Method for Recovering Copper Oxide Nanoflowers from Acidic Waste Etching Solution

Abstract

This application relates to the technical field of waste etching solution treatment, and provides a method for recovering copper oxide nanoflowers from acidic waste etching solution, including: mixing the acidic waste etching solution containing copper ions and a mixed alkali solution to obtain a reaction solution with a pH of 8-13, and heating and reacting the reaction solution for crystallization to form copper oxide nanoflower crystals. The mass concentration of the alkaline substance in the mixed alkali solution is 40%-47%, and the alkaline substance includes hydroxide-based alkali and carbonate-based alkali with a mass ratio of (2.5-7.8):1; and calcining the copper oxide nanoflower crystals to obtain copper oxide nanoflowers. This application realizes the recovery of high-purity and highly active copper oxide nanoflower products from acidic waste etching solution, and not only has a simple process but also a low cost.

Description

Technical Field

[0001] This application relates to the technical field of waste etching solution treatment, and particularly to a method for recovering copper oxide nanoflowers from acidic waste etching solution. Background Art

[0002] The etching solution commonly used in the manufacturing process of printed circuit boards can be acidic cupric chloride etching solution with components of cupric chloride and hydrochloric acid, or alkaline cupric chloride etching solution with components of cupric chloride and ammonia water. Among them, after the etching process, the etching solution forms waste etching solution containing high-concentration copper ions after dissolving copper. In traditional technologies, the methods for recovering copper from waste etching solution mainly include chemical precipitation method, solvent extraction method, and ion exchange method.

[0003] Copper oxide, as an important inorganic functional material, is widely used in the fields of electronics, energy, catalysis, chemical industry, etc. Especially in the electronics industry, copper oxide is used as a raw material for copper electroplating, an electrode material for solar cells, and a catalyst for chemical reactions. Among them, nano-copper oxide shows broad application prospects in the fields of electronics, energy, and catalysis due to its unique physical and chemical properties. However, how to recover high-purity nano-copper oxide from waste etching solution with complex components is still a technical problem to be solved urgently. Summary of the Invention

[0004] Based on this, it is necessary to provide a method capable of recovering copper oxide nanoflowers from acidic waste etching solution.

[0005] This application provides a method for recovering copper oxide nanoflowers from acidic waste etching solution, and the method includes:

[0006] Mixing acidic waste etching solution containing copper ions and mixed alkali solution to obtain a reaction solution with a pH of 8-13, and heating the reaction solution for reaction crystallization to form copper oxide nanoflower crystals. The mass concentration of the alkaline substance in the mixed alkali solution is 40%-47%, and the alkaline substance includes hydroxide alkali and carbonate alkali with a mass ratio of (2.5-7.8):1; and,

[0007] Calcining the copper oxide nanoflower crystals to obtain copper oxide nanoflowers.

[0008] In some embodiments, the pH of the reaction solution obtained by mixing acidic waste etching solution and the mixed alkali solution is 9.5-12.

[0009] In some embodiments, during the reaction crystallization process, the temperature of the reaction solution is 70°C-95°C.

[0010] In some embodiments, the reaction crystallization time is 0.5 h-2 h.

[0011] In some embodiments, during the reaction crystallization process, the reaction solution is stirred at a stirring speed of 10 rpm to 70 rpm.

[0012] In some embodiments, the hydroxide-based base includes at least one of sodium hydroxide and potassium hydroxide.

[0013] In some embodiments, the carbonate-based base includes at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate.

[0014] In some embodiments, the calcination temperature is 200 °C to 600 °C, and the time is 0.5 h to 1.5 h.

[0015] In some embodiments, the acidic waste etching solution further contains impurity ions, and the impurity ions include at least one of iron ions, arsenic ions, and nickel ions. After removing the impurities from the acidic waste etching solution, the acidic waste etching solution containing copper ions is formed.

[0016] In some embodiments, the method for removing impurities includes: adding an oxidant to the acidic waste etching solution, and then adding metatitanic acid to adsorb and remove the impurity ions.

[0017] In some embodiments, the mass concentration of copper ions in the acidic waste etching solution is 50 g / L to 200 g / L.

[0018] In some embodiments, the copper oxide nanoflowers include a plurality of copper oxide porous nanosheets. The thickness of the copper oxide porous nanosheets is 10 nm to 100 nm, the length is 500 nm to 1000 nm, and the width is 300 nm to 1000 nm.

[0019] In some embodiments, the volume average particle size D50 of the copper oxide nanoflowers is 10 μm to 100 μm.

[0020] Compared with the traditional technology, the present application has at least the following beneficial effects:

[0021] The present application uses a mixed alkali solution with a specific composition to react and crystallize with the acidic waste etching solution. During the reaction crystallization process, by controlling the pH, the content of the hydroxide-based base, and the carbonate-based base, copper ions can be first converted into copper hydroxide and basic copper carbonate intermediates and then decomposed into copper oxide. Among them, the present application can promote the oriented nucleation and two-dimensional growth of the Cu(OH)2 precursor to form copper oxide nanosheets (with a thickness of about 10 nm), and CO3 in basic copper carbonate 2-The decomposition and release of CO2 can play the roles of stirring, shearing, and microbubble templating, thereby guiding the formation of pores and driving the self-assembly of nanosheets to form cupric oxide nanoflower crystals with a three-dimensional nanoflower structure. The cupric oxide nanoflower crystals basically do not contain basic copper carbonate and copper hydroxide. After being calcined, they can form high-purity cupric oxide nanoflowers with a porous structure, which are applicable to fields such as copper electroplating, energy storage, solar cells, and chemical catalysts in the electronics industry. The recovery process of this application is simple and low-cost, realizing the recovery of high-purity cupric oxide nanoflowers from acidic waste etching solution, and the cupric oxide nanoflowers also have the characteristic of quickly dissolving in acidic solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 SEM comparison diagrams of the cupric oxide nanoflowers prepared in Example 1 of this application at different magnification ratios.

[0023] Figure 2 TEM diagram and EDX diagram of the cupric oxide nanoflowers prepared in Example 1 of this application.

[0024] Figure 3 X-ray diffraction diagram of the cupric oxide nanoflowers prepared in Example 1 of this application.

[0025] Figure 4 X-ray photoelectron spectroscopy (XPS) diagram of the cupric oxide nanoflowers prepared in Example 1 of this application.

[0026] Figure 5 SEM comparison diagrams of the cupric oxide nanoflowers prepared in Example 2 of this application at different magnification ratios.

[0027] Figure 6 SEM comparison diagrams of the cupric oxide nanoflowers prepared in Example 3 of this application at different magnification ratios.

[0028] Figure 7 SEM comparison diagrams of the cupric oxide nanoflowers prepared in Example 11 of this application at different magnification ratios.

[0029] Figure 8 SEM comparison diagrams of the cupric oxide products prepared in Comparative Example 1 of this application at different magnification ratios.

[0030] Figure 9 SEM comparison diagrams of the cupric oxide products prepared in Comparative Example 2 of this application at different magnification ratios.

[0031] Figure 10 X-ray diffraction diagram of the cupric oxide crystals after the reaction crystallization in step S2 of Comparative Example 3 of this application.

[0032] Figure 11SEM comparison diagrams of the copper oxide products prepared in Comparative Example 3 of this application at different magnification ratios.

[0033] Figure 12 SEM comparison diagrams of the copper oxide products prepared in Comparative Example 4 of this application at different magnification ratios.

[0034] Figure 13 SEM comparison diagrams of the copper oxide products prepared in Comparative Example 5 of this application at different magnification ratios. Detailed implementation manners

[0035] The following further details this application in conjunction with the implementation manners and examples. These implementation manners and examples are only used to illustrate this application and not to limit the scope of this application. The purpose of providing these implementation manners and examples is to make the understanding of the disclosed content of this application more thorough and comprehensive. It should also be understood that this application can be implemented in many different forms and is not limited to the implementation manners and examples described herein. Those skilled in the art can make various changes or modifications without departing from the connotation of this application, and the equivalent forms obtained also fall within the protection scope of this application. In addition, in the following description, a large number of specific details are given to provide a more thorough understanding of this application. It should be understood that this application can be implemented without one or more of these details.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in the specification of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0037] In this application, "optionally", "optional", "option", mean having or not having, that is, any one selected from two parallel options of "having" or "not having". If "optional" appears multiple times in a technical solution, without special instructions and without contradictions or mutual restrictions, each "optional" is independent of each other.

[0038] In this application, in "the first aspect", "the second aspect", etc., the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0039] In this application, for the technical features described in an open-ended manner, it includes a closed technical solution composed of the listed features, and also includes an open-ended technical solution containing the listed features.

[0040] In this application, when it comes to numerical intervals (i.e., numerical ranges), unless otherwise specified, the distribution of the selectable numerical values within the numerical interval is considered continuous, and includes the two numerical endpoints of the numerical interval (i.e., the minimum value and the maximum value), as well as each numerical value between these two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to the integers within the numerical interval, it includes the two endpoint integers of the numerical range, as well as each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical ranges disclosed in this application should be understood to include any and all sub-ranges subsumed therein. The "numerical values" in this numerical interval can be any quantitative values, such as numbers, percentages, ratios, etc. The "numerical interval" is allowed to broadly include quantitative intervals such as percentage intervals, ratio intervals, and ratio value intervals.

[0041] All documents mentioned in this application are incorporated herein by reference as if each document was individually incorporated by reference. Unless it conflicts with the application purpose and / or technical solution of this application, the cited documents involved in this application are incorporated by reference in their entirety and for all purposes. When this application involves cited documents, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also incorporated by reference. When this application involves cited documents, the examples and preferred methods of the relevant technical features cited can also be incorporated as references into this application, but only to the extent that this application can be implemented. It should be understood that when the cited content conflicts with the description in this application, this application shall prevail or be amended adaptively according to the description in this application.

[0042] In the traditional technology, sodium hydroxide, potassium hydroxide, calcium carbonate, sodium carbonate, etc. are added to the acidic waste etching solution to precipitate basic copper carbonate or copper hydroxide. Among them, basic copper carbonate is an amorphous precipitate with a loose structure and a large specific surface area. It adsorbs a lot of impurities, is easy to peptize, and has a large water content. Therefore, basic copper carbonate is not easy to filter and wash, and copper oxide can only be obtained after calcination. The copper hydroxide precipitate is unstable and easily dehydrates to form muddy copper oxide. The muddy copper oxide contains more impurities, and the particles of the muddy copper oxide are small, the structure is loose, and it is relatively viscous, which is not conducive to the filtration and washing of the copper oxide product. In addition, most of the copper oxide nanoflowers are prepared by the method of crystal growth. It is necessary to directly grow copper oxide with a nanoflower structure on a specific growth substrate by a liquid phase method in cooperation with a surfactant, which is not only costly but also has a complex preparation process.

[0043] This application provides a method for recovering copper oxide nanoflowers from an acidic waste etching solution, and the method includes:

[0044] Mix the acidic waste etching solution containing copper ions and the mixed alkali solution to obtain a reaction solution with a pH of 8 - 13, and heat and react the reaction solution to crystallize to form cupric oxide nanowire crystals. The mass concentration of the alkaline substance in the mixed alkali solution is 40% - 47%, and the alkaline substance includes hydroxide-based alkali and carbonate-based alkali with a mass ratio of (2.5 - 7.8):1; and,

[0045] Calcine the cupric oxide nanowire crystals to obtain cupric oxide nanowires.

[0046] Among them, the pH of the reaction solution obtained by mixing can be 8.0, 8.4, 8.8, 9.2, 9.6, 10.0, 10.4, 10.8, 11.2, 11.6, 12.0, 12.4, 12.8 or 13.0. The mass concentration of the alkaline substance in the mixed alkali solution can be 40.0%, 40.5%, 41.0%, 41.5%, 42.0%, 42.5%, 43.0%, 43.5%, 44.0%, 44.5%, 45.0%, 45.5%, 46.0%, 46.5% or 47.0%. The mass ratio of the hydroxide-based alkali to the carbonate-based alkali can be 2.5:1, 3.0:1, 3.5:1, 4.0:1, 4.5:1, 5.0:1, 5.5:1, 6.0:1, 6.5:1, 7.0:1, 7.5:1 or 7.8:1.

[0047] In this application, a mixed alkali solution with a specific composition is used to react and crystallize with the acidic waste etching solution, which can form high-purity cupric oxide nanowire crystals with a nanowire structure. And the cupric oxide nanowire crystals basically do not contain basic copper carbonate and copper hydroxide. After being calcined, it can form high-purity cupric oxide nanowires with a porous structure, which are suitable for fields such as copper electroplating, energy storage, solar cells and chemical catalysts in the electronics industry. The recovery process of this application is simple and has low cost, realizing the recovery of high-purity cupric oxide nanowires from the acidic waste etching solution. The cupric oxide nanowires also have the characteristic of quickly dissolving in acidic solutions.

[0048] By controlling the composition and content of the alkaline substance in the mixed alkali solution as above in this application, it effectively ensures that cupric oxide nanowire crystals can be formed after reaction crystallization, avoiding the formation of intermediate structures such as basic copper carbonate and copper hydroxide, which affect the purity of the cupric oxide nanowires formed after calcination and the nanowire structure. If the mass concentration of the alkaline substance in the mixed alkali solution is relatively low, it may lead to incomplete reaction and the inability to form a nanowire structure. If the mass concentration of the alkaline substance in the mixed alkali solution is relatively high, it may lead to incomplete crystallization of the product and the inability to form a porous structure of the nanowires, thereby affecting the dissolution rate of the cupric oxide nanowires formed after calcination.

[0049] If the proportion of hydroxide bases in the alkaline substance is relatively high, it will result in the formation of copper oxide particles containing more copper hydroxide. Copper hydroxide usually appears as blue flocculent precipitates and can be converted into copper oxide through high-temperature decomposition. However, due to particle sintering densification and Ostwald ripening effects, it is impossible to form copper oxide products with a nanoflower structure after calcination. If the proportion of carbonate bases in the alkaline substance is relatively high, it will cause the formed copper oxide particles to contain more basic copper carbonate. Similarly, basic copper carbonate can also be converted into copper oxide through high-temperature decomposition. However, due to the morphological limitations of the precursor, the basic copper carbonate precursor is irregular dense particles, and the decomposed copper oxide tends to inherit its dense structure. At the same time, the decomposition reaction of basic copper carbonate is intense, and the rapid escape of CO2 and H2O (especially at high temperatures) will destroy the precursor framework, leading to the collapse of the pore structure rather than the formation of an ordered porous network, thus making it impossible to form copper oxide products with a nanoflower structure after calcination.

[0050] It should be noted that in the acidic waste etching solution of the present application, copper ions react with hydroxides to form copper hydroxide intermediates and react with carbonates to form basic copper carbonate. Under the reaction environment of the present application, copper hydroxide is unstable and will decompose to form copper oxide; basic copper carbonate reacts with sodium hydroxide to form copper oxide and carbonate. Therefore, the formed copper oxide nanoflower crystals in the present application basically do not contain copper hydroxide and basic copper carbonate.

[0051] It can be understood that the present application does not make specific requirements and special limitations on the preparation method of the mixed alkali solution, as long as a mixed alkali solution with the above composition can be formed. For example, the mixed alkali solution can be prepared by mixing a solution containing hydroxide bases and a solution containing carbonate bases.

[0052] In some embodiments, the pH of the reaction solution obtained by mixing the acidic waste etching solution and the mixed alkali solution is 9.5 - 12. The present application further adjusts the pH of the mixed reaction solution to ensure that the copper ions in the acidic waste etching solution react completely, improving the recovery rate. And it can effectively reduce the copper salts remaining on the surface of the copper oxide nanoflower crystals, avoiding the influence of the remaining copper salts on the conversion and purity of the copper oxide nanoflower during the calcination process.

[0053] In some embodiments, during the reaction crystallization process, the temperature of the reaction solution is 70°C - 95°C, for example, it can be 70°C, 72°C, 74°C, 76°C, 78°C, 80°C, 82°C, 84°C, 86°C, 88°C, 90°C, 92°C, 94°C or 95°C. It can be selected as 80°C - 95°C.

[0054] By selecting the temperature of the reaction solution during the reaction crystallization process as above, from the perspective of kinetic control, since the increase in temperature accelerates Cu 2+The hydrolysis and precipitation reaction shortens the nucleation induction period, and the conversion rate of the Cu(OH)2 intermediate to CuO is moderate, which is conducive to the oriented growth of nanosheets; moreover, the CO3 2- The CO2 bubbles generated by the decomposition of 2- form a microbubble template to assist in pore generation, making the crystallization process tend to grow into a nanoflower-like structure, further ensuring the formation of copper oxide nanoflowers after calcination. If the temperature is relatively low, due to insufficient reaction kinetics and slow reaction speed, it may lead to the inability to form a porous and complete nanoflower structure, and there are problems such as loose lamellae; if the temperature is relatively high, due to violent reactions, it may lead to explosive growth of crystals and particle agglomeration, still unable to form a nanoflower structure.

[0055] In some embodiments, the reaction crystallization time is 0.5 h to 2 h, for example, it can be 0.5 h, 0.6 h, 0.8 h, 1.0 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h or 2.0 h.

[0056] In some embodiments, during the reaction crystallization, the reaction solution is stirred, and the stirring speed is 10 rpm to 70 rpm. For example, it can be 10 rpm, 15 rpm, 20 rpm, 25 rpm, 30 rpm, 35 rpm, 40 rpm, 45 rpm, 50 rpm, 55 rpm, 60 rpm, 65 rpm or 70 rpm. Optionally, the stirring speed can be selected from 10 rpm to 60 rpm.

[0057] In this application, the stirring speed in the reaction crystallization process is selected as above to promote the uniform mixing of Cu 2+ and OH - / CO3 2- to avoid explosive nucleation caused by too high local concentration, and the appropriate shear force can disperse the initially aggregated nanosheets, promote their oriented arrangement, and ensure the crystallization growth of copper oxide nanoflowers; when the stirring speed is relatively high, it will destroy the self-assembly process of the nanosheets, resulting in the inability of the crystals to grow and the inability to form copper oxide nanoflowers after calcination.

[0058] In some embodiments, the hydroxide-based base includes at least one of sodium hydroxide and potassium hydroxide.

[0059] In some embodiments, the carbonate-based base includes at least one of sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate.

[0060] In some embodiments, the calcination temperature is 200 °C to 600 °C, for example, it can be 200 °C, 250 °C, 300 °C, 350 °C, 400 °C, 450 °C, 500 °C, 550 °C or 600 °C, and can be selected as 500 °C to 590 °C.

[0061] In some embodiments, the calcination time is 0.5 h to 1.5 h, and for example, it can be 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h, 1.0 h, 1.1 h, 1.2 h, 1.3 h, 1.4 h, or 1.5 h.

[0062] By selecting the calcination time and temperature as above in this application, the crystallization of copper oxide can be further improved, and the thickness of the nanosheets can be increased (from 10 nm to 15 nm); it can also reduce lattice distortion and effectively maintain the integrity of the nanoflower structure, thus ensuring the formation of a stable copper oxide nanoflower product. If the calcination temperature is relatively high, local sintering may occur, making the edges of the copper oxide nanosheets blurred, further reducing the specific surface area, and even causing the overall framework of the nanoflower to collapse, destroying the structure of the copper oxide nanoflower; if the calcination time is relatively long, the Ostwald ripening effect during the calcination process may be aggravated, the grains are further coarsened, resulting in a decrease in porosity. Although the mechanical strength can be improved, the active sites will be reduced. If the calcination temperature is relatively low or the time is relatively short, the internal stress of the crystal residue and the brittleness of the sheets may not be effectively improved, leading to problems such as insufficient strengthening of the nanoflower structure, low product purity, and low dissolution rate.

[0063] In some embodiments, the acidic waste etching solution further contains impurity ions, and the impurity ions include at least one of iron ions, arsenic ions, and nickel ions. After removing the impurities from the acidic waste etching solution, the acidic waste etching solution containing copper ions is formed. Optionally, the mass concentration of iron ions in the acidic waste etching solution can be 5 mg / L to 80 mg / L, and the mass concentration of AsO4 3- can be 1 mg / L to 30 mg / L, and the mass concentration of nickel ions can be 1 mg / L to 20 mg / L.

[0064] In some embodiments, the method for removing impurities includes: adding an oxidant to the acidic waste etching solution and then adding metatitanic acid to adsorb and remove the impurity ions.

[0065] In some embodiments, when the color of the acidic waste etching solution turns light green, the addition of the oxidant is stopped.

[0066] In some embodiments, the oxidant includes hydrogen peroxide.

[0067] In some embodiments, the addition amount of metatitanic acid per unit volume of the acidic waste etching solution is 0.1 g / L to 2 g / L, and for example, it can be 0.1 g / L, 0.4 g / L, 0.8 g / L, 1.2 g / L, 1.4 g / L, 1.6 g / L, or 2.0 g / L.

[0068] In some embodiments, during the impurity removal process, the pH of the acidic waste etching solution is 0.2 to 2, and for example, it can be 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, or 2.0.

[0069] In some embodiments, during the impurity removal process, the temperature of the acidic waste etching solution is 15°C to 50°C, and for example, it can be 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, or 50°C.

[0070] In some embodiments, the impurity removal time is 10 min to 100 min, and for example, it can be 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, or 100 min.

[0071] In some embodiments, the acidic waste etching solution is stirred during the impurity removal process.

[0072] In some embodiments, the mass concentration of copper ions in the acidic waste etching solution is 50 g / L to 200 g / L, and for example, it can be 50 g / L, 60 g / L, 80 g / L, 120 g / L, 140 g / L, 160 g / L, 180 g / L, or 200 g / L.

[0073] In some embodiments, the copper oxide nanoflowers include a plurality of copper oxide porous nanosheets, and the thickness of the copper oxide porous nanosheets is 10 nm to 100 nm, the length is 500 nm to 1000 nm, and the width is 300 nm to 1000 nm.

[0074] In some embodiments, the volume average particle size D50 of the copper oxide nanoflowers is 10 μm to 100 μm.

[0075] Exemplarily, a method for recovering copper oxide nanoflowers from the above acidic waste etching solution is provided, which specifically includes the following steps:

[0076] S1, Add an oxidant to the acidic waste etching solution containing copper ions and impurity ions until the acidic waste etching solution turns light green, and then add metatitanic acid to stir and remove impurities from the acidic waste etching solution to remove the impurity ions in the acidic waste etching solution. Among them, the addition amount of metatitanic acid per unit volume of the acidic waste etching solution is 0.1 g / L to 2 g / L, the pH of the acidic waste etching solution during the impurity removal process is 0.2 to 2, the temperature is 15°C to 50°C, and the impurity removal time is 10 min to 100 min.

[0077] S2. Prepare a mixed alkali solution with the mass concentration of the alkaline substance being 40% - 47%, wherein the alkaline substance includes an alkali of hydroxide type and an alkali of carbonate type with a mass ratio of (2.5 - 7.8):1. Mix the mixed alkali solution with the acidic waste etching solution after impurity removal in step S1 to obtain a reaction solution with a pH of 8 - 13. Heat and stir the reaction solution, and carry out reaction crystallization for 0.5 h - 2 h at 70°C - 95°C with a stirring speed of 10 rpm - 70 rpm to form copper oxide nanowrinkle crystals. It can be understood that after the reaction is completed, the reaction solution is filtered and washed to separate and obtain copper oxide nanowrinkle crystals.

[0078] S3. Calcinate the copper oxide nanowrinkle crystals formed in step S2 at 200°C - 600°C for 0.5 h - 1.5 h to obtain a high-purity and active copper oxide nanowrinkle product.

[0079] The following will describe the implementation solutions of the present application in detail with reference to the embodiments. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application. For the experimental methods without specific conditions noted in the following embodiments, priority is given to the guidance given in the present application, and it can also be carried out according to the experimental manuals or conventional conditions in the art, or according to the conditions recommended by the manufacturer, or referring to the experimental methods known in the art.

[0080] In the following embodiments, the copper ion concentration in the acidic waste etching solution used is 105.2 g / L, the iron ion concentration is 23.4 mg / L, the concentration of AsO4 3- is 4.6 mg / L, and the concentration of nickel ions is 3.6 mg / L. The density of the acidic waste etching solution is 1.103 g / L.

[0081] Example 1

[0082] S1. Add hydrogen peroxide with a mass concentration of 30% to 1 L of acidic waste etching solution until the acidic waste etching solution shows a light green color, and then add 1 g of metatitanic acid to stir and remove impurities in the acidic waste etching solution at pH 1.5 and a temperature of 30°C for 30 min to remove iron, arsenic, and nickel impurity ions in the acidic waste etching solution.

[0083] S2. Mix a sodium hydroxide solution with a mass concentration of 50% and a sodium carbonate solution with a mass concentration of 29% in a volume ratio of 3:1 to obtain a mixed alkali solution. The mass concentration of the alkaline substance in the mixed alkali solution is 44.75%, and the mass ratio of sodium hydroxide to sodium carbonate in the alkaline substance is 6.17:1. Mix the above mixed alkali solution with the acidic waste etching solution after impurity removal in step S1 to obtain a reaction solution with a pH of 11. Heat and stir the reaction solution, and carry out reaction crystallization for 1 h at 80°C with a stirring speed of 30 rpm. After the reaction is completed, filter and wash the reaction solution to separate and form copper oxide nanowrinkle crystals.

[0084] S3. Calcinate the copper oxide nanoflower crystals formed in step S2 at 550 °C for 1 h to obtain a high-purity and active copper oxide nanoflower product.

[0085] Among them, Figure 1 are SEM images of the formed copper oxide nanoflowers in Example 1 at different ratios. Figure 1 As can be seen from a) and b) in, the product obtained in Example 1 appears as a black fine powder in appearance and has a multi-porous nanoflower structure microscopically. Further, from Figure 1 as can be seen from c) in, the copper oxide nanoflowers are composed of multiple nanosheets. Therefore, the average particle size of the copper oxide nanoflowers prepared in Example 1 is 20 µm and has a porous structure. Furthermore, Figure 2 are the transmission electron microscope (TEM) image and energy-dispersive X-ray spectroscopy (EDX) image of the formed copper oxide nanoflowers in Example 1. It can be seen from the TEM image that the copper oxide nanoflowers have a porous structure, and through the elemental analysis of the EDX image, it can be seen that copper and oxygen elements are evenly distributed in the copper oxide nanoflowers, indicating its high purity and no impurities. Figure 3 is the X-ray diffraction pattern of the material in Example 1. It can be seen that the structure of the copper oxide nanoflowers is tenorite, belonging to the monoclinic system, with the chemical formula CuO, the space group C2 / c, and the unit cell parameters: a = 4.6853 Å, b = 3.4257 Å, c = 5.1303 Å, α = 90.0°, β = 99.549°, γ = 90.0°, and the unit cell volume 79.55 Å 3 , and the Z value is 4. Figure 4 is the X-ray photoelectron spectroscopy (XPS) image of the material in Example 1, and a detailed surface elemental composition and chemical state analysis of the copper oxide nanoflowers was carried out. It can be seen that there are two main peaks in the Cu 2p spectrum: the 2p3 / 2 peak is located at 933.6 eV and the 2p1 / 2 peak is located at 953.8 eV. Both of these peaks indicate that the oxidation state of Cu is +2, which is consistent with the chemical structure of CuO. In the O 1s spectrum, the peak at 529.6 eV belongs to lattice oxygen, and the peaks at 531.2 eV and 532.8 eV belong to adsorbed oxygen species, further revealing the surface chemical state of the copper oxide nanoflowers.

[0086] Example 2

[0087] S1. Add hydrogen peroxide with a mass concentration of 30% to 1 L of acidic waste etching solution until the acidic waste etching solution shows a light green color, and then add 2 g of metatitanic acid to the acidic waste etching solution and stir for impurity removal for 20 min at pH 2 and a temperature of 40 °C to remove iron, arsenic, and nickel impurity ions in the acidic waste etching solution.

[0088] S2. Mix a sodium hydroxide solution with a mass concentration of 50% and a sodium carbonate solution with a mass concentration of 29% in a volume ratio of 1.5:1 to obtain a mixed alkali solution. The mass concentration of the alkaline substances in the mixed alkali solution is 41.6%, and the mass ratio of sodium hydroxide to sodium carbonate in the alkaline substances is 2.6:1. Mix the above-mentioned mixed alkali solution with the acid waste etching solution after impurity removal in step S1 to obtain a reaction solution with a pH of 8. Heat and stir the reaction solution, and carry out reaction crystallization for 2 h at 95 °C and a stirring speed of 65 rpm. After the reaction is completed, filter and wash the reaction solution to separate and form copper oxide nanoflower crystals.

[0089] S3. Calcinate the copper oxide nanoflower crystals formed in step S2 at 500 °C for 1.5 h to obtain a high-purity and active copper oxide nanoflower product. The SEM image is as Figure 5 shown. The product appearance presents a black fine powder, and the microstructure is a multi-porous nanoflower structure.

[0090] Example 3

[0091] S1. Add hydrogen peroxide with a mass concentration of 30% to 1 L of acid waste etching solution until the acid waste etching solution shows a light green color, and then add 2 g of metatitanic acid to stir and remove impurities in the acid waste etching solution at a pH of 0.2 and a temperature of 15 °C for 40 min to remove iron, arsenic, and nickel impurity ions in the acid waste etching solution.

[0092] S2. Mix a sodium hydroxide solution with a mass concentration of 50% and a sodium carbonate solution with a mass concentration of 29% in a volume ratio of 4.5:1 to obtain a mixed alkali solution. The mass concentration of the alkaline substances in the mixed alkali solution is 46.2%, and the mass ratio of sodium hydroxide to sodium carbonate in the alkaline substances is 7.76:1. Mix the above-mentioned mixed alkali solution with the acid waste etching solution after impurity removal in step S1 to obtain a reaction solution with a pH of 13. Heat and stir the reaction solution, and carry out reaction crystallization for 0.5 h at 70 °C and a stirring speed of 15 rpm. After the reaction is completed, filter and wash the reaction solution to separate and form copper oxide nanoflower crystals.

[0093] S3. Calcinate the copper oxide nanoflower crystals formed in step S2 at 600 °C for 0.5 h to form a high-purity and active copper oxide nanoflower product. The SEM image is as Figure 6 shown. The product appearance presents a black fine powder, and the microstructure is a multi-porous nanoflower structure.

[0094] Example 4

[0095] The copper oxide nanoflowers were recovered from the acidic waste etching solution according to the method of Example 1, except that in step S2, the mixed alkali solution was mixed with the purified acidic waste etching solution to obtain a reaction solution with a pH of 9. The formed product had a black fine powder appearance and a multi-porous nanoflower structure microscopically.

[0096] Example 5

[0097] The copper oxide nanoflowers were recovered from the acidic waste etching solution according to the method of Example 1, except that in step S2, the temperature of the reaction solution during the reaction crystallization process was 60 °C. The formed product had a blue-brown fine powder appearance and a multi-porous nanoflower structure microscopically.

[0098] Example 6

[0099] The copper oxide nanoflowers were recovered from the acidic waste etching solution according to the method of Example 1, except that in step S2, the temperature of the reaction solution during the reaction crystallization process was 75 °C. The formed product had a black fine powder appearance and a multi-porous nanoflower structure microscopically.

[0100] Example 7

[0101] The copper oxide nanoflowers were recovered from the acidic waste etching solution according to the method of Example 1, except that in step S2, the temperature of the reaction solution during the reaction crystallization process was 100 °C. The formed product had a brownish-black fine powder appearance, but there were agglomerated particles and a multi-porous nanoflower structure microscopically.

[0102] Example 8

[0103] The copper oxide nanoflowers were recovered from the acidic waste etching solution according to the method of Example 1, except that in step S2, the stirring speed of the reaction solution was 5 rpm. The formed product had a brownish-black fine powder appearance, with relatively large particles and a multi-porous nanoflower structure microscopically.

[0104] Example 9

[0105] The copper oxide nanoflowers were recovered from the acidic waste etching solution according to the method of Example 1, except that in step S2, the stirring speed of the reaction solution was 80 rpm. The formed product had a brownish-black fine powder appearance and a multi-porous nanoflower structure microscopically.

[0106] Example 10

[0107] The copper oxide nanoflowers were recovered from the acidic waste etching solution according to the method of Example 1, except that in step S3, the calcination temperature was 150 °C. The formed product had a brownish-black fine powder appearance and a multi-porous nanoflower structure microscopically.

[0108] Example 11

[0109] The copper oxide nanoflowers were recovered from the acidic waste etching solution according to the method of Example 1, except that the calcination temperature in step S3 was 700 °C. The SEM image of the formed copper oxide nanoflowers is as shown in Figure 7 . The formed product appears as a black fine powder, and there are some lumps. Microscopically, it has a porous nanoflower structure.

[0110] Example 12

[0111] The copper oxide nanoflowers were recovered from the acidic waste etching solution according to the method of Example 1, except that the calcination time in step S3 was 20 min. The formed product appears as a dark brown fine powder. Microscopically, it has a porous nanoflower structure.

[0112] Example 13

[0113] The copper oxide nanoflowers were recovered from the acidic waste etching solution according to the method of Example 1, except that the calcination time in step S3 was 2 h. The formed product appears as a black fine powder, but there are some lumps. Microscopically, it has a porous nanoflower structure.

[0114] Comparative Example 1

[0115] The copper oxide nanoflowers were recovered from the acidic waste etching solution according to the method of Example 1, except that the mass concentration of the mixed alkali solution was 35%. The SEM image of the formed copper oxide is as shown in Figure 8 . The product appears as a grayish-green fine powder, with obvious agglomerated particles. The microscopic structure is dense and does not have a nanoflower structure.

[0116] Comparative Example 2

[0117] The copper oxide nanoflowers were recovered from the acidic waste etching solution according to the method of Example 1, except that the mass concentration of the mixed alkali solution was 55%. The SEM image of the formed copper oxide is as shown in Figure 9 . The product appears as a dark gray fine powder. Microscopically, it does not have a nanoflower structure.

[0118] Comparative Example 3

[0119] The copper oxide nanoflowers were recovered from the acidic waste etching solution according to the method of Example 1, except that the mass ratio of sodium hydroxide to sodium carbonate in the mixed alkali solution was 2:1. The SEM image of the formed copper oxide is as shown in Figure 11 . The product appears as a brownish-black fine powder. Microscopically, it does not have a porous nanoflower structure.

[0120] Comparative Example 4

[0121] The copper oxide nanoflowers were recovered from the acidic waste etching solution according to the method of Example 1, except that the mass ratio of sodium hydroxide to sodium carbonate in the mixed alkali solution was 9:1. The SEM image of the formed copper oxide is as shown inFigure 12 As shown, the appearance of the product presents a brownish - tan fine powder, and microscopically, it does not have a nanoflower structure.

[0122] Comparative Example 5

[0123] Copper oxide nanoflowers were recovered from acidic waste etching solution according to the method of Example 1, except that step S3 was not carried out, and the copper oxide nanoflower crystals were directly used as the recovered product. The SEM image of the copper oxide nanoflower crystals is as Figure 13 shown. The appearance of the product presents a brownish - tan fine powder. Although it has a nanoflower structure microscopically, its porosity is poor.

[0124] The recovered products prepared in the above - mentioned examples and comparative examples were tested. The test methods included:

[0125] Standard characterization of product morphology: The recovered product was observed using SEM.

[0126] Purity test: The proportion of copper oxide in the recovered product.

[0127] Test for copper content in the overflow mother liquor: The copper content in the overflow mother liquor discharged in step S2 during the preparation process was detected.

[0128] Dissolution rate test: The recovered product was dissolved in an acidic solution with a mass ratio of concentrated sulfuric acid (mass concentration of 98%) to water of 1:9, and the time for complete dissolution was recorded.

[0129] The test results are shown in Table 1.

[0130] Table (1) Comparing Example 1 with Example 4, it can be seen that by further controlling the pH of the reaction solution in the present application, the crystallization of copper oxide can be made more uniform, the crystal configuration is more complete, and thus it has a better dissolution effect.

[0133] As can be seen from the above table:

[0132]

[0131]

[0134] (2) Comparing Example 1 with Examples 5 - 7, it can be seen that by controlling the temperature of the reaction solution during the reaction crystallization process in the present application, if the temperature is relatively low, it may cause insufficient reaction driving force and slow reaction speed, resulting in loose nanoflower - structured lamellae and poor porosity effect, affecting the dissolution effect of the product. If the temperature is relatively high, it may cause violent reactions, leading to explosive crystal growth and particle agglomeration problems, affecting the dissolution effect of the product. Therefore, an appropriate temperature is beneficial to the directional growth of nanosheets, effectively ensuring the formation of copper oxide products with a nanoporous nanoflower structure.

[0135] (3) Comparing Example 1 with Examples 8 - 9, it can be seen that by controlling the stirring speed during the reaction crystallization process in this application, it is possible to avoid excessive local concentration leading to burst nucleation and the inability of crystals to grow, thereby promoting the oriented arrangement of copper oxide, ensuring the crystalline growth of copper oxide nanoflowers, and enhancing the dissolution effect. If the stirring speed is relatively low, it may result in a relatively high copper content in the overflow mother liquor, causing problems such as incomplete copper ion reaction, insufficient liquid shear force, and crystal aggregation.

[0136] (4) Comparing Example 1 with Examples 10 - 13, it can be seen that by controlling the calcination temperature and time in this application, it is possible to avoid local sintering, agglomeration, and damage to the microscopic morphology, thereby significantly improving the crystallinity of CuO and enhancing the dissolution effect. Combining Figure 7 It can be seen that in Example 11, the edges of the nanosheets are blurred, the nanoflower structure is damaged, resulting in a further reduction in the specific surface area, thus affecting the dissolution effect.

[0137] (5) Comparing Example 1 with Comparative Examples 1 - 5, it can be seen that in Comparative Example 1, the mass concentration of the mixed alkali solution is relatively low, and the copper content in the overflow mother liquor discharged from the reaction crystallization is high, resulting in a relatively low primary recovery rate of copper resources, increasing the difficulty and cost of subsequent wastewater treatment. At the same time, Comparative Example 1 also has problems such as insufficient energy for copper oxide conversion and the easy generation of by-products (basic copper chloride). Combining Figure 8 From the SEM images, it can be seen that in Comparative Example 1, the particles are severely agglomerated, and there is almost no nanoflower structure. Its material has a small specific surface area and a slow dissolution rate. In Comparative Example 2, the mass concentration of the mixed alkali solution is relatively high, and due to incomplete crystallization, a nanoflower structure cannot be formed (as shown in the Figure 9 SEM images), and there are also problems such as alkali waste and increased washing water consumption. In Comparative Example 3, the proportion of sodium hydroxide is relatively low. As shown in the Figure 10 X-ray diffraction pattern, the content of basic copper carbonate is relatively high during the formation of the intermediate. The gas generated during its decomposition is likely to damage the nanostructure and affect the crystalline growth of the nanosheets, causing the collapse of the nanoflower structure. Therefore, a nanoflower structure cannot be formed (as shown in the Figure 11 SEM images). In Comparative Example 4, the proportion of sodium hydroxide is relatively high, and the copper oxide grows in an amorphous form with a finer crystal form. As shown in the Figure 12 SEM images, a nanoflower structure still cannot be formed. In Comparative Example 5, no calcination treatment is carried out. As shown in the Figure 13 SEM images, the formed copper oxide nanoflower crystals have distorted copper oxide crystal forms and reduced crystallinity. Although they have a nanoflower structure, the pore effect is poor. According to the BET test, the specific surface area of copper oxide in Comparative Example 5 is 2.41 m 2 / g, and the pore volume is 0.012 cm 3 / g, while the specific surface area of Example 1 after calcination treatment reaches 9.31 m 2 / g, the pore volume reaches 0.025 cm 3 / g.

[0138] In summary, the present application uses a mixed alkali solution with a specific composition to react and crystallize with an acidic waste etching solution, which can form cupric oxide nanoflower crystals with a high crystallinity nanoflower structure and fast dissolution characteristics, and the cupric oxide nanoflower crystals basically do not contain basic copper carbonate and copper hydroxide. After being calcined, it can form high-purity cupric oxide nanoflowers with a porous structure, which are suitable for fields such as copper electroplating, energy storage, solar cells, and chemical catalysts in the electronics industry. The recovery process of the present application is simple and has low cost, realizing the recovery of high-purity cupric oxide nanoflowers from acidic waste etching solutions.

[0139] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0140] The above-described embodiments only represent several implementation manners of the present application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A method for recovering copper oxide nanoflowers from acidic waste etching solution, characterized in that, The method includes: Mixing an acidic waste etching solution containing copper ions and a mixed alkali solution to obtain a reaction solution with a pH of 8 - 13, heating the reaction solution for reaction crystallization, and stirring the reaction solution during the reaction crystallization process at a stirring speed of 10 rpm - 70 rpm to form copper oxide nanoflower crystals. The mass concentration of the alkaline substance in the mixed alkali solution is 40% - 47%, and the alkaline substance includes a hydroxide base and a carbonate base with a mass ratio of (2.5 - 7.8):1; and, Calcining the copper oxide nanoflower crystals at a calcining temperature of 200°C - 600°C for a time of 0.5 h - 1.5 h to obtain copper oxide nanoflowers, and the copper oxide nanoflowers include a plurality of copper oxide porous nanosheets.

2. The method for recovering cupric oxide nanoflowers from the acidic waste etching solution according to claim 1, characterized in that, The pH of the reaction solution obtained by mixing the acidic waste etching solution and the mixed alkali solution is 9.5 - 12.

3. The method for recovering cupric oxide nanoflowers from the acidic waste etching solution according to claim 1, characterized in that, The method also satisfies at least one of the following conditions: (1) During the reaction crystallization process, the temperature of the reaction solution is 70°C - 95°C; (2) The reaction crystallization time is 0.5 h - 2 h.

4. The method for recovering cupric oxide nanoflowers from the acidic waste etching solution according to claim 1, characterized in that, The method also satisfies at least one of the following conditions: (1) The hydroxide base includes at least one of sodium hydroxide and potassium hydroxide; (2) The carbonate base includes at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate.

5. The method for recovering cupric oxide nanoflowers from the acidic waste etching solution according to any one of claims 1-4, characterized in that, The acidic waste etching solution also contains impurity ions, and the impurity ions include at least one of iron ions, arsenic ions, and nickel ions. After removing the impurities from the acidic waste etching solution, the acidic waste etching solution containing copper ions is formed.

6. The method for recovering cupric oxide nanoflowers from the acidic waste etchant according to claim 5, characterized in that, The method for removing impurities includes: adding an oxidizing agent to the acidic waste etching solution and then adding metatitanic acid to adsorb and remove the impurity ions.

7. The method for recovering cupric oxide nanoflowers from the acidic waste etching solution according to any one of claims 1-4, characterized in that, The mass concentration of copper ions in the acidic waste etching solution is 50 g / L - 200 g / L.

8. The method for recovering cupric oxide nanoflowers from acidic waste etching solution according to any one of claims 1-4, characterized in that, The thickness of the copper oxide porous nanosheets is 10 nm - 100 nm, the length is 500 nm - 1000 nm, and the width is 300 nm - 1000 nm; The volume average particle size D50 of the copper oxide nanoflowers is 10 μm - 100 μm.

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