Week 8 mainly consisted of working in lab, attending some REU meetings, and going to see a baseball game with other REU students.
In lab, I continued working with cellulose-polyacrylic acid (PAA) membranes and tried an experiment on polyvinylidene fluoride (PVDF) and PVDF-PAA membranes. Early in the week, I continued to study how much the cellulose-PAA membrane can reject molecules of different sizes. One notable conclusion that I made is that the membrane could have some holes that are larger than its ordinary pores that inhibit its rejection of small and moderately-sized molecules. This conclusion stems from the fact that the membrane only rejected 83% of a molecule that was at least 200x larger than the two molecules that I tested before it, which were both poorly rejected by the membrane. After finishing my testing of the rejection of a cellulose-PAA membrane, I tried to capture calcium ions with a similar membrane. The beginning of this process involved soaking the membrane in a high-pH solution to aid in the deprotonation of the functional groups in PAA, so that they could become negatively charged and be used to attract positive ions. After this, I passed a calcium chloride solution through the membrane to expose these groups to positive calcium ions. In carrying out a calcium capture with this membrane, I hope to gain insight on its ability to capture iron (II), an ion that is a precursor for the formation of nanoparticles that can break down dangerous organic compounds in water. Outside of these performance tests, I measured the surface charge of a cellulose-PAA sample at different pH values using an electrokinetic analyzer. From this measurement, I noticed that there was a steep decrease in surface charge over the pH range of 3-5. This makes sense because that is roughly the range in which the groups in the PAA on the membrane surface transition between being neutrally and negatively charged. Lastly, I measured the contact angle of a PVDF membrane and a PVDF-PAA membrane. Though I carried out this measurement before, I used a different method this time, called the captive bubble method, in an effort to obtain results that I can compare with data on cellulose and cellulose-PAA membranes that I plan on collecting using the same method.
Outside of the lab, I got to attend two helpful REU meetings this week. One of these was about EndNote, which can be used to organize citations in a paper or report in Microsoft Word. While I knew a little about using this program to store references and generate citations, I never knew about its organizational uses in word, so learning a bit about these things was helpful. The other meeting was a talk regrading poster presentations. One concept that I found interesting was the idea of organizing a poster around what one plans to say when presenting it. I hope to use this idea when finalizing the organization of my poster.
In addition to attending some meetings, I went to a Lexington Legends baseball game with some other REU students on Thursday (7-19-18). It was a beautiful night and it was fun to watch professional baseball, which is something that I have enjoyed doing with family and friends in the past.
Next week, I look forward to continuing my lab work and working on some final projects, including the poster and the final paper.
In lab, I continued working with cellulose-polyacrylic acid (PAA) membranes and tried an experiment on polyvinylidene fluoride (PVDF) and PVDF-PAA membranes. Early in the week, I continued to study how much the cellulose-PAA membrane can reject molecules of different sizes. One notable conclusion that I made is that the membrane could have some holes that are larger than its ordinary pores that inhibit its rejection of small and moderately-sized molecules. This conclusion stems from the fact that the membrane only rejected 83% of a molecule that was at least 200x larger than the two molecules that I tested before it, which were both poorly rejected by the membrane. After finishing my testing of the rejection of a cellulose-PAA membrane, I tried to capture calcium ions with a similar membrane. The beginning of this process involved soaking the membrane in a high-pH solution to aid in the deprotonation of the functional groups in PAA, so that they could become negatively charged and be used to attract positive ions. After this, I passed a calcium chloride solution through the membrane to expose these groups to positive calcium ions. In carrying out a calcium capture with this membrane, I hope to gain insight on its ability to capture iron (II), an ion that is a precursor for the formation of nanoparticles that can break down dangerous organic compounds in water. Outside of these performance tests, I measured the surface charge of a cellulose-PAA sample at different pH values using an electrokinetic analyzer. From this measurement, I noticed that there was a steep decrease in surface charge over the pH range of 3-5. This makes sense because that is roughly the range in which the groups in the PAA on the membrane surface transition between being neutrally and negatively charged. Lastly, I measured the contact angle of a PVDF membrane and a PVDF-PAA membrane. Though I carried out this measurement before, I used a different method this time, called the captive bubble method, in an effort to obtain results that I can compare with data on cellulose and cellulose-PAA membranes that I plan on collecting using the same method.
Outside of the lab, I got to attend two helpful REU meetings this week. One of these was about EndNote, which can be used to organize citations in a paper or report in Microsoft Word. While I knew a little about using this program to store references and generate citations, I never knew about its organizational uses in word, so learning a bit about these things was helpful. The other meeting was a talk regrading poster presentations. One concept that I found interesting was the idea of organizing a poster around what one plans to say when presenting it. I hope to use this idea when finalizing the organization of my poster.
In addition to attending some meetings, I went to a Lexington Legends baseball game with some other REU students on Thursday (7-19-18). It was a beautiful night and it was fun to watch professional baseball, which is something that I have enjoyed doing with family and friends in the past.
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