I tried particle separations with the 30kD cellulose membranes from Millipore using the same setup as previous experiments. Basically the results are that neither 5 nor 20nm particles pass through the membranes whether in water or 10mM KCl. Absorbance Data: Sizing Data: No peaks were found in the nm range for any of the filtrates….
As mentioned previously, gold colloids are not stable in high salts because salts reduce the repulsive forces between particles and cause aggregation. I have been able to dissolve naked gold colloids in 10mM KCl without aggregation, but the particles crash out at 100mM KCl. There are a couple of strategies that can be used to…
I obtained gold in 5nm, 20nm, 40nm, and 60nm through Mort/Oberdorster Lab. Separations were performed with fully crystallized samples from SC 073. Here are sizing and absorbance data: In Water I have tried 24 hour separations in diH2O (SC 073) with these particles. Here are the results: No 525nm peak in filtrate for 5nm sample. …
I set up separations of 5nm Au nanoparticles in both H2O and KCl in a new system. The stir cell isn’t always reliable for separations due to leaking and contaminating (?) particles from the plastic. To perform these separations, I added 20ul of sample to a sepcon and wetted the backside of the sepcon with…
These are a couple of figures that may appear in the supplementary materials for the permeability paper. The first tries to explain that most of our permeability is due to the largest pores. The lines plotted are the cumulative number of pores at each size (blue) and the cumulative permeability (green). The lines show that…
This is a follow-up to my last post about gold separations. Using the Tecan, I’ve scanned the absorbance spectrum of all the gold particles we posses in water, 10 mM KCl, and 100 mM KCl. Here are the results: The internal peaks are between 515 and 525 nm and are the same for both water…
Two of the newer wafers, SC 073 and SC 074, came back with ~30 intact samples. This would be more than enough for the separation work that I’m trying to finish, so I decided to see if they were any good. SC 073 had an area in quadrant I that was caught in the middle…
A long running side story to my research has been attempted separations of nanogold. The basic idea is that we want to separate EM quality gold nanoparticles with the membrane, but I have had problems detecting gold in the filtrate with the zetasizer. We think this might be a result of the negatively charged gold…
My previous post on Electroomosis theory describes the deviation between expected and calculated zeta potential using the Smoluchowski equation. In this post I will explain another method of solving for the zeta potential and I will consider the mistakes made in the previous calculations. In a paper by Kim(Mukhtar) in J. Membrane Sci. (1996), the…
This post explains that electroosmosis in our material is higher than we expected. Jim suggested that maybe we don’t have fully developed flow in our thin material. Here I attempt to find the entrance length, or distance until fully developed flow, in our material. One needs to keep in mind that this is a continuum…