CuS / diatomite composite adsorbent, and preparation method and application thereof
By growing CuS nanosheets in situ on the surface of diatomaceous earth, a CuS/diatomaceous earth composite adsorbent is formed, which solves the problems of insufficient adsorption capacity of diatomaceous earth and easy aggregation of CuS particles, and realizes efficient adsorption and recovery of silver ions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- LUOYANG NORMAL UNIV
- Filing Date
- 2023-08-03
- Publication Date
- 2026-06-02
AI Technical Summary
The existing diatomaceous earth has a limited adsorption capacity for silver ions, and CuS nanoparticles are prone to agglomeration, making recycling difficult and limiting their practical application in the field of precious metal recycling.
By pre-modifying the surface charge of diatomaceous earth and growing CuS nanosheets in situ on its surface, a CuS/diatomaceous earth composite adsorbent is formed. The S2- active ions are used to improve the chemical adsorption effect, thus solving the problem of insufficient CuS particle loading.
It significantly improved the adsorption capacity of diatomaceous earth for silver ions, enhanced the loading capacity of CuS nanoparticles and their binding force with silver ions, and improved the recovery efficiency.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of adsorbent preparation technology, specifically relating to the preparation and application of a CuS / diatomite composite adsorbent with high silver ion adsorption capacity. Background Technology
[0002] Silver ions, as a precious metal, possess excellent electrical and thermal conductivity and ductility, playing a vital role in industries such as antibacterial, electroplating, pharmaceuticals, chemicals, and photography. However, in recent years, with the decreasing or depletion of rich and easily processed silver ore deposits, global silver resources have been gradually exhausted. The enrichment and recovery of silver ions can not only protect the environment but also conserve resources and address the scarcity of precious metal resources in my country. Among the many common methods for treating silver-containing wastewater, adsorption is favored by researchers due to its advantages such as simple operation, high efficiency, low cost, regenerable adsorbents, and flexible design. For adsorption methods, the selection of the adsorbent is crucial. Compared with carbonaceous and polymer adsorbents, natural porous minerals have advantages such as strong adsorption capacity, stable physicochemical properties, high temperature resistance, excellent environmental compatibility, and low cost, giving them a significant advantage in the harmless treatment of heavy metals. Diatomite is an important mineral resource in my country, with its main mineral component being diatomaceous opal. This biomass-derived mineral possesses a unique hierarchical porous structure and abundant surface hydroxyl groups, exhibiting strong electronegativity, making it an excellent natural adsorbent for heavy metals. However, in practical industrial applications, the adsorption of small molecule pollutants by diatomaceous earth minerals mainly relies on physical diffusion, with adsorption capacities generally not exceeding 50 mg / L. Furthermore, its limited surface active sites and weak chemical adsorption and bonding abilities limit its direct application for silver ion adsorption. Typically, diatomaceous earth is used as a carrier, undergoing surface functionalization treatments, such as loading nanoparticles with abundant active functional groups, to increase the contact area between active sites and metal ions, thereby improving the relatively weak adsorption capacity of diatomaceous earth for heavy metals. Meanwhile, certain transition metal sulfide nanoparticles, such as MoS2, ZnS, MnS, and CuS, contain abundant active S groups on their surfaces. 2- CuS nanoparticles exhibit a strong van der Waals bond to heavy metal ions, compared to MoS2, ZnS, and other metal sulfides. 2+ CuS nanoparticles exhibit superior adsorption properties. However, considering their small particle size, tendency to aggregate, easily masked surface active sites, and difficulty in recycling, the practical application of CuS nanoparticles in the field of precious metal recovery is currently very limited. Summary of the Invention
[0003] To address the shortcomings of existing technologies, the present invention aims to provide a CuS / diatomaceous earth composite adsorbent, a method for preparing the CuS / diatomaceous earth composite adsorbent, and an application of the CuS / diatomaceous earth composite adsorbent in the adsorption and enrichment of silver ions in water solutions. The CuS / diatomaceous earth composite adsorbent of the present invention achieves uniform loading of CuS on the diatomaceous earth surface, has a simple and mild preparation method, low raw material costs, and can significantly improve the adsorption capacity of diatomaceous earth for silver ions.
[0004] To achieve the above objectives, the specific solution adopted by the present invention is as follows:
[0005] A method for preparing a CuS / diatomaceous earth composite adsorbent, characterized by: firstly, pre-modifying the surface charge of diatomaceous earth, and then growing a layer of CuS nanosheets in situ on the surface of the modified diatomaceous earth to obtain the CuS / diatomaceous earth composite adsorbent; the main steps are as follows:
[0006] 1) Weigh the original diatomaceous earth according to the solid-liquid ratio of 1:20~1:80 and pour it into a strong cationic polyelectrolyte aqueous solution with a mass fraction of 0.5%~2%. Stir for 2~6 hours, centrifuge, discard the supernatant, and dry in an oven at 40~90℃.
[0007] 2) Disperse the diatomaceous earth impregnated with the above-mentioned strong polycationic electrolyte into an aqueous solution according to a solid-liquid ratio of 1:80~1:200. After stirring and mixing for 20~30 min, sonicate in soft mode for 5~15 min to obtain a suspension.
[0008] 3) Weigh 4-8 mmol of copper salt and add it to 30-50 mL of the above suspension. Stir vigorously for 20-40 min. Then add thiosulfate in an equal molar amount to the copper salt to the above suspension to obtain a mixture. After the mixture is reacted in a water bath, the precipitate is washed with water, centrifuged, and dried at 40-90℃ to obtain CuS / diatomite composite adsorbent.
[0009] As a further optimization of the above preparation method: the diatomaceous earth shell mentioned in preparation step 1) is composed of centered diatoms, and the diatom shell content is more than 60%.
[0010] As a further optimization of the above preparation method: the strong cationic polyelectrolyte is one or more of polydimethyldiallylammonium chloride, polyquaternary ammonium salt, polyallylamine hydrochloride, or polyamine.
[0011] As a further optimization of the above preparation method: the copper salt is one or more of copper nitrate, copper sulfate, and copper chloride.
[0012] As a further optimization of the above preparation method: the thiosulfate is sodium thiosulfate or potassium thiosulfate.
[0013] As a further optimization of the above preparation method: the water bath reaction conditions mentioned in preparation step 3) are: heating in a water bath at 70°C for 4 hours.
[0014] A CuS / diatomite composite adsorbent is prepared by the above method. The prepared CuS nanoparticles are uniformly loaded on the surface of diatomite, and the prepared CuS / diatomite composite adsorbent retains the macroporous structure of diatomite well.
[0015] The above-mentioned CuS / diatomite composite adsorbent is used for the adsorption of heavy metal silver ions.
[0016] The present invention has the following beneficial effects:
[0017] 1. Loading CuS nanoparticles onto the surface of diatomaceous earth will introduce S. 2- Active ions, thus enabling the utilization of S 2- It exhibits a strong chemical adsorption effect on specific heavy metal ions, thus improving the problem of low adsorption capacity of diatomaceous earth for silver ions.
[0018] 2. After charge modification of the diatomaceous earth surface using a strong cationic electrolyte, compared with the unmodified CuS / diatomaceous earth composite adsorbent, the loading of CuS particles on its surface is significantly increased. Therefore, the diatomaceous earth surface exhibits a strong van der Waals binding force with silver ions. 2- The number of active ions increased significantly, greatly enhancing the adsorption capacity for silver ions.
[0019] 3. Utilizing the carrier effect of diatomaceous earth to improve the aggregation problem of CuS nanoparticles, making their surface S 2- The increased contact opportunities between active ions and silver ions enhance the utilization efficiency of CuS nanoparticles in the adsorption and recovery of silver ions. Attached Figure Description
[0020] Figure 1 Scanning electron microscope image of the CuS / diatomite composite adsorbent prepared in Example 1;
[0021] Figure 2 The scanning electron microscope image of the CuS / diatomite composite adsorbent prepared in Example 2;
[0022] Figure 3 The X-ray diffraction pattern of the CuS / diatomite composite adsorbent prepared in Example 2 is shown. Detailed Implementation
[0023] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention.
[0024] Example 1
[0025] A method for preparing a CuS / diatomaceous earth composite adsorbent with high silver ion adsorption capacity, characterized by the following main steps:
[0026] 1) Weigh 2.0 g of Zhejiang diatomaceous earth raw soil according to a solid-liquid ratio of 1:20 and pour it into 40 mL of 0.5% polydimethyldiallylammonium chloride aqueous solution. Stir for 2 h, centrifuge, discard the supernatant, and dry in an oven at 40℃.
[0027] 2) Take 0.2 g of the Zhejiang diatomaceous earth impregnated and dried by the above polydimethyldiallylammonium chloride aqueous solution and disperse it into 40 mL of aqueous solution. After stirring and mixing for 20 min, sonicate in soft mode for 5 min.
[0028] 3) Weigh 4 mmol of copper sulfate and add it to the above suspension at a molar ratio of 1:1, and stir vigorously for 20 min. Then add 4 mmol of potassium thiosulfate to the above suspension. After the mixture is reacted in a water bath, the precipitate is washed with water, centrifuged, and dried at 40℃ to obtain the CuS / diatomaceous earth composite adsorbent.
[0029] The following adsorption tests were conducted on the CuS / diatomaceous earth composite adsorbent:
[0030] At room temperature, 5 mg of CuS / diatomaceous earth composite adsorbent was added to 10 mL of 500 mg / L silver nitrate solution. After shaking for 24 h, the solution was centrifuged (200 rpm) and filtered through a 0.22 μm filter membrane. The silver ion content in the filtrate was measured using inductively coupled atomic emission spectrometry (ICAES). Analysis showed that the adsorption capacity of this composite adsorbent for silver ions was 551.9 mg / g.
[0031] Compare with Example 1
[0032] The difference from Example 1 is that steps 1) and 2) are omitted, and the other preparation steps of the adsorbent used are the same as in Example 1.
[0033] The difference from Example 1 is that Zhejiang diatomaceous earth and polydimethyldiallylammonium chloride aqueous solution are no longer added, while the types and amounts of other raw materials remain unchanged.
[0034] The adsorption test was the same as in Example 1. Analysis showed that the pure-phase CuS adsorbent had an adsorption capacity of 423.7 mg / g for silver ions.
[0035] Example 2
[0036] A method for preparing a CuS / diatomaceous earth composite adsorbent with high silver ion adsorption capacity, characterized by the following main steps:
[0037] 1) Weigh 2.0 g of Jilin diatomaceous earth raw soil according to a solid-liquid ratio of 1:40 and pour it into 80 mL of 0.5% polydimethyldiallylammonium chloride aqueous solution. Stir for 4 h, centrifuge, discard the supernatant, and dry in an oven at 80℃.
[0038] 2) Take 0.3 g of the dried Jilin diatomaceous earth impregnated with the above polydimethyldiallylammonium chloride aqueous solution and disperse it into 40 mL of aqueous solution according to the solid-liquid ratio of 1:133. After stirring and mixing for 30 min, sonicate in soft mode for 10 min.
[0039] 3) Weigh 6 mmol of copper nitrate and add it to the above suspension at a molar ratio of 1:1, and stir vigorously for 30 min. Then add 6 mmol of sodium thiosulfate to the above suspension. After the mixture is reacted in a water bath, the precipitate is washed with water, centrifuged, and dried at 80℃ to obtain the CuS / diatomaceous earth composite adsorbent.
[0040] The following adsorption tests were conducted on the CuS / diatomaceous earth composite adsorbent:
[0041] At room temperature, 5 mg of CuS / diatomaceous earth composite adsorbent was added to 10 mL of 500 mg / L silver nitrate solution. After shaking for 24 h, the solution was centrifuged (200 rpm) and filtered through a 0.22 μm filter membrane. The silver ion content in the filtrate was measured using inductively coupled atomic emission spectrometry (ICAES). Analysis showed that the adsorption capacity of this composite adsorbent for silver ions was 827.9 mg / g.
[0042] Compare with Example 2
[0043] The difference from Example 2 is that step 1 is omitted, and the other preparation steps of the adsorbent used are the same as in Example 2.
[0044] The difference from Example 2 is that the aqueous solution of polydimethyldiallylammonium chloride is no longer added, while the types and amounts of other raw materials remain unchanged.
[0045] The adsorption test was the same as in Example 2. Analysis showed that the obtained CuS / diatomaceous earth composite adsorbent, without modification by polydiallylammonium chloride aqueous solution, had an adsorption capacity of 465.2 mg / g for silver ions.
[0046] Example 3
[0047] A method for preparing a CuS / diatomaceous earth composite adsorbent with high silver ion adsorption capacity, characterized by the following main steps:
[0048] 1) Weigh 1.0 g of Jilin diatomaceous earth raw soil according to the solid-liquid ratio of 1:80, pour it into 80 mL of 2% polyamine aqueous solution, stir for 6 h, centrifuge, discard the supernatant, and dry it in an oven at 90℃.
[0049] 2) Take 0.4 g of the dried Jilin diatomaceous earth impregnated with the above polyamine aqueous solution at a solid-liquid ratio of 1:80, disperse it in 32 mL of aqueous solution, stir and mix for 30 min, and then sonicate in soft mode for 15 min.
[0050] 3) Weigh 8 mmol of copper chloride and add it to the above suspension at a molar ratio of 1:1, and stir vigorously for 40 min. Then add 8 mmol of sodium thiosulfate to the above suspension. After the mixture is reacted in a water bath, the precipitate is washed with water, centrifuged, and dried at 90℃ to obtain the CuS / diatomaceous earth composite adsorbent.
[0051] The following adsorption tests were conducted on the CuS / diatomaceous earth composite adsorbent:
[0052] At room temperature, 5 mg of CuS / diatomaceous earth composite adsorbent was added to 10 mL of 500 mg / L silver nitrate solution. After shaking for 24 h, the solution was centrifuged (200 rpm) and filtered through a 0.22 μm filter membrane. The silver ion content in the filtrate was measured using inductively coupled atomic emission spectrometry (ICAES). Analysis showed that the adsorption capacity of this composite adsorbent for silver ions was 723.4 mg / g.
[0053] It should be noted that the above-described embodiments should be understood as illustrative, not as limiting the scope of protection of this invention. The scope of protection of this invention is defined by the claims. For those skilled in the art, some non-essential improvements and adjustments made to this invention without departing from the essence and scope of this invention still fall within the scope of protection of this invention.
Claims
1. An application of a CuS / diatomaceous earth composite adsorbent in the adsorption of heavy metal silver ions, characterized in that: First, the surface charge of diatomaceous earth is pre-modified, and then a layer of CuS nanosheets is grown in situ on the surface of the modified diatomaceous earth to obtain a CuS / diatomaceous earth composite adsorbent. The specific steps are as follows: 1) Weigh the raw diatomaceous earth according to the solid-liquid ratio of 1g:20ml~1g:80ml and pour it into a strong cationic polyelectrolyte aqueous solution with a mass fraction of 0.5%~2%. After stirring for 2~6 hours, centrifuge, discard the supernatant, and dry it in an oven at 40~90℃. 2) Disperse the diatomaceous earth impregnated with strong cationic polyelectrolyte into the aqueous solution according to the solid-liquid ratio of 1g:80ml~1g:200ml, stir and mix for 20~30 min, and then sonicate in soft mode for 5~15 min to obtain a suspension. 3) Weigh 4-8 mmol of copper salt and add it to 30-50 mL of suspension. Stir vigorously for 20-40 min. Then add thiosulfate in an equal molar amount to the copper salt to the suspension to obtain a mixture. After the mixture is reacted in a water bath, the precipitate is washed with water, centrifuged, and dried at 40-90℃ to obtain CuS / diatomite composite adsorbent.
2. The application according to claim 1, characterized in that: In step 1), the original diatomaceous earth shell is composed of centered diatoms, and the diatom shell content is more than 60%.
3. The application according to claim 1, characterized in that: The strong cationic polyelectrolyte is one or more of polyquaternary ammonium salts and polyamines.
4. The application according to claim 1, characterized in that: The copper salt is one or more of copper nitrate, copper sulfate, and copper chloride.
5. The application according to claim 1, characterized in that: The thiosulfate is sodium thiosulfate or potassium thiosulfate.
6. The application according to claim 1, characterized in that: In step 3), the water bath reaction conditions are: heating in a water bath at 70°C for 4 hours.