Week 5 -- Formulation of a Procedure

So, this week, it was mock AP week, meaning I couldn’t go into the lab and get much work done. I mostly stayed home and read papers on the photocatalytic degradation step, as the paper I originally took the procedure from was extremely vague in the sense that they didn’t provide me with any concentrations or numbers. For instance, the paper mentioned the “addition of 1mL H2O2”, without telling me concentration. As I said in a previous post, this was a problem, due to there being a peak at which H2O2 drives the reaction forward without inhibiting it. Upon reading a few sources, I found that most value lie between 1-20mM. I settled on 10mM, and how I’ll reach such a small concentration is by serial dilution.

If any readers have taken Honors Chemistry, surely you remember the lab where you diluted Kool Aid down by orders of magnitude of 10 each time. I intend to do the same thing with Hydrogen Peroxide. I will first get to 0.1M, by using 1mL of my stock (30%, which is around 9.8M, which I rounded up to 10M for simplicity) and 99mL of water. This gets me to 100mM. Then, I dilute this tenfold with 10mL of this new solution with 90mL water, getting to my desired volume of 10mM. As for the other concentrations, I also calculated it. In a previous post, I also mentioned that the Methylene Blue I’m using is different from the papers, as they used a powder, but I’m using a solution. My solution is approximately 0.23% dye, meaning about 2.3 grams per mL. If I want the 2mg they mentioned in the paper, I will need approximately 0.87mL of solution, or, rounded for simplicity, 0.85mL. Adding this to about 9.15mL of water will get me to what the paper used: 2mg in 10mL.

The UV light also produced another issue. While the manual I found online says it supports bulbs at 200 ish nm and 300 ish nm (I need 365nm). However, as the lamp I have uses a bulb, I am unsure if it has one of the two specifications, as whoever used it prior to me totally could have bought a new bulb and swapped it in. Therefore, I am essentially running of an educated guess: I can see the light (I didn’t stare at the light though don’t worry), so it can’t be too low. The fluorescence emitted by paper matches the images I found online of people using lights of similar wavelength.