EcoCapture —Using MXene Membranes to Revolutionize CO2 Capture

If I asked someone how they thought the human race will end, they’d probably come up with a few answers that sound like they’re straight out of a movie: world-wide famine, severe natural disaster, extinction of crucial species, or even unlivable temperatures.

What if I told you that all of these are possible, and will most likely happen by 2100? This is planet Earth’s reality, and we owe it all to climate change.

By definition, climate change refers to long-term shifts in temperatures and weather patterns. Even though these changes can be natural, for the past two centuries human activities have sped them up significantly. The number one accelerator, as most of us know, is fossil fuels and their carbon dioxide emissions.

Current Methods for Carbon Capture

With a problem as large as this, it’s easy to assume that solutions already exist to combat it. One of the most prevalent ones is direct air capture (DAC), which has been developed since 1999. This technology works to capture CO2 directly from the atmosphere, and then store it underground or reutilize it for other purposes. While this method is about 90% effective, it doesn’t come without its issues.

DAC is a very energy intensive process, with the majority of the electricity used stemming from fossil fuels. This process has been shown to emit even more CO2 than it captures in some instances, counteracting its environmental impact. Additionally, manufacturing costs and the price of electricity make it extremely expensive, reducing the incentive for corporations and individuals to buy it. What if both of these issues could be solved, all with a nanoparticle membrane?

EcoCapture and its Capabilities

Let us introduce to you EcoCapture, a gas separation membrane that filters out carbon dioxide from other elements in the atmosphere and contains it. From there, the CO2 can be stored underground or used for other purposes. With this technology, we aim to reduce the impacts of climate change and global warming worldwide.

Our technology revolves around MXene (Max — ene) membranes, which are created by etching layers out of MAX phases. Let’s dive a little bit deeper into what each of these are:

MAX Phases

MAX phases are a group of materials that have unique properties, blending characteristics of both metals and ceramics. The name “MAX” stands for the combination of three elements: M for a transition metal, A for an A-group element on the periodic table, and X for carbon and/or nitrogen. The most common MAX phase is titanium aluminum carbide (Ti3AlC2), where the M is titanium, the A is aluminum, and the X is carbon. They’re known for being strong, heat-resistant, and able to withstand extreme conditions, which makes them perfect for gas separation.

MXene Membranes

An MXene membrane is a type of membrane made from MXene, a two-dimensional material derived from MAX phases. These membranes are usually composed of stacked layers of MXene nanosheets arranged in a specific configuration. The question is, how do we get those nanosheets?

Based on the image above, here is a breakdown this process:

1. Pieces of the ‘A’ layer (aluminum in this case) are selectively removed from MAX phases using a hydrofluoric acid (HF solution). This leaves behind a stack of transition metal carbide/nitride layers.
2. Using sonication (high frequency sound waves) or handshaking causes the individual layers to swell and separate to form MXene nanosheets.

Once fully constructed, these membranes have pores similar to a sponge, allowing them to be useful in spaces like water treatment, electronics, and energy storage. This property also makes it a good candidate for gas separation.

MXene membranes for Separating Hydrogen Gas

In 2018, researchers at Drexel University discovered that MXene membranes have the ability to passively filter out and capture hydrogen gas. To do this, they used a unique type of hydrofluoric acid while chemically etching out the MXene nanosheets. This created nanopores that fit the molecular shape of hydrogen, allowing those molecules to pass through while blocking other gases. Based on this finding, what’s stopping us from using a different acid to capture other gases, like CO2? That’s our mission at EcoCapture.

Hydrogen vs. Carbon Dioxide Molecules

Hydrogen and CO2 molecules exhibit fundamental differences in their chemical compositions and structures. Hydrogen molecules consist of two hydrogen atoms and has a low molecular weight, while CO2 molecules consist of one carbon atom bonded to two oxygen atoms and a higher molecular weight. The size difference between the two is also drastic, with CO2 molecules being about 4.69 times larger than hydrogen.

Because of this, materials used for creating membranes to contain hydrogen will usually not work for carbon dioxide. While the ones used by Drexel University were chemically etched to be useful for hydrogen, gasses of different shapes and sizes need to be etched differently using different hydrofluoric acids

Modifying MXene Membranes for CO2 Capture

We’ve covered the bases of the technology involved in our solution, but how exactly do we utilize it? Eco Capture involves using these MXene membranes, with a few tweaks, to capture CO2 directly from the atmosphere. Let’s break down our solution a bit more:

Using Different Hydrofluoric Acids to Control Pore Size

As mentioned previously, pores are one of the key ways to capture CO2, as this is where all atmospheric gas attempts to enter, but only certain molecules can remain there.

The best way to explain this process is to compare it to a child’s shape sorter toy, with the square hole being our “pore”. If we tried to fit the long, rectangular peg in there, it would obviously not fit and we would put it to the side. While the circular peg would fit through that hole, it would immediately fall through and land on the floor. If we placed the square peg there, however, it would fit perfectly and stay in the hole.

By creating membranes using a unique type of hydrofluoric acid, EcoCapture’s MXene nanosheets contain nanopores that mirror the linear shape of CO2 molecules. This makes it easier for them to get “stuck” in the pores of the membrane and allows smaller molecules to pass through while preventing bigger molecules from entering altogether.

Using Amino-functionalization for Attracting CO2

In addition to pore size, one of the other main ways EcoCapture membranes attract CO2 is through amino-functionalization, or adding amino (-NH2) groups to the surface of the MXene membranes.

These amino groups attract carbon dioxide, similar to a magnetic force, and form hydrogen bonds with the molecules to ensure they stay inside the membrane. Because amino groups selectively bond with CO2 over other gasses in the atmosphere, there is a smaller chance of other gases becoming captured in the membrane.

Removal and Utilization of Captured CO2 From the Membranes

With our membranes, captured carbon dioxide remains in the membrane until it is forcefully removed through a process called vacuum regeneration. During this, the membranes are subjected to a light vacuum suction, lowering the partial pressure of CO2 surrounding the membrane and driving the desorption of CO2 molecules from the membrane surface. This vacuum suction continues and guides the carbon dioxide to a storage container.

From there, the gas can be stored or used in multiple ways. The most economically feasible option is to store it underground, similar to current methods of carbon capture. It’s also possible, however, to reutilize this captured CO2 in fuels, concrete, and more. While EcoCapture focuses on the capture of carbon dioxide and not it’s use cases, in the future we may look into how we can reuse captured gas.

Membrane Placement and Their Versatility

One of the most beneficial aspects of MXene membranes is the temperatures they can effectively operate in, which range from 68–212 degrees Fahrenheit (20–100 degrees Celsius). In many regions across the world, the everyday climate fits this range, meaning that EcoCapture membranes could be used there year-round.

Additionally, our membranes can be smaller than most carbon solution and don’t require an industrial plant to operate them. Depending on the usage of captured carbon, EcoCapture membranes can be placed almost anywhere with the right climate, including major cities.

Benefits of This Over Other CO2 Extraction Methods

Unlike direct air capture, our membranes filter through air passively, meaning that no energy is required in the process of capturing the CO2. While it would take electricity to produce the membrane, transport the gas, and utilize it for other purposes, we can ensure that this would come from non-carbon emitting resources, like solar or wind.

Our Role in the Fight Against Climate Change

Don’t get us wrong — preventing carbon dioxide from ever reaching the atmosphere, whether through clean energy sources or carbon capture, is essential to ensure climate change doesn’t worsen. Without addressing the CO2 that’s currently there, however, there’s little hope of society actually improving the climate crisis.

With EcoCapture, we are able to collect carbon directly from the atmosphere, allowing the world to make a dent in the fight against rising CO2 emissions. All of the negative impacts of climate change, from rising temperatures to increased natural disasters, would be reduced, creating a brighter future for generations to come.

If you want to learn more about EcoCapture, click here to view our website :)

TLDR:

• EcoCapture utilizes MXene membranes for efficient carbon dioxide (CO2) capture.
• MXene membranes are tailored for selective CO2 filtering while allowing other gases to pass through.
• The technology operates passively, requiring no additional energy for CO2 capture.
• Captured CO2 can be stored underground or repurposed for various applications.
• EcoCapture aims to mitigate the impacts of climate change by directly addressing atmospheric CO2 levels.
• MXene membranes offer scalability and operational flexibility, making EcoCapture a transformative solution for combating climate change.