*Article* **Zwitterionic Nanocellulose-Based Membranes for Organic Dye Removal**

**Carla Vilela 1,\*, Catarina Moreirinha 1, Adelaide Almeida 2, Armando J. D. Silvestre 1 and Carmen S. R. Freire 1**


Received: 10 April 2019; Accepted: 24 April 2019; Published: 30 April 2019

**Abstract:** The development of e fficient and environmentally-friendly nanomaterials to remove contaminants and pollutants (including harmful organic dyes) ravaging water sources is of major importance. Herein, zwitterionic nanocomposite membranes consisting of cross-linked poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) and bacterial nanocellulose (BNC) were prepared and tested as tools for water remediation. These nanocomposite membranes fabricated via the one-pot polymerization of the zwitterionic monomer, 2-methacryloyloxyethyl phosphorylcholine, within the BNC three-dimensional porous network, exhibit thermal stability up to 250 ◦C, good mechanical performance (Young's modulus ≥ 430 MPa) and high water-uptake capacity (627%–912%) in di fferent pH media. Moreover, these zwitterionic membranes reduced the bacterial concentration of both gram-positive (*Staphylococcus aureus*) and gram-negative (*Escherichia coli*) pathogenic bacteria with maxima of 4.3– and 1.8–log CFU reduction, respectively, which might be a major advantage in reducing or avoiding bacterial growth in contaminated water. The removal of two water-soluble model dyes, namely methylene blue (MB, cationic) and methyl orange (MO, anionic), from water was also assessed and the results demonstrated that both dyes were successfully removed under the studied conditions, reaching a maximum of ionic dye adsorption of *ca*. 4.4–4.5 mg g<sup>−</sup>1. This combination of properties provides these PMPC/BNC nanocomposites with potential for application as antibacterial bio-based adsorbent membranes for water remediation of anionic and cationic dyes.

**Keywords:** bacterial nanocellulose; poly(2-methacryloyloxyethyl phosphorylcholine); zwitterionic nanocomposites; dye removal; water remediation; antibacterial activity
