Week 2 -- Preliminary Tests

Last week, I did literature review and formulated a rough procedure. This week, I set to testing this procedure. The first barrier I had to overcome was dissolving Cupric Oxide (CuO) to isolate copper ions. The papers I had read up to that point mentioned a concentration of 1% volume to volume ratio of acetic acid (found in vinegar) to water, but I found that the concentration was too weak. To solve this, I initially tried a “stress test”, using the most concentrated acid I could find to attempt and dissolve the acid. The result I observed, after letting the mixture settle, was a clear and dark blue solution — perfect. Going off of another source, I tried this again with 0.3 Molar (diluted) acetic acid, which worked as well, but only after I boiled it on the stir plate’s max setting (to increase reaction rate). After cooling to room temperature, I dissolved 1 gram of chitosan into the solution. This is where trial one went wrong: after stirring for two hours, I observed two chunks of slimy substance, which upon neutralization via 1M NaOH and drying in an oven at 80 degrees Celsius overnight, resulted in a slimy substance the next day — not the result I wanted. On the second attempt, I adapted my approach, slowly adding chitosan and gently heating to allow small amounts of chitosan to slowly dissolve before adding more, resulting in a more continuous, gel-like solution. After adding NaOH and neutralizing and drying, I found a better result, with a rubbery film over a near transparent liquid (residue of copper that isn’t needed). The rubbery solid was put in a desiccator over the weekend and then ground with a mortar and pestle to get a flaky, dark teal substance — the catalyst.

This week was mostly for troubleshooting and making adjustments to the literature procedure to see if it’d work. The literature used sonication equipment, muffle ovens, and vacuum ovens, none of which I had. I had to test if each of my substitutes would work, and if so, perfect them. And with the week over, I have my conclusion: replace muffle ovens for the thermally decomposed product — it will reduce to reactivity but will suffice for me. Sonication — instead of adding chitosan in one go and sonicating it, I will slowly add it, while gently heating it to prevent burning the chitosan while allowing a greater reaction rate while using a magnetic stirrer on the highest setting. Vacuum oven — instead of 1 night, I will use the desiccator for a whole weekend to remove moisture. Next week, I hope to start preliminary testing on Methylene blue, as there is a lot of ambiguity in that procedure too, namely, the concertation of Hydrogen peroxide used to generate the ROS (reactive oxygen species) to start the degradation.