Application is in the textile industry (dyes) with further reuse of H-acid. Generally, a hybrid membrane system(MF-UF-NF/BMED) will work to reach a clear H-acid brine, but I'm curious about the last step - the H-acid purification. Does NF can work well, or it is better to use a bipolar membrane? Maybe a kind of hybrid ion exchange-nanofiltration system?

Do you have any different opinions or some practical experience to share?