Lemon, meet World!
Tanay N -
This week I was on our senior trip to Disneyland and Knott’s Berry Farm. Although I’m a bit sad that it’s over, it means that I’m back to senior project!
I’d like to start off by first announcing the name I gave to my At-Home Direct Air Capture Unit: Lemon! The name is inspired by the “hydrated lime,” which is the main sorbent I will be testing in my project.
As promised in my last blog post, this one will be dedicated to explaining the necessity of certain materials and the intermediary reactions that facilitate the uptake of CO2. Below is an image of how Lemon currently looks (I plan on making an exterior design towards the end of my project)
Challenges
Firstly, I encountered a challenge when deciding how I wanted to design Lemon: the surface area of reaction. When the Ca(OH)2 is piled up, the CO2 can’t react with the inner layers of the sorbent; spreading the sorbent out only goes so far. This is why a pool of water to generate humidity is needed. The humidity causes Calcium hydroxide to form cracks and pores in its structure, further increasing the surface area. Nevertheless, making it too wet can fill in those same pores, halting the reaction. This distinction is precisely why airflow is so crucial to Lemon’s operation. Airflow prevents the Calcium hydroxide powder from becoming overly wet, while also allowing the powder to reform cracks after it has been dried.
As you can see in the picture above, Lemon consists of a smaller closed reaction chamber to foster a humid environment. At the same time, if this is a closed chamber, how does the CO2 enter the unit? In other words, how do I suction the CO2 into the reaction chamber? I realized I could simply pump air (which naturally contains CO2) through the water, allowing CO2 to escape the water as a gas and spread out into the reaction chamber.
The blue rectangular prism shown is the air stone. This is also a major component, as the air stone allows for the CO2 present in regular air coming from the air pump/air tubing to diffuse evenly through the water and bubble out faster. During Lemon’s actual testing, I will need to monitor the unit for any mold or damages, as the water cannot be removed; the chamber needs a continuous supply of water. The air stone has to be constantly soaked, otherwise it will rise to the top.
Testing and Experimentation
With Lemon, I plan on testing a variety of variables. The first tests will be as displayed in the above photo. Furthermore, later tests will include another opening on the opposite side of the fan to create an air current, as well as the fan directionality being switched. I also want to see if humidity is a real concern, and if I can instead use a larger lid than a cream cheese container to achieve the same result.
In addition to Calcium hydroxide, I want to take inventory of the chemicals available in my school’s chemistry lab and see if they could be involved in a reaction with CO2. This would involve much reading; however, I am not one to stray from a challenge!
Another idea that I was pondering about was an aqueous solution. This would also involve extensive research into acid-base chemistry but may possibly work because I can dissolve the Calcium hydroxide. The product would still be solid Calcium carbonate, as this is a precipitate (insoluble in water). Nonetheless, I only have so much time and will have to plan accordingly if I wanted to add on a Lemon 2.0 version.
Future Plans
Despite all of this, I’m learning a lot not only about chemistry, but also physical design! I look forward to continuing my research into titrations/acid-base reactions and diving deeper into instrumentation for the myriad of tests I will conduct with Lemon. Currently, with my end goal being to test all of Lemon by the end of March and having milestones planned in my journey, I hope I can progress the field of at-home Direct Air Capture.
I am also enthusiastic to meet with my on-site mentor, Dr. Green, to conduct laboratory work in order to optimize large-scale Direct Air Capture systems sitting in factories and industrial settings and seek his guidance on progress I’ve made so far with Lemon. I also am grateful for my faculty mentor Ms. Holtzman for her constant support with the construction and testing of Lemon.
In the coming weeks, I will be in Spain on a family trip (hopefully I can tour one of their DAC labs!) and will directly work as a Counselor for a Climate Camp in Tucson. As a result of my situation, I will be diving deeper into understanding intermediary chemical reactions and their applied functions in my Lemon unit. In my next blog post, I will go into the beginnings of my research paper as well as what I’ve learned so far.
Thank you so much for reading!
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