Paul "Tae Won" Lim's blog

I tested synthesis of nZVI using high pH borohydride solution. The reason for this test is that the BH4 can react with water while it is being "waited" to be added to the synthesis chamber. The reaction process includes a equilibrium where OH is produced. Thus, if we increase pH, it is possible to "stop" the BH4 from reacting with water. When I tested, the minimum pH to stop BH4 from reacting with water was ~pH 12-13. I went ahead and synthesized FeCMC-BH. It failed, as the nZVI formed was not nanosized; it was in mm~cm rather than nm in size.

nZVI detecting IP measurement is working really well.
My mentor (Jim Nurmi) and I thought of a better set up for the field application. Rather than trying to put electrodes in ground to measure IP under the ground, we decided that making a flow-through cell will be more efficient. I would set up a pump at a location and pump groundwater through the IP set up, then back into the groundwater. If the measurement is taken over time at various distances from the source, it is possible to even calculate the horizontal velocity of FeCMC-BH particles.

So I have successfully setup a pump-solution-through-column system.
I have done couple experiments, and the glass-packed column seems to be behaving similarly as not-packed column. The magnitude of absolute phase shift increased, probably because there is less electrolytes present in the column as the glass beads are taking large portion of volume in the column. 

Here is a graph that shows this trend:

I started testing my "poor man's induced polarization box"
I prepared it by getting a small plastic container and covering the top with cardboard box and a layer of styrofoam. Then, four stainless steel rods were taped around the sides and at the tip, only leaving ~1.5cm exposed to the outer environment. Then, those steel rods were inserted, not touching the bottom of the box but deep enough to stay submerged when water/solution is introduced. Then those rods were connected to the voltage source and voltmeter to take IP measurements.

Trial 1

This week, I worked on optimizing the synthesis of  Fe-CMC-BH.
There were numerous variables such as rate of addition of reagents, the method of dissolving CMC, ways to introduce Iron to CMC solution and such. Dr. Nurmi introduced a more advanced way of mixing the solutions: the homogenizer. It seems to be effective, but not quite sure why it is effective as of now.

I also made a different testing method of Induced Polarization. I am introducing four rods into a surface. Yet to test this new system.

This week has been mostly reviewing the data I have and presenting them at two presentations- in the group meeting and in the CMOP midterm presentation.

Well the content of this blog entry got deleted somehow.
Brief Description:

I started testing the phase difference of Fe-CMC BH and oxidized Fe-CMC BH (prepared by just letting it oxidize in the atmospheric condition).

Here is first graph, which shows that there is a similar pattern observed for both oxidized and non oxidized Fe-CMC BH. This makes  sense as this induced polarization method is designed to measure the inductance and resistance of "things" present in the system.

I have gathered more data this week to draw a reasonable/firm conclusion before I started narrowing down my focus.

I re-did older experiments because I started gathering data at higher frequency than before (Before: 1-1,000 Hz, Now: 1-10000 Hz) as higher frequency gives more distict data set.

For past few days, I have gathered more data than this blog can hold.

Here are some interesting data that make this project of detecting nanoscale Zero Valent Iron seem promising.

1. Using Induced Polarization system, I introduced different amounts of nZVI (Fe cmc-BH) to aerobic and anaerobic system. Here are the resulting Phase Difference. (Phase Difference is defined as the phase difference between applied sinusoidal AC voltage and detected voltage.)

Before I start writing what I have been researching, here is some background info on reason why I am trying to "detect nanoscale Zero Valent Iron (nZVI)"

Background info: