Microbots to Clean Nuclear Pollution

Figure 1: System Image of Microbots [1]

Team 5: Orca-Tech Water Cleaning Robot Presentation Video https://mediaspace.carleton.ca/media/presentationoffindingsgroup5/1_20halnoj

Overview

Microbots will be placed into bodies of water that are polluted with uranium/nuclear waste. The microbots will be able to absorb the uranium, propel itself inside the contaminated waters, and be able to be magnetically controlled for easy removal of the microbots.

References

[1] “Microrobots clean up radioactive waste (w/video),” Nanowerk, 30-Oct-2019. [Online]. Available: https://www.nanowerk.com/nanotechnology-news2/newsid=53925.php. [Accessed: 20-Sep-2020].

Structure and Stability of the Microrods: Tara Yusuf

Figure 2: A Metal-Organic Framework [2]

Microrods are essentially microscopic rods. The microbots used in this project are self-propelled microrods. They are used in this project to absorb Uranium from water bodies. They are made based on chemical structures known as Metal-Organic Frameworks (MOFs). A MOF is a structure that consists of metal units which are joined by organic linkers [2]. A MOF is shown in fig. 2.

 The ball-like structures seen in Figure 2 are the metal units [2]. The connecting lines seen in the figure are Organic linkers. This arrangement allows for the presence of pores in the structure. These structures also have a large surface area to volume ratio, that is, for small volumes occupied by the MOFs, they have relatively large surface areas. It is therefore noted that microrods are very porous structures and they have large surface areas. These properties allow for the absorption of large amounts of Uranium.

References

[1]A. M. Pourrahimi, Y. Ying, Z. Sofer, S. Matejkova, and M. Pumera, “Radioactive Uranium Preconcentration via Self-Propelled Autonomous Microrobots Based on Metal−Organic Frameworks,” ACS Nano, 08-Oct-2019. [Online]. Available: https://pubs-acs-org.proxy.library.carleton.ca/doi/pdf/10.1021/acsnano.9b04960. [Accessed: 20-Sep-2020].

[2]  Noro, S., 2020. Metal-Org Noro, S., 2020. Metal-Organic Frameworks Can Separate Gases Despite The Presence Of Water. [online] Asia Research News. Available at: <https://www.asiaresearchnews.com/content/metal-organic-frameworks-can-separate-gases-despite-presence-water> [Accessed 23 November 2020]

Magnetic Control: Evan Saikaley

Figure 2: Bar magnet surrounded by iron filings [1]

Metal doping is a process where a small amount of a substance, the dopant, is introduced to another material to change its properties [2]. Template based interfacial synthesis is a method of metal doping that allows for the precise placement of dopant onto a material while working with extremely small-scale objects, such as individual atoms or small chemical compounds [3]. Magnetic fields are a form of “invisible wind” that can be emitted either naturally by a magnetic substance, such as that found in fridge magnets, or artificially using electricity and a wire coil, such as those found in electric motors. Researchers from several universities have found a way to combine these concepts as well as others to create Microbots. These are microscopic devices that can move around in water contaminated with nuclear waste and collect the radioactive uranium particles [4]. The researchers used magnets to control and collect the microbots from the water.

References

[1] Magnetic field lines from a bar magnet visualized using iron filings. University of Calgary, 2018.

[2] J. V. Hernández, S. Coste, A. G. Murillo, F. C. Romo, and A. Kassiba, “Effects of metal doping (Cu, Ag, Eu) on the electronic and optical behavior of nanostructured TiO2,” Journal of Alloys and Compounds, 24-Mar-2017. [Online]. Available: https://www.sciencedirect.com/science/article/abs/pii/S0925838817310812. [Accessed: 23-Sep-2020].

[3] M. Pérez-Page, E. Yu, J. Li, M. Rahman, D. M. Dryden, R. Vidu, and P. Stroeve, “Template-based syntheses for shape controlled nanostructures.,” Advances in colloid and interface science, 27-Sep-2016. [Online]. Available: https://escholarship.org/uc/item/0m23w188. [Accessed: 27-Oct-2020].

[4] A. M. Pourrahimi, Y. Ying, Z. Sofer, S. Matejkova, and M. Pumera, “Radioactive Uranium Preconcentration via Self-Propelled Autonomous Microrobots Based on Metal−Organic Frameworks,” ACS Nano, 08-Oct-2019. [Online]. Available: https://pubs-acs-org.proxy.library.carleton.ca/doi/pdf/10.1021/acsnano.9b04960. [Accessed: 20-Sep-2020].

 Catalytic Self-Propulsion - Hammad Khan

Figure 1: Catalytic platinum nanoparticles labeled on a microbot [Hammad Khan]



The microbots which are being used to clean nuclear waste, will have a side covered in catalytic platinum nanoparticles. The catalytic nanoparticles serve the purpose of propelling the microbots. The catalytic platinum nanoparticles react with a lower activation energy, which allows the reaction between the platinum and hydrogen peroxide to happen more frequently. This frequent reaction between the platinum and hydrogen peroxide creates oxygen bubbles and propels the microbots to 60 times their body length per second. Through multiple tests, the microbots performed the  best when they were fit with catalytic nanoparticles and placed in hydrogen peroxide. The microbots were able to achieve 96% removal of the uranium.

References

[1] A. M. Pourrahimi, Y. Ying, Z. Sofer, S. Matejkova, and M. Pumera, “Radioactive Uranium Preconcentration via Self-Propelled Autonomous Microrobots Based on Metal−Organic Frameworks,” ACS Nano, 08-Oct-2019. [Online]. Available: https://pubs-acs-org.proxy.library.carleton.ca/doi/pdf/10.1021/acsnano.9b04960. [Accessed: 20-Sep-2020].

[2] R. U. OpenStax, “12.7 Catalysis,” Chemistry. [Online]. Available: https://opentextbc.ca/chemistry/chapter/12-7-catalysis/. [Accessed: 02-Nov-2020].