Regenerable polymer/ceramic hybrid nanofiltration membrane based on polyelectrolyte assembly by layer-by-layer technique

A new regenerable nanofiltration membrane based on LbL film assembly of PDADMAC/PSS on a ceramic support is presented. Using a constant flux coating method the large pores of the ceramic support with a diameter of about 100 nm could be covered and closed with only 3 bilayers. The performance of the presented membrane is comparable to today's nanofiltration membranes. Remarkably, the stability is superior as the membranes withstand backwashing as well as low and high pH. The intrinsic contradiction of a stable but also regenerable membrane is addressed as well. The LbL film is deconstructed using high concentrated salt solution, ionic surfactants, and hypochlorite in succession. After deconstruction the film is rebuilt resulting in exactly the same properties as observed before film deconstruction. Due to the ability of regeneration the more stable but also more expensive ceramic support can be reused. The regeneration was conducted within the membrane housing demonstrating its practical viability for membrane assembly and regeneration within modules being potentially on-site in a membrane plant.