Cellulose acetate/cellulose nanofiber membranes for whey and fruit juice microfiltration

Abstract

Asymmetric membranes based on cellulose acetate (CA) and cellulose nanofibers (CNF) were prepared by non-solvent induced phase separation. The effect of CNF addition on the morphology, water flux and filtration performance of the CA membranes was investigated. Field emission scanning electron micrographs showed the formation of large macrovoids at low CNF content, while the increase of the CNF content resulted in a sponge-like morphology due to changes in the demixing process rate during membrane formation. Porosity and pure water flux increased with the increment of CNF content. In addition to this, molecular weight cut-off was 200 kg mol−1 for nearly all composite membranes studied. CA/CNF5 composite membranes were also tested to clarify strawberry and raspberry juices as well as whey. Clarification of fruit juices and whey was shown by the decrease of turbidity and solid content. Moreover, the maintenance of antioxidant capacity, as well as overall color for strawberry and raspberry juices, could be seen leading to the conclusion that this composite membrane can be useful in juice production.