This review covers the use of nanocelluloses in water treatment applications with particular focus on membranes and filters made either entirely from (nano)cellulose or in composite approaches. Nanocelluloses are among the emerging materials of this century, having found an abundance of potential applications in the fields of composites, medicine, functional additives or water treatment. Water treatment applications in particular have received significant academic and commercial attention, with a large variety of approaches developed in order to address arguably one of the largest problems that humanity is confronted with in the 21st century: clean water. In this regard, treatment of both potable water and wastewater is of high importance. The reason for the viability of nanocelluloses as base material relies upon their high specific surface area and abundance of OH groups that already exhibit certain attraction toward pollutants carrying ionic structures or dyes and also can be easily modified to significantly increase the affinity of nanocelluloses toward these pollutants. Nanocelluloses in their various forms (cellulose nanocrystals, cellulose nanofibrils, bacterial cellulose) have been applied in water treatment, with membranes and filters (size exclusion, e.g. for nanoparticle filtration, or affinity membranes) as well as adsorbents (e.g. heavy metal ions, dyes, nitrates) being the most studied. © 2020 The Author. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Copper is a major problem in industrial wastewater streams, seriously affecting the quality of potential drinking water. Several approaches, including continuous membrane processes or batch-wise application of adsorbents, are in use to tackle this problem. Unfortunately, these processes suffer from their particular drawbacks, such as low permeance or disposal of saturated adsorbents. However, a combination of these processes could constitute a step towards a more efficient copper removal solution. Here, we present a nanopaper ion-exchanger prepared from cellulose nanofibrils produced from fibre sludge, a paper industry waste stream, for the efficient, continuous removal of copper from aqueous solutions. This nanopaper ion-exchanger comprises phosphorylated cellulose nanofibrils that were processed into nanopapers by papermaking. The performance of these phosphorylated nanopaper membranes was determined with respect to their rejection of copper and permeance. It was shown that this new type of nanopaper is capable of rejecting copper ions during a filtration process by adsorption. Results suggest that functional groups on the surface of the nanopapers contribute to the adsorption of copper ions to a greater extent than phosphate groups within the bulk of the nanopaper. Moreover, we demonstrated that those nanopaper ion-exchangers could be regenerated and reused and that in the presence of calcium ions, the adsorption capacity for copper was only slightly reduced.

The production of nanopapers from nanocellulose suspensions by a papermaking-process and their utilization as organic solvent nanofiltration membranes is demonstrated.