Most of us, when we need some specific chemical or solution, take it for granted that we can got the appropriate supplier and purchase what we need. Like every other product on the market, we put very little thought into the incredible science and technology that goes into production. By Marb isn’t most people and his interests lie in those processes — particularly as they relate to chemistry. He demonstrates that once again in his newest video, which showcases the construction of a homemade Birkeland-Eyde reactor for producing nitric acid.
Nitrogen-based fertilizers are, without exaggeration, crucial for the modern farming that makes it possible to feed the people of the world. But how do you enrich soil with nitrogen? By getting nitrogen into a suitable format for fertilization.
In the beginning of the 20th century, Norwegian scientist Kristian Birkeland and his business partner, Sam Eyde, created the Birkeland-Eyde process. That’s quite complicated, but the basic idea is that it uses electrical arcs to turn nitrogen in the air (about 78% of Earth’s air is nitrogen) into nitric acid. That can then be used to make nitrate for use in fertilizers. The Birkeland-Eyde process uses a lot of energy and is inefficient, which was why it fell out of favor about a century ago. But the science is still interesting, which led Marb to the creation of this reactor.
The details are technical, but the operating principle of this reactor is understandable to most laypeople. The reactor pulls in air and dries it. The dry air then goes into a reaction chamber that has electrodes spaced apart to create an electrical arc when supplied with high voltage alternating current (about 5kV at 50Hz). Thanks to chemistry we don’t have the education to explain, that makes nitrogen dioxide gas. The gas flows into a flask water, where it dissolves and makes nitric acid, ready for purification.
Marb’s experimental reactor automates most of that under the control of an Arduino Uno board. It pumps through the air, via a tube filled with desiccant for drying, and controls the power (though a complex setup of power supplies and transformers) going to the electrodes.
That worked and Marb was able to produce a small amount of nitric acid. But there is room for efficiency improvements. Tweaks to the operating patterns would, in theory, increase the yield. It still wouldn’t be useful if the goal is to make a bunch of fertilizer, but it is an interesting practical science experiment.
