Sweet Potato Leaves as Natural Protectors Against Sea Water Metal Corrosion

Greg Howard
25th April, 2024

Sweet Potato Leaves as Natural Protectors Against Sea Water Metal Corrosion

Image Source: Natural Science News, 2024

Key Findings

  • Researchers at Hunan University found sweet potato leaf extract (SPL) can protect aluminum alloy from seawater corrosion
  • SPL achieved a 94.6% corrosion inhibition efficiency after 36 hours of exposure
  • The study suggests SPL is an eco-friendly alternative to traditional toxic corrosion inhibitors
Corrosion, the gradual destruction of materials by chemical or electrochemical reaction with their environment, is a significant challenge in the maintenance of metal structures, especially those exposed to harsh conditions like seawater. This problem not only compromises the integrity of structures but also incurs substantial economic costs. To combat corrosion, scientists have been on a quest to develop corrosion inhibitors—substances that, when added in small amounts to an environment, significantly reduce the rate of corrosion. Researchers at Hunan University[1] have made a significant contribution to this field by turning to nature for a solution. They have successfully used sweet potato leaf extract (SPL) as an eco-friendly corrosion inhibitor for 6N01 aluminum alloy in seawater. Aluminum alloys are widely used in marine applications due to their strength-to-weight ratio and resistance to corrosion. However, they are still susceptible to damage, and traditional inhibitors often contain toxic chemicals that are harmful to the environment. The study from Hunan University used a simple water-based method to extract compounds from sweet potato leaves and tested their effectiveness at preventing corrosion. Using weight loss measurements and electrochemical tests, they found that SPL could achieve a corrosion inhibition efficiency of 94.6% after the aluminum alloy was immersed in seawater for 36 hours at room temperature. This finding aligns with previous research, such as the study on glucomannan modified with dopamine (GAD)[2], which also formed a protective layer on mild steel surfaces. Like GAD, SPL was observed to adhere to the metal surface, creating a barrier against corrosive elements in seawater. Similarly, the use of water-soluble imidazoline on A572 Gr.65 steels[3] showed high inhibition efficiency by forming a stable rust layer. These studies all underscore the importance of creating a protective layer on metals to prevent corrosion. The Hunan University team's analysis revealed that SPL adheres to the Langmuir adsorption isotherm, a model that describes how molecules distributed in a liquid or gas adhere to a surface, creating a single layer. This behavior was also noted in the study of chitosan-based carbon dots (CA-CDs) as corrosion inhibitors[4], where the adsorption of inhibitors followed the Langmuir model, involving both chemical bonding and physical adherence to the metal surface. In the case of SPL, the adsorption involves both physisorption, which is the weak, reversible adhesion of molecules to a surface due to van der Waals forces, and chemisorption, which involves the formation of a stronger, more permanent chemical bond. The researchers used quantum chemical calculations to further validate the chemical adsorption process and to understand how the electronic structures of the active components in SPL contributed to their effectiveness. The study's use of Fourier transform infrared (FT-IR) and ultraviolet-visible (UV-vis) spectroscopies helped identify the specific compounds in SPL responsible for the corrosion inhibition. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) provided visual and elemental evidence of the protective layer formed by SPL on the aluminum alloy surface. The research conducted at Hunan University is a step forward in the development of sustainable corrosion inhibitors. By using natural plant extracts, which are biodegradable and non-toxic, this approach not only helps protect metal structures from corrosion but also reduces the environmental impact compared to traditional inhibitors. The findings also encourage further exploration of plant-based compounds for corrosion protection, potentially leading to a new generation of green corrosion inhibiting technologies.

HerbsPlant ScienceMarine Biology

References

Main Study

1) In-Depth Insight into Corrosion Inhibition Performance of Sweet Potato Leaf Extract as a Green and Efficient Inhibitor for 6N01 Al Alloy in the Seawater: Experimental and Theoretical Perspectives.

Published 23rd April, 2024

https://doi.org/10.1021/acs.langmuir.4c00148

Related Studies

2) Dopamine modified natural glucomannan as a highly efficient inhibitor for mild steel: Experimental and theoretical methods.

https://doi.org/10.1016/j.ijbiomac.2023.124712

3) Corrosion Inhibition Mechanism of Water-Soluble Imidazoline on A572 Gr.65 Steel in 3.5 wt % NaCl Solution.

https://doi.org/10.1021/acs.langmuir.3c02781

4) Natural chitosan-based carbon dots as an eco-friendly and effective corrosion inhibitor for mild steel in HCl solution.

https://doi.org/10.1016/j.ijbiomac.2023.126449


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