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Week 4

During week 4, I got to perform some new experiments in the lab and enjoy a lunch with others in the program.

One major experiment that I got to do in lab was the addition of polyacrylic acid (PAA) to a manufactured polyvinylidene fluoride (PVDF) membrane, which if done correctly, allows the pores of the membrane to change size depending on the pH of the inlet solution and the membrane. Therefore, the amount of fluid that can flow through these membranes depends on pH. I attempted to observe this behavior by performing filtrations using the setup below and recording how long it took for a certain amount of fluid to pass through the membrane at different pHs. According to theory, the


flow rate should go down as the pH increases. While I was able to observe this behavior when going from a pH of 4 to 5.5, the opposite occurred when I increased the pH from 5.5 to 9. Therefore, I will spend some time next week redoing this experiment with a different sample to see if I can obtain expected results across the board.

Another cool experiment that I got to do was the measurement of the hydrophilicity of both the unmodified, manufactured PVDF membrane and the one that includes PAA. To quantify this property, I measured something called water contact angle, which is the angle that a water droplet makes with the membrane surface; possible data for the unmodified membrane is shown below. Contact angle is an indication of hydrophilicity because the more hydrophilic a surface is, the wider the water will spread out across it, and thus, the lower the contact angle. After testing contact angle at a few spots on both types of membranes, I found that the average contact angle of the surface of the PAA-modified membrane was slightly lower than that of the unmodified membrane's surface, so the modified membrane was slightly more hydrophilic.


As always, Dr. DB, one of my faculty advisors, and my labmates gave me helpful advice throughout the week, which I greatly appreciate. Specifically, I would like to thank Dr. DB and Andrew Colburn for critiquing the content for a presentation that I have coming up, Andrew and Saiful Islam for answering any questions that I had, and Saiful for spending a significant amount of time training me this week. Also, Ashish Aher, a labmate, and Nathan Puckett, a staff member in my lab, gave me helpful tidbits of advice and/or training this week. Overall, the amount of help that I have received thus far has led me to realize that there is such a strong sense of community in the laboratory that I am working in.

Outside of lab, I got to enjoy a lunch with my fellow REU students on Friday. It was cool to hang out others and hear a little bit about their research experiences. Also, through some random conversations, I got to know one of my lab mentors as well as one of my lab mates a little better.

Next week, I look forward to continuing my work in lab, hearing a bit more about what others are doing this summer via their presentations throughout the week, and capping off the week with a tour of Alltech.

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