Researchers have discovered a unique synergistic effect between the microalgae Chlorella sp. and the chemical corrosion inhibitor benzotriazole (BTA) in protecting carbon steel from corrosion in alkaline seawater environments. This groundbreaking finding could have significant implications for the construction and maintenance of reinforced concrete structures, which are prone to corrosion-related damage, especially in marine settings. The study sheds light on a novel approach that combines biological and chemical methods to enhance the corrosion resistance of carbon steel, offering a promising solution for the long-term durability of critical infrastructure. Reinforced concrete, Corrosion, Microalgae, Benzotriazole
Tackling the Corrosion Challenge in Reinforced Concrete Structures
Reinforced concrete (RC) structures are ubiquitous in our modern world, used in a wide range of applications from bridges and buildings to nuclear power plants and offshore platforms. These sturdy structures rely on the combination of concrete and steel reinforcement to provide both strength and durability. However, one of the biggest challenges faced by RC structures is the threat of corrosion, which can severely compromise their structural integrity and lead to catastrophic failures.
Corrosion is a complex and pervasive issue, particularly in marine environments where structures are exposed to aggressive factors like chloride ions, seawater, and various microorganisms. These factors can work together to accelerate the deterioration of the steel reinforcement, causing cracks, spalling, and even complete structural collapse over time.
Exploring the Synergistic Potential of Chlorella and Benzotriazole
In a groundbreaking study, a team of researchers from Ningbo University and the University of Macau have investigated a novel approach to combat the corrosion of Q235 carbon steel, a commonly used material in RC structures. The key to their solution lies in the synergistic combination of the microalgae Chlorella sp. and the chemical corrosion inhibitor benzotriazole (BTA).
The researchers conducted a comprehensive laboratory investigation to explore the corrosion inhibition behavior of this unique duo on the Q235 carbon steel specimens in an alkaline artificial seawater environment. They employed a range of advanced techniques, including weight loss measurements, electrochemical measurements, and surface analysis, to assess the effectiveness of the Chlorella-BTA system compared to BTA alone.
Table 1 Electrochemical impedance spectroscopy parameters of Q235 carbon steel specimens in the control, BTA, and algae-BTA groups after 384 h of immersion.
Unveiling the Synergistic Corrosion Inhibition Mechanisms
The study’s findings were remarkable. The researchers discovered that the presence of Chlorella sp. could significantly enhance the corrosion inhibition efficiency of BTA on the carbon steel specimens. Specifically, the potentiodynamic polarization curves and weight loss measurements revealed that the Chlorella-BTA system was more effective in reducing the corrosion rates compared to BTA alone.
The researchers propose that the mechanisms behind this synergistic effect involve the formation of a more compact and stable passive film on the steel surface. The X-ray photoelectron spectroscopy (XPS) analysis showed that the passive film in the Chlorella-BTA system contained a higher proportion of iron oxides, hydroxides, and carbonates, as well as unique iron-BTA-extracellular polymeric substance (EPS) and iron-BTA complexes.
These complex layers effectively inhibit both the anodic and cathodic corrosion reactions, providing a robust and long-lasting protection for the carbon steel. The researchers believe that the natural adhesion properties of Chlorella sp. allow it to access the steel surface more quickly than BTA alone, facilitating the formation of these protective layers.
Implications and Future Directions
The findings of this study have significant implications for the construction and maintenance of reinforced concrete structures, particularly in marine environments. By combining the corrosion inhibition capabilities of a biological agent (Chlorella sp.) and a chemical inhibitor (BTA), the researchers have demonstrated a novel and promising approach to enhancing the durability and lifespan of critical infrastructure.
This synergistic strategy offers several advantages over traditional purely chemical-based methods. The integration of a biological component adds an environmentally friendly and cost-effective dimension to the corrosion control solution, making it a more sustainable option for the long-term. Additionally, the combined approach could provide more robust and long-lasting protection against the complex and dynamic corrosion challenges faced in marine settings.
As the researchers highlight, this study paves the way for future research and applications that explore the synergistic potential of biological and chemical corrosion inhibitors. By continuing to investigate and optimize these hybrid solutions, engineers and scientists can work towards developing more resilient and sustainable infrastructure that can withstand the ravages of time and the elements.
Author credit: This article is based on research by Shan Chen, Shen Zhang, Mingzhe Yuan, Ping Zhang.
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