I’ve got quite an interesting problem I’ve run into.
I’m testing a new nano emulsion formulation someone sent me and I seem to be running into an issue where it is beginning to gel and clump up. The gelation seems to be reverse above ~40C and it takes some time for it to form, but eventually it does.
I don’t know the ingredients because NDA, but I’m working on getting it, I’m assuming there’s some kind of carboxyl group (free fatty acid) or some kind of ester like pectin that gels in the presence of calcium that’s causing this.
I’m trying to mitigate it by using DI water, but I think cations that are shed by the ultrasound are the culprit of those pesky cations. I also tried using baking soda to try and precipitate any of those hard ions, but I’m not sure if that will do the trick.
I think I have a reasonable idea of what’s going on, I think the hard ions (calcium/magnesium) are crosslinking droplets together. Typically, this causes pectin chains or FFAs to bind together. Instead, the droplets are what are being bridged. I should also note that the gel eventually sinks to the bottom while the top stays fractioned out. I’ll give it a try when I can, but I’m not sure it will help.
Plus I’m trying to figure out why it’s happening and prevent it. I’ll give it a shot if possible.
Did a bit more reading into low methoxy pectin gelation (calcium gelatin pectin) as this is also similar to me and it seems that even something like calcium sulfate will still cause gelation, just slower because it is less soluble in water.
Sometimes counterintuitively, adding some gelling agent such as xanthan gum can stabilize solutions because it reduces the mobility of the molecules such that they don’t necessarily have space to move and link up. You could try adding a low percent.
That is interesting as well, I may give that a try, though I am looking for something thinner.
In the same lane as activity, I think carbonate is not a good enough ligand for calcium in this case since its only bidentitic, I’m going to try citrate (3-) as well to see if that helps. While it has a higher solubility in water, I can also add a lot more to the solution do drive it to crash out (Ksp).