When building bases on the Moon or Mars, the ideal way to cut costs is to source building materials locally. However, manufacturing and processing methods for building materials widely used on Earth are difficult to implement on the Moon or Mars.
A research team led by Azmin F. Islam of Washington State University and Soumik Banerjee have developed a new technology that can melt mineral elements from rocks and print them using 3D printers.Ionic liquid“The ionic liquid most suitable for regolith on the Moon and Mars was chosen. Results:From hundreds of thousands of candidates, we select the six most suitable for them.I was able to do it. By narrowing down the candidates in advance, there is a possibility that they will be used in future experimental research.
■ The difficulty of purchasing building materials on the Moon and Mars has been a long-standing problem
The most ideal environment for conducting research on the Moon or Mars is one in which humans can stay for a long period of time, and to achieve this it is necessary to create bases in which humans can live permanently. Transporting the building materials needed to build the base from the ground would be very expensive, so it would be ideal to process local rocks to make building materials, and research is still ongoing to find the best way to do this.
Related Article: Source as locally as possible. Using “regolith” on the moon’s surface to support sustainable manned exploration (July 20, 2019)
Related article: It turns out that mixing Martian regolith with titanium alloys can increase its strength (September 23, 2022)
Rocks on the Moon and Mars are composed of a sand-like material called regolith, which has very fine, sharp shapes due to the impacts of micrometeorites and solar wind. The simplest method is to reinforce the regolith, treat it and use it like bricks, but to create more durable and complex structures, metal frames are required. To create these building materials, mineral elements must be extracted from regolith.
On Earth, it is common to extract metallic elements only by melting rocks at high temperatures, electrolyzing them, or mixing them with other materials. However, on the Moon and Mars, it is difficult to obtain energy to generate heat and electricity, and materials to mix. While some methods require little energy, many are still difficult to implement because they require large amounts of water, a precious resource on the Moon and Mars.
■Extraction of minerals using “ionic liquid”
The Islam and Banerjee research team said,Ionic liquid” An ionic liquid is literally a liquid substance made of ions. Sodium chloride is a very familiar example of a substance made up of ions, but it is usually a solid, as it does not liquefy unless heated to 800°C. However, some Substances composed of ions have the unusual property of remaining in a liquid state even at room temperature.This is an ionic liquid.
Ionic liquids are mainly used in battery development research because they easily conduct electricity, but they also have another property: they dissolve metallic elements when they come into contact with the minerals that make up rocks. This means that ionic liquids can be used to extract mineral elements from rocks at low energy costs. Ionic liquids are difficult to evaporate and have high chemical stability, so they can be reused many times. The rock extraction process can also produce oxygen and water as byproducts. Best of all, its liquid nature makes it suitable for making building materials using 3D printers.
However, ionic liquids consist of a mixture of multiple substances, and there are countless candidates. There are arguably countless types and combinations of minerals that make up the debris of the Moon and Mars. It is not realistic to experimentally measure extraction efficiency for each of these combinations.
■ Narrow down the optimal ionic liquid from hundreds of thousands of candidates
Islam and Banerjee conducted research through machine learning and modeling to find the optimal ionic liquid. We have investigated which type of ionic liquid has superior performance in extracting sodium, magnesium and aluminium, which are typical mineral elements found in regolith and each of which has a different valence.
Results,From hundreds of thousands of candidates, we finally narrowed it down to six types of ionic liquids.I was able to. When selecting these ionic liquids, Mr. Islam and Mr. Banerjee take into account the size of the cations present in the ionic liquid, the number of electrons on the surface of the liquid (surface charge density), and the ease of movement of the ions to determine extraction efficiency, which have been shown to have a significant impact.
Islam and Banerjee are already working with researchers at the University of Colorado to test some candidates. This type of trial is possible because the pool of candidates has been narrowed down beforehand. Regarding this achievement, Banerjee said: “The machine learning work has taken us from an altitude of 20,000 feet to an altitude of 1,000 feet. The 1,000-foot level.”
Mr. Islam and Mr. Banerjee plan to conduct extraction experiments on larger sizes to test whether the ionic liquid can indeed be used in the production of construction materials for building foundations.
- Azmin F. Islam and Soumik Banerjee. “Towards the extraction of minerals from regolith: a theoretical study of the melt structure and dynamics of metal ions in ionic liquids.” (Journal of Physical Chemistry B)
- F. Rexby, et al. “Dissolving metal oxide with ionic liquids: dissolution coefficient analysis.” (Journal of Molecular Fluids)
- Tina Hilding. “Potential solvents identified for construction on the Moon and Mars”. (Washington State University)
Written by Riri Aya
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