CN103966610A - Compound corrosion inhibiter and preparing method thereof - Google Patents

Abstract

A compound corrosion inhibitor of the present invention is composed of a solvent and a solute, the solvent is simulated seawater desalination primary reverse osmosis water, and the solute is composed of 2-undecyl-N-carboxymethyl-N-hydroxyethylimidazoline (UHCI) and zinc sulfate (ZnSO ₄ ), the total concentration of 2-undecyl-N-carboxymethyl-N-hydroxyethylimidazoline and zinc sulfate is 100mg/L, 2-undecyl The concentration ratio of -N-carboxymethyl-N-hydroxyethylimidazoline and zinc sulfate is (40mg/L-80mg/L): (20mg/L-60mg/L). The present invention also provides a preparation method of the above compound corrosion inhibitor. The invention improves the corrosion inhibition effect on carbon steel by adjusting the compounding ratio of UHCI and ZnSO ₄ , and the corrosion inhibition efficiency is better than the effect of 100mg/LUHCI used alone. The invention has the advantages of small dosing amount, low processing cost and convenient on-site implementation.

Description

A kind of composite corrosion inhibitor and preparation method thereof

technical field

The invention belongs to the field of chemical industry, and in particular relates to a corrosion inhibitor, in particular to a compound corrosion inhibitor used in seawater desalination primary reverse osmosis water production medium and a preparation method thereof.

Background technique

With the increasing shortage of fresh water resources, the application of seawater desalination and reverse osmosis technology has effectively solved the shortage of industrial and domestic water in coastal areas, and alleviated the problem of water resource shortage in coastal areas. Today, seawater desalination primary reverse osmosis water is widely used in high water consumption enterprises such as power plants and chemical plants, and the problem of strong corrosion to metals is becoming increasingly prominent. In practical application, it is found that the first-stage reverse osmosis produced water from seawater desalination is also highly corrosive to carbon steel pipelines, and the pipeline water is usually light yellow, accompanied by a large number of suspended corrosion products, which not only greatly reduces the quality of water supply, but also seriously Corrosion is also a direct threat to the safety of water distribution networks.

At present, it is generally used to add chemicals to seawater desalination primary reverse osmosis product water to adjust the alkalinity, pH value and other indicators to reduce corrosion. However, although these methods can achieve good results in inhibiting corrosion, there are also problems such as large dosage of chemicals, very high treatment costs, and difficulties in on-site implementation.

Contents of the invention

In view of the defects in the above-mentioned prior art, the technical problem to be solved by the present invention is to provide a compound corrosion inhibitor and its preparation method, and the described compound corrosion inhibitor and its preparation method should solve the problems of the prior art. The corrosion inhibition method for seawater desalination first-stage reverse osmosis produced water has a large amount of dosing, high treatment costs, and technical problems in on-site implementation.

A compound corrosion inhibitor of the present invention is composed of a solvent and a solute. The solvent is simulated seawater desalination primary reverse osmosis water, and its conductivity is 200-250μs/cm. The solute is composed of 2-11 Alkyl-N-carboxymethyl-N-hydroxyethylimidazoline (UHCI) with zinc sulfate (ZnSO ₄ ), 2-undecyl-N-carboxymethyl-N-hydroxyethylimidazoline and sulfuric acid The total concentration of zinc is 100mg/L, the concentration ratio of 2-undecyl-N-carboxymethyl-N-hydroxyethylimidazoline and zinc sulfate is (40mg/L-80mg/L): (20mg/L -60mg/L).

Further, the conductivity of the first-stage reverse osmosis produced water from simulated seawater desalination is 230 μs/cm.

The present invention also provides a preparation method of the above-mentioned composite corrosion inhibitor, which includes a step of measuring simulated seawater desalination primary reverse osmosis water, and a step of weighing 2-undecyl-N-carboxymethyl -N-hydroxyethylimidazoline and zinc sulfate steps, then 2-undecyl-N-carboxymethyl-N-hydroxyethylimidazoline (UHCI) and zinc sulfate (ZnSO ₄ ) were added to simulated seawater successively In the desalinated first-stage reverse osmosis product water, the concentration of the 2-undecyl-N-carboxymethyl-N-hydroxyethylimidazoline is 40mg/L-80mg/L, and the concentration of the zinc sulfate is 20mg/L L-60mg/L, stir evenly to get the compound corrosion inhibitor mentioned above.

The corrosion inhibitor 2-undecyl-N-carboxymethyl-N-hydroxyethylimidazoline (UHCI) and zinc sulfate (ZnSO ₄ ) used in the present invention are both environment-friendly compounds. Under the same condition, the corrosion inhibition effect on carbon steel can be improved by adjusting the compound ratio of UHCI and ZnSO ₄ . The corrosion inhibition efficiency of 100mg/L UHCI on carbon steel reaches 67.9%. When the total concentration of 100mg/L UHCI and ZnSO ₄ compound ratio is (40mg/L-80mg/L): (20mg/L-60mg/L) , the corrosion inhibition efficiency is better than that of 100mg/L UHCI used alone, showing that there is a synergistic effect between the two.

The 2-undecyl-N-carboxymethyl-N-hydroxyethylimidazoline used in the present invention is odorless and low-toxic, has a pH value of 7.0 to 9.5, and has good antistatic properties, wettability and biodegradability. It is less irritating to human skin and is a green and environment-friendly corrosion inhibitor. Another ingredient, zinc sulfate, is non-toxic. Therefore, this compound corrosion inhibitor is a kind of green environment-friendly corrosion inhibitor.

Compared with the prior art, the technical progress of the present invention is remarkable. The present invention keeps the total concentration of the corrosion inhibitor constant, and improves the corrosion inhibition efficiency of the corrosion inhibitor on carbon steel in the first-stage reverse osmosis water production medium of seawater desalination through compounding, and the dosage of the agent is small, and the treatment cost is small. Low cost and convenient on-site implementation.

Description of drawings

Figure 1. Polarization curves of carbon steel electrodes soaked in simulated first-stage reverse osmosis product water from seawater desalination containing different compounding ratios of corrosion inhibitors for 1 day. Curve 1 in the figure is blank; Curve 2 is 100mg/L UHCI; Curve 3 is 40mg/L UHCI+60mg/L ZnSO ₄ ; Curve 4 is 50mg/L UHCI+50mg/L ZnSO ₄ ; Curve 5 is 60mg/L UHCI +40mg/L ZnSO _{4 ;} Curve 6 is 80mg/L UHCI+20mg/L ZnSO ₄ .

Figure 2. Physical pictures of carbon steel electrodes under different conditions (a) before the experiment; (b) blank; (c) 100mg/L imidazoline solution; (d) total concentration of 100mg/L, imidazoline and zinc sulfate The ratio is 50mg/L: 50mg/L.

Detailed ways

The present invention will be described in further detail below by way of examples and in conjunction with the accompanying drawings, but the present invention is not limited.

For 2-undecyl-N-carboxymethyl-N-hydroxyethylimidazoline (UHCI) alone, and for 2-undecyl-N-carboxymethyl-N-hydroxyethylimidazoline ( UHCI) and zinc sulfate (ZnSO ₄ ) composite corrosion inhibitors for carbon steel corrosion inhibition effect comparison, including the following steps:

(1) Corrosion inhibition effect of 100mg/L UHCI on carbon steel when used alone

The polarization curve was used to study the corrosion inhibition effect on carbon steel when 100mg/L UHCI was used alone in simulated seawater desalination primary reverse osmosis product water;

(2) Corrosion inhibition effect of UHCI and ZnSO ₄ on carbon steel

The polarization curve was used to study the corrosion inhibition effect of UHCI combined with ZnSO ₄ on carbon steel in the simulated seawater desalination primary reverse osmosis product water when the total concentration was 100mg/L.

Polarization curve acquisition method

The experiment was carried out in a three-electrode system. The test medium was simulated seawater desalination first-stage reverse osmosis product water with or without corrosion inhibitor. The working electrode was a No. 20 carbon steel electrode, sealed with epoxy resin, and the working area was 1cm ² , the surface is polished and polished by the main machine of 1 ^# ~ 6 ^# metallographic sandpaper, degreased with absolute ethanol, and rinsed with deionized water. The auxiliary electrode and reference electrode were Pt electrode and saturated calomel electrode (SCE), respectively. Polarization curves were measured using a Model 2273 electrochemical workstation from Princeton Applied Research Corporation, with a polarization curve scan rate of 5 mv/s and a scan potential of -1 to -0.1V.

Example 1

A compound corrosion inhibitor for carbon steel in seawater desalination first-stage reverse osmosis water production medium, which is composed of solvent and solute, wherein the solvent is simulated seawater desalination first-stage reverse osmosis water production, its conductivity is 230μs/cm, and solute Composed of 2-undecyl-N-carboxymethyl-N-hydroxyethylimidazoline (UHCI) and zinc sulfate (ZnSO ₄ ), the total concentration is 100mg/L, the concentration ratio of UHCI and ZnSO ₄ , That is, UHCI: ZnSO ₄ is 40 mg/L: 60 mg/L.

The preparation method of the compound corrosion inhibitor of above-mentioned a kind of carbon steel is as follows:

40 mg/L of 2-undecyl-N-carboxymethyl-N-hydroxyethyl imidazoline (UHCI) and 60 mg/L of zinc sulfate (ZnSO ₄ ) were successively added to the simulated seawater desalination primary reaction Permeate into the product water and stir evenly.

The electrode is sealed with epoxy resin, the working area is 1cm ² , the surface is polished and polished with 1 ^# ~ 6 ^# metallographic sandpaper host, degreased with absolute ethanol, rinsed with deionized water, and put into the electrode containing 100mg/L UHCI , (40mg/L UHCI+60mg/L ZnSO ₄ ) simulated seawater desalination primary reverse osmosis product water, the polarization curve test results show that (40mg/L UHCI+60mg/L ZnSO ₄ ) corrosion inhibition effect is better than 100mg/L L UHCI.

Example 2

A compound corrosion inhibitor for carbon steel in seawater desalination first-stage reverse osmosis water production medium, which is composed of solvent and solute, wherein the solvent is simulated seawater desalination first-stage reverse osmosis water production, its conductivity is 230μs/cm, and solute Composed of 2-undecyl-N-carboxymethyl-N-hydroxyethylimidazoline (UHCI) and zinc sulfate (ZnSO ₄ ), the total concentration is 100mg/L, the concentration ratio of UHCI and ZnSO ₄ , That is, UHCI: ZnSO ₄ is 50 mg/L: 50 mg/L.

The preparation method of the compound corrosion inhibitor of above-mentioned a kind of carbon steel is as follows:

Add 50 mg/L 2-undecyl-N-carboxymethyl-N-hydroxyethyl imidazoline (UHCI) and 50 mg/L zinc sulfate (ZnSO ₄ ) to the simulated seawater desalination primary reaction Permeate into the product water and stir evenly.

The electrode is sealed with epoxy resin, the working area is 1cm ² , the surface is polished and polished with 1 ^# ~ 6 ^# metallographic sandpaper host, degreased with absolute ethanol, rinsed with deionized water, and put into the electrode containing 100mg/L UHCI , (50mg/L UHCI+50mg/L ZnSO ₄ ) simulated seawater desalination primary reverse osmosis product water, the polarization curve test results show that (50mg/L UHCI+50mg/L ZnSO ₄ ) corrosion inhibition effect is better than 100mg/L L UHCI.

Example 3

A compound corrosion inhibitor for carbon steel in seawater desalination first-stage reverse osmosis water production medium, which is composed of solvent and solute, wherein the solvent is simulated seawater desalination first-stage reverse osmosis water production, its conductivity is 230μs/cm, and solute Composed of 2-undecyl-N-carboxymethyl-N-hydroxyethylimidazoline (UHCI) and zinc sulfate (ZnSO ₄ ), the total concentration is 100mg/L, the concentration ratio of UHCI and ZnSO ₄ , That is, UHCI: ZnSO ₄ is 60 mg/L: 40 mg/L.

The preparation method of the compound corrosion inhibitor of above-mentioned a kind of carbon steel is as follows:

60 mg/L of 2-undecyl-N-carboxymethyl-N-hydroxyethylimidazoline (UHCI) and 40 mg/L of zinc sulfate (ZnSO ₄ ) were successively added to the simulated seawater desalination primary reaction Permeate into the product water and stir evenly.

The electrode is sealed with epoxy resin, the working area is 1cm ² , the surface is polished and polished with 1 ^# ~ 6 ^# metallographic sandpaper host, degreased with absolute ethanol, rinsed with deionized water, and put into the electrode containing 100mg/L UHCI , (60mg/L UHCI+40mg/L ZnSO ₄ ) simulated seawater desalination primary reverse osmosis product water, the polarization curve test results show that (60mg/L UHCI+40mg/L ZnSO ₄ ) corrosion inhibition effect is better than 100mg/L L UHCI.

Example 4

A compound corrosion inhibitor for carbon steel in seawater desalination first-stage reverse osmosis water production medium, which is composed of solvent and solute, wherein the solvent is simulated seawater desalination first-stage reverse osmosis water production, its conductivity is 230μs/cm, and solute Composed of 2-undecyl-N-carboxymethyl-N-hydroxyethylimidazoline (UHCI) and zinc sulfate (ZnSO4), the total concentration is 100mg/L, the concentration ratio of UHCI and ZnSO4 is UHCI : ZnSO4 is 80 mg/L: 20 mg/L.

The preparation method of the compound corrosion inhibitor of above-mentioned a kind of carbon steel is as follows:

80 mg/L of 2-undecyl-N-carboxymethyl-N-hydroxyethylimidazoline (UHCI) and 20 mg/L of zinc sulfate (ZnSO4) were successively added to the simulated seawater desalination primary reverse osmosis In the water, stir evenly.

The electrode is sealed with epoxy resin, the working area is 1cm ² , the surface is polished and polished with 1#~6# metallographic sandpaper host, degreased with anhydrous ethanol, rinsed with deionized water, and put into the electrode containing 100mg/L UHCI , (80mg/L UHCI+20mg/L ZnSO4) simulated seawater desalination primary reverse osmosis product water, the polarization curve test results show that (80mg/L UHCI+20mg/L ZnSO4) has better corrosion inhibition effect than 100mg/L UHCI of.

Polarization curve analysis

Figure 1 is the polarization curve of a carbon steel electrode soaked in simulated seawater desalination first-stage reverse osmosis product water containing different compounding ratios of corrosion inhibitors for 1 day. The electrochemical parameters obtained from the polarization curve analysis are listed in Table 1.

Table 1 Electrochemical parameters obtained from the analysis of Fig. 1

It can be seen from Table 1 that the corrosion potential E _corr of carbon steel electrodes shifted positively after adding UHCI alone and compound corrosion inhibitors; the corrosion current density I _corr of carbon steel electrodes with corrosion inhibitors all decreased significantly. When the total concentration is 100mg/L, the compounding ratio of UHCI and _ZnSO4 is 40 mg/L:60 mg/L, 50 mg/L:50 mg/L, 60 mg/L:40 mg/L and 80 mg/L respectively. mg/L: The corrosion inhibition efficiencies at 20 mg/L were 68.8%, 92.7% and 85.3%, respectively, all of which were greater than the corrosion inhibition efficiency (67.9%) at 100 mg/L, which indicated that there was a relatively strong relationship between UHCI and ZnSO ₄ Good synergistic corrosion inhibition effect.

Physical map analysis

Figure 2 is the physical picture of the carbon steel electrode under different conditions (a) before the experiment (b) blank (c) 100mg/L imidazoline solution (d) the total concentration is 100mg/L, the compounding ratio of imidazoline and zinc sulfate is 50mg/L: 50mg/L. It is obvious from the figure that the total concentration is 100 mg/L, and the compound ratio of imidazoline and zinc sulfate is 50 mg/L: 50 mg/L has better corrosion inhibition effect.

The above content is only a basic description of the concept of the present invention, and any equivalent transformation made according to the technical solution of the present invention shall fall within the scope of protection of the present invention.

Claims (3)

1. A composite corrosion inhibitor, consisting of a solvent and a solute, characterized in that: the solvent is simulated seawater desalination primary reverse osmosis water, its conductivity is 200 ~ 250μs/cm, and the solute is composed of Composition of 2-undecyl-N-carboxymethyl-N-hydroxyethylimidazoline (UHCI) and zinc sulfate (ZnSO ₄ ), 2-undecyl-N-carboxymethyl-N-hydroxyethyl The total concentration of imidazoline and zinc sulfate is 100mg/L, and the concentration ratio of 2-undecyl-N-carboxymethyl-N-hydroxyethylimidazoline and zinc sulfate is (40mg/L-80mg/L): (20mg/L-60mg/L). 2. A compound corrosion inhibitor according to claim 1, characterized in that: the electrical conductivity of the simulated seawater desalination primary reverse osmosis product water is 230 μs/cm. 3. The preparation method of a kind of composite corrosion inhibitor as claimed in claim 1, is characterized in that: comprise a step of measuring simulated seawater desalination first-stage reverse osmosis product water, a step of weighing 2-undecyl -N-carboxymethyl-N-hydroxyethylimidazoline and zinc sulfate step, then 2-undecyl-N-carboxymethyl-N-hydroxyethylimidazoline (UHCI) with zinc sulfate (ZnSO ₄ ) Adding simulated seawater desalination primary reverse osmosis product water successively, the concentration of the 2-undecyl-N-carboxymethyl-N-hydroxyethylimidazoline is 40mg/L-80mg/L, the sulfuric acid The concentration of zinc is 20mg/L-60mg/L, and the compound corrosion inhibitor mentioned above can be obtained by stirring evenly.