the nanomaterial that will reduce the impact of corrosion
What is corrosion?
The term corrosion refers to the destruction of a material because of its chemical or electrochemical interactions with the surrounding medium. The importance of its prevention and/or control is due to the fact that, being a natural phenomenon, once started it is practically impossible to stop. Therefore, an uncontrolled evolution will invariably compromise the integrity and useful life of the materials, generating the industry involved direct and indirect expenses due to loss of product, stoppage of activities due to maintenance until the replacement of machinery or structures.
“Economic losses caused by corrosion exceed 3.4% of global GDP”
Microbiologically influenced corrosion
Microbiologically influenced corrosion (MIC) can be defined as the electrochemical process in which microorganisms such as algae, fungi and bacteria initiate, facilitate, or accelerate a corrosion reaction, generally located in the form of cracks. or pitting on both metal and concrete surfaces. Although corrosion involves various variables, it is estimated that MIC participates in 20 to 40% of all corrosion failures, particularly in hydraulic and oil infrastructure, with costs close to 2 billion dollars annually.
Why do you start the MIC?
The presence of humidity in any environment is the ideal habitat for the growth of numerous communities of microorganisms that, combined with optimal conditions of temperature, pH, nutrient flow, etc., promotes their adhesion and growth on surfaces, forming a biofilm that is not removed, it grows into a hardened, obstructive biomass within which sulfate-reducing bacteria, acid-producing bacteria, iron-reducing bacteria, and gel-forming bacteria promote corrosion or MIC through destructive electrochemical reactions of the surfaces.
How do you combat it?
There are three most common methods to try to combat MIC, the first is mechanical cleaning of surfaces to remove biofilms, ideally in incipient stages, however, it is not always possible to access all exposed areas, making their efficiency difficult. The second is the use of biocidal agents that, in addition to being expensive, most may not be friendly to human health and the environment. Finally, and perhaps the most suitable method is the placement of external barriers in the form of coatings or polymeric films to prevent direct contact of the metal or concrete structures with the aggressive medium.
Corrosion control in concrete
The options available to protect concrete against corrosion from its fresh state are the additions of pozzolanic materials, fly ash, blast furnace slag, sulfate-free aggregates, polymer fibers, use of sulfate-resistant cement or modified with nanoparticles such as nanotubes and carbon nanofibers, silica nanoparticles, alumina or titanium dioxide. For protection in the hardened state, it is common to apply physical barriers such as anti-corrosion coatings or polymeric films and, for the protection of metal structures, in addition to anti-corrosion coatings, you can use galvanized, tinned structures or the placement of magnesium sacrificial anodes. However, it is considered that, due to the natural porosity of concrete, there are no totally efficient methods that attack the problem of corrosion towards the interior of structures.
Corrosion in concrete can occur due to carbonation, ingress of chlorides and sulfates or due to microbiological attack. When the concrete has reinforcing steel and is attacked by corrosion, oxide can grow 2 to 4 times the volume of the original steel, causing loss of adhesion of concrete and put the resistance of the material at risk. Furthermore, the porosity of the concrete, in addition to allowing the passage of moisture for the entry of aggressive ions, also offers millions of ideal niches for the retention of microorganisms and for the subsequent formation of MIC-initiating biofilms, not only because they favor their anchoring, but because they make their removal difficult and promote the advancement of corrosion.
“It is expected that by 2032 the corrosion inhibitors market will amount to 12.5 billion, and in 2022 this figure will be around 8.3 billion.”
Graphene and graphene oxide are multifunctional carbon nanomaterials with extraordinary properties that, when incorporated as a nanofiller in other compounds such as coatings, plastics or cement, have the ability to molecularly organize their structure in such a way that they improve their resistance to chemical, physical and microbiological attacks. Among their particularities is that they are inert nanostructures, that is, they are stable, they do not react with other materials and they do not suffer oxidation or corrosion. They are extremely thin and light, but at the same time, very resistant and flexible. They are impermeable even to gases and have highly efficient antimicrobial mechanisms.
Below is a summary of some of the most notable research on the use of graphene as an alternative against microbiologically influenced corrosion (MIC):
2015- The Department of Materials Science and Engineering at Rensselaer Polytechnic Institute, New York, USA, modified polyurethane coatings with graphene identifying 10 times greater protection against MIC compared to unmodified polyurethane coatings.
2017- The Nanobiomaterials laboratory of the Federico Santa María Technical University, Valparaíso, Chile, evaluated the direct effect of graphene placed on nickel substrates and its interaction with bacteria that cause corrosion. The results showed an impermeable barrier generated by graphene that blocked the interaction between bacteria and the metal, but without a bactericidal effect.
2021- The Department of Civil and Environmental Engineering, South Dakota School of Mines and Technology, USA, reported that multiple layers of graphene restricted MIC attack on copper and nickel surfaces 10 times more.
2021– The School of Engineering at the University of Glasgow, Scotland, examined the deterioration of graphene oxide (GO)-modified cement pastes exposed to acidic environments. The results demonstrated that the presence of GO reduces the loss of mass in the concrete due to these attacks, recognizing it as a potential additive to modify the microstructure and useful life of concrete in the face of aggressive environments such as those present in chemical product warehouses to systems. of wastewater.
Energeia Fusion (Graphenemex®), the leading Mexican company in Latin America in the production of graphene materials, after a long journey of research, in 2018 launched the Graphenergy Line on the market, which includes a series of anticorrosive and antimicrobial coatings with graphene nanotechnology and the first additive for concrete with graphene oxide in the world, whose individual or combined use promises great benefits against corrosion.
Graphenergy Construction is a water-based additive with graphene oxide designed to improve the quality of cement structures in terms of mechanical resistance and durability. The added value that graphene oxide offers to concrete in the fight against MIC from the outside to the inside is the result of a series of events that begin by favoring the hydration of the cement, acting as water reservoirs and as a platform for the growth of crystals. of C-S-H and to dissipate the heat of hydration; improves the interfacial transition zones between the cement paste and the aggregates, helping to reduce the size and volume of the pores, this in turn favors an increase in mechanical resistance, reduces permeability, increases its resistivity, that is, reduces the transfer of electrical charges into the interior of the concrete, delaying the onset of corrosion and, finally, modifying the electrostatic charges and the wettability of the surfaces, making the formation of biofilms that cause MIC difficult.
Graphenergy coatings formulated with graphene oxide offer great resistance against corrosion in coastal and non-coastal areas, as well as excellent antimicrobial protection without biocidal mechanisms, since their effect consists of preventing the adhesion of microorganisms to surfaces. In addition, its impermeability, resistance to abrasion and resistance against the intense effects of the elements increase its useful life and, therefore, substantially reduce the maintenance costs of both metal and concrete structures.
- The Many Faces of Graphene as Protection Barrier. Performance under Microbial Corrosion and Ni Allergy Conditions. Materials 2017, 10, 1406;
- Effect of graphene oxide on the deterioration of cement pastes exposed to citric and sulfuric acids. Cement and Concrete Composites, 2021, 124, 104252;
- Superiority of Graphene over Polymer Coatings for Prevention of Microbially Induced Corrosion. Scientific Reports, 2015, 5:13858;
- Atomic Layers of Graphene for Microbial Corrosion PreventionACS Nano 2021, 15, 1, 447;
- Microbiologically induced corrosion of concrete in sewer structures: A review of the mechanisms and phenomena. Construction and Building Materials. 2020, 239, 117813;
- Microbiologically Induced Corrosion of Concrete and Protective Coatings in Gravity Sewers. Chinese Journal of Chemical Engineering, 2012, 20(3) 433;
- In situ Linkage of Fungal and Bacterial Proliferation to Microbiologically Influenced Corrosion in B20 Biodiesel Storage Tanks. Front. Microbiol. 2020, 11;
- Chapter 1 – Failure of the metallic structures due to microbiologically induced corrosion and the techniques for protection. Handbook of Materials Failure Analysis. With Case Studies from the Construction Industries. 2018, 1;
- Maleic anhydride-functionalized graphene nanofillers render epoxy coatings highly resistant to corrosion and microbial attack. Carbon, 2020, 159, 586;
- Gerhardus Koch, Cost of corrosion, In Woodhead Publishing Series in Energy, Trends in Oil and Gas Corrosion Research and Technologies, Woodhead Publishing, 2017;