I’m not an expert and haven’t worked with this ingredient, but I ran a quick search on this forum and found an old post by @chemicalmatt:
“SD is a very good emulsifier - only when acidified into a tertiary amine salt to about pH 5 - but especially so when used in conjunction with alkyl quats such as CETAC, STEARAC and BEHENTAC, etc. Be advised you will obtain sharply different viscosity and stability outcomes depending upon the organic acid used. If you can afford glutamic acid that will work best, but good old inexpensive lactic acid 88% works nicely too.”
Hope that helps.