This week I sulfidized a lot of coupons, I digested coupons, I brainstormed protocols, and I presented preliminary data.

Oh, I just realized I need to make a comment about the previous sentence.  A long time ago, before I was a teacher, I worked in a factory that made circuit boards.  We made huge 3’x2′ sheets with lots of layers and lots of individual small circuit boards to cut out later.  To prove the boards were good, we cut out small rectangles from the sheet, next to the circuit boards, to check the inside layers.  Everyone called those cutouts coupons.  I guess the sheet did look like a newspaper spread with holes where someone cut out coupons.  So when we have a membrane and I cut out a piece to analyze, I call it a coupon.  And “digesting coupons” means dissolving them, or at least dissolving everything except the plastic backing.  So let me start again.

This week I sulfidized a lot of 1″ circular cutouts from membranes, I digested said cutouts, I brainstormed protocols, and I presented preliminary data.

The first thing I discovered is that my quest for efficiency produced inconsistent results.  In processing things quickly (and efficiently I might add – I would still be running coupons 1″ circular cutouts today otherwise) the process turned anaerobic (no oxygen) and produced colors different from previous work.  I also had 3x the standard deviation in silver loading.  So I am rethinking (with my mentor’s help) the protocol to produce silver membranes and sulfidized membranes.  Again for my quest for efficiency, I am building a frame this weekend to try and triple the membrane throughput.  I’ll post a picture if it works.

So I got to present my data.  It shows that partially sulfidized silver nano particles do stay in membranes longer.  Perhaps a lot longer, like months instead of weeks.  Not only was it good to present a positive outcome, I now know that even if everything else breaks down, I have data for the poster.  This photo shows the digested coupons 1″ membrane cutouts. The dark color hints that maybe even 2% nitric acid is inadequate to remove sulfidized silver nano particles.  I’ll find out this week.

Richard Daines