biodiesel and diesel are chemically different, but maybe the following may also work for biodiesel - ethoxylated fatty or oxo alcohols with low degree of ethoxylation, e.g. Synperonic 91/4, Brij 30, Lutensol TO5. Mix them with the oil then add slowly (dropwise) the water.

I new a guy who needed the same thing - after few attempts, he was happy with SDS. He obtained very stable water-biodiesel emulsions with SDS only. But there are many types of biodiesel (his was a by-product of ethanol production from softwood).

By the way SDS has low capability to form and especially to stabilize w/o emulsions.

 Thanks so very much for your kind comments.

Unfortunately, I have not access to some of your suggested material in my laboratory.

last week was a good days for me because after many tries, I gained to make stable micro emulsion finally.

and I am working on it to obtain nano emulsion now.

Thank you so much for your excellent comments.

With best regards

for water in diesel it should be lower degree of ethoxylation, except long hydrophobic part C18 or longer.

Dear Ramón

It was so interesting for me that when I was trying on the span & tween in different ratios, I found that you recommended here.

Thanks very much