Pickling corrosion inhibitor, its preparation method and application

Abstract

This invention discloses a method for preparing an acid pickling corrosion inhibitor, specifically comprising the following steps: Boiler water is distilled under reduced pressure and dried to obtain organic compound A; organic compound A is extracted with anhydrous ethanol, filtered, and washed to obtain organic compound B; toluidine, 80% sulfuric acid, potassium iodide, and organic compound B are added to a reactor and heated under reflux at 135–155°C for 12–18 hours to remove acid-insoluble substances. The filtrate is then neutralized with sodium hydroxide solution, concentrated under reduced pressure, and back-extracted with anhydrous ethanol. After drying, the acid pickling corrosion inhibitor is obtained. This invention effectively realizes the resource utilization of brewing boiler water, and the prepared acid pickling corrosion inhibitor exhibits excellent corrosion inhibition performance.

Description

Technical Field

[0001] This invention belongs to the field of resource utilization technology, specifically relating to an acid pickling corrosion inhibitor, its preparation method, and its application. Background Technology

[0002] According to incomplete statistics, the production of baijiu (Chinese liquor) generates 15-20 tons of brewing wastewater for every ton of baijiu produced. Therefore, brewing wastewater has become an urgent issue for the green and high-quality development of the baijiu industry. Bottom-boiler water, a significant component of brewing wastewater, originates from the baijiu distillation process. It is a liquid formed by the repeated condensation and settling of water vapor during grain gelatinization and mash distillation, which mixes with existing moisture at the bottom of the pot. As the steam medium in the mash distillation process, it continuously dissolves and leaches organic components from the mash, making it a typical high-concentration organic wastewater. To increase liquor yield, yellow water is added to the pot during the distillation process, further complicating the composition of the bottom-boiler water and increasing its treatment difficulty. Direct discharge would not only cause serious environmental pollution but also result in resource waste due to the underutilization of organic components in the bottom-boiler water.

[0003] However, the low utilization rate of organic resources in wastewater not only leads to resource waste but also results in the generation of harmful gases and greenhouse gas emissions due to aerobic and anaerobic treatment. Furthermore, the resulting sludge further exacerbates the treatment and disposal costs for enterprises. Wastewater resource utilization, as well as the extraction of other resources and energy from wastewater, is of great significance for alleviating supply and demand imbalances, reducing water pollution, ensuring water ecological security, increasing water resource supply, and optimizing water supply structure. Baijiu brewing uses grains as raw materials, and the resulting wastewater is rich in starch, sugars, organic acids, esters, alcohols, etc., with few harmful substances and reuse value. Therefore, a treatment method that can fully recycle resources while taking into account environmental, social, and economic benefits will inevitably become the main direction for wastewater treatment in the baijiu industry in the future.

[0004] Corrosion inhibitors are agents (chemical substances or complexes) that can effectively mitigate metal corrosion. They are generally added to the environment in which the metal is located to protect it. Due to their good performance, low price, and ease of use, corrosion inhibitors are widely used in industrial production. Professor Zheng Jiashen, a renowned corrosion inhibitor researcher in my country, pointed out that exploring the extraction and separation of corrosion inhibitor components from natural plants, marine flora and fauna, and industrial and agricultural waste, and then chemically modifying them to improve their performance, is one of the future development directions for corrosion inhibitors. Therefore, recycling the abundant organic matter in the bottom water of brewing vessels as a corrosion inhibitor not only helps reduce resource waste but also mitigates environmental pollution during emissions, which is of significant practical importance for maintaining sustainable development and achieving a dual-carbon economy. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of the existing technology, the purpose of this invention is to provide an acid pickling corrosion inhibitor, its preparation method and application. This invention can effectively realize the resource utilization of brewing bottom water, and the prepared acid pickling corrosion inhibitor has good corrosion inhibition performance.

[0006] The technical solution of this invention is implemented as follows:

[0007] A method for preparing an acid pickling corrosion inhibitor specifically includes the following steps:

[0008] (1) Organic compound A is obtained by vacuum distillation and drying of the water in the brewing pot;

[0009] (2) Organic compound A obtained in step (1) is extracted with anhydrous ethanol, filtered and washed to obtain organic compound B;

[0010] (3) Add toluidine, 80% sulfuric acid, potassium iodide and organic compound B obtained in step (2) into the reactor, heat and reflux at 135~155 °C for 12~18 h, remove acid-insoluble matter, neutralize the filtrate with sodium hydroxide solution, desalt with anhydrous ethanol, and distill under reduced pressure to dryness to obtain the pickling corrosion inhibitor.

[0011] Furthermore, in step (1), before vacuum distillation, the water is first allowed to stand and filter to remove suspended solids from the brewing pot water.

[0012] Furthermore, in step (2), organic compound A is subjected to multiple ultrasonic extractions using anhydrous ethanol. During each extraction, the mass-to-volume ratio of organic compound A to anhydrous ethanol is 1 g: 10~30 mL.

[0013] Furthermore, the toluidine in step (3) includes p-toluidine, m-toluidine, o-toluidine, and their homologues.

[0014] Furthermore, in step (3), the mass ratio of organic compound B to toluidine is 1:0.8~1, the amount of potassium iodide added is 15~25% of toluidine, and the amount of 80% sulfuric acid added is 4~6 times that of toluidine.

[0015] Further, after the reaction in step (3) is completed, the target product is dissolved in sulfuric acid solution, the acid-insoluble matter is removed by filtration, and the product is washed with sulfuric acid solution multiple times until the filtered liquid is colorless. Then the filtrate is neutralized with sodium hydroxide solution. The neutralized filtrate is desalted with anhydrous ethanol and distilled under reduced pressure to dryness to obtain the acid pickling corrosion inhibitor.

[0016] Furthermore, the concentration of the sulfuric acid solution is 1.0~3.0 mol / L; the concentration of the sodium hydroxide solution is 1~6.0 mol / L.

[0017] The aforementioned pickling corrosion inhibitor is used in acidic solution environments for steel pickling and oil and gas acidizing.

[0018] Further, the acidic solution is an aqueous solution of sulfuric acid, hydrochloric acid or nitric acid, the concentration of the acidic solution is 0.1~6 mol / L, and the amount of pickling corrosion inhibitor added is 0.05~1 g / L.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. This invention uses brewing pot water as raw material to prepare an acidic corrosion inhibitor, realizing the resource utilization of organic matter in the brewing pot water. The prepared acidic corrosion inhibitor exhibits excellent corrosion inhibition performance, with an inhibition efficiency exceeding 96%. After carbon steel is corroded in a strong acid medium with the added corrosion inhibitor, the sample surface is relatively smooth, without quality defects such as black spots or darkening.

[0021] 2. This invention utilizes organic matter from brewing pot water to prepare an acid pickling corrosion inhibitor, providing a new approach and option for corrosion inhibitor preparation. Furthermore, the raw materials for preparing the corrosion inhibitor are widely available and low-cost, the preparation process is green and environmentally friendly, and the preparation method is simple and easy to industrialize, showing promising application prospects. Attached Figure Description

[0022] Figure 1 - Infrared spectrum of the corrosion inhibitor prepared in Example 1.

[0023] Figure 2 - Elemental analysis results of the corrosion inhibitor prepared in Example 1.

[0024] Figure 3 - Polarization curves of carbon steel electrodes in 0.5 mol / L H2SO4 containing different concentrations of corrosion inhibitor at different temperatures.

[0025] Figure 4-3 SEM images of carbon steel at 0 ℃ in 0.5 mol / L H2SO4 with and without corrosion inhibitor (1.0 g / L corrosion inhibitor).

[0026] Figure 5 - Polarization curves of carbon steel electrodes in 1.0 mol / L HCl containing different concentrations of corrosion inhibitor at different temperatures.

[0027] Figure 6-3 SEM images of carbon steel at 0 °C in 1.0 mol / L HCl with and without corrosion inhibitor (1.0 g / L corrosion inhibitor). Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0029] I. Preparation method of pickling corrosion inhibitor from organic matter in brewing pot bottom water.

[0030] Example 1

[0031] 1) The water sample from the brewing pot was first allowed to stand for 24 hours. Large insoluble particles such as rice husks, wheat bran, and broken grains in the brewing pot water settled naturally. Then, the sample was filtered under reduced pressure, and the filtrate was collected. The water was recovered by vacuum distillation. When there were no water droplets on the wall of the reflux condenser, the distillation was stopped. Then, the sample was dried at low temperature (low temperature drying below 50 °C or freeze drying are both acceptable) to obtain a reddish-brown viscous liquid substance, which was recorded as the organic matter in the brewing pot water.

[0032] 2) Take 10 g of organic matter from the bottom of the pot, add 100 mL of anhydrous ethanol, and extract by ultrasonication for 20 min. Repeat twice to separate the solid and liquid phases and remove the insoluble solid phase. Distill the liquid phase components under reduced pressure to obtain brown organic residue, which will be used for the subsequent synthesis of corrosion inhibitors.

[0033] 3) 7.00 g of the organic residue from the bottom pot water obtained in step 2), 6.79 g of p-toluidine, 1.37 g of potassium iodide, and 34.83 g of 80% sulfuric acid were placed in a 500 mL flask and heated under reflux at 145 °C for 15 h. After the reaction was complete, 100 mL of 2.0 M H₂SO₄ solution was added to dissolve the product, which was then filtered. The product was washed repeatedly with 2.0 M H₂SO₄ until the filtered liquid was colorless. The filtrate was neutralized with 6 M NaOH solution, concentrated by vacuum distillation, and then back-extracted with anhydrous ethanol. The Na₂SO₄ solid was filtered off, and the liquid phase was evaporated to dryness to obtain the modified corrosion inhibitor (a dark brown viscous oily substance), labeled HCHSJ. The yield of the synthesis was calculated based on the complete conversion of toluidine, with a maximum conversion rate of 81.92%.

[0034] 1. The corrosion inhibitor HCHSJ obtained in this embodiment was subjected to infrared spectroscopy detection, and the results are as follows: Figure 1 As shown.

[0035] The figure shows that the corrosion inhibitor HCHSJ operates at a wavenumber of 3431 cm⁻¹. -1 There is a strong absorption peak at 2925 cm⁻¹, which is the stretching vibration peak of NH and the stretching vibration peak of OH. -1 The corresponding stretching vibration peak of CH is 1714 cm⁻¹. -1 The broad and weak peaks at 1622 and 1509 cm⁻¹ represent the stretching vibration peaks of C=O. -1 The peak at 1382 cm⁻¹ represents the stretching vibration peak of the C=C double bond and the skeletal vibration peak of the benzene ring. -1 and 1125 cm -1 The peaks at these locations correspond to the stretching vibration peaks of N=O and CO, respectively.

[0036] 2. The corrosion inhibitor HCHSJ obtained in this embodiment was subjected to elemental analysis, and the results are as follows: Figure 2 As shown.

[0037] As can be seen from the figure, the synthetic corrosion inhibitor HCHSJ is mainly composed of elements such as C, H, O, N, and S. The presence of heteroatoms such as O, N, and S can serve as active sites for the synthetic corrosion inhibitor HCHSJ, interacting with the metal surface and thus giving it potentially good corrosion inhibition performance.

[0038] II. Performance study of corrosion inhibitor HCHSJ.

[0039] 1. At different temperatures, carbon steel electrodes were placed in 0.5 mol / L H2SO4 solution, and different concentrations of the corrosion inhibitor prepared in Example 1 were added. Potentiodynamic polarization curves were obtained, as shown below. Figure 3 As shown.

[0040] from Figure 3 It can be seen that the addition of corrosion inhibitor HCHSJ had no significant effect on the shape of the polarization curve, indicating that HCHSJ did not change the reaction mechanism of carbon steel in 0.5 M H2SO4 solution. It mainly prevents corrosion of carbon steel by adsorbing onto the carbon steel surface and occupying active sites on the surface. However, from... Figure 3 As can be seen, after adding the corrosion inhibitor HCHSJ, both the cathode and anodic branches of the polarization curve shift towards lower current density, indicating that the corrosion inhibitor HCHSJ can simultaneously inhibit the dissolution of carbon steel at the anode and the evolution of hydrogen at the cathode.

[0041] right Figure 3 The polarization curves in the figure, and the corrosion electrochemical parameters obtained by extrapolation using the Tafel linear segment are shown in Table 1. The formula for calculating the corrosion inhibition efficiency (η) is shown in Equation (1-1).

[0042]

[0043] In the formula: i corr, inh and i corr,0 These represent the corrosion current densities of carbon steel electrodes in solutions with added corrosion inhibitors and in blank solutions, respectively.

[0044] As can be seen from Table 1, the addition of corrosion inhibitor HCHSJ affects the corrosion potential E. corr The effect is relatively small, but with the increase of the concentration of corrosion inhibitor HCHSJ, the corrosion current density i corr The value gradually decreases, indicating that the adsorption of corrosion inhibitor HCHSJ on the carbon steel surface inhibits the corrosion of carbon steel, and the corresponding corrosion inhibition efficiency also increases. With increasing temperature, the corrosion current density i... corrrThe increase in the value indicates that the acid solution enhances the corrosion of carbon steel. However, the corrosion inhibition efficiency of the corrosion inhibitor HCHSJ on carbon steel did not change significantly with increasing temperature. In fact, the corrosion inhibition efficiency increased slightly at the inhibitor concentration of 0.1 g / L and above, reaching a maximum of 99.2% at 50 °C. This indicates that the corrosion inhibitor HCHSJ has excellent corrosion inhibition performance for carbon steel in 0.5 M H2SO4 solution.

[0045] Table 1. Electrochemical parameters of carbon steel electrodes in 0.5 mol / L H2SO4 containing different concentrations of corrosion inhibitor.

[0046]

[0047] 2. Weight loss experiment and surface morphology analysis of carbon steel in 0.5 mol / L H2SO4 solution

[0048] The corrosion rate of carbon steel at 30℃ in 0.5 mol / L H2SO4 with no corrosion inhibitor and with different concentrations of corrosion inhibitor was determined by the weight loss method. The results are shown in Table 2.

[0049] Table 2. Weight loss data of carbon steel after immersion in 0.5 M H2SO4 solution with different concentrations of corrosion inhibitor HCHSJ for 4 h at 30 ℃.

[0050]

[0051] Table 2 shows that, compared to the blank solution without corrosion inhibitor, the corrosion rate v decreases and the corrosion inhibition efficiency η increases with the increase of the concentration of corrosion inhibitor HCHSJ. The corrosion rate of carbon steel in 0.5 M H2SO4 is 0.4481 g·m⁻¹. -2 ·h -1 The corrosion rate of carbon steel in a 0.5 M H2SO4 solution with 1.0 g / L corrosion inhibitor HCHSJ was 0.0062 g·m. -2 ·h -1 The corrosion inhibition efficiency is as high as 98.62%, indicating that the corrosion inhibitor HCHSJ significantly inhibits the corrosion of carbon steel in 0.5 M H2SO4.

[0052] Furthermore, the corrosion morphology of the sample surface was tested using scanning electron microscopy (SEM) after the experiment. The SEM images of carbon steel in 0.5 mol / L H2SO4 at 30 ℃ with and without corrosion inhibitor (control group) and with 1.0 g / L corrosion inhibitor (experimental group) are shown below. Figure 4 As shown, where Figure 4 (a) is the control group. Figure 4 (b) is the experimental group.

[0053] from Figure 4 As can be seen, the carbon steel surface in the control group was severely corroded, while the carbon steel sample in the experimental group showed only slight corrosion with no obvious corrosion marks. This indicates that the corrosion inhibitor HCHSJ has a good inhibitory effect on the corrosion of carbon steel in 0.5 M H2SO4 solution.

[0054] 3. At different temperatures, carbon steel electrodes were placed in 1 mol / L HCl solution, and different concentrations of the corrosion inhibitor prepared in Example 1 were added to obtain potentiodynamic polarization curves, such as... Figure 5 As shown.

[0055] from Figure 5 It can be seen that the shape of the polarization curve did not change significantly with the addition of the corrosion inhibitor HCHSJ, indicating that the addition of HCHSJ did not change the reaction mechanism of carbon steel in HCl solution. This suggests that HCHSJ mainly exerts its corrosion inhibition effect by adsorbing onto the active sites on the carbon steel surface. Figure 5 As can be seen, after adding the corrosion inhibitor HCHSJ, both the cathode and anodic branches of the polarization curve shifted significantly towards the direction of lower current density. This indicates that the corrosion inhibitor HCHSJ can simultaneously inhibit the dissolution of carbon steel at the anode and the evolution of hydrogen at the cathode, suggesting that HCHSJ is a mixed corrosion inhibitor for carbon steel in HCl.

[0056] right Figure 5 The polarization curves in the figure, and the corrosion electrochemical parameters obtained by extrapolation using the Tafel linear segment are shown in Table 3.

[0057] Table 3 Electrochemical parameters of carbon steel electrodes in 1.0 mol / L HCl containing different concentrations of corrosion inhibitors

[0058]

[0059] As can be seen from Table 3, the corrosion potential E corr Overall, the corrosion current density (i) shifts negatively with increasing HCHSJ concentration, and this shift becomes more pronounced with increasing temperature, indicating that HCHSJ has a more significant impact on the cathodic reaction. As the concentration of HCHSJ increases, the corrosion current density (i) also increases. corr The decrease in the value indicates that the adsorption of corrosion inhibitor HCHSJ on the carbon steel surface inhibits the corrosion of the carbon steel, and the corresponding corrosion inhibition efficiency also increases. With the increase of test temperature, the corrosion current density i... corr An increase in the value indicates that the acid solution enhances the corrosion of carbon steel. However, the corrosion inhibition efficiency of the corrosion inhibitor HCHSJ did not change significantly with increasing temperature, remaining above 96%, and reaching a maximum of 99.0% at 30 ℃, indicating that the corrosion inhibitor HCHSJ has good corrosion inhibition performance for carbon steel in HCl solution.

[0060] 3. Weight loss experiment and surface morphology analysis of carbon steel in 1.0 mol / L HCl solution.

[0061] The corrosion rate of carbon steel in 1.0 mol / L HCl with no corrosion inhibitor and with different concentrations of corrosion inhibitor were determined by the weight loss method at different temperatures. The results are shown in Table 4.

[0062] Table 4. Weight loss data of carbon steel after immersion in 1.0 mol / L HCl solution with different concentrations of corrosion inhibitor HCHSJ for 4 h.

[0063]

[0064] Table 4 shows that, compared to the blank solution without corrosion inhibitor, the corrosion rate v decreases and the corrosion inhibition efficiency η increases with increasing concentration of the corrosion inhibitor HCHSJ. At 30, 40, and 50 °C, the corrosion rates of carbon steel in 1.0 mol / L HCl were 0.2406, 0.3826, and 0.5056 g·m⁻¹, respectively. -2 ·h -1 The corrosion rates after adding 1.0 g / L corrosion inhibitor HCHSJ were 0.0046, 0.0073, and 0.0112 g·m⁻¹, respectively. -2 ·h -1 The corrosion inhibition efficiencies were as high as 98.11%, 98.08%, and 97.79%, respectively, indicating that the corrosion inhibitor HCHSJ significantly suppressed the corrosion of carbon steel in 1.0 mol / L HCl.

[0065] Furthermore, the corrosion morphology of the sample surface at 30℃ was tested using scanning electron microscopy (SEM) after the experiment. The SEM images of carbon steel in 1.0 mol / L HCl with no corrosion inhibitor (control group) and with 1.0 g / L corrosion inhibitor (experimental group) are shown below. Figure 6 As shown, where Figure 6 (a) is the control group. Figure 6 (b) is the experimental group.

[0066] from Figure 6 As can be seen, the carbon steel surface in the control group was severely corroded, while the carbon steel sample in the experimental group showed only slight corrosion with no obvious corrosion marks. This indicates that the corrosion inhibitor HCHSJ has a good inhibitory effect on the corrosion of carbon steel in 1.0 mol / L HCl solution.

[0067] Finally, it should be noted that the above embodiments of the present invention are merely illustrative examples and not intended to limit the implementation of the invention. Those skilled in the art can make other variations and modifications based on the above description. It is impossible to exhaustively list all possible implementations here. All obvious variations or modifications derived from the technical solutions of this invention are still within the scope of protection of this invention.

Claims

1. A method for preparing an acid pickling corrosion inhibitor, characterized in that, Specifically, the following steps are included: (1) Organic compound A is obtained by vacuum distillation and drying of the water in the brewing pot; (2) The organic compound A obtained in step (1) is extracted with anhydrous ethanol and filtered to obtain a liquid phase, and the liquid phase is distilled under reduced pressure to obtain organic compound B; (3) Add toluidine, 80% sulfuric acid, potassium iodide and organic compound B obtained in step (2) into the reactor, heat and reflux at 135~155 °C for 12~18 h, remove acid-insoluble matter, neutralize the filtrate with sodium hydroxide solution, desalt with anhydrous ethanol, and distill under reduced pressure to dryness to obtain the pickling corrosion inhibitor.

2. The method for preparing an acid pickling corrosion inhibitor according to claim 1, characterized in that, In step (1), before vacuum distillation, the water is first allowed to stand and filter to remove suspended solids from the brewing pot water.

3. The method for preparing an acid pickling corrosion inhibitor according to claim 1, characterized in that, In step (2), organic compound A is subjected to multiple ultrasonic extractions with anhydrous ethanol. During each extraction, the mass-to-volume ratio of organic compound A to anhydrous ethanol is 1 g: 10~30 mL.

4. The method for preparing an acid pickling corrosion inhibitor according to claim 1, characterized in that, The toluidines in step (3) include p-toluidine, m-toluidine, o-toluidine, and their homologues.

5. The method for preparing an acid pickling corrosion inhibitor according to claim 1, characterized in that, In step (3), the mass ratio of organic compound B to toluidine is 1:0.8~1, the amount of potassium iodide added is 15~25% of toluidine, and the amount of 80% sulfuric acid added is 4~6 times that of toluidine.

6. The method for preparing an acid pickling corrosion inhibitor according to claim 1, characterized in that, After the reaction in step (3) is completed, the target product is dissolved in sulfuric acid solution, filtered to remove acid-insoluble matter, and the product is washed with sulfuric acid solution multiple times until the filtered liquid is colorless. Then, the filtrate is neutralized with sodium hydroxide solution. The neutralized filtrate is desalted with anhydrous ethanol and distilled under reduced pressure to dryness to obtain the acid pickling corrosion inhibitor.

7. The method for preparing an acid pickling corrosion inhibitor according to claim 6, characterized in that, The concentration of sulfuric acid solution is 1.0~3.0 mol / L; the concentration of sodium hydroxide solution is 1~6.0 mol / L.

8. A pickling corrosion inhibitor, characterized in that, It is prepared using the preparation method of any one of claims 1 to 7 for an acid pickling corrosion inhibitor.

9. The application of the pickling corrosion inhibitor according to claim 8 in acidic solution environments of steel pickling and oil and gas acidizing mining.

10. The application of the pickling corrosion inhibitor according to claim 9, characterized in that, The acidic solution is an aqueous solution of sulfuric acid, hydrochloric acid, or nitric acid, with a concentration of 0.1~6 mol / L, and the amount of pickling corrosion inhibitor added is 0.05~1 g / L.

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