Corrosion inhibition metal pickling solution as well as preparation method and application thereof

Abstract

The invention relates to the field of pickling, in particular to a corrosion inhibition metal pickling solution, a preparation method and application thereof. Two reagents, namely a carbon dot corrosion inhibitor with a nano structure and a compound agent compounded with a surfactant and the corrosion inhibitor, are synthesized respectively, so that the pickling solution which has a good corrosion inhibition effect and is environment-friendly can be synthesized, and the cleaning effect on pickling can be improved by adding the compound agent. Compared with a pickling solution in the prior art, the pickling solution has the advantages that the corrosion inhibition effect on the metal surface can be improved, the natural chitosan compound is adopted for reagent synthesis, the final pickling solution has better environmental protection performance, and environmental pollution is reduced while the corrosion inhibition effect is guaranteed.

Description

Technical Field

[0001] The invention relates to the field of pickling, and in particular to a corrosion-inhibiting metal pickling solution, a preparation method and application thereof. Background Art

[0002] At present, there are many problems with the pickling solution commonly used in the electroplating pre-treatment process, such as the inability to effectively control the corrosion of metal materials by acid, poor corrosion inhibition effect, and poor environmental performance. Especially when processing materials with high carbon content and heat treatment materials, the surface oxide film of the pickling treatment is prone to produce black carbon ash, which affects the electroplating bonding strength and plating speed. At the same time, too thick oxide scale will lead to a long pickling time, which will cause excessive corrosion of the material. In addition, high-strength materials are also prone to increase the possibility of hydrogen embrittlement during the pickling process.

[0003] In the electroplating pretreatment process, the use of corrosion inhibitors is essential to protect metal materials from acid corrosion. However, the commonly used corrosion inhibitors currently have many defects, including poor corrosion inhibition effect, improper proportion control that easily leads to metal corrosion, poor effect under strong acid conditions, and poor environmental performance. These problems are particularly prominent when dealing with materials with high carbon content and heat treatment materials. Summary of the invention

[0004] In order to solve the above problems, the embodiments of the present application provide a corrosion-inhibiting metal pickling solution, a preparation method and its application. By adding corrosion inhibitors and corrosion-inhibiting compound surfactants to the acid solution, the corrosion resistance of the metal in an acid environment can be significantly improved, and the pollution to the environment can be reduced.

[0005] In order to achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows: In a first aspect, a corrosion-inhibiting metal pickling solution is provided, comprising an acid solution, a corrosion inhibitor and a surfactant, wherein the corrosion inhibitor is a sulfur-doped carbon nanodot polymer corrosion inhibitor, and the content of the corrosion inhibitor is 1-30 g / L; the surfactant is an equimolar compound of 2-aminobenzimidazole and a cationic biosurfactant, and the content of the surfactant is 10-40 g / L; the acid solution is a hydrochloric acid solution, and the content of the acid solution is 40-500 ml / L.

[0006] In some specific implementations, the corrosion inhibitor is a sulfur-doped chitosan derivative carbon dot corrosion inhibitor synthesized by a hydrothermal method based on chitosan Schiff base, 8-hydroxyquinoline and thiourea.

[0007] In some specific implementations, the cationic biosurfactant is an alkyl glycoside derivative surfactant synthesized from alkyl glycoside ester and tertiary amine polyether.

[0008] In a second aspect, a method for preparing a corrosion-inhibiting metal pickling solution is provided, which is used to prepare the corrosion-inhibiting metal pickling solution described in any of the above items, comprising the following steps: Step 1: Using chitosan Schiff base, 8-hydroxyquinoline and thiourea as raw materials, a sulfur-doped chitosan derivative carbon dot corrosion inhibitor is synthesized by a hydrothermal method; Step 2: Using alkyl glycoside ester and tertiary amine polyether to synthesize an alkyl glycoside derivative surfactant, and compounding the alkyl glycoside derivative surfactant with 2-aminobenzimidazole in equimolar amounts to obtain a compound agent; Step 3: Preparing a hydrochloric acid solution with a concentration of 10% to 40% as an acid solution, and adding the sulfur-doped chitosan derivative carbon dot corrosion inhibitor and the compound agent to the acid solution, and mixing them evenly to obtain a corrosion-inhibiting metal pickling solution.

[0009] In some specific implementations, the step one further comprises: dissolving equal weights of the chitosan Schiff base, 8-hydroxyquinoline and thiourea in an equimolar amount of hydrochloric acid solution to obtain a mixed solution, heating and drying the mixed solution to obtain an intermediate product, and filtering, dialyzing and drying the intermediate product in sequence to obtain the sulfur-doped chitosan derivative carbon dot corrosion inhibitor.

[0010] In some specific implementations, the step 2 further comprises: stirring and mixing the epoxy-terminated polyethylene glycol monomethyl ether and N,N-dimethylethylenediamine, and subjecting the mixed solution to reduced pressure distillation to obtain the tertiary amine polyether.

[0011] In some specific implementations, the molar ratio of the epoxy group and the secondary amine in the epoxy-terminated polyethylene glycol monomethyl ether and N,N-dimethylethylenediamine is 2.0:1.3, the stirring mixing temperature is 80° C., and the stirring time is four hours.

[0012] In some specific implementations, the step 2 further includes: dissolving the alkyl glycoside ester and the tertiary amine polyether in an N,N-dimethylformamide solution in a mass ratio of 1:1.2, stirring based on catalyst conditions and condensing and refluxing at 105°C to obtain an intermediate product, filtering, distilling under reduced pressure and washing with a solvent, and drying to obtain the alkyl glycoside derivative surfactant.

[0013] In some specific implementations, the catalyst is potassium iodide, and the catalyst content is 0.5% of the total reaction materials.

[0014] In a third aspect, there is provided a use of the above-mentioned corrosion-inhibiting metal pickling solution in cleaning iron products before electroplating.

[0015] In the technical solution provided in the embodiment of the present application, by synthesizing two reagents, namely, a carbon dot corrosion inhibitor with a nanostructure and a compounding agent compounded with a surfactant and a corrosion inhibitor, a pickling solution with good corrosion inhibition effect and environmental protection can be synthesized, and the addition of the compounding agent can improve the cleaning effect of pickling. Compared with the pickling solution in the prior art, the corrosion inhibition effect on the metal surface can be improved, and the natural chitosan compound is used to synthesize the reagent, so that the final pickling solution has more environmentally friendly performance, while ensuring the corrosion inhibition effect and reducing the pollution to the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 It is a flow chart of the method for preparing the corrosion-inhibiting metal pickling solution provided in the embodiment of the present application.

[0018] Figure 2 It is a schematic diagram of the corrosion efficiency results of the corrosion-inhibiting metal pickling solution provided in the examples of the present application.

[0019] Figure 3 It is a schematic diagram of the corrosion inhibition efficiency results of the corrosion inhibition metal pickling solution provided in the examples of the present application.

[0020] Figure 4 It is a Nyquist diagram of the electrochemical impedance spectroscopy test results of the corrosion-inhibiting metal pickling solution provided in the examples of the present application.

[0021] Figure 5 It is a Bode diagram of the electrochemical impedance spectroscopy test results of the corrosion-inhibiting metal pickling solution provided in the examples of the present application.

[0022] Figure 6 It is a schematic diagram of the potentiodynamic polarization test results of the corrosion-inhibiting metal pickling solution provided in the embodiments of the present application.

[0023] Figure 7 It is a schematic diagram of the reaction gas detection results of the corrosion-inhibiting metal pickling solution provided in the embodiment of the present application.

[0024] Figure 8 It is a schematic diagram of comparative experimental results provided in an embodiment of the present application.

[0025] Fig. 9 This is another schematic diagram of comparative experimental results provided in an embodiment of the present application. DETAILED DESCRIPTION

[0026] To make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below. If the specific conditions are not specified in the embodiments, they are carried out according to the normal conditions or the conditions recommended by the manufacturer. If the reagents or instruments used do not specify the manufacturer, they are all conventional products that can be purchased commercially. The embodiments described below are some embodiments of the present invention, rather than all embodiments. In conjunction with the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the art without making creative work are within the scope of protection of the present invention.

[0027] In a specific embodiment of the present invention, the present invention provides a corrosion-inhibiting metal pickling solution, which is composed of at least three components, including at least an acid solution, a corrosion inhibitor and a surfactant.

[0028] Among them, the acid solution is the main component of the pickling solution, which is used to remove oxides and rust on the metal surface; specifically, in this embodiment, the acid solution is a hydrochloric acid solution, and the content of the acid solution is 40~500ml / L. The corrosion inhibitor is used to reduce the corrosion of the pickling solution to the metal substrate. Specifically, in this embodiment, the corrosion inhibitor is a sulfur-doped carbon nanodot polymer corrosion inhibitor, and the content of the corrosion inhibitor is 1~30g / L. The surfactant can reduce the surface tension of the liquid, making it easier for the pickling solution to penetrate and wet the surface of the object being cleaned, thereby improving the cleaning effect. Specifically, in this embodiment, the surfactant is an equimolar compound of 2-aminobenzimidazole and a cationic biosurfactant, and the content of the surfactant is 10~40g / L.

[0029] In this embodiment, the corrosion inhibitor is not a single compound in the prior art, but a biomass carbon point obtained by synthesis. Specifically, the corrosion inhibitor is a sulfur-doped chitosan derivative carbon point corrosion inhibitor synthesized by a hydrothermal method using chitosan Schiff base, 8-hydroxyquinoline and thiourea. Among them, the chitosan Schiff base has a Schiff base structure, and the chitosan Schiff base is modified by 8-hydroxyquinoline hydrochloride to obtain a chitosan derivative, and the chitosan derivative is carbon-doped to form a sulfur-doped carbon-based nanopolymer, which can be used as a green corrosion inhibitor. Carbon point corrosion inhibitors have the characteristics of easy access to raw materials, wide sources and simple preparation process, and also have low in vitro and in vivo toxicity, biocompatibility and degradability, so this type of corrosion inhibitor is conducive to reducing environmental pollution and human health risks.

[0030] In this embodiment, the surfactant used is also not a compound in the prior art, and is also obtained based on synthesis and compounding. The logic of such a setting is that the surfactant in this embodiment is not only used to reduce the surface tension of the liquid and reduce the generation of foam to reduce acid mist, but also to improve the corrosion inhibition effect. The corrosion inhibition effect in the pickling process can be achieved by compounding the corrosion inhibition component in combination with the corrosion inhibitor.

[0031] Specifically, the biosurfactant in this embodiment is a compound obtained by equimolar compounding of 2-aminobenzimidazole and a cationic biosurfactant. Among them, the cationic biosurfactant is an alkyl glycoside derivative surfactant synthesized based on alkyl glycoside ester and tertiary amine polyether. Among them, for the overall acid solution, the surfactant is not only used to improve the cleaning effect, but also as a solution system of the corrosion inhibitor, which can be combined with the above-mentioned carbon dots to form a systematic corrosion inhibitor.

[0032] The corrosion inhibition principle of surfactants is that when surfactants are used in solutions, they can form a protective film on the surface of the metal to be cleaned, thereby further improving the corrosion inhibition effect.

[0033] However, it is worth noting that the corrosion inhibition efficiency of the surfactant used alone decreases significantly with the increase of temperature. The pickling process is an obvious exothermic process, and the temperature in the reaction process will decrease as time increases. Therefore, in order to improve the corrosion inhibition effect of the surfactant while ensuring that the cleaning effect of the surfactant remains unchanged, the method of compounding the corrosion inhibitor is used in this embodiment. Among them, a compound corrosion inhibitor selected in this embodiment is 2-aminobenzimidazole. After adding 2-aminobenzimidazole and compounding with the surfactant, the corrosion effect of the solution can be suppressed at high temperature, thereby making up for the disadvantage of poor heat resistance of the surfactant and improving the efficiency of the surfactant.

[0034] In addition, in this embodiment, a cationic surfactant is used as the surfactant. Compared with ordinary surfactants, cationic surfactants have better electron donating ability. The improved electron donating ability makes it easier to combine with metals to form an adsorption film, thereby improving the corrosion inhibition effect of the surfactant. Therefore, in this embodiment, by compounding the cationic surfactant with 2-aminobenzimidazole, the corrosion inhibition ability of the surfactant in the overall reaction process is improved.

[0035] Furthermore, the cationic surfactant in this embodiment is an alkyl glycoside surfactant. Among them, the alkyl glycoside is a green surfactant that can introduce cations and polyoxyethylene chains into the structure on the basis of retaining the advantages of the alkyl glycoside, effectively improving the solvent affinity of the alkyl glycoside, so that it is easy to penetrate and wet the surface of the object to be cleaned, further improving the cleaning effect of the pickling solution.

[0036] Therefore, in this embodiment, by introducing a cationic alkyl polyglucoside derivative surfactant and compounding it with 2-aminobenzimidazole, the corrosion inhibition effect and cleaning effect of the pickling solution are improved as a whole. In addition, due to the green performance of the alkyl polyglucoside derivative, the environmental pollution of the pickling solution is reduced, and it has higher environmental protection performance.

[0037] Based on the above-mentioned corrosion-inhibiting metal pickling solution, a preparation method is also provided in this embodiment, which is obtained by mixing the above-mentioned corrosion inhibitor, the corresponding compound of the surfactant and the acid solution. Because the compound corresponding to the above-mentioned carbon dot corrosion inhibitor and the surfactant is not directly available for purchase. Therefore, in this embodiment, the above-mentioned reagents need to be synthesized before the solution is mixed. For details about the preparation method in this embodiment, please refer to Figure 1 , including the following specific steps: Step S1. Using chitosan Schiff base, 8-hydroxyquinoline and thiourea as raw materials, a sulfur-doped chitosan derivative carbon dot corrosion inhibitor is synthesized by a hydrothermal method.

[0038] In this step, chitosan Schiff base, 8-hydroxyquinoline and thiourea are dissolved in an equimolar amount of hydrochloric acid solution to obtain a mixed solution, the mixed solution is heated and dried to obtain an intermediate product, and the intermediate product is filtered, dialyzed and dried in sequence to obtain a sulfur-doped chitosan derivative carbon dot corrosion inhibitor.

[0039] Specifically, the same mass of chitosan Schiff base, 8-hydroxyquinoline and thiourea are dissolved in an equimolar amount of hydrochloric acid solution, and then fully dissolved to obtain a mixed solution, and the mixed solution is transferred to a high-temperature autoclave for hot air drying and heating at 200°C for 24 hours. After the heating is completed, the mixture is cooled to room temperature to obtain a mixture, and the mixture is filtered based on a 0.22μm filter membrane to obtain a crude product.

[0040] It is worth noting that the mixture is still a solution at room temperature. The mixture is dialyzed in deionized water to remove unreacted small molecule impurities, and finally the solvent is removed by rotary evaporation to collect the final product and freeze-dry under vacuum to completely dehydrate to obtain the final solid product, which is a sulfur-doped chitosan derivative carbon dot corrosion inhibitor.

[0041] Step S2. synthesizing an alkyl glycoside derivative surfactant from an alkyl glycoside ester and a tertiary amine polyether, and compounding the alkyl glycoside derivative surfactant with 2-aminobenzimidazole in equimolar amounts to obtain a compounding agent.

[0042] The tertiary amine polyether in this embodiment is obtained by synthesis. Specifically, epoxy-terminated polyethylene glycol monomethyl ether and N,N-dimethylethylenediamine are stirred and mixed at a stirring and mixing temperature of 80°C for four hours, and the mixed solution is subjected to reduced pressure distillation to obtain the tertiary amine polyether. The molar ratio of epoxy-terminated polyethylene glycol monomethyl ether and the secondary amine in N,N-dimethylethylenediamine is 2.0:1.3.

[0043] Then, the alkyl glucoside ester and the tertiary amine polyether are dissolved in an N,N-dimethylformamide solution in a mass ratio of 1:1.2, and stirred under the condition of potassium iodide as a catalyst, condensed and refluxed at 105°C to obtain an intermediate product, and the intermediate product is filtered, vacuum distilled and solvent washed in sequence, and dried to obtain an alkyl glucoside derivative surfactant. Then, the obtained alkyl glucoside derivative surfactant is equimolarly compounded with 2-aminobenzimidazole to obtain the final compounding agent.

[0044] In this embodiment, the content of potassium iodide accounts for 0.5% of the total reaction substances.

[0045] Step S3. Prepare a hydrochloric acid solution with a concentration of 10% to 40% as an acid solution, and add the sulfur-doped chitosan derivative carbon dot corrosion inhibitor and the compounding agent into the acid solution, and mix them evenly to obtain a corrosion-inhibiting metal pickling solution.

[0046] In this embodiment, the content of sulfur-doped chitosan derivative carbon dots corrosion inhibitor is 1-30 g / L, the content of compounding agent is 10-40 g / L, and the content of acid solution is 40-500 ml / L. The above reagents are mixed and stirred to obtain the final corrosion-inhibiting metal pickling solution.

[0047] The corrosion-inhibiting metal pickling solution and the corresponding preparation method of the present invention are further illustrated by specific examples below.

[0048] Example 1 In this embodiment, a corrosion-inhibiting metal pickling solution is provided, comprising the following components: 1g / L of corrosion inhibitor, 10g / L of compounding agent, and 500ml / L of 40% hydrochloric acid solution. Among them, the corrosion inhibitor is a sulfur-doped carbon nanodot polymer corrosion inhibitor, and the compounding agent is an equimolar compound of 2-aminobenzimidazole and a cationic biosurfactant mixture.

[0049] The preparation method of the corrosion-inhibiting metal pickling solution in this embodiment comprises the following steps: Step S1. Using chitosan Schiff base, 8-hydroxyquinoline and thiourea as raw materials, a sulfur-doped chitosan derivative carbon dot corrosion inhibitor is synthesized by a hydrothermal method.

[0050] Step S2. synthesizing an alkyl glycoside derivative surfactant from an alkyl glycoside ester and a tertiary amine polyether, and compounding the alkyl glycoside derivative surfactant with 2-aminobenzimidazole in equimolar amounts to obtain a compounding agent.

[0051] Step S3. Prepare a hydrochloric acid solution with a concentration of 40% as the acid solution, and add the sulfur-doped chitosan derivative carbon dot corrosion inhibitor and the compounding agent into the acid solution, and mix them evenly to obtain a corrosion-inhibiting metal pickling solution.

[0052] Example 2 In this embodiment, a corrosion-inhibiting metal pickling solution is provided, comprising the following components: 10g / L of corrosion inhibitor, 20g / L of compounding agent, 400ml / L of 40% hydrochloric acid solution. Among them, the corrosion inhibitor is a sulfur-doped carbon nanodot polymer corrosion inhibitor, and the compounding agent is an equimolar compound of 2-aminobenzimidazole and a cationic biosurfactant mixture.

[0053] The preparation method of the corrosion-inhibiting metal pickling solution in this embodiment comprises the following steps: Step S1. Using chitosan Schiff base, 8-hydroxyquinoline and thiourea as raw materials, a sulfur-doped chitosan derivative carbon dot corrosion inhibitor is synthesized by a hydrothermal method.

[0054] Step S2. synthesizing an alkyl glycoside derivative surfactant from an alkyl glycoside ester and a tertiary amine polyether, and compounding the alkyl glycoside derivative surfactant with 2-aminobenzimidazole in equimolar amounts to obtain a compounding agent.

[0055] Step S3. Prepare a hydrochloric acid solution with a concentration of 40% as the acid solution, and add the sulfur-doped chitosan derivative carbon dot corrosion inhibitor and the compounding agent into the acid solution, and mix them evenly to obtain a corrosion-inhibiting metal pickling solution.

[0056] Example 3 In this embodiment, a corrosion-inhibiting metal pickling solution is provided, comprising the following components: 15g / L of corrosion inhibitor, 25g / L of compounding agent, and 400ml / L of 30% hydrochloric acid solution. Among them, the corrosion inhibitor is a sulfur-doped carbon nanodot polymer corrosion inhibitor, and the compounding agent is an equimolar compound of 2-aminobenzimidazole and a cationic biosurfactant mixture.

[0057] The preparation method of the corrosion-inhibiting metal pickling solution in this embodiment comprises the following steps: Step S1. Using chitosan Schiff base, 8-hydroxyquinoline and thiourea as raw materials, a sulfur-doped chitosan derivative carbon dot corrosion inhibitor is synthesized by a hydrothermal method.

[0058] Step S2. synthesizing an alkyl glycoside derivative surfactant from an alkyl glycoside ester and a tertiary amine polyether, and compounding the alkyl glycoside derivative surfactant with 2-aminobenzimidazole in equimolar amounts to obtain a compounding agent.

[0059] Step S3. Prepare a hydrochloric acid solution with a concentration of 30% as the acid solution, and add the sulfur-doped chitosan derivative carbon dot corrosion inhibitor and the compounding agent into the acid solution, and mix them evenly to obtain a corrosion-inhibiting metal pickling solution.

[0060] Example 4 In this embodiment, a corrosion-inhibiting metal pickling solution is provided, comprising the following components: 20g / L of corrosion inhibitor, 30g / L of compounding agent, and 300ml / L of 30% hydrochloric acid solution. Among them, the corrosion inhibitor is a sulfur-doped carbon nanodot polymer corrosion inhibitor, and the compounding agent is an equimolar compound of 2-aminobenzimidazole and a cationic biosurfactant mixture.

[0061] The preparation method of the corrosion-inhibiting metal pickling solution in this embodiment comprises the following steps: Step S1. Using chitosan Schiff base, 8-hydroxyquinoline and thiourea as raw materials, a sulfur-doped chitosan derivative carbon dot corrosion inhibitor is synthesized by a hydrothermal method.

[0062] Step S2. synthesizing an alkyl glycoside derivative surfactant from an alkyl glycoside ester and a tertiary amine polyether, and compounding the alkyl glycoside derivative surfactant with 2-aminobenzimidazole in equimolar amounts to obtain a compounding agent.

[0063] Step S3. Prepare a hydrochloric acid solution with a concentration of 30% as the acid solution, and add the sulfur-doped chitosan derivative carbon dot corrosion inhibitor and the compounding agent into the acid solution, and mix them evenly to obtain a corrosion-inhibiting metal pickling solution.

[0064] Example 5 In this embodiment, a corrosion-inhibiting metal pickling solution is provided, comprising the following components: 25g / L of corrosion inhibitor, 35g / L of compounding agent, and 300ml / L of 40% hydrochloric acid solution. Among them, the corrosion inhibitor is a sulfur-doped carbon nanodot polymer corrosion inhibitor, and the compounding agent is an equimolar compound of 2-aminobenzimidazole and a cationic biosurfactant mixture.

[0065] The preparation method of the corrosion-inhibiting metal pickling solution in this embodiment comprises the following steps: Step S1. Using chitosan Schiff base, 8-hydroxyquinoline and thiourea as raw materials, a sulfur-doped chitosan derivative carbon dot corrosion inhibitor is synthesized by a hydrothermal method.

[0066] Step S2. synthesizing an alkyl glycoside derivative surfactant from an alkyl glycoside ester and a tertiary amine polyether, and compounding the alkyl glycoside derivative surfactant with 2-aminobenzimidazole in equimolar amounts to obtain a compounding agent.

[0067] Step S3. Prepare a hydrochloric acid solution with a concentration of 30% as the acid solution, and add the sulfur-doped chitosan derivative carbon dot corrosion inhibitor and the compounding agent into the acid solution, and mix them evenly to obtain a corrosion-inhibiting metal pickling solution.

[0068] Example 6 In this embodiment, a corrosion-inhibiting metal pickling solution is provided, comprising the following components: 30g / L of corrosion inhibitor, 40g / L of compounding agent, and 200ml / L of 40% hydrochloric acid solution. Among them, the corrosion inhibitor is a sulfur-doped carbon nanodot polymer corrosion inhibitor, and the compounding agent is an equimolar compound of 2-aminobenzimidazole and a cationic biosurfactant mixture.

[0069] The preparation method of the corrosion-inhibiting metal pickling solution in this embodiment comprises the following steps: Step S1. Using chitosan Schiff base, 8-hydroxyquinoline and thiourea as raw materials, a sulfur-doped chitosan derivative carbon dot corrosion inhibitor is synthesized by a hydrothermal method.

[0070] Step S2. synthesizing an alkyl glycoside derivative surfactant from an alkyl glycoside ester and a tertiary amine polyether, and compounding the alkyl glycoside derivative surfactant with 2-aminobenzimidazole in equimolar amounts to obtain a compounding agent.

[0071] Step S3. Prepare a hydrochloric acid solution with a concentration of 40% as the acid solution, and add the sulfur-doped chitosan derivative carbon dot corrosion inhibitor and the compounding agent into the acid solution, and mix them evenly to obtain a corrosion-inhibiting metal pickling solution.

[0072] Experimental Example 1 In this example, the corrosion rate and corrosion inhibition efficiency of the corrosion-inhibiting metal pickling solutions corresponding to Examples 1 to 6 were tested by the weight loss method. Specifically, the corrosion rate and corrosion inhibition efficiency of the pickling solutions of different components in Examples 1 to 6 on N80 carbon steel were measured by the weight loss method at 30°C. The results can be found in Figure 2 and Figure 3 ,in Figure 2 Used to illustrate the corrosion rate of the corrosion-inhibiting metal pickling solution corresponding to Examples 1 to 6, Figure 3 Used to illustrate the corrosion inhibition efficiency of the corrosion-inhibiting metal pickling solution corresponding to Examples 1 to 6.

[0073] from Figure 2 It can be seen that with the increase of the concentration of the corrosion inhibitor and the compound, the corrosion efficiency gradually decreases, while the corrosion inhibition efficiency gradually increases. Moreover, for the components of the corrosion inhibitor and the compound used in Example 2, the corrosion inhibition efficiency has exceeded 90%, which shows that the pickling solution corresponding to the component ratio in Example 2 has a high corrosion inhibition effect, indicating that the use of sulfur-doped carbon nanodot polymer corrosion inhibitor and surfactant can effectively inhibit the corrosion of carbon steel in hydrochloric acid.

[0074] Experimental Example 2 In this embodiment, electrochemical impedance spectroscopy and potentiodynamic polarization tests were performed on Examples 1 to 6 using an electrochemical test method. The electrochemical measurements were performed on an electrochemical station equipped with a three-electrode system, including a working electrode, a reference electrode, and an auxiliary electrode. Before each electrochemical test, the carbon steel sample was polished step by step using SiC sandpaper and then rinsed with deionized water and isopropanol, respectively.

[0075] The open circuit potential test was first performed for 0.5 h to ensure that the system was in a steady state, and then an electrochemical impedance spectroscopy test was performed with a sinusoidal alternating current amplitude of 5 mv and a frequency range of 100 kHz to 10 mHz.

[0076] For electrochemical impedance spectroscopy results, please refer to Figure 4 and Figure 5 , Figure 4 is the electrochemical impedance Nyquist plot, Figure 5 is the electrochemical impedance Bode diagram. Figure 4 and Figure 5 It can be seen that the shapes of the curves in the Nyquist and Bode plots corresponding to the pickling solutions without the components of Examples 1 to 6 above, i.e. the blank group (Blank group) and the pickling solutions with the components of Examples 1 to 6 added are similar, which indicates that adding corrosion inhibitors and compounding agents to the acid solution will not change the corrosion mechanism of the acid solution. Figure 4 As shown in the corresponding Nyquist diagram, when the above-mentioned corrosion inhibitors and compounding agents of different components are not added, the contact between the carbon steel surface and the solution will cause severe corrosion, so the capacitance arc diameter and impedance modulus of the carbon steel are relatively small. After adding corrosion inhibitors and compounding agents in different proportions in Examples 1 to 6, both values ​​increase accordingly, and as the concentration of corrosion inhibitors and compounding agents increases, the radius of the capacitance arc shows an upward trend. This is because the carbon steel surface is covered by more particles with corrosion inhibition effects. In other words, the density of the protective film formed on the carbon steel surface increases with the concentration of corrosion inhibitors and compounding agents. And, according to Figure 5It can be seen that as the concentration of corrosion inhibitors and compound agents increases, the corrosion rate tends to gradually slow down.

[0077] Experimental Example 3 In order to further illustrate the technical effects of the pickling solution corresponding to Examples 1 to 6, this example tests the corrosion inhibition effect by establishing an equivalent circuit simulation. The impedance spectra are obtained by using the equivalent circuit and the existing simulation calculation software ZSimWin to fit under different conditions, and the relevant fitting parameters are summarized in Table 1. Among them, Rs ( / Ω·cm -2 ) is the solution resistance, Rp ( / Ω·cm -2 ) is the polarization resistance, CPE1Y0×10 -4 / (S·s n cm -2 ) is a double-layer CPE component, CPE2Y0×10 -4 / (S·s n cm -2 ) represents film capacitor.

[0078] Rs CPE1 CPE2 R Blank Group 1.19 15.24 - 4.87 Example 1 2.071 1.812 54.725 41.54 Example 2 2.253 1.666 34.381 62.56 Example 3 1.866 1.456 25.425 114.28 Example 4 2.059 1.362 13.168 118.43 Example 5 2.117 1.179 11.521 127.03 Example 6 2.148 0.9532 5.438 199.81 Table 1. Fitting parameters It can be seen from Table 1 that the change of the resistance Rs of the solution for different embodiments under different conditions is not obvious, which means that the properties of the acid solution are not affected by adding corrosion inhibitors and compounding agents in Examples 1 to 6. In addition, as the concentration of the corrosion inhibitors and compounding agents in Examples 1 to 6 increases, the polarization resistance Rp increases continuously, so that the pickling solution after adding the above reagents can continuously replace the water molecules on the surface of the carbon steel during the reaction process, thereby forming a protective film, and the protective film becomes more and more dense as the concentration increases.

[0079] Experimental Example 4 In order to further illustrate the technical effect of the pickling solution corresponding to Example 1-Example 6, in this embodiment, the environmental protection of the reaction gas is detected by setting up gas detection. Specifically, by setting the reaction scenes of the blank group (Blank) Example 1-Example 6, the acid mist gas concentration of the reaction gas is detected by the acid mist detector, and the gas sensitivity detection of the acid mist detector is used as the evaluation data, the evaluation data is RLS, where the RLS intensity refers to the intensity of Rayleigh Light Scattering (RLS). RLS is a physical phenomenon. When light passes through a medium, the particles in the medium scatter light to form RLS. The RLS intensity will change with the change of external conditions. For example, the change of the pH value of the solution will cause the RLS intensity to change. Specifically, when the pH value of the solution gradually increases, the RLS intensity will gradually weaken.

[0080] For detailed results, please refer to Figure 7 As shown, as the concentration of corrosion inhibitor and compounding agent added in the pickling solution increases, the RLS intensity gradually decreases, indicating that the pickling solution in Examples 1 to 6 can reduce the generation of acid mist during the pickling process, thereby reducing pollution to the environment and is an environmentally friendly pickling solution.

[0081] Comparative Example 1 In this example, the surface reactions of the pickling solution in Example 6 and the pickling solution to which the corrosion inhibitor of the prior art is added are compared by observation.

[0082] For details, please refer to Figure 8 ,exist Figure 8 The left side of the middle shows the surface reaction state of the pickling solution to which the prior art Nottin corrosion inhibitor is added. Figure 8 The right side of the figure shows the surface reaction state of the pickling solution in Example 6. Figure 8 It can be seen that the reaction on the left shows that the screw turns black after soaking, while the reaction on the right shows that the original color of the metal is maintained.

[0083] See also Fig. 9 ,exist Fig. 9 The left side of the middle diagram shows another reaction state of the pickling solution to which the prior art Nottin corrosion inhibitor is added. Fig. 9 The right side shows the surface reaction state of the pickling solution in Example 6. Fig. 9 It can be seen that for the reaction on the left side, bubbles are densely distributed on the surface of the screw, indicating that the reaction at this time is relatively strong, while there are basically no bubbles generated on the surface of the screw on the right side.

[0084] With respect to the corrosion-inhibiting metal pickling solution and the corresponding preparation method provided in Examples 1 to 6, by synthesizing two reagents, namely, a carbon dot corrosion inhibitor with a nanostructure and a compounding agent compounded with a surfactant and a corrosion inhibitor, a pickling solution with good corrosion inhibition effect and environmental protection can be synthesized, and the addition of the compounding agent can improve the cleaning effect of pickling. Compared with the pickling solution in the prior art, the corrosion inhibition effect on the metal surface can be improved, and the natural chitosan compound is used for the synthesis of the reagent, and the final pickling solution has more environmentally friendly performance, which reduces the pollution to the environment while ensuring the corrosion inhibition effect.

[0085] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A corrosion-inhibiting metal pickling solution, comprising an acid solution, a corrosion inhibitor and a surfactant, characterized in that: The corrosion inhibitor is a sulfur-doped carbon nanodot polymer corrosion inhibitor, the content of which is 1-30 g / L, the surfactant is a compound prepared by mixing 2-aminobenzimidazole and a cationic biosurfactant in equal moles, the content of which is 10-40 g / L, and the acid solution is a hydrochloric acid solution, the content of which is 40-500 ml / L.

2. The corrosion-inhibiting metal pickling solution according to claim 1, characterized in that: The corrosion inhibitor is a sulfur-doped chitosan derivative carbon dot corrosion inhibitor synthesized by a hydrothermal method based on chitosan Schiff base, 8-hydroxyquinoline and thiourea.

3. The corrosion-inhibiting metal pickling solution according to claim 1, characterized in that: The cationic biosurfactant is an alkyl glycoside derivative surfactant synthesized from alkyl glycoside ester and tertiary amine polyether.

4. A method for preparing a corrosion-inhibiting metal pickling solution, used for preparing the corrosion-inhibiting metal pickling solution according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step 1: Using chitosan Schiff base, 8-hydroxyquinoline and thiourea as raw materials, a sulfur-doped chitosan derivative carbon dot corrosion inhibitor is synthesized by a hydrothermal method; Step 2: synthesizing an alkyl glycoside derivative surfactant from an alkyl glycoside ester and a tertiary amine polyether, and compounding the alkyl glycoside derivative surfactant with 2-aminobenzimidazole in equal moles to obtain a compounding agent; Step 3: Prepare a hydrochloric acid solution with a concentration of 10% to 40% as an acid solution, and add the sulfur-doped chitosan derivative carbon dot corrosion inhibitor and the compounding agent into the acid solution, and mix them evenly to obtain a corrosion-inhibiting metal pickling solution.

5. The method for preparing a corrosion-inhibiting metal pickling solution according to claim 4, characterized in that: The step one also includes: The chitosan Schiff base, 8-hydroxyquinoline and thiourea in equal weights are dissolved in an equimolar amount of hydrochloric acid solution to obtain a mixed solution, the mixed solution is heated and dried to obtain an intermediate product, and the intermediate product is filtered, dialyzed and dried in sequence to obtain the sulfur-doped chitosan derivative carbon dot corrosion inhibitor.

6. The method for preparing a corrosion-inhibiting metal pickling solution according to claim 4, characterized in that: The step 2 also includes: The epoxy-terminated polyethylene glycol monomethyl ether and N,N-dimethylethylenediamine are stirred and mixed, and the mixed solution is subjected to reduced pressure distillation to obtain tertiary amine polyether.

7. The method for preparing a corrosion-inhibiting metal pickling solution according to claim 6, characterized in that: The molar ratio of the epoxy group and the secondary amine in the epoxy-terminated polyethylene glycol monomethyl ether and N,N-dimethylethylenediamine is: 2.0:1.3, the stirring mixing temperature is 80°C and the stirring time is four hours.

8. The method for preparing a corrosion-inhibiting metal pickling solution according to claim 4, characterized in that: The step 2 also includes: The alkyl glucoside ester and the tertiary amine polyether are dissolved in an N,N-dimethylformamide solution in a mass ratio of 1:1.2, and stirred under catalyst conditions and condensed and refluxed at 105° C. to obtain an intermediate product, and the intermediate product is filtered, distilled under reduced pressure and washed with a solvent in sequence, and then dried to obtain the alkyl glucoside derivative surfactant.

9. The method for preparing a corrosion-inhibiting metal pickling solution according to claim 8, characterized in that: The catalyst is potassium iodide, and the content of the catalyst is 0.5% of the total reaction material.

10. An application of the corrosion-inhibiting metal pickling solution according to claim 1, characterized in that: The corrosion-inhibiting metal pickling solution is used for cleaning iron products before electroplating.

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