The performance of a graphene oxide thin film composite membrane for sweet whey ultrafiltration

Membranes manufactured from graphene oxide (GO) have received significant attention for desalination and nanofiltration applications due to their exceptional mechanical strength, chemical stability and high selectivity. However, the performance of GO membranes in food processing applications is less well understood. In this work, the performance of a GO membrane, advertised as being of 1 kDa molecular weight cutoff, is compared to that of two commercial polymeric membranes of different molecular weight cut-off (advertised as 10 kDa and 1 kDa) for the ultrafiltration of sweet whey from the dairy industry. At bench scale, the GO membrane had comparable rejection for both total solids and protein to the 10 kDa polymeric membrane, but with more than double the flux, provided by a much lower intrinsic membrane resistance. Analysis of the membrane fouling process suggested that the GO membrane fouled more slowly than the 1 kDa polymeric membrane, but the fouling process was not significantly different to that reported in the literature for polymeric membranes in this application. Pilot scale trials conducted using a commercial spiral wound module of 1.2 m² area of the GO membrane confirmed that the membrane retained a higher flux. This flux was, however, reduced from the bench scale value.