Nano-sized cuprous thiocyanate, preparation method and application thereof

Abstract

The present application relates to wastewater treatment material technical field, specifically to a kind of nanometer cuprous thiocyanate, preparation method and application;The preparation method includes the following steps: S1, copper sulfate is stirred and dissolved in water and stirred uniformly, and blue transparent solution is obtained;S2, slowly drop sodium thiosulfate solution into blue transparent solution, and green transparent solution is obtained;S3, slowly drop sodium thiocyanate solution into green transparent solution and react to obtain white precipitate;S4, filter and collect white precipitate and repeatedly clean with anhydrous ethanol and distilled water to remove sodium thiocyanate impurities on the surface of white precipitate, then dry, grind to obtain nanometer cuprous thiocyanate.The application of nanometer cuprous thiocyanate prepared by the present application to adsorb tetracycline antibiotics in wastewater has the advantages of strong stability compared with copper sulfide, not easy to be oxidized by air, and can be recycled multiple times, so that resources are maximized.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment materials technology, specifically to a nano-sized cuprous thiocyanate, its preparation method, and its application. Background Technology

[0002] Antibiotics are widely used in medicine, animal husbandry, and other fields due to their broad-spectrum antibacterial properties, low cost, and high quality. However, antibiotics cannot be completely absorbed by humans and animals, and most of them are discharged into the environment or wastewater treatment plants in their original form. Traditional wastewater treatment plants lack specific technologies for antibiotic removal, thus failing to efficiently remove antibiotics from wastewater. This leads to the continuous accumulation of antibiotics in the environment, causing serious pollution.

[0003] The adsorption method is simple to operate, has low energy consumption, high adsorption rate, and does not cause secondary pollution to the environment.

[0004] Copper sulfides are highly effective at removing tetracycline hydrochloride antibiotics and are non-toxic, making them widely used in research on tetracycline removal. However, copper sulfides are easily oxidized upon contact with oxygen in the air, exhibiting poor stability. For example, when Jiang Mengyun synthesized copper sulfide using copper chloride as the copper source and sodium sulfide as the sulfur source, peaks of copper oxide and copper sulfide appeared on the XRD pattern after about 15 days (Jiang Mengyun. Study on the adsorption behavior of tetracycline by copper sulfides with different crystallinities [D]. Nanjing University of Information Science and Technology. 2017.). Cuprous thiocyanate is not only non-toxic and non-polluting but also highly stable, remaining stable below 360℃ and only being oxidized by strong oxidizing agents. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the objective of this invention can be achieved through the following technical solutions:

[0006] A method for preparing nano-sized cuprous thiocyanate, the method comprising the following steps:

[0007] S1. Dissolve copper sulfate in water by stirring until homogeneous, resulting in a blue transparent solution;

[0008] S2. Slowly add sodium thiosulfate solution to the blue transparent solution to obtain a green transparent solution;

[0009] S3. Sodium thiocyanate solution is slowly added dropwise to a green transparent solution to produce a white precipitate.

[0010] S4. Filter and collect the white precipitate, and repeatedly wash it with anhydrous ethanol and distilled water to remove sodium thiocyanate impurities from the surface of the white precipitate. Then dry and grind it to obtain nano-sized cuprous thiocyanate.

[0011] Preferably, the molar ratio of copper sulfate, sodium thiosulfate, and sodium thiocyanate is (0.8-1.2):(0.8-1.2):(0.8-1.5), and the concentration of sodium thiocyanate is 0.2-0.6 mol / L.

[0012] Preferably, in step S1, the stirring speed is 100-200 rpm and the stirring time is 2-4 h.

[0013] Preferably, in step S3, the reaction temperature when adding sodium thiocyanate solution is 20-30°C and the reaction time is 2-6 hours.

[0014] A nano-sized cuprous thiocyanate was prepared by the preparation method described above.

[0015] Preferably, the cuprous thiocyanate has a crystal form of β-CuSCN and a particle size of 100-200 nm.

[0016] The above-described application of nano-sized cuprous thiocyanate as an adsorbent in the adsorption of tetracycline antibiotics in wastewater.

[0017] Preferably, the application method is as follows: after filtering and adjusting the pH value of tetracycline-containing antibiotics, nano-sized cuprous thiocyanate is added, and adsorption is carried out in a dark place away from light. The adsorbed nano-cuprous thiocyanate can be regenerated and reused after desorption with desorption solution. During adsorption, the pH is adjusted to 7-8.5, and the adsorption time is controlled at 24-48 hours.

[0018] The beneficial effects of this invention are:

[0019] 1. The cuprous thiocyanate synthesized by this invention has the advantages of inexpensive and readily available raw materials, low reaction temperature, short reaction time, simple process flow, no harm to the environment, and easy to realize large-scale industrial production.

[0020] 2. The nano-sized cuprous thiocyanate prepared by this invention has the advantages of strong stability and low susceptibility to air oxidation when adsorbing tetracycline antibiotics in wastewater compared with ordinary copper sulfides.

[0021] 3. The cuprous thiocyanate prepared by this invention has excellent adsorption performance for tetracycline antibiotics in wastewater. Due to its strong stability, it can be recycled multiple times, thus maximizing resource utilization. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0023] Figure 1 The image shows the microstructure of cuprous thiocyanate prepared in Example 1 of this invention.

[0024] Figure 2 The XRD spectrum of cuprous thiocyanate prepared in Example 1 of this invention is shown.

[0025] Figure 3 The graph shows the relationship between equilibrium pH and adsorption amount measured in Examples 1-3 and Comparative Examples 1 and 2 of this invention.

[0026] Figure 4 The image shows the FTIR spectra of cuprous thiocyanate before and after adsorption of tetracycline antibiotics prepared in Example 1 of this invention.

[0027] Figure 5 The number of cycles of the tetracycline antibiotics adsorbed by cuprous thiocyanate prepared in Examples 1-3 and Comparative Examples 1 and 2 of this invention are given. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1

[0030] A method for preparing nano-sized cuprous thiocyanate, the method comprising the following steps:

[0031] The preparation method of nano-sized cuprous thiocyanate includes the following steps:

[0032] S1. Take 8 mmol of CuSO4·5H2O and put it into a beaker containing 20 mL of distilled water. Stir with a magnetic stirrer for 2 hours at a speed of 200 rpm to obtain a blue transparent solution.

[0033] S2. Slowly add 20 mL of 0.4 mol / L sodium thiosulfate solution to the blue transparent solution to obtain a green transparent solution;

[0034] S3. Slowly add 20 mL of 0.4 mol / L sodium thiocyanate solution to a green transparent solution. After reacting at room temperature (25°C) for 4 hours, a white precipitate is obtained.

[0035] S4. Filter and collect the white precipitate, then wash it thoroughly 3-4 times with anhydrous ethanol and distilled water. Place it in a vacuum drying oven and bake at 55°C for 8 hours. Finally, grind it into powder to obtain nano-sized cuprous thiocyanate. Characterize the obtained nano-sized cuprous thiocyanate using tests such as… Figure 1 As shown, its microstructure exhibits an irregular shape with a particle size of 100-200 nm. Figure 2 It can be seen that the XRD diffraction peaks of the prepared nano-sized cuprous thiocyanate are consistent with those of standard card 29-0581, corresponding to the hexagonal crystal system β-CuSCN.

[0036] Example 2

[0037] A method for preparing nano-sized cuprous thiocyanate, the method comprising the following steps:

[0038] S1. Take 6.4 mmol of CuSO4·5H2O and put it into a beaker containing 20 mL of distilled water. Stir with a magnetic stirrer for 2 hours at a speed of 200 rpm to obtain a blue transparent solution.

[0039] S2. Slowly add 20 mL of 0.32 mol / L sodium thiosulfate solution to the blue transparent solution to obtain a green transparent solution;

[0040] S3. Slowly add 20 mL of 0.4 mol / L sodium thiocyanate solution to a green transparent solution. After reacting at room temperature (25°C) for 4 hours, a white precipitate is obtained.

[0041] S4. Filter and collect the white precipitate and wash it thoroughly with anhydrous ethanol and distilled water 3-4 times. Then place it in a vacuum drying oven and dry it at 55°C for 8 hours. Finally, grind it into powder to obtain nano-sized cuprous thiocyanate.

[0042] Example 3

[0043] S1. Take 8 mmol of CuSO4·5H2O and put it into a beaker containing 20 mL of distilled water. Stir with a magnetic stirrer for 2 hours at a speed of 200 rpm to obtain a blue transparent solution.

[0044] S2. Slowly add 20 mL of 0.4 mol / L sodium thiosulfate solution to the blue transparent solution to obtain a green transparent solution;

[0045] S3. Slowly add 20 mL of 0.48 mol / L sodium thiocyanate solution to a green transparent solution. After reacting at room temperature (25°C) for 4 hours, a white precipitate is obtained.

[0046] S4. Filter and collect the white precipitate and wash it thoroughly with anhydrous ethanol and distilled water 3-4 times. Then place it in a vacuum drying oven and dry it at 55°C for 8 hours. Finally, grind it into powder to obtain nano-sized cuprous thiocyanate.

[0047] Comparative Example 1

[0048] The preparation method of Comparative Example 1 is the same as that of Example 1, except that the molar ratio of copper sulfate, sodium thiosulfate and sodium thiocyanate in Comparative Example 1 is 1:1:2.

[0049] Comparative Example 2

[0050] Comparative Example 2 was prepared using the same method as Example 1, except that the molar ratio of copper sulfate, sodium thiosulfate, and sodium thiocyanate in Comparative Example 1 was 2:2:1.

[0051] Test experiment:

[0052] Nanoscale cuprous thiocyanate prepared in Examples 1, 2, 3 and Comparative Examples 1, 2 was used to adsorb tetracycline antibiotics in wastewater.

[0053] The specific adsorption method is as follows: 50 mL of 500 mg / L tetracycline hydrochloride antibiotics is added to each of several beakers. Suspended impurities are removed by filtration. The pH of the wastewater is then adjusted with 0.1 mol / L HCl or 0.1 mol / L NaOH solution. Then, 0.0125 g of nano-sized cuprous thiocyanate prepared in Examples 1, 2, 3 and Comparative Examples 1 and 2 is added to each beaker. The beakers are then placed in a water bath shaker and shaken in the dark at 25°C and 120 r / min. The concentration of tetracycline hydrochloride antibiotics is measured after 48 hours.

[0054] The pH value of the wastewater is controlled between pH 6.4 and 7.8.

[0055] Take out the adsorbed nano-sized cuprous thiocyanate from the above five beakers and place it in the desorption solution (a mixed solution of 100 mL of 0.04 mol / L hydrochloric acid and 40% anhydrous ethanol). Stir for 6 hours at a speed of 180 r / min to carry out desorption. After the desorption is completed, add 500 mg / L of tetracycline hydrochloride antibiotic for adsorption. Repeat the desorption and adsorption six times under the same conditions.

[0056] The relationship between equilibrium pH and adsorption capacity obtained from the above tests is summarized as follows: Figure 3 ,Depend on Figure 3It was found that the nano-sized cuprous thiocyanate prepared in Example 1 exhibited the highest adsorption capacity for tetracycline, reaching a maximum of 1308.88 mg / g at equilibrium pH = 7.56. This indicates that nano-sized cuprous thiocyanate has excellent adsorption effect on tetracycline antibiotics under these conditions. The adsorption capacity initially increased and then decreased with increasing pH, which is related to the charges carried by tetracycline and cuprous thiocyanate at different pH values. At pH < 3.3, tetracycline is positively charged, while cuprous thiocyanate is also positively charged, making adsorption difficult. In the pH range of 3.3-6.5, tetracycline is uncharged, while cuprous thiocyanate is negatively charged, making adsorption easier. As the pH further increases, tetracycline gradually becomes negatively charged, and the electronegativity of cuprous thiocyanate also increases, resulting in a slower increase in adsorption capacity at pH = 7.56. The cuprous thiocyanate prepared in Examples 1-3 showed significant adsorption capacity for tetracycline, while the cuprous thiocyanate prepared in Comparative Examples 1 and 2 did not show significant adsorption effect on tetracycline regardless of the pH value.

[0057] FTIR spectra of cuprous thiocyanate prepared in Example 1 before and after adsorption were analyzed.

[0058] Depend on Figure 4 The characteristic peaks of tetracycline antibiotics are as follows: 1457 cm⁻¹ corresponds to the C=C skeleton, 1527 cm⁻¹ to the amide group on ring A, 1582 cm⁻¹, 1617 cm⁻¹, and 1672 cm⁻¹ correspond to the C=O group on ring C, ring A, and the amide group on ring A, respectively; 2861 cm⁻¹ is the -CH₃ peak; 2928 cm⁻¹ is the amine group on dimethylamine; and 2991 cm⁻¹ is the -OH peak. Unadsorbed cuprous thiocyanate did not exhibit these characteristic peaks in these relevant wavelength regions. After adsorption, cuprous thiocyanate showed a characteristic peak of the C=C skeleton at 1453 cm⁻¹, indicating that tetracycline was indeed adsorbed onto the cuprous thiocyanate. Compared to tetracycline, the characteristic peaks of the C=O group on ring C and ring A at 1591 cm⁻¹ and 1613 cm⁻¹, respectively, shifted, suggesting that the complexation may be related to these groups.

[0059] The desorption and adsorption data of six tetracycline antibiotics in wastewater prepared using cuprous thiocyanate in Examples 1-3 and Comparative Examples 1 and 2 were combined into... Figure 5 ,Depend on Figure 5It can be seen that the adsorption capacity of nano-sized cuprous thiocyanate decreased sharply during the first four cycles of use, from 1282 mg / g to 1130 mg / g, a decrease of approximately 11.9%. From the fifth cycle onwards, the decrease in adsorption capacity became slower, from 1130 mg / g to 1128 mg / g, indicating that the adsorption performance of cuprous thiocyanate had basically reached an equilibrium state. After six cycles of use, the adsorption capacity remained at 1116 mg / g, which is 87.1% of the initial adsorption capacity, indicating that cuprous thiocyanate has good recyclability. In Examples 1-3, the adsorption capacity did not change significantly during the six cycles of adsorption. In Comparative Examples 1 and 2, the adsorption capacity decreased gradually with each of the six cycles, and the reduction effect was significant.

[0060] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0061] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. The application of nano-sized cuprous thiocyanate as an adsorbent in the adsorption of tetracycline antibiotics in wastewater, characterized in that, The preparation method of the nano-sized cuprous thiocyanate includes the following steps: S1. Dissolve copper sulfate in water by stirring until homogeneous, resulting in a blue transparent solution; S2. Slowly add sodium thiosulfate solution to the blue transparent solution to obtain a green transparent solution; S3. Sodium thiocyanate solution is slowly added dropwise to a green transparent solution to produce a white precipitate. S4. Filter and collect the white precipitate, and wash it repeatedly with anhydrous ethanol and distilled water to remove sodium thiocyanate impurities from the surface of the white precipitate. Then dry and grind it to obtain nano-sized cuprous thiocyanate. The molar ratio of copper sulfate, sodium thiosulfate, and sodium thiocyanate is (0.8-1.2):(0.8-1.2):(0.8-1.5), and the concentration of sodium thiocyanate is 0.2-0.6 mol / L.

2. The application of nano-sized cuprous thiocyanate as an adsorbent in the adsorption of tetracycline antibiotics in wastewater according to claim 1, characterized in that: In step S1, the stirring speed is 100-200 rpm; the stirring time is 2-4 hours.

3. The application of nano-sized cuprous thiocyanate as an adsorbent in the adsorption of tetracycline antibiotics in wastewater according to claim 1, characterized in that: In step S3, the reaction temperature when adding sodium thiocyanate solution is 20-30℃ and the reaction time is 2-6 hours.

4. The application of nano-sized cuprous thiocyanate as an adsorbent in the adsorption of tetracycline antibiotics in wastewater according to claim 1, characterized in that, The method for adsorbing tetracycline antibiotics in wastewater is as follows: after filtering and adjusting the pH value of the tetracycline antibiotics, nano-sized cuprous thiocyanate is added, and adsorption is carried out in a dark place away from light. The adsorbed nano-cuprous thiocyanate can be regenerated and reused after desorption with desorption solution. During adsorption, the pH is adjusted to 7-8.5, and the adsorption time is controlled at 24-48 hours.

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