HEMMA / R-SiO2-NH2 adsorbent as well as preparation method and application thereof

Abstract

The invention discloses an HEMMP / R-SiO2-NH2 adsorbent as well as a preparation method and application thereof, and belongs to the technical field of adsorbents. The method comprises the following steps: carrying out amine functionalization on a silicon dioxide sphere with a central radiation hole to prepare an amine-functionalized silicon dioxide sphere, loading HEMAP by using an impregnation method on the basis of the amine-functionalized silicon dioxide sphere, and adsorbing and recovering palladium metal in an aqueous solution by virtue of coordination of N atoms in amino groups, O atoms in HEMAP and Pd. According to the method, the adsorption effect of silicon dioxide on palladium metal is remarkably improved, meanwhile, dual adsorption of Pd < 2 + > and PdCl4 < 2-> is achieved, palladium metal in the aqueous solution is more effectively recycled, Pd < 2 + > in the aqueous solution can be reduced into elemental Pd, and secondary utilization is facilitated. The method has important significance on saving palladium resources, walking a sustainable development road and protecting the environment, and meanwhile, a new idea is provided for preparing an adsorbent which is low in cost and high in efficiency and is used for recycling palladium metal.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of adsorbents. More particularly, the present application relates to a HEMAP / R-SiO2-NH2 adsorbent, a preparation method and applications thereof. BACKGROUND

[0002] The noble metal palladium has excellent physical and chemical properties, has very wide application in industry and high economic value, and plays a very important role in the preparation and production process of some noble metal catalysts. However, the content of palladium in the earth's crust is relatively low and is scattered, mainly exists in the form of natural metal and intermetallic compound, sulfur arsenic compound and the like in nature, and the yield is much lower than that of gold, silver and other metals. Moreover, palladium element is not degradable in nature, and is harmful to organisms when flowing into the ecological environment. Recycling palladium element from secondary resources not only avoids resource waste, reduces the production cost and use cost of noble metal catalysts, but also reduces the pressure of natural mineral development, is more conducive to protecting the ecological environment, and meets the concept of sustainable green development.

[0003] Although the traditional recovery methods such as solvent extraction method, precipitation method and membrane separation method have certain effects, there are problems such as low adsorption efficiency, high price and secondary pollution. The adsorption method is more suitable for recycling palladium element in aqueous solution due to high selectivity, simple operation, small dosage and environmental friendliness. The most important factor affecting the adsorption effect is the preparation of the adsorbent. In recent years, the adsorbent has attracted widespread attention. Common adsorbents include silica adsorbents, ion exchange resin adsorbents and skeleton metal adsorbents. However, the adsorption method still has problems such as low adsorption capacity, complex preparation process, low yield and the like, and still has challenges in the solution system containing multiple Pd complexes.

[0004] Porous silica is a kind of silica material with rich pore structure, which has good adsorption performance, low thermal conductivity, high specific surface area and high stability, and has a large number of pores inside to provide a large number of active sites. The porous silica alone has poor adsorption effect on Pd(II), so researchers modify it to improve the adsorption capacity. At present, researchers mainly study the adsorption of single Pd complex, but there are still certain limitations in multiple synergistic adsorption. In the preparation process, there are also problems such as high equipment requirement, complex preparation process and low yield. Therefore, it is urgent to develop a noble metal enrichment material with high selectivity, high adsorption capacity, high adsorption rate, simple preparation, economic and environmental protection and reusability, which can safely and efficiently recover palladium metal from secondary resources. SUMMARY

[0005] An object of the present application is to solve at least the above problems and to provide at least the advantages described later.

[0006] To achieve these objectives and other advantages according to the present invention, a method for preparing a HEMAP / R-SiO2-NH2 adsorbent is provided, comprising the following steps: S1. Dissolve the template agent in an ethanol solution, sonicate, then add the silicon source and anhydrous toluene, stir thoroughly, add the alkaline solution, stir until clear, stop stirring, let stand at room temperature for a period of time, after the reaction is complete, centrifuge the mixture to obtain a solid product, wash the solid product until neutral and dry, calcine to obtain R-SiO2 spheres; S2. Disperse R-SiO2 spheres ultrasonically in anhydrous toluene, stir and reflux under nitrogen atmosphere, add surface modifier after thorough mixing and continue reaction, stir and reflux for a period of time, centrifuge the mixture to obtain solid product, wash until neutral and dry to obtain R-SiO2-NH2 spheres; S3. Disperse R-SiO2-NH2 spheres ultrasonically in an anhydrous organic solvent, add HEMAP, and load HEMAP onto R-SiO2-NH2 spheres using an impregnation method. After uniform loading, rotary evaporate and dry the mixture to obtain HEMAP / R-SiO2-NH2 adsorbent.

[0007] Preferably, the template agent in step S1 includes one or more of hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, octadecyltrimethylammonium chloride, and octadecyltrimethylammonium bromide, the alkaline solution includes one or more of ammonia, sodium hydroxide, and potassium hydroxide, and the silicon source is TEOS.

[0008] Preferably, in step S1, the ratio of silicon source to alkaline solution by volume v / v is 1:(150~300), and the ratio of silicon source to template agent by volume w / w is 1:(1.1~1.5).

[0009] Preferably, in step S1, the ultrasonic power is 100~300 W and the ultrasonic time is 3~5 min; The stirring speed before settling is 500~1000 r / min The calcination conditions include: calcination atmosphere is air, calcination temperature is 500~700℃, and calcination time is 5~10 h.

[0010] Preferably, the surface modifier described in step S2 includes one or more of (3-aminopropyl)triethoxysilane and (3-aminopropyl)trimethoxysilane.

[0011] Preferably, in step S2, the ultrasonic power is 100~300 W and the ultrasonic time is 3~5 min; After adding the surface modifier, the reaction temperature under stirring and reflux was 100~120℃, the stirring speed was 500~1000 r / min, and the reaction time was 20~30 h.

[0012] Preferably, the anhydrous organic solvent in step S3 includes any one of methanol, ethanol, ethyl acetate, dichloromethane, and petroleum ether.

[0013] Preferably, in step S3, the ratio of R-SiO2-NH2 spheres to HEMAP is 1:(1~2). The ultrasonic power is 100~300 W, and the ultrasonic time is 3~5 min; The reaction conditions for rotary evaporation include: a rotary evaporation temperature of 30~40℃, a rotary evaporation time of 10~20 min, and a rotary evaporation speed of 80~100 r / min.

[0014] The present invention also provides a HEMAP / R-SiO2-NH2 adsorbent, which is obtained by the preparation method described above.

[0015] The present invention also provides a use of the HEMAP / R-SiO2-NH2 adsorbent, specifically its application in the adsorption and recovery of palladium from aqueous solutions.

[0016] The present invention has at least the following beneficial effects: The present invention not only significantly improves the adsorption effect of silicon dioxide on palladium metal, but also achieves the adsorption of Pd... 2+ PdCl4 2- The dual adsorption process allows for more effective recovery of palladium metal from aqueous solutions, and can also remove Pd from aqueous solutions. 2+ It is reduced to elemental Pd, facilitating secondary utilization. This is of great significance for conserving palladium resources, pursuing sustainable development, and protecting the environment. It also provides a new approach for preparing low-cost, high-efficiency adsorbents for palladium metal recovery.

[0017] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0018] Figure 1 The image shows a scanning electron microscope (SEM) image of the R-SiO2 support prepared in Example 1. Figure 2 The image shows a scanning electron microscope (SEM) image of the support R-SiO2-NH2 prepared in Example 2. Figure 3 Here is a scanning electron microscope image of the adsorbent 2HEMAP / R-SiO2 prepared in Example 3; Figure 4 The image shows a scanning electron microscope (SEM) image of the adsorbent HEMAP / R-SiO2 prepared in Example 4. Figure 5The image shows a scanning electron microscope (SEM) image of the adsorbent 2HEMAP / R-SiO2-NH2 prepared in Example 5. Figure 6 The image shows a scanning electron microscope (SEM) image of the adsorbent HEMAP / R-SiO2-NH2 prepared in Example 6. Figure 7 This is a high-magnification transmission electron microscope image of the carrier R-SiO2 after adsorption prepared in Example 1; Figure 8 This is a high-magnification transmission electron microscope image of the carrier R-SiO2-NH2 after adsorption prepared in Example 2; Figure 9 This is a high-magnification transmission electron microscope image of the adsorbent 2HEMAP / R-SiO2 prepared in Example 3 after adsorption. Figure 10 This is a high-magnification transmission electron microscope image of the adsorbent HEMAP / R-SiO2 prepared in Example 4 after adsorption. Figure 11 This is a high-magnification transmission electron microscope image of the adsorbent 2HEMAP / R-SiO2-NH2 prepared in Example 5 after adsorption. Figure 12 This is a high-magnification transmission electron microscope image of the adsorbent HEMAP / R-SiO2-NH2 prepared in Example 6 after adsorption. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0020] It should be noted that, unless otherwise specified, the experimental methods described in the following implementation plan are all conventional methods, and the reagents and materials described are also unless otherwise specified.

[0021] <Example 1> The preparation method of R-SiO2 includes the following steps: S1. Dissolve 1g CTAB (hexadecyltrimethylammonium bromide) in anhydrous ethanol solution, sonicate (200W, 4min), then add 1.5mL TEOS (tetraethoxysilane) and 5mL anhydrous toluene, and stir thoroughly at 600rpm for 13min. S2. Disperse ammonia water (37%wt) thoroughly in deionized water to prepare an ammonia solution (v / v=35:1) (ammonia solution: TEOSv / v=200:1). Mix the ammonia solution with the S1 solution thoroughly, stir at 750 r / min until a clear solution is obtained, then stop stirring and let it stand at room temperature for 4~6 hours to allow the reaction to proceed. S3. After the reaction is complete, the solid product obtained by centrifugation of the mixture is washed with anhydrous ethanol until neutral, dried under vacuum at 60°C, and calcined at 500°C in air for 6 hours to obtain R-SiO2 spheres.

[0022] <Example 2> The preparation method of R-SiO2-NH2 includes the following steps: S1. Disperse 1g of R-SiO2 spheres in anhydrous toluene by ultrasonication (200W, 4min) and stir and reflux at 70℃ under nitrogen atmosphere for 1h (750rpm) to ensure thorough mixing. S2. After thorough mixing, add 2 mL of (3-aminopropyl)trimethoxysilane and continue stirring and refluxing (750 rpm) for 24 h. S3. After the reaction is complete, the solid product obtained by centrifugation of the mixture is washed with anhydrous ethanol until neutral, and dried under vacuum at 60°C to obtain R-SiO2-NH2 spheres.

[0023] <Example 3> The preparation method of 2HEMAP / R-SiO2 includes the following steps: S1. Disperse 0.1g of R-SiO2 spheres in ethyl acetate by ultrasonication (200W, 4min), add 0.2g of HEMAP (2-hydroxyethyl methacrylate phosphate), and stir thoroughly to mix evenly; S2. HEMAP was loaded into R-SiO2 spheres by impregnation. After uniform loading, the mixture was evaporated at 100 rpm and 40°C for 15 min using a rotary evaporator and dried at 60°C to obtain 2HEMAP / R-SiO2 adsorbent.

[0024] <Example 4> The preparation method of HEMAP / R-SiO2 includes the following steps: S1. Disperse 0.1g of R-SiO2 spheres in ethyl acetate by ultrasonication (200W, 4min), add 0.1g of HEMAP, and stir thoroughly to mix evenly; S2. HEMAP was loaded into R-SiO2 spheres by impregnation. After uniform loading, the mixture was evaporated at 100 rpm and 40°C for 15 min using a rotary evaporator and dried at 60°C to obtain HEMAP / R-SiO2 adsorbent.

[0025] <Example 5> The preparation method of 2HEMAP / R-SiO2-NH2 includes the following steps: S1. Disperse 0.1g of R-SiO2-NH2 spheres in ethyl acetate by ultrasonication (200W, 4min), add 0.2g of HEMAP, and stir thoroughly to mix evenly; S2. HEMAP was loaded into R-SiO2-NH2 by impregnation. After uniform loading, the mixture was evaporated at 100 rpm and 40°C for 15 min using a rotary evaporator and dried at 60°C to obtain 2HEMAP / R-SiO2-NH2 adsorbent.

[0026] <Example 6> The preparation method of HEMAP / R-SiO2-NH2 includes the following steps: S1. Disperse 0.1g of R-SiO2-NH2 spheres in ethyl acetate by ultrasonication (200W, 4min), add 0.1g of HEMAP, and stir thoroughly to mix evenly; S2. HEMAP was loaded into R-SiO2-NH2 spheres by impregnation. After uniform loading, the mixture was evaporated at 100 rpm and 40°C for 15 min using a rotary evaporator and dried at 60°C to obtain HEMAP / R-SiO2-NH2 adsorbent.

[0027] <Adsorbent Performance Testing> The specific surface area, pore volume under standard conditions, and average pore diameter of the adsorbents in Examples 1-5 were measured using the BET method, and the results are shown in Table 1 below: Table 1. Specific surface area, pore volume, and average pore diameter of each group of adsorbents. Group Adsorbent Specific surface area (m 2 / g)]]> Pore volume (cm 3 / g)]]> Average pore size (nm) Example 1 [R-SiO2] 860.98 215.44 98.57 Example 2 [R-SiO2-NH2] 646.62 110.39 75.72 Example 3 2 HEMAP / R-SiO2 253.34 83.67 47.39 Example 4 HEMAP / R-SiO2 283.34 113.67 67.39 Example 5 2 HEMAP / R-SiO2-NH2 171.90 71.27 26.98 Example 6 HEMAP / R-SiO2-NH2 231.69 101.21 56.73 According to the data in Table 1, compared with Example 1, the specific surface area and pore volume of the carrier after surface modification in Example 2 were significantly reduced. Compared with Examples 1 and 2, the specific surface area and pore volume of HEMAP loaded in Examples 3, 4, 5 and 6 were significantly reduced, indicating that HEMAP was successfully loaded inside the carrier. Compared with Examples 3 and 4, the specific surface area, pore volume and average pore size of R-SiO2 spheroidamine with central radial pores in Examples 5 and 6 were significantly reduced.

[0028] <Adsorption Performance Test> Using the palladium content in PdCl2 and H2PdCl4 solutions at pH=2 before and after adsorption as standards, the adsorption efficiency and adsorption effect were calculated. PdCl2 and H2PdCl4 solutions of a certain concentration at pH=2 were prepared, and appropriate amounts were placed in flasks. A certain amount of adsorbent was added and uniformly dispersed in the solution to be adsorbed. Adsorption was carried out at room temperature with shaking for 24 hours. The palladium content in the solution before and after adsorption was measured, and the results were calculated using the formula... Calculate the adsorption efficiency E and the maximum adsorption capacity Q, c0 (initial concentration), c (equilibrium concentration), M (adsorbent mass), and V (solution volume).

[0029] Table 2 Adsorption data for each group of adsorbents According to the data in Table 2, HEMAP / R-SiO2 prepared in Examples 3 and 4 showed excellent adsorption performance in the adsorption and recovery of palladium from PdCl2 aqueous solution. HEMAP / R-SiO2-NH2 prepared in Examples 5 and 6 also showed excellent adsorption performance in the adsorption and recovery of palladium from both PdCl2 aqueous solution and H2PdCl4 solution. Among them, HEMAP / R-SiO2-NH2 in Example 5, obtained after surface functionalization and loading modification, showed excellent performance in the palladium recovery reaction in aqueous solution. The adsorption efficiency was 83.08% and the maximum adsorption capacity was 141.23 mg / g when the PdCl2 concentration was 170 mg / g, and the adsorption efficiency was 82.31% and the maximum adsorption capacity was 164.62 mg / g when the H2PdCl4 concentration was 200 mg / g, which far exceeded that of similar adsorbents. At the same time, it can achieve the simultaneous adsorption of palladium in two forms.

[0030] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for preparing a HEMAP / R-SiO2-NH2 adsorbent, characterized by, The method comprises the following steps: S1, dissolving the template agent in an ethanol solution, after ultrasonic treatment, adding a silicon source and anhydrous toluene, after fully stirring, adding an alkali solution, stopping stirring after stirring to be clear, standing at room temperature for a period of time, centrifuging the mixture after full reaction to obtain a solid product, washing the solid product to be neutral and drying, and calcining to obtain R-SiO2 balls; S2, dispersing the R-SiO2 balls in anhydrous toluene by ultrasonic treatment, stirring and refluxing under a nitrogen atmosphere, adding a surface modifier after fully mixing, and continuing to react, centrifuging the mixture after stirring and refluxing for a period of time to obtain a solid product, washing the solid product to be neutral and drying to obtain R-SiO2-NH2 balls; S3, dispersing the R-SiO2-NH2 balls in an anhydrous organic solvent by ultrasonic treatment, adding HEMAP, loading HEMAP in the R-SiO2-NH2 balls by an immersion method, uniformly loading, rotary evaporating the mixture and drying to obtain a HEMAP / R-SiO2-NH2 adsorbent.

2. The preparation method of the HEMAP / R-SiO2-NH2 adsorbent as described in claim 1, characterized in that, The template agent in step S1 includes one or more of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, octadecyltrimethylammonium chloride, and octadecyltrimethylammonium bromide, the alkali solution includes one or more of ammonia, sodium hydroxide, and potassium hydroxide, and the silicon source is TEOS.

3. The preparation method of the HEMAP / R-SiO2-NH2 adsorbent as described in claim 1, characterized in that, The ratio of the amount of the silicon source to the amount of the alkali solution in step S1 is 1: (150-300) v / v, and the ratio of the amount of the silicon source to the amount of the template agent is 1: (1.1-1.5) w / w.

4. The preparation method of the HEMAP / R-SiO2-NH2 adsorbent as described in claim 1, characterized in that, In step S1, the ultrasonic power is 100-300 W, and the ultrasonic time is 3-5 min. The stirring speed before standing is 500-1000 r / min. The calcination conditions include: the calcination atmosphere is air, the calcination temperature is 500-700℃, and the calcination time is 5-10 h.

5. The preparation method of the HEMAP / R-SiO2-NH2 adsorbent as described in claim 1, characterized in that, The surface modifier in step S2 includes one or more of (3-aminopropyl)triethoxysilane and (3-aminopropyl)trimethoxysilane.

6. The preparation method of the HEMAP / R-SiO2-NH2 adsorbent as described in claim 1, characterized in that, In step S2, the ultrasonic power is 100-300 W, and the ultrasonic time is 3-5 min. After adding the surface modifier, the reaction temperature for stirring and refluxing is 100-120℃, the stirring speed is 500-1000 r / min, and the reaction time is 20-30 h.

7. The method for preparing the HEMAP / R-SiO2-NH2 adsorbent as described in claim 1, characterized in that, The anhydrous organic solvent in step S3 includes any one of methanol, ethanol, ethyl acetate, dichloromethane, and petroleum ether.

8. The method for preparing the HEMAP / R-SiO2-NH2 adsorbent as described in claim 1, characterized in that, In step S3, the ratio of the amount of the R-SiO2-NH2 balls to the amount of the HEMAP is 1: (1-2) w / w. The ultrasonic power is 100-300 W, and the ultrasonic time is 3-5 min. The rotary evaporation conditions include: the rotary evaporation temperature is 30-40℃, the rotary evaporation time is 10-20 min, and the rotary evaporation speed is 80-100 r / min.

9. A HEMAP / R-SiO2-NH2 adsorbent obtained by the preparation method of any one of claims 1-8.

10. Use of HEMAP / R-SiO2-NH2 adsorbent characterized in that, The application of the HEMAP / R-SiO2-NH2 adsorbent of claim 9 in adsorbing and recovering palladium elements in an aqueous solution.

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