When using buffers to maintain pH for sorption isotherms using natural waters, we are seeing a pH shift of 0.25 over a 24 h reaction. Are there ways to keep the pH more uniform than this?
You can increase the buffering capacity by increasing the buffer concentration.
You can maximize the buffering capacity at a given buffer concentration by choosing a buffering compound that has its pKa as close as possible to the pH you are trying to keep.
One thing that we're also concerned with in using Good buffers is the formation of hydroxl radicals and their impact on redox chemistry. For our alkaline system, what appears to be a good option is the CHES buffer (pKa 9.5).
GoldBio has a useful selection guide as well: https://www.goldbio.com/documents/3565/Ultimate%20Buffer%20Selection%20guide-%20Arranged%20By%20FamilyCMPSD.pdf