption material.

2. The method for preparing a crown ether-inorganic ion modified adsorbent material according to claim 1, characterized in that: The metal cation salt is selected from at least one of lithium salt, potassium salt and sodium salt; And / or, the concentration of the metal cation salt solution is 0.1-3 mol / L.

3. The method for preparing a crown ether-inorganic ion modified adsorbent material according to claim 2, characterized in that: The metal cation salt is selected from at least one of lithium sulfate, lithium nitrate, lithium chloride, potassium sulfate, potassium nitrate, potassium chloride, sodium sulfate, sodium nitrate and sodium chloride.

4. The method for preparing a crown ether-inorganic ion modified adsorbent material according to any one of claims 1 to 3, characterized in that: The liquid-to-solid ratio of the metal cation salt solution to the adsorption matrix material is 20-100 ml / g; And / or, the conditions for the ion exchange are: a stirring speed of 100-500 rpm, a reaction temperature of 25-95° C., a reaction time of 1-8 h, and an exchange number of at least 2 times.

5. The method for preparing a crown ether-inorganic ion modified adsorption material according to any one of claims 1 to 3, characterized in that: The crown ether is selected from at least one of 18-crown-6, aza-18-crown-6, thia-18-crown-6 and dibenzo-18-crown-6; And / or, the concentration of the crown ether in the organic solution is 10-100 g / L.

6. The method for preparing a crown ether-inorganic ion modified adsorption material according to any one of claims 1 to 3, characterized in that: The organic solvent is selected from at least one of N,N-dimethylformamide, dichloromethane, tetrahydrofuran, benzene and toluene.

7. The method for preparing a crown ether-inorganic ion modified adsorption material according to any one of claims 1 to 3, characterized in that: The liquid-to-solid ratio of the crown ether-containing organic solvent to the ion exchange modified sample is 20-100 ml / g.

8. The method for preparing a crown ether-inorganic ion modified adsorption material according to any one of claims 1 to 3, characterized in that: The impregnation conditions are: reaction time is 1-24 h, and reaction temperature is 25-80°C.

9. The crown ether-inorganic ion modified adsorption material prepared by the method according to any one of claims 1 to 8.

10. Use of the crown ether-inorganic ion modified adsorption material according to claim 9 as a thallium adsorption material.

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