Nafion-coated SiN Salt Water Filtrations (Part II)
After all the nafion-coated pnc-Si chips that Jirachai gave me broke during my last attempt to filter salt water, Jirachai was kind enough to supply me with a new batch of chips, this one a mix of SiN and pnc-Si, both covered in a thin film of nafion. The idea was that since Nafion is a proton conductor, if we used a thin film of it as a filter, somehow salt might be held back behind the membrane while pure water goes through it.
Separation results:
As in the previous post (linked above), I spun the samples until I could collect 100 uL of filtrate. I chose 1000 rpm just to be sure that the chips wouldn’t break. Weirdly the NPN seemed more fragile than the pnc-Si during the separations. All results were consistent with the salt solutions passing through the nafion and silicon layers unaffected.
SEM images:
I had a lot of trouble getting good images of the nafion film on the pnc-Si – I think I was a little overzealous with the conductive glue we use to affix the chips to a sample holder and I burst all the windows. But the SiN was pretty well behaved. Everything was coated in ~6 nm Pt.
SiN:
These are from the pnc-Si membranes. This first is a corner of a broken window.
Second is an edge:
