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Surface chemistry reveals corrosive secrets

Journal of Physical Chemistry A Reprinted with permission of. Copyright 2021 American Chemical Society. “width =” 800 “height =” 530 “/>

Polished iron exposed to electrolytes decomposes to form a film of iron carbonate and calcium carbonate when exposed to a heterogeneous mixture of oxygen and platelets. Credits: Mikhail Trought, Perrine Group.Reprinted with permission of Physical Chemistry Magazine A.. Copyright 2021 American Chemical Society.

It is easy to see with the naked eye that rusting occurs when old nails are left in the rain. The need for sharp eyes and a sensitive nose in microscopy and spectroscopy is to observe how iron corrodes to form new minerals, especially in water with a pinch of sodium and calcium.


The early stages of this process, thanks to new technology developed by chemists at Michigan Technological University, Water surface analysis.A team led by chemistry assistant professor Catherine Perine recently published the latest treatise. Physical Chemistry Magazine A..

The main findings of this group are that cations in solution (positively charged sodium or calcium ions) are combined with atmospheric oxygen. carbon dioxide.. Gradual exposure to oxygen and carbon dioxide creates a carbonate film that is unique to cations. Iron hydroxides of various shapes and forms are not cation-specific and are not gradually exposed to air.

A better understanding of this process and the rate of mineral formation opens up the possibility of improving carbon dioxide recovery, monitoring water quality by-products and improving infrastructure management of old bridges and pipes.

The methodology will be interdisciplinary

Rust and its associated iron ore are part of the well-known life on Earth’s surface, but the environment they form is extremely complex and diverse.Rust usually consists of iron oxide And iron hydroxide, corrosion can also lead to the formation of iron carbonate and other minerals. For each form, it is difficult to understand the best conditions to prevent or grow it. Perine points to major environmental issues such as the Flint Water Crisis, as an example where something as simple as rust can easily fall into more complex and unwanted subsequent reactions.

Interactions between iron, water, oxygen and ions quickly become complex. Since it is difficult to study the air-solution-solid solution interface, chemist Catherine Perine will lead a team to observe how iron minerals such as rust are formed 3 more accurately. We have developed a step-by-step method.Credit: Reissue with the permission of The Physical Chemistry Magazine A.. Copyright 2021 American Chemical Society.

“We want to measure and reveal chemical reactions in real-world environments,” said Perine, whose team focuses specifically on thin layers and membranes where surface chemistry, water, metals, and air all interact. He added that. “We are at a high level [surface] What is a surface mechanism and how, depending on the sensitivity of the analytical tools to regain the correct information [iron] Transform. “

Studying the surface science of materials is interdisciplinary in nature. From materials science to geochemistry, from civil engineering to chemistry, Perine sees her work as a bridge to help other disciplines better inform about processes, models, interventions and innovations. This requires high precision and sensitivity in her group’s work.

There are other ways to monitor surface corrosion and film growth, but in Perrine’s lab. Surface chemistry An approach that can be adapted to analyze other reduction and oxidation processes in complex environments.In a series of treatises, they have their 3-step process -Evaluate changes in electrolyte composition and use oxygen and carbon dioxide from the air as reactants, Various minerals observed at the vapor-liquid-solid interface..

Accurate measurement is a molecular lens to see chemistry

The analytical techniques used by the team are surface-sensitive. Polarized Modulated Infrared Reflection Absorption Spectroscopy (PM-IRRAS), Attenuated Total Reflectivity-Fourier Transform Infrared Spectroscopy (ATR-FTIR) Spectroscopy, X-ray Photoelectron Spectroscopy (XPS), and Atomic Force Microscope (AFM).

“Spectroscopy teaches us chemistry; microscopy teaches us physical changes,” Perine said. “It’s really difficult [image] These corrosion experiments [in real-time with AFM] This is because the surface is constantly changing and the solution changes during corrosion. “

The image reveals a sequence of surface drilling, chewing, and degradation called corrosion, which produces nucleation sites for mineral growth. The important part is to monitor the early stages as a function of time.

“Corrosion and film growth can be seen as a function of time. Calcium chloride [solution] Higher chloride ions tend to corrode the surface faster, but they also produce more carbonates, “says Perine. Video recorded by her labYou can see how the sodium chloride solution gradually corrodes the iron surface and continues to form rust as the solution dries.

She adds it since then iron Because is ubiquitous in the environmental system, slowing mineral formation and careful observation will adjust variables for how it changes with exposure to different solutions and air.

The team’s surface catalytic approach helps researchers better understand basic environmental sciences and other types of surface processes. Their methods uncover the mechanisms that contribute to polluted water, reduce carbon dioxide, prevent bridge collapse, stimulate smarter designs and cleaner fuels, and into geochemical processes on Earth. We hope it helps to provide you with deeper insights.


Studies using atom probe tomography reveal cracks in iron crystals that can be “healed”


For more information:
Chathura de Alwis et al, Effect of cations on iron interface oxidation and atmospheric corrosion on minerals, Physical Chemistry Magazine A (2021). DOI: 10.1021 / acs.jpca.1c06451

Quote: Surface Chemistry, Corrosive Secrets Obtained from https://phys.org/news/2021-10-surface-chemistry-reveals-corrosive-secrets.html on October 13, 2021 (October 2021) 13th) will be revealed

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Surface chemistry reveals corrosive secrets

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