Positively charged nanofiltration membranes: Review of current fabrication methods and introduction of a novel approach

The new membrane was characterised using a number of state-of-the-art techniques, including a novel use of atomic force microscopy to determine pore size. Streaming potential measurements confirmed that this new membrane is indeed positively charged in the pH range below pH 9, which covers the majority of normal operating conditions. The performance characteristics for the new membrane were very favourable, with a pure water flux determined to be 20 LMH bar−1 and a rejection of MgCl of 96%. Thus, this new membrane both adds to and complements the existing short supply of positively charged NF membranes and is suitable for applications such as the recovery of valuable cationic macromolecules in the bioprocess and pharmaceutical industries or removal of multi-valent cations such as dyes and heavy metals in the paper and pulp, textiles, nuclear, and automotive industries.