Week 8 -- Testing onsite
April 28, 2026
So, after last week’s “successful” trial, I have started testing onsite. I met with Kevan initially on Wednesday, and I got experience in a much more advanced lab. For instance, I didn’t have to manually shake my aliquots, but instead I could use a vortexer to quickly mix up my sample. The UV-Vis was also a lot more sensitive than what we had at school: I had to consider the tiny amounts of leaching from my catalyst, and the 1-to-31 diluted 10mM introduction of H2O2 into my solution, all of which I didn’t ever have to consider with the schools very much insensitive spectrophotometers. On a side note, though, the computer that runs the program is a Windows XP. Anyways, onto my trials.
On Wednesday, I was figuring some things out, such as how to use the spectrophotometer, and what volumes to use, since the pipettes in the lab went up to 1mL. I essentially halved all the volumes, so while I might have been using a 0.5mL of my solution and 3mL of water in the cuvette before, I started using 0.25mL and 1.5mL instead, to fit in the 2mL centrifuge tubes. However, the results weren’t the greatest. I saw null results everywhere, which leads me to believe that there might be some noise coming in due to the dye staining the cuvettes. Next time, I intend on running a control, in the sense that I don’t even start the reaction, I just put the catalyst and dye together, but with no peroxide to generate ROS. That way, if the dye is truly staining, I will be able to see and compare the data sets to see change. Next week, I will also start making solutions to simulate ocean conditions. I found another good source and have some numbers to aim for now.
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Hi Chris, how did you account for the leaching from your catalyst and the addition of diluted H2O2 into the sample?
Hi naman,
I blanked the UV-Vis with my catalyst and H2O2. I essentially mixed a dummy solution with no dye but with the same amount of water and catalyst and let it stir for half an hour in the dark to ensure that all was accounted for
Hi Chris, What happens to the copper ions? If the catalyst removed the dye but accidentally leaks copper into the water, could that be toxic to the marine life its trying to protect?
Hello meher,
This is a good point, and you could say it is one of the trade-offs to this catalyst. Now, in a professional setting, I could verify if my copper was coordinated right, but with what I have, I cannot see if my copper is coordinated perfectly to chitosan, leading to increased leaching. But yes, this is a tradeoff, where on one hand, you can remove pollutants, but on the other hand, you leak some copper ions out.
Hi Chris, how effective would photocatalysts be at larger scales, such as in the ocean? Would currents affect the effectiveness of the photocatalyst?
Hi Chris, when you start the ocean simulations, are you planning to test pH, salinity, and hardness one variable at a time, or in combinations?
Hi Chris, when you run the no-peroxide control, how will you separate dye staining from actual adsorption onto the copper-chitosan catalyst?