阅读说明：本技术 一种抑制碳钢腐蚀的缓蚀剂制备及其评估方法 (Preparation and evaluation method of corrosion inhibitor for inhibiting carbon steel corrosion ) 是由 宋吉明 方晶 于 2021-01-27 设计创作，主要内容包括：本发明公开了一种抑制碳钢腐蚀的缓蚀剂制备及其评估方法,包括以下步骤：称取一定质量的生姜粉末,选用乙醇为溶剂,采用超声辅助溶剂提取法得到姜辣素提取液,将提取液过滤浓缩后,冷冻干燥,得到姜辣素粗提物,将姜辣素粗提物加入盐酸溶液中,分别配制含有不同浓度缓蚀剂的盐酸介质溶液,然后将碳钢浸入盐酸介质溶液中一段时间,分别通过失重法、电化学测试法来计算缓蚀效率,评估姜辣素粗提物作为缓蚀剂的抑制效果,结果表明姜辣素粗提物作为一种缓蚀剂,对碳钢的腐蚀具有很好的抑制作用。本发明缓蚀剂制备方法简单,实验操作步骤便捷,对生产设备要求低,缓蚀剂成本低,缓蚀效果好；评估方法科学合理,具有说服力。(The invention discloses a preparation method and an evaluation method of a corrosion inhibitor for inhibiting carbon steel corrosion, which comprises the following steps: weighing ginger powder with a certain mass, selecting ethanol as a solvent, obtaining a gingerol extracting solution by adopting an ultrasonic-assisted solvent extraction method, filtering and concentrating the extracting solution, freeze-drying to obtain a gingerol crude extract, adding the gingerol crude extract into a hydrochloric acid solution, respectively preparing hydrochloric acid medium solutions containing corrosion inhibitors with different concentrations, then soaking carbon steel into the hydrochloric acid medium solution for a period of time, respectively calculating corrosion inhibition efficiency by a weight loss method and an electrochemical test method, and evaluating the inhibition effect of the gingerol crude extract as a corrosion inhibitor. The corrosion inhibitor has the advantages of simple preparation method, convenient experimental operation steps, low requirement on production equipment, low cost and good corrosion inhibition effect; the assessment method is scientific and reasonable and convincing.)

1. A preparation method and an evaluation method of a corrosion inhibitor for inhibiting carbon steel corrosion comprise the following steps:

(1) selecting ethanol as a solvent, putting ginger powder with a certain mass into a round-bottom flask, adding 200-400 mL of ethanol, performing ultrasonic treatment for 30-60 min, and heating and refluxing for extraction for 1-3 h to obtain a gingerol crude extract;

(2) filtering the extracting solution, concentrating to 20-40 mL, and freeze-drying to obtain a gingerol crude extract;

(3) weighing the crude extract for multiple times respectively, and adding into 1M hydrochloric acid solution to prepare a plurality of hydrochloric acid medium solutions containing corrosion inhibitors with certain concentration;

(4) respectively soaking carbon steel into hydrochloric acid medium solutions containing corrosion inhibitors with different concentrations for 3-4 hours at a certain temperature;

(5) the carbon steel is weighed before and after immersion respectively by adopting a weight loss method, and the weight loss is respectively marked as W₀And W₁Calculating corrosion rate and corrosion inhibition efficiency by a formula;

(6) the electrochemical method test is respectively carried out on the carbon steel in hydrochloric acid medium solutions containing corrosion inhibitors with different concentrations.

2. The method for preparing and evaluating a corrosion inhibitor for inhibiting corrosion of carbon steel according to claim 1, wherein the ginger powder in step (1) has a mass of 10.0 g.

3. The method for preparing and evaluating a corrosion inhibitor for inhibiting corrosion of carbon steel according to claim 1, wherein the concentration of the corrosion inhibitor in the step (3) is 0 g/L to 2.0 g/L.

4. The method for preparing and evaluating a corrosion inhibitor for inhibiting corrosion of carbon steel according to claim 1, wherein the temperature in the step (4) is 25 ℃ to 60 ℃.

5. The method for preparing and evaluating a corrosion inhibitor for inhibiting corrosion of carbon steel according to claim 1, wherein the electrochemical test method in the step (6) is a potentiodynamic polarization curve test and an AC impedance test.

6. The method for preparing and evaluating a corrosion inhibitor for inhibiting corrosion of carbon steel according to any one of claims 1 to 6.

Technical Field

The invention relates to the technical field of corrosion inhibitors, in particular to a preparation method and an evaluation method of a corrosion inhibitor for inhibiting carbon steel corrosion.

Background

Carbon steel is a steel material commonly used in industry, and due to the influence of acid pickling, oil well acidification and the like, the steel materials are corroded to different degrees, so that the problems of economic loss, equipment loss, environmental pollution and the like are caused. To solve such corrosion problems, corrosion prevention is often adopted. Among the corrosion prevention methods, the corrosion inhibitor is most effective and most economical and practical. At present, most industrially used are organic compounds containing heterocyclic rings of atoms such as N, O, S and multiple bonds, which have good corrosion inhibition effect, but are toxic and not easy to degrade due to high cost, and thus cannot be widely used industrially. In the preparation of the corrosion inhibitor, a weight loss method is mostly adopted to evaluate the inhibition effect of the corrosion inhibitor, and no relevant patent reports other methods exist. A large number of researches find that the plant contains natural corrosion inhibition components, can be extracted as a green corrosion inhibitor, has a simple extraction process, and has the advantages of rich resources, low cost, no toxicity, no harm and the like.

Patent CN110863208A (Lihuijing, a carbon steel pickling inhibitor based on polygonatum polysaccharide) discloses a polygonatum polysaccharide corrosion inhibitor, which can prevent the consumption of metal or acid liquor in the pickling process of carbon steel and products thereof. Patent CN110983344A (dung end, a camellia oleifera shell compound corrosion inhibitor, and a preparation method and application thereof) discloses a method for using a camellia oleifera shell extract, an aromatic aldehyde compound, an anionic surfactant and other compound corrosion inhibitors to reduce corrosion of carbon steel in an acid pickling process, but the method has complex extraction and compound processes and higher cost, and has no convincing power because only a weight loss method is used for explaining the corrosion inhibition effect of the corrosion inhibitor. Compared with the prior art, the preparation method is simpler and more convenient, has low requirements on experimental operation, the ginger is a common plant, the experimental cost is lower, the extraction process is simple, the environment is friendly, and the weight loss method and the electrochemical method are adopted to simultaneously evaluate the corrosion inhibition effect of the gingerol crude extract as the corrosion inhibitor on the carbon steel sheet in the acid solution. The results show that the crude extract of gingerol is used as a corrosion inhibitor, the corrosion inhibition efficiency is very high, and related articles and patent reports using gingerol as the corrosion inhibitor do not exist at present.

Ginger is an Asian traditional plant used as both medicine and food, the rhizome of the ginger is a common seasoning in daily cooking, and the rhizome, the peel and the leaf of the ginger can be used as medicines. Gingerol is the main active ingredient in ginger, and a large number of researches prove that gingerol has stronger oxidation resistance, so that gingerol has theoretical possibility as a green corrosion inhibitor. Therefore, the crude extract of gingerol in ginger is used as a corrosion inhibitor, the inhibition effect of the crude extract on the corrosion of carbon steel in an acid solution is explored, the corrosion inhibitor is environment-friendly, the economic loss caused by the corrosion of carbon steel in industry is reduced, and a new way is provided for the development and utilization of ginger resources.

Disclosure of Invention

The invention aims to utilize a gingerol crude extract in ginger as a corrosion inhibitor and evaluate the inhibition effect of the gingerol crude extract on corrosion of carbon steel in an acid solution by a weight loss method and an electrochemical method. The invention obtains gingerol crude extract by adopting an ultrasonic-assisted solvent extraction method, then uses the gingerol crude extract as a corrosion inhibitor, adds the gingerol crude extract into a hydrochloric acid solution, respectively soaks carbon steel into hydrochloric acid medium solutions containing corrosion inhibitors with different concentrations, calculates the corrosion inhibition efficiency of the carbon steel by utilizing a weight loss method and an electrochemical test method, and evaluates the inhibition effect of gingerol as the corrosion inhibitor. In order to solve the above technical problems, the present invention provides the following solutions:

1. a preparation method and an evaluation method of a corrosion inhibitor for inhibiting carbon steel corrosion comprise the following steps:

(1) selecting ethanol as a solvent, putting ginger powder with a certain mass into a round-bottom flask, adding 200-400 mL of ethanol, performing ultrasonic treatment for 30-60 min, and heating and refluxing for 1-3 h to obtain a gingerol crude extract;

(2) filtering the extracting solution, concentrating to 20-40 mL, and freeze-drying to obtain a gingerol crude extract;

(3) weighing the crude extract for multiple times respectively, and adding into 1M hydrochloric acid solution to prepare a plurality of hydrochloric acid medium solutions containing corrosion inhibitors with certain concentration;

(4) respectively soaking carbon steel into hydrochloric acid medium solutions containing corrosion inhibitors with different concentrations for 3-4 hours at a certain temperature;

(5) the carbon steel is weighed before and after immersion respectively by adopting a weight loss method, and the weight loss is respectively marked as W₀And W₁Calculating corrosion rate and corrosion inhibition efficiency by a formula;

(6) respectively testing carbon steel in hydrochloric acid medium solutions containing corrosion inhibitors with different concentrations by adopting an electrochemical method;

further, in the step (5), the calculation formulas of the corrosion rate and the corrosion inhibition efficiency of the weight loss method are respectively as follows:

ν=(W₀-W₁) V (St), where v is the corrosion rate in g.m^-2·h^-1(ii) a S is the surface area of the steel sheet in m²(ii) a t is corrosion time in h; w₀、W₁Mass before and after etching, respectively, in g.

η=(ν₀-ν₁)/ν₀X 100%, wherein eta is corrosion inhibition efficiency,%; v is₀V and v₁Corrosion rates in g.m, for the corrosion inhibitors not present and for the corrosion inhibitors present, respectively^-2·h^-1。

Further, the electrochemical method test in the step (6) is a potentiodynamic polarization curve test and an alternating current impedance test which are both carried out by utilizing an electrochemical workstation (CHI-660E model, Shanghai Chenghua instruments, Inc.);

further, in the step (6), the scanning interval of the polarization curve is the open circuit potential +/-250 mV, the scanning speed is 1 mV/s, and the corrosion inhibition efficiency (eta) is calculated through the polarization curve, wherein the calculation formula is as follows:

η=（J₀-J)/J×100%，J₀and J is the current density of carbon steel in hydrochloric acid medium solution without and with corrosion inhibitor, and the unit is mA/cm²E is the corrosion potential in mV;

further, in the step (6), an alternating current impedance (EIS) measurement frequency range is 1 to 100000 Hz, and an amplitude is 10 mV. Calculating the corrosion inhibition efficiency (eta) through alternating-current impedance, wherein the calculation formula is as follows:

η=（R_ct-R_ct ⁰)/R_ct×100%, R_ct ⁰and R_ctCorrosion inhibition in the absence and presence of carbon steelThe charge transfer resistance in the hydrochloric acid medium solution is obtained by software Z View 3.0 simulation, and the unit is omega cm²，R_sThe resistance of the solution in omega cm²。

Description of the drawings:

FIG. 1 is a graph showing the corrosion rate of carbon steel in the hydrochloric acid medium containing different concentrations of the corrosion inhibitor in example 1.

FIG. 2 is a graph showing the change of corrosion inhibition efficiency of hydrochloric acid medium containing corrosion inhibitors of different concentrations in carbon steel in example 1.

FIG. 3 is a plot of the polarization of carbon steel in the hydrochloric acid medium containing different concentrations of corrosion inhibitor of example 2.

FIG. 4 is an AC impedance spectrum of carbon steel in hydrochloric acid medium solution containing different concentrations of corrosion inhibitor in example 2.

The specific implementation mode is as follows:

the invention is illustrated in detail below with reference to the examples:

example 1: weight loss method test

(1) Selecting ethanol as solvent, placing 10.0 g of rhizoma Zingiberis recens powder in round bottom flask, adding 200 mL of ethanol, ultrasonic treating for 30 min, heating at 80 deg.C, reflux extracting for 2 hr to obtain gingerol crude extractive solution;

(2) filtering the extracting solution, concentrating to 20 mL, and freeze-drying to obtain a gingerol crude extract;

(3) weighing the crude extract, adding into 1M hydrochloric acid solution, and respectively preparing into hydrochloric acid medium solutions of 0 g/L, 0.2 g/L, 0.6 g/L, 1.0 g/L, 1.4 g/L and 1.8 g/L;

(4) respectively soaking carbon steel into the hydrochloric acid medium solution containing the corrosion inhibitors with different concentrations for 4 hours at the temperature of 25 ℃;

(5) weighing the carbon steel before and after immersion, and calculating the corrosion rate and corrosion slowing efficiency of the carbon steel by a formula;

as can be seen from the attached drawings 1 and 2, at a certain temperature, the corrosion rate of the carbon steel is gradually reduced along with the increase of the concentration of the corrosion inhibitor, and the corrosion inhibition efficiency is gradually increased, which shows that the gingerol crude extract is an effective corrosion inhibitor and has better inhibition performance on the corrosion of the carbon steel in hydrochloric acid.

Example 2: electrochemical method of testing

(1) Obtaining a crude gingerol extract in the same way as in the example 1, and preparing hydrochloric acid medium solutions containing corrosion inhibitors with different concentrations in the same way;

(2) sealing the carbon steel sample by using epoxy resin, and reserving 1 cm²A working area;

(3) immersing carbon steel into hydrochloric acid medium solution containing corrosion inhibitors with different concentrations for 1 h to obtain stable open-circuit potential;

(4) performing a potentiodynamic polarization curve test and an alternating current impedance test on carbon steel by using an electrochemical workstation (CHI-660E model, Shanghai Chenghua instruments, Ltd.) respectively;

TABLE 1 polarization parameters of carbon steels in hydrochloric acid solution

Concentration (g/L)	-E/mV	-J/(mA·cm-2)	η（%)
				0.2	0.40	0.00255	83.16
0.6	0.40	0.00126	91.68
				1.0	0.40	0.00056	96.30
1.4	0.40	0.00049	96.76
				1.8	0.40	0.00020	98.67
Blank space	0.38	0.01514	/

As shown in table 1, the corrosion inhibition efficiency is obtained by calculation of corrosion current density, and the corrosion inhibition efficiency is observed to increase along with the increase of the concentration of the corrosion inhibitor and is consistent with the trend measured by a weight loss method, which indicates that the gingerol crude extract has good inhibition effect as the corrosion inhibitor;

as shown in Table 2, the corrosion inhibition efficiency is calculated through the charge transfer resistance, the corrosion inhibition efficiency is seen to increase along with the increase of the concentration of the corrosion inhibitor, and the trend of the corrosion inhibition efficiency is consistent with the trend of the test results of a weight loss method and a polarization curve, and the gingerol crude extract is an effective corrosion inhibitor and can effectively inhibit the corrosion action of carbon steel in a hydrochloric acid medium solution.

TABLE 2 impedance parameters of carbon steels in hydrochloric acid solution

Concentration (g/L)	Rs/(Ω·cm-2)	Rct/(Ω·cm-2)	η（%)
				0.2	1.53	50.08	78.29
0.6	2.02	76.82	85.85
				1.0	1.75	111.20	90.22
1.4	1.52	130.00	91.64
				1.8	1.43	206.00	94.72
Blank space	1.57	10.87	/

Therefore, the gingerol crude extract is prepared by an ultrasonic-assisted solvent extraction method, and then the effect of the gingerol crude extract as a corrosion inhibitor is evaluated by adopting a weight loss method and an electrochemical method respectively, and the result shows that the gingerol crude extract has stronger inhibition effect on the corrosion of carbon steel, and the higher the concentration of the gingerol crude extract is, the stronger the inhibition effect is.