The concern for me with a long soak time with carbon in the mix would be the comments everywhere about carbon absorbing cannabinoids after extended contact.
I’d also be concerned that extended exposure to an acid washed bentonite might steal cannabinoids from my solution. That’s what I like about the concept of the t-5 neutral bentonite clay out there. I’ve even considered a neutral carbon to compliment, but without the stark difference in polarity between solvent and media I’m not sure if the results would be very impressive without really long exposure times and/or agitating.
My understanding is acid washed bentonite is negatively charged due to acid washing, in much the same fashion carbon is negatively charged, and I believe it is the negative charge, coupled with the ability to store the polar molecules somewhat permanently within the particles, that both risk capturing our cannabinoids to a degree.(if that understanding is inaccurate please correct me)
Balancing media polarity against the polarity of the solvent carrying the oil through the media might be beneficial here.
On a side note, @Dred_pirate confirmed the concern about silica dissolving into ethanol solutions in small amounts, but any amount in my mind would be highly unacceptable. Does anyone know offhand if that would only apply to silica or also to magisil and magisil PR?
Also, I know carbon and bentonite tend to work better at warmer temps, but would using them with a solution in the -30 or colder range help because of the temps affect on solvent polarity?