semipermeable membrane: Where do you buy 'em?

[veens-zevenhonderdvijf]

Hi,

I'm working on the electrodeposition of manganese. I need a
semipermeable membrane for my electrical cell. I have one but if it
breakes down then I don't have another. The guy who gave it to me
doesn't know where their company got it from.

It needs to block manganese (Mn2+) ions. Water and other ions like
ammonium and sulfate can go through.

Any help is welcome!

Thanks in advance: Jan Veenstra

(Please reply in this newsgroup as the reply adress is fake because I
don't like spam.)