MICP-based offshore structure interface corrosion prevention method

Abstract

The invention discloses an MICP-based marine structure interface corrosion prevention method, belongs to the technical field of marine structure corrosion prevention, and aims to improve the corrosion resistance of a marine structure in a marine environment and prolong the service life of the marine structure. The method comprises the following steps: S1, interface pretreatment: pretreating an offshore structure interface to obtain a clean interface; s2, preparing an MICP treatment solution, namely preparing the MICP treatment solution containing a microbial agent, nutrient substances and an additive; s3, coating treatment is conducted, specifically, the pretreated offshore structure interface is coated with the MICP treating fluid prepared in the step S2; and S4, curing treatment is conducted, specifically, the offshore structure interface coated with the MICP treating fluid is placed under the marine environment condition to be subjected to curing treatment. The compactness and stability of the anti-corrosion layer can be further improved, the anti-corrosion effect is enhanced, the service life of the offshore structure can be remarkably prolonged, and the method has wide application prospects in the technical field of anti-corrosion of the offshore structure.

Description

Technical Field

[0001] The invention relates to the technical field of offshore structure anticorrosion, and in particular to an offshore structure interface anticorrosion material based on MICP. Background Art

[0002] As the global demand for clean energy continues to grow, offshore wind power, as an important renewable energy source, is expanding in scale. However, offshore structures have been in a harsh marine environment for a long time and face serious corrosion problems. Seawater has the characteristics of high salinity, strong alkalinity, high humidity and complex microbial communities. These factors work together to make offshore structures very susceptible to corrosion, thereby reducing the structural strength and service life of the structure, increasing maintenance costs, and may even cause safety accidents.

[0003] At present, the commonly used methods for corrosion protection of offshore structure interfaces mainly include coating corrosion protection and cathodic protection. Coating corrosion protection is to apply anti-corrosion coatings, such as vinyl chloride coatings, polyurethane coatings, etc., to the interface of the structure, but the coatings are prone to aging, peeling and other problems under the long-term marine environment, and their durability is limited. Cathodic protection uses an external current or sacrificial anode to make the metal structure a cathode for protection, but this method consumes a lot of electricity or metal materials, and the protection effect on complex structures may not be ideal. In addition, these traditional corrosion protection methods may cause environmental pollution during the construction process, and the subsequent maintenance is more cumbersome.

[0004] As an emerging green and environmentally friendly technology, microbial induced calcium carbonate precipitation (MICP) technology has been applied to the fields of building material reinforcement and cultural relics protection in recent years. This technology uses the metabolic activities of microorganisms to induce the precipitation of calcium carbonate under specific conditions. The formed calcium carbonate crystals have good filling and cementing properties, which can effectively improve the density and durability of the material. The application of MICP technology in the field of interface corrosion protection of offshore structures is expected to overcome the shortcomings of traditional corrosion protection methods and provide a long-term and environmentally friendly corrosion protection solution for offshore structures. Summary of the invention

[0005] The purpose of the present invention is to provide an offshore structure interface anti-corrosion method based on MICP, so as to improve the corrosion resistance of the offshore structure in the marine environment and extend its service life.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides an offshore structure interface anti-corrosion method based on MICP, comprising the following steps:

[0008] S1. Interface pretreatment: pretreatment of the offshore structure interface to obtain a clean interface;

[0009] S2, preparing a MICP treatment solution, preparing a MICP treatment solution containing a microbial agent, nutrients and additives;

[0010] S3, coating treatment, coating the MICP treatment solution prepared in S2 on the pre-treated offshore structure interface;

[0011] S4, curing treatment, placing the offshore structure interface coated with the MICP treatment liquid under marine environmental conditions for curing treatment.

[0012] The present invention ensures the cleanliness of the interface through pretreatment, and utilizes microbial liquid to catalyze the hydrolysis of urea to produce carbonate ions, which react with calcium ions in a calcium chloride solution to form calcium carbonate precipitates, thereby forming a strong and dense anti-corrosion layer on the interface of the offshore structure. This not only effectively isolates the direct contact between seawater and structural materials and slows down the corrosion rate, but also enhances the durability of the offshore structure, thereby achieving environmentally friendly and long-lasting anti-corrosion protection.

[0013] Optionally or preferably, the method for pre-treating the offshore structure interface in step S1 is: mechanically grinding and / or chemically cleaning and / or high-pressure water jetting the offshore structure interface.

[0014] In the present invention, the structural interface is pretreated to remove oil stains, rust, marine organism attachment and other impurities on the interface, so that the structural interface is clean and flat, which is convenient for subsequent coating of the MICP treatment solution.

[0015] Optionally or preferably, the microbial agent in step S2 is a urease-producing bacterium, including one or more of Bacillus pasteurianus, Bacillus stutzeri or Bacillus halophilus.

[0016] Optionally or preferably, the microbial agent in step S2 is cultured in a culture medium;

[0017] The culture medium components include 20 g / L yeast extract, 15 g / L ammonium chloride and 0.1 mmol / L nickel chloride, and the bacterial liquid concentration is 1×10 6 CFU / mL-1×10 9 CFU / mL.

[0018] In the present invention, urease-producing bacteria are selected as microbial agents, such as Bacillus pasteurianus, Bacillus stutzeri or Bacillus halophilus, etc. These strains have strong urease activity and can effectively catalyze the hydrolysis of urea to produce carbonate ions, which then combine with calcium ions to form calcium carbonate precipitation. The microbial agent is cultured in a culture medium to a logarithmic growth phase, and then the cells are collected by centrifugation, washed with physiological saline and resuspended, and the concentration of the bacterial solution is adjusted to obtain a higher urease activity, induce the generation of more calcium carbonate precipitation, and thus have a better cementation effect.

[0019] Optionally or preferably, the nutrients in step S2 include urea and calcium chloride;

[0020] The urea concentration is 0.5 mol / L-1 mol / L, the calcium chloride concentration is 0.5 mol / L-1 mol / L; and the molar ratio of urea to calcium chloride is 1:0.5-1:2.

[0021] The present invention adds nutrients, mainly including urea and calcium chloride, to the microbial agent solution. Urea, as a nitrogen source for microbial metabolism, decomposes under the action of urease to produce ammonia and carbonate ions; calcium chloride provides calcium ions and reacts with carbonate ions to generate calcium carbonate precipitation. By controlling the concentration and molar ratio of urea and calcium chloride, the generation amount (rate) of calcium carbonate precipitation is guaranteed.

[0022] Optionally or preferably, the additives in step S2 include 1%-5% by mass of organosilicon-modified epoxy resin and nano-silicon dioxide particles.

[0023] The invention further improves the performance of the anti-corrosion layer by adding additives to the MICP treatment liquid; wherein an organic silicon modified epoxy resin is added as a binder to enhance the bonding force between the treatment liquid and the structural interface; and silicon dioxide particles are added to improve the hardness and wear resistance of the anti-corrosion layer.

[0024] Optionally or preferably, the method of coating the prepared MICP treatment liquid on the pretreated offshore structure interface in step S3 is: coating the MICP treatment liquid on the clean interface by spraying, brushing or dipping.

[0025] Optionally or preferably, the marine environmental conditions in step S4 include:

[0026] The temperature is 20℃-35℃; the humidity is 50%-90%; the pH value of seawater is 7.5-9.0; the salinity of seawater is 20‰-35‰;

[0027] The curing treatment time is 24h-72h.

[0028] Optionally or preferably, the offshore structure interface described in step S1 includes an offshore tower specimen, an offshore blade specimen and an offshore tower specimen.

[0029] Optionally or preferably, the coating thickness in step S3 is 0.1 mm-1 mm.

[0030] Based on the above technical solution, the present invention can at least produce the following technical effects:

[0031] The invention provides an offshore structural surface anticorrosion method based on MICP. Compared with the traditional anticorrosion method, the invention avoids the use of a large number of chemical preservatives, reduces the pollution to the marine environment, and meets the requirements of sustainable development. The calcium carbonate anticorrosion layer formed by the method has good density and stability, can effectively prevent corrosive media such as seawater, oxygen, and chloride ions from contacting the structural metal interface, and provides long-term anticorrosion protection. Since the microorganisms still have a certain activity in the anticorrosion layer, when the anticorrosion layer is locally damaged, the microorganisms can induce calcium carbonate precipitation in the presence of nutrients, and perform a certain degree of self-repair on the damaged part, thereby further improving the reliability of the anticorrosion system.

[0032] The anti-corrosion method of the present invention can be applied to different offshore structural interfaces, such as complex-shaped structural interfaces such as towers, blades, and tower frames, and can be adjusted and optimized accordingly according to different corrosion environments and structural materials, and has wide application adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a flow chart of the offshore structure interface anticorrosion method based on MICP of the present invention;

[0034] Figure 2 is a curve diagram showing the change of interface impedance of an offshore tower specimen with test frequency in the first embodiment of the present invention;

[0035] Figure 3 is a curve diagram showing the variation of the wear thickness of the interface of the offshore blade specimen with the scouring time in the second embodiment of the present invention;

[0036] Figure 4 It is a curve diagram showing the change of metal ion concentration in the simulated seawater solution with immersion time. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work belong to the scope of protection of the present invention.

[0038] See also Figure 1 , a method for anti-corrosion of offshore structure interface based on MICP, comprising the following steps:

[0039] S1. Interface pretreatment: pretreating the interface of the offshore structure to obtain a clean interface; the pretreatment method is mechanical grinding or chemical cleaning or high-pressure water jet, so as to remove oil stains, rust, marine biological attachments and other impurities on the interface, so as to make the structure interface clean and flat, so as to facilitate the subsequent coating of the MICP treatment solution.

[0040] S2, preparing a MICP treatment solution, preparing a MICP treatment solution containing a microbial agent, nutrients and additives;

[0041] Wherein, the microbial agent is a urease-producing bacterium, including one or more of Bacillus pasteurianus, Bacillus stutzeri or Bacillus halophilus;

[0042] The nutrients include urea and calcium chloride, the urea concentration is 0.5 mol / L-1 mol / L, the calcium chloride concentration is 0.5 mol / L-1 mol / L; and the molar ratio of urea to calcium chloride is 1:0.5-1:2;

[0043] The additives include organic silicon modified epoxy resin and nano silicon dioxide particles with a mass fraction of 1% to 5%.

[0044] The microbial inoculum was cultured in a culture medium until the logarithmic growth phase, and then the cells were collected by centrifugation, washed with saline and resuspended, and the concentration of the bacterial solution was adjusted to 1×10 6 CFU / mL-1×10 9 CFU / mL; the above culture medium ingredients include 20g / L yeast extract, 15g / L ammonium chloride and 0.1mmol / L nickel chloride.

[0045] S3, coating treatment, coating the MICP treatment solution prepared in S2 on the pre-treated offshore structure interface; the coating method includes spraying, brushing or dipping, and the coating thickness is 0.1mm-1mm.

[0046] S4, curing treatment, placing the offshore structure interface coated with the MICP treatment liquid under marine environmental conditions for curing treatment; the above-mentioned marine environmental conditions include: temperature of 20°C-35°C; humidity of 50%-90%; seawater pH of 7.5-9.0; seawater salinity of 20‰-35‰; and curing treatment time of 24h-72h.

[0047] Embodiment 1:

[0048] In this embodiment, the offshore structure is an offshore tower specimen, and a method for anti-corrosion of an offshore tower specimen interface based on MICP is provided, comprising the following steps:

[0049] S1. Interface pretreatment: first remove the rust and old coating on the interface by mechanical grinding, then clean the oil on the interface with acetone, and then rinse it with a high-pressure water jet to obtain a clean and smooth interface;

[0050] S2. Prepare MICP treatment solution, select Bacillus pasteurianus as the microbial agent, culture it in the culture medium until the logarithmic growth phase, collect the bacteria by centrifugation, wash with physiological saline and resuspend, and adjust the bacterial solution concentration to 5×10 6 CFU / mL; urea and calcium chloride were added to the bacterial solution, the molar ratio of urea to calcium chloride was 1:1, the urea concentration was 0.5 mol / L, the calcium chloride concentration was 0.5 mol / L, and 5% by mass of organic silicon-modified epoxy resin and nano-silicon dioxide particles were added to prepare a MICP treatment solution;

[0051] S3, coating treatment, using spraying method to evenly coat the MICP treatment liquid on the tower specimen interface, and the coating thickness is controlled at 0.5mm;

[0052] S4, curing treatment, placing the tower specimen coated with the treatment liquid in an environmental box at a temperature of 25°C and a humidity of 60% for curing treatment for 48 hours; during this period, white calcium carbonate precipitation was observed to gradually appear on the interface of the tower specimen, forming an anti-corrosion layer;

[0053] S5. Performance test: salt spray test and electrochemical impedance spectroscopy test were conducted on the untreated and treated tower specimens. The salt spray test was conducted in accordance with standard ASTMB117. After 1000 hours of salt spray test, the anti-corrosion layer on the interface of the treated specimen was basically intact, with no obvious signs of corrosion, while a large number of rust spots appeared on the interface of the untreated control specimen. The electrochemical impedance spectroscopy test results are as follows: Figure 2 As shown by Figure 2 It can be seen that at each test frequency, the impedance of the interface of the treated specimens is higher than that of the untreated specimens, indicating that its anti-corrosion performance is effectively enhanced.

[0054] Embodiment 2:

[0055] In this embodiment, the offshore structure is an offshore blade specimen, and a method for anti-corrosion of an offshore blade specimen interface based on MICP is provided, comprising the following steps:

[0056] S1. Interface pretreatment: First, use chemical cleaning methods to remove marine biological attachments and oil stains on the interface, then use sandpaper to gently polish the interface to make it rough, and finally rinse it with clean water;

[0057] S2. Prepare MICP treatment solution using a mixed bacterial agent of Bacillus stutzeri and Bacillus halophilus at a mixing ratio of 1:1; after culturing the mixed bacterial agent to the logarithmic growth phase, collect the bacteria by centrifugation, wash with physiological saline and resuspend, and adjust the bacterial solution concentration to 5×10 7CFU / mL; urea and calcium chloride were added to the bacterial solution, the molar ratio of urea to calcium chloride was 1:1.5, the urea concentration was 0.5 mol / L, the calcium chloride concentration was 0.75 mol / L, and 3% by mass of organic silicon-modified epoxy resin and nano-silicon dioxide particles were added to prepare a MICP treatment solution;

[0058] S3, coating treatment, using brushing to evenly coat the MICP treatment liquid on the blade specimen interface, with a coating thickness of 0.3 mm;

[0059] S4, curing treatment, placing the blade specimen coated with the treatment liquid in an environment with a temperature of 30°C and a humidity of 70% for curing for 36 hours; after curing, a uniform and dense anti-corrosion layer is formed on the interface of the blade specimen, and due to the addition of nano-silicon dioxide particles, the interface of the anti-corrosion layer has a certain degree of roughness;

[0060] S5. Performance test: The untreated and treated blade specimens were subjected to scouring tests in a simulated marine environment. In the scouring test, a simulated seawater solution was used as the scouring medium. The composition and concentration of the simulated seawater solution are shown in Table 1. Its pH value is 7.5 and its salinity is 30‰. The flow rate is set to 5m / s. After 120, 240, 360, 480, 600, and 720 hours of scouring, the corresponding wear thickness of the blade specimen interface is as follows: Figure 3 As shown by Figure 3 It can be seen that the wear thickness of the interface of the treated blade specimens is within 3 mm, which is only slight wear, while the interface of the untreated blade specimens is severely corroded, with the maximum wear thickness reaching 6.2 mm.

[0061] Table 1 Composition and concentration of simulated seawater solution

[0062]

[0063] Embodiment three:

[0064] In this embodiment, the offshore structure is an offshore tower specimen, and a method for anti-corrosion of an offshore tower specimen interface based on MICP is provided, comprising the following steps:

[0065] S1. Interface pretreatment: pretreatment is performed by combining high-pressure water jet and chemical cleaning to completely remove various impurities and corrosion products on the interface. After obtaining a clean interface, it is dried with hot air;

[0066] S2. Prepare MICP treatment solution, select Bacillus stutzeri as the microbial agent, and adjust the concentration of the bacterial solution to 5×10 8CFU / mL; the molar ratio of urea to calcium chloride in the nutrients is 1:2, the urea concentration is 0.5 mol / L, the calcium chloride concentration is 1.0 mol / L, and 1% by mass of organic silicon modified epoxy resin and nano-silicon dioxide particles are added to prepare a MICP treatment solution;

[0067] S3, coating treatment, using brushing to evenly coat the MICP treatment liquid on the tower specimen interface, with a coating thickness of about 0.8 mm;

[0068] S4, curing treatment, the coated tower specimen is placed in an environment with a temperature of 25°C and a humidity of 85% for curing for 60 hours; during the curing process, the microbial agent also induces the formation of calcium carbonate precipitation at the interface of the nano-silicon dioxide particles, so that the nano-silicon dioxide particles are closely combined with the anti-corrosion layer;

[0069] S5. Performance test: Long-term immersion test was conducted on untreated and treated tower specimens. The tower specimens were immersed in simulated seawater solution and the metal ion concentration in the solution was tested after immersion for 120, 240, 360, 480, 600, and 720 hours. The results were as follows: Figure 4 As shown by Figure 4 It can be seen that after the treated specimens were immersed for 120 hours, the metal ion concentration in the solution was low. As time went on, the concentration increased slightly and stabilized at 111.6 ppm after 480 hours. After the untreated specimens were immersed for 720 hours, the metal ion concentration in the solution reached 259.2 ppm, indicating that the anti-corrosion layer formed by the method of the present invention has good barrier properties.

[0070] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for anticorrosion of offshore structure interface based on MICP, characterized in that: The following steps are involved: S1. Interface pretreatment: pretreatment of the offshore structure interface to obtain a clean interface; S2, preparing a MICP treatment solution, preparing a MICP treatment solution containing a microbial agent, nutrients and additives; S3, coating treatment, coating the MICP treatment solution prepared in S2 on the pre-treated offshore structure interface; S4, curing treatment, placing the offshore structure interface coated with the MICP treatment liquid under marine environmental conditions for curing treatment.

2. The method for anticorrosion of offshore structure interface based on MICP according to claim 1, characterized in that: The method for pre-treating the offshore structure interface in step S1 is: mechanically grinding and / or chemically cleaning and / or high-pressure water jetting the offshore structure interface.

3. The method for anticorrosion of offshore structure interface based on MICP according to claim 1, characterized in that: The microbial agent in step S2 is urease-producing bacteria, including one or more of Bacillus pasteurianus, Bacillus stutzeri or Bacillus halophilus.

4. The method for anticorrosion of offshore structure interface based on MICP according to claim 1, characterized in that: The microbial agent described in step S2 is cultured in a culture medium; The culture medium components include 20 g / L yeast extract, 15 g / L ammonium chloride and 0.1 mmol / L nickel chloride, and the bacterial liquid concentration is 1×10 6 CFU / mL-1×10 9 CFU / mL.

5. The method for anticorrosion of offshore structure interface based on MICP according to claim 1, characterized in that: The nutrients in step S2 include urea and calcium chloride; The urea concentration is 0.5 mol / L-1 mol / L, the calcium chloride concentration is 0.5 mol / L-1 mol / L; and the molar ratio of urea to calcium chloride is 1:0.5-1:

2.

6. The method for anticorrosion of offshore structure interface based on MICP according to claim 1, characterized in that: The additives in step S2 include 1% to 5% by mass of organosilicon-modified epoxy resin and nano-silicon dioxide particles.

7. The method for anticorrosion of offshore structure interface based on MICP according to claim 1, characterized in that: The method of coating the prepared MICP treatment liquid on the pre-treated offshore structure interface in step S3 is: coating the MICP treatment liquid on the clean interface by spraying, brushing or dipping.

8. The method for anticorrosion of offshore structure interface based on MICP according to claim 1, characterized in that: The marine environmental conditions in step S4 include: The temperature is 20℃-35℃; the humidity is 50%-90%; the pH value of seawater is 7.5-9.0; the salinity of seawater is 20‰-35‰; The curing treatment time is 24h-72h.

9. The method for anticorrosion of offshore structure interface based on MICP according to claim 1, characterized in that: The offshore structure described in step S1 includes an offshore tower specimen, an offshore blade specimen and an offshore tower specimen.

10. The method for anticorrosion of offshore structure interface based on MICP according to claim 1, characterized in that: The coating thickness in step S3 is 0.1 mm-1 mm.

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