Water purification through membrane separation has gained significant attention, but the performance of these membranes is severely degraded due to fouling.

The goal of this project at the University of Toledo in the US was to develop low-biofouling membranes, through the functionalisation of cellulose acetate (CA) membranes with metal chelating ligands charged with biocidal metal ions, i.e. copper ions.

To this end, glycidyl methacrylate (GMA), an epoxy, was used to attach a chelating agent, iminodiacetic acid (IDA), to facilitate the charging of copper to the membrane surface.

The cellulose acetate and copper-charged membranes were characterised chemically and structurally. The permeation experiments were conducted with deionised (DI) water, and then subjected to protein rejection measurements.

The permeation of the copper-charged membranes was initially lower than the CA membrane during the filtration of DI water.

The membranes were then subjected to bovine serum albumin (BSA) and lipase filtration. The copper-charged membrane showed higher permeation values of both proteins compared to CA membranes. This resulted from an increased resistance from the IDA and copper on the surface during DI water filtration, and later, from reduced fouling from both proteins.

The rejection of BSA and lipase was the same for both the copper-charged and CA membranes. Therefore, the modified membranes have a potential to be used as low-biofouling membranes in the future.

Desalination, Volume 338, 1 April 2014, Pages 17–25.