Bacterial Nanocellulose/MoS Hybrid Aerogels As Bifunctional Adsorbent/Photocatalyst Membranes for Water Decontamination

To address the problems associated with the use of unsupported nanomaterials, in general, and molybdenum disulfide (MoS), in particular, we report the preparation of self-supported hybrid aerogel membranes that combine the mechanical stability and excellent textural properties of bacterial nanocellulose (BC)-based organic macro/mesoporous scaffolds with the excellent adsorption-cum-photocatalytic properties and high contaminant removal performance of MoS nanostructures. A controlled hydrothermal growth and precise tuning of the synthetic parameters allowed us to obtain BC/MoS-based porous, self-supported, and stable hybrid aerogels with a unique morphology resulting from a molecular precision in the coating of quantum-confined photocatalytic MoS nanostructures (2-4 nm crystallite size) on BC nanofibrils. These BC/MoS samples exhibit high surface area (97-137 m·g) and pore volume (0.28-0.36 cm·g) and controlled interlayer distances (0.62-1.05 nm) in the MoS nanostructures. Modification of BC with nanostructured MoS led to an enhanced pollutants removal efficiency of the hybrid aerogels both by adsorptive and photocatalytic mechanisms, as indicated by a detailed study using a specifically designed membrane photoreactor containing the developed photoactive/adsorptive BC/MoS hybrid membranes. Most importantly, the prepared BC/MoS aerogel membranes showed high performance in the photoassisted removal of both organic dye (methylene blue (MB)) molecules (96% removal within 120 min, = 0.0267 min) and heavy metal ions (88% Cr(VI) removal within 120 min, = 0.0012 min), separately and/or simultaneously, under UV-visible light illumination as well as excellent recyclability and photostability. Samples with interlayer expanded MoS nanostructures were particularly more efficient in the removal of smaller species (CrO) as compared to larger (MB) dye molecules. The prepared hybrid aerogel membranes show promising behavior for application in water purification, representing a significant advancement in the use of self-supported aerogel membranes for photocatalytic applications in liquid media.