CN112680733A

CN112680733A - Steel corrosion prevention method based on microbial technology

Info

Publication number: CN112680733A
Application number: CN202011404277.2A
Authority: CN
Inventors: 钱春香; 范文斌; 芮雅峰; 陈燕强
Original assignee: Southeast University
Current assignee: Southeast University
Priority date: 2020-12-04
Filing date: 2020-12-04
Publication date: 2021-04-20
Also published as: WO2022116598A1

Abstract

The invention discloses a steel anticorrosion method based on a microbial technology, which comprises the following steps: inoculating spores of bacillus into a proper culture medium for culturing to obtain a concentrated bacterial liquid of the bacillus; adding a calcium source into the bacterial liquid, dissolving to obtain a microorganism suspension, and standing for later use; and adding the steel sample subjected to rust removal and drying into the microbial suspension, and placing the steel sample in a room temperature environment for deposition of a protective layer to form an organic-inorganic composite protective layer on the surface of the steel sample, wherein the organic protective layer comprises a microbial extracellular polymer, and the inorganic protective layer comprises spherical calcium carbonate. According to the invention, a compact protective layer is deposited on the surface of the steel through microorganism induced deposition and metabolism, so that corrosion caused by substance exchange (chemical or electrochemical reaction) between a steel substrate material and the outside is isolated, and the corrosion resistance of the steel can be obviously improved; moreover, the method is simple and easy to operate, green, environment-friendly and pollution-free.

Description

Steel corrosion prevention method based on microbial technology

Technical Field

The invention relates to a steel corrosion prevention method, in particular to a steel corrosion prevention method based on a microbial technology, and belongs to the technical field of metal corrosion prevention.

Background

As is well known, steel materials have high strength and hardness, can meet the requirements of good plasticity and processability, are structural materials with the largest use amount, and are widely applied to infrastructure engineering. However, whether used in the atmosphere for a long time or left in the atmosphere for a long time, the steel surface gradually reacts with the surrounding medium chemically or electrochemically, causing corrosion of the surface. The slight rust can cause the surface to lose metallic luster, reduce the precision, and the surface can generate rust pits when the surface is serious, so that the mechanical property of the steel material product is deteriorated, even the steel material product is broken, and the service life of the steel material product is influenced. Meanwhile, research and investigation have found that the main cause affecting the durability of reinforced concrete is the deterioration of members caused by corrosion of reinforcing steel bars. The research on the corrosion reason of steel and the corresponding anticorrosion measures are necessary and beneficial.

The common anticorrosion measures are generally to coat the surface of a material matrix with a coating containing heavy metals such as tin, copper and zinc or volatile organic compounds, and although the coating has a good anticorrosion effect and is easy to be widely applied, the coating brings potential health threats and is not beneficial to the green and environment-friendly concept. The cathodic protection method is to add more active metal to the surface of the steel structure to replace the corrosion of steel. Are commonly used for underwater or underground steel corrosion protection. The electrochemical protection method is a method for protecting steel from corrosion based on the principle of the primary battery theory, and according to the primary battery theory, corrosion protection of steel can be achieved as long as the reaction of the primary battery causing chemical corrosion can be eliminated. Although the cathodic protection method and the electrochemical protection method have good protection effect on steel corrosion prevention, the treatment period is long, the energy consumption and the time consumption are high, and the ecological concept of greening and environmental protection is not facilitated.

For reinforced concrete engineering, the corrosion resistance of reinforced concrete is usually improved by using a rust inhibitor containing organic components, the main components of the rust inhibitor can affect the basic mechanical properties of concrete to different degrees, and more serious engineering accidents can be caused under serious conditions. Therefore, there is a current necessity to develop a renewable, environmentally friendly preservation technology.

Disclosure of Invention

The purpose of the invention is as follows: aiming at the problems of the existing steel corrosion prevention measures, the invention provides a steel corrosion prevention method based on the microbial technology, which essentially prevents the chemical and electrochemical reactions between a steel substrate and the outside and improves the rust resistance of the steel surface by inducing, mineralizing and depositing by microorganisms and forming an organic-inorganic composite protective layer on the steel surface by metabolites.

The technical scheme is as follows: the invention relates to a steel anticorrosion method based on microbial technology, which comprises the following steps:

(1) inoculating spores of bacillus into a proper culture medium for culturing to obtain a concentrated bacterial liquid of the bacillus; adding a calcium source into the bacterial liquid, dissolving to obtain a microorganism suspension, and standing for later use;

(2) adding the steel sample subjected to rust removal and drying into the microbial suspension, and placing the steel sample in a room temperature environment for deposition of a protective layer to form an organic-inorganic composite protective layer on the surface of the steel sample, wherein the organic protective layer comprises a microbial extracellular polymer, and the inorganic protective layer comprises spherical calcium carbonate;

(3) and taking out the sample, washing and drying.

During the steel sheet soaking process, the microbial metabolism secretes one organic layer of extracellular polymer to wrap the steel sheet closely, and the inorganic layer of calcium carbonate is deposited to adhere to the organic layer in the presence of organic calcium source to prevent oxygen and other cathode depolarizer from reaching the metal surface and blocking electron transfer and prevent steel corrosion.

In the step (1), the calcium source is preferably an organic calcium source, and the addition amount of the calcium source is preferably (1.0-1.3) g/200 ml.

The components of the culture medium can comprise beef extract, peptone and ammonium salt or sodium salt; preferably, each liter of culture medium contains 3-5 g of beef extract, 5-8 g of peptone and 0-3 g of ammonium salt or 3-5 g of sodium salt.

Preferably, the preparation method of the concentrated bacterial liquid comprises the following steps: and (3) dissolving the powdery bacillus in deionized water according to the mass (10-20) g/L, and inoculating the germinated spores to a corresponding culture medium for culture. Wherein, the culturing process of the bacillus can comprise the following steps: preparing a culture medium, then sterilizing the prepared culture medium, inoculating spores according to the quantity of 10ml of bacterial liquid per liter of culture medium after sterilization is finished, then placing the inoculated culture medium in a shaking incubator for culture, and taking out the cells after the total number of the cells is cultured until the OD value reaches more than 1 to obtain the concentrated bacterial liquid of the bacillus. Preferably, the sterilization conditions of the culture medium are: and placing the culture medium in a sterilization tank, and sterilizing for 20-30 min at the temperature of 115-121 ℃ and the pressure of 0.1-0.12 MPa. Further, the culture temperature in the shaking incubator is set to be 25-30 ℃.

In the step (2), the deposition time of the protective layer is preferably 2 to 5 days.

Has the advantages that: compared with the prior art, the invention has the advantages that: (1) according to the invention, a steel sample is soaked in the bacterial liquid suspension, a compact protective layer is deposited on the surface of the steel through the action of microorganism induced mineralization deposition and metabolism, and the corrosion caused by the matter exchange (chemical or electrochemical reaction) between a steel matrix material and the outside is isolated, so that the corrosion resistance of the steel can be obviously improved; meanwhile, the method is simple and easy to operate; (2) the components of the protective layer formed on the surface of the steel by induced mineralization deposition through the microbial technology are similar to those of the concrete, and the mechanical property of the concrete cannot be deteriorated, so that the method can be applied to reinforced concrete engineering; (3) the microorganisms adopted in the invention are mineralized microorganisms, can produce spores, are suitable for the field of engineering materials, are green, environment-friendly and pollution-free, and are harmless to human bodies.

Drawings

FIG. 1 is a schematic view of a steel sample immersed in a microbial suspension to form a protective layer; wherein, 1 is a steel sheet sample, 2 is a copper wire, and 3 is a microorganism suspension liquid;

FIG. 2 is a diagram showing the surface corrosion condition of a steel sample after being immersed in a microbial suspension (a) and a culture medium calcium source solution (b) without a bacterial liquid for mineralization for 5 days;

FIG. 3 is SEM microscopic view and energy spectrum of steel sample soaked in microbe suspension to deposit protecting layer, wherein, (a) is SEM image of organic protecting layer-extracellular polymer formed by microbe metabolism on steel surface; (b) is a spectrum diagram of extracellular polymeric substances formed by the metabolism of microorganisms on the surface of steel; (c) SEM picture of inorganic protective layer-calcium carbonate formed by microorganism on the surface of steel; (d) an energy spectrum diagram of inorganic protective layer-calcium carbonate formed by microorganisms on the surface of steel;

FIG. 4 is an impedance spectrum of electrochemical measurements of steel samples immersed in different solutions.

Detailed Description

The technical solution of the present invention is further explained with reference to the drawings and the embodiments.

In order to better improve the corrosion resistance of steel, the invention provides a steel corrosion prevention method based on a microbial technology, which is a method for remarkably improving the corrosion resistance of the steel surface by depositing an organic-inorganic composite protective layer on the steel surface by utilizing the microbial technology at a green environment-friendly low cost, essentially stopping the chemical and electrochemical reactions between a steel substrate and the outside and remarkably improving the corrosion resistance of the steel surface.

Example 1

(1) Rust removing and polishing a steel sample, and then putting the steel sample into an oven for later use;

the steel sample was plain carbon steel and the sample size was 20mm x 20mm x 10 mm. The rust removal process of the steel sample comprises the following steps: preparing 50ml of acid washing solution with the ratio of industrial hydrochloric acid to deionized water (1:1), wherein the purity of the hydrochloric acid is 36.48%, and then preparing two portions of 3% Na₂CO₃100ml of neutralizing solution. Putting a steel sample to be derusted into an acid pickling solution for acid pickling, fully shaking for 5-10 minutes, taking out the sample after the surface is not corroded, and putting a first part of 3% Na₂CO₃Soaking the neutralized solution for 3-5 min to remove residual hydrochloric acid solution, taking out, and adding another 3% Na₂CO₃And soaking the neutralization solution for 20-30 minutes to passivate the surface. Then taking out, washing with distilled water and drying. The samples were sequentially sanded with 400/600/800 mesh waterproof sandpaper until the surface was smooth and free of rust pits. And finally, cleaning the polished sample by using absolute ethyl alcohol, sucking the sample to be dry, and putting the sample into an oven for later use.

(2) According to the formula of 3g/L beef extract, 5g/L peptone, 5g/L NaCl, (NH)₄)₂SO₄Weighing the above components at a ratio of 1g/L, and making into liquid cultureAnd sterilizing for 30min under the conditions that the temperature is controlled at 120 ℃ and the pressure is 0.1-0.12 MPa.

(3) After the sterilization is finished, spores of bacillus are inoculated into a prepared culture medium, then the culture medium is placed into a shaking incubator for culture, and after two days of culture, an absorbance value (OD value) is measured by an enzyme-labeling instrument to be 1.02. Used for testing and standby.

(4) Then 200ml of the inoculated and cultured concentrated bacterial liquid is weighed, 1.3g of organic calcium source solution is added, and the microbial suspension is obtained after complete dissolution. Referring to FIG. 1, a steel sample 1 after removing rust and polishing was tied up with a copper wire 2, suspended in the microbial suspension 3, and mineralized in a ventilated and dried room temperature environment. Meanwhile, the steel sample after rust removal and drying is put into a culture medium calcium source solution only containing the same culture medium and calcium source components for mineralization by the same method to serve as a control group 1; and another group of control groups 2 are arranged, and the steel samples which are subjected to rust removal and drying are placed into deionized water to be soaked by adopting the same method.

After soaking for five days, taking out three groups of steel samples, washing, drying in a drying oven, and observing the corrosion condition of the surfaces of the samples by using a body microscope. FIG. 2(a) is a diagram showing the surface corrosion condition of a steel sample after being immersed in a microbial suspension (a) and mineralized for 5 days, wherein the steel sample placed in the microbial suspension has no corrosion on the surface and a film-shaped protective layer on the surface; FIG. 2(b) is a graph showing the corrosion state of the surface of the steel sample of control 1 after being immersed in the culture medium calcium source solution (b) containing no bacteria solution for 5 days, wherein the surface of the steel sample has been significantly corroded and no protective layer is formed on the surface of the sample.

Then, observing the microstructure and the morphology of the surface protective layer of the steel sample by using a field Scanning Electron Microscope (SEM), the organic-inorganic composite film is deposited on the surface of the sample. The results of the energy spectrometer show that the organic component is long-strip-shaped microbial Extracellular Polymer (EPS) containing C, O elements, as shown in figures 3(a) -3 (b); the inorganic component is spherical calcium carbonate containing C, O, Ca three elements, as shown in FIGS. 3(c) -3 (d).

The steel samples with organic-inorganic composite protective layers deposited on the surfaces and the steel samples soaked in the control group 1 and the control group 2 are processedAnd (3) testing the corrosion resistance, wherein the testing method comprises the following steps: the test is carried out by an electrochemical workstation, the electrolyte is 3.5 percent NaCl solution, and the test frequency range of the alternating current impedance spectrum is (10)^-2～10⁵) Hz, the disturbance amplitude range is selected to be +/-10 mv, a steel sheet sample is selected as a working electrode, a stainless steel sheet is selected as an auxiliary electrode, a saturated calomel electrode is selected as a reference electrode, and the electrochemical performances of the steel sample with the organic-inorganic composite protective layer deposited on the surface, the steel sample soaked in the control group 1 and the steel sample soaked in the control group 2 are respectively tested. FIG. 4 is the results of electrochemical performance tests on three groups of steel samples, and the results show that the electrochemical impedance spectrum of the steel sample with the organic-inorganic composite protective layer deposited on the surface thereof prepared by the present invention shows that the capacitive resistance radius is the largest, the open-circuit potential is-165 mv, while the open-circuit of the steel sample of the control group 1 is-529 mv, and the open-circuit of the steel sample of the control group 1 is-723 mv; according to the metal corrosion standard of the Chinese metallurgy industry, when the potential is more than-250 mv, no corrosion occurs, and when the potential is less than-400 mv, corrosion occurs. As can be seen, the organic-inorganic composite protective layer deposited on the surface of the sample slows down the corrosion of corrosive media to steel, and shows a better corrosion prevention effect.

Example 2

(1) The steel sample was rust-removed and polished by the method of example 1 and then placed in an oven for use.

(2) According to the formula of 4g/L beef extract, 6g/L peptone, 3.5g/L NaCl and NH₄Weighing the components at Cl 1g/L to prepare a liquid culture medium, and sterilizing for 30min at the temperature of 121 ℃ and the pressure of (0.1-0.12) MPa.

(3) After the sterilization is finished, spores of bacillus are inoculated into a prepared culture medium, then the culture medium is placed into a shaking incubator for culture, and after two days of culture, an absorbance value (OD value) is measured by an enzyme-labeling instrument to be 1.12. Used for testing and standby.

(4) Then 200ml of inoculated and cultured concentrated bacterial liquid is weighed, 1.1g of organic calcium source solution is added, after the bacterial liquid is dissolved, the sample which is well derusted and polished is tied by iron wires, and the sample is hung in the concentrated bacterial liquid which is dissolved with the calcium source and is placed in an open, ventilated and dry environment for mineralization.

And after the steel sample is mineralized by the microorganisms for five days, taking out the steel sample, drying the steel sample in a drying box, and observing the surface of the sample by using a body type microscope to find that the surface of the sample is not rusted and has a film-shaped protective layer.

Observing the microstructure and the form of the surface protective layer of the steel sample by using a field scanning electron microscope, and finding that a layer of organic-inorganic composite film is deposited on the surface of the sample. The results of the energy spectrometer prove that the composite membrane consists of a long-strip extracellular polymeric substance EPS organic layer and a spherical calcium carbonate inorganic layer.

The corrosion resistance of the steel sample deposited with the organic-inorganic protective layer in the embodiment is tested by the test method in the embodiment 1, and the electrochemical test result shows that the corrosion potential is close to that in the embodiment 1 and is-158 mv.

Example 3

(2) According to the formula of 4.5g/L beef extract, 7g/L peptone, 4g/L NaCl, (NH)₄)₂SO₄Weighing the components at a ratio of 2g/L, preparing into liquid culture medium, and sterilizing at 121 deg.C and 0.1-0.12 MPa for 30 min.

(3) After the sterilization is finished, spores of bacillus are inoculated into a prepared culture medium, then the culture medium is placed into a shaking incubator for culture, and after two days of culture, an absorbance value (OD value) is measured by an enzyme-labeling instrument to be 1.28. Used for testing and standby.

(4) Then 200ml of inoculated and cultured concentrated bacterial liquid is weighed, 1.2g of organic calcium source solution is added, after the bacterial liquid is dissolved, the sample which is well derusted and polished is tied by iron wires, and the sample is hung in the concentrated bacterial liquid which is dissolved with the calcium source and is placed in an open, ventilated and dry environment for mineralization.

The corrosion resistance of the steel sample deposited with the organic-inorganic protective layer in the embodiment is tested by the test method in the embodiment 1, and the electrochemical test result shows that the corrosion potential is close to that of the embodiment 1 and is-164 mv.

Claims

1. A steel anticorrosion method based on a microbial technology is characterized by comprising the following steps:

(2) adding the steel sample subjected to rust removal and drying into the microbial suspension, and placing the steel sample in a room temperature environment for deposition of a protective layer to form an organic-inorganic composite protective layer on the surface of the steel sample, wherein the organic protective layer is a microbial extracellular polymer, and the inorganic protective layer is spherical calcium carbonate;

(3) and taking out the sample, washing and drying.

2. The method for preventing corrosion of a steel product by a microbial technique according to claim 1, wherein the calcium source in step (1) is an organic calcium source and is added in an amount of (1.0 to 1.3) g/200 ml.

3. The method for preserving steel based on the microbiological technology as claimed in claim 1, wherein in step (1), the components of the culture medium include beef extract, peptone and ammonium salt or sodium salt, wherein each liter of the culture medium contains 3-5 g of beef extract, 5-8 g of peptone and 0-3 g of ammonium salt or sodium salt.

4. The method for preventing corrosion of steel according to claim 1, wherein the method for preparing the concentrated bacterial liquid in step (1) comprises: and (3) dissolving the powdery bacillus in deionized water according to the mass (10-20) g/L, and inoculating the germinated spores to a corresponding culture medium for culture.

5. The method for preserving steel products based on the microbiological technology as claimed in claim 4, wherein the culture medium is prepared first, then the prepared culture medium is sterilized, after sterilization is finished, spores are inoculated according to the bacterial liquid amount of 10ml per liter of the culture medium, then the inoculated culture medium is placed in a shaking incubator for cultivation, the total number of cells is cultivated until the OD value reaches more than 1, and then the cells are taken out, so that the concentrated bacterial liquid of the bacillus is obtained.

6. A method for preventing corrosion of steel according to claim 5, wherein the culture medium is sterilized in a sterilization tank at 115 to 121 ℃ under 0.1 to 0.12MPa for 20 to 30 min.

7. The method for preserving steel on the basis of the microbial technology as claimed in claim 5, wherein the culture temperature in the shaking incubator is 25 to 30 ℃.

8. The method for preventing corrosion of steel according to claim 1, wherein the protective layer is deposited for 2 to 5 days in the step (2).