To address the problems associated with the use of unsupported nanomaterials, in general, and molybdenum disulfide (MoS 2 ), 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 2 nanostructures. A controlled hydrothermal growth and precise tuning of the synthetic parameters allowed us to obtain BC/MoS 2 -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 2 nanostructures (2−4 nm crystallite size) on BC nanofibrils. These BC/MoS 2 samples exhibit high surface area (97−137 m 2 •g −1 ) and pore volume (0.28−0.36 cm 3 •g −1 ) and controlled interlayer distances (0.62−1.05 nm) in the MoS 2 nanostructures. Modification of BC with nanostructured MoS 2 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 2 hybrid membranes. Most importantly, the prepared BC/MoS 2 aerogel membranes showed high performance in the photoassisted in-flow removal of both organic dye (methylene blue (MB)) molecules (96% removal within 120 min, K obs = 0.0267 min −1 ) and heavy metal ions (88% Cr(VI) removal within 120 min, K obs = 0.0012 min −1 ), separately and/or simultaneously, under UV−visible light illumination as well as excellent recyclability and photostability. Samples with interlayer expanded MoS 2 nanostructures were particularly more efficient in the removal of smaller species (CrO 4 2− ) as compared to larger (MB) dye molecules. The prepared hybrid aerogel membranes show promising behavior for application in in-flow water purification, representing a significant advancement in the use of selfsupported aerogel membranes for photocatalytic applications in liquid media.

No abstract

Silica wet gels were prepared from hydrolysis of tetraethoxysilane (TEOS) with additions of sodium dodecyl sulfate (SDS). The surfactant was removed after gelation. Wet gels exhibited mass-fractal structure with mass-fractal dimension D (typically around 2.25) in a length scale extending from a characteristic size ξ (typically about 10 nm) of the mass-fractal domains to a characteristic size a0 (typically between 0.3 and 0.4 nm) of the primary particles building up the fractal domains. ξ increased while D and a0 diminished slightly as the SDS quantity increased. Aerogels with typical specific surface of 1000 m(2)/g and density of 0.20 g/cm(3) were obtained by supercritical drying of the wet gels after washing with ethanol and n-hexane. The pore volume and the mean pore size increased with the increase of the SDS quantity. The aerogels presented most of the mass-fractal characteristics of the original wet gels at large length scales and exhibited at a higher resolution level at about 0.7 nm a crossover to a mass-surface fractal structure, with apparent mass-fractal dimension Dm ∼ 2.4 and surface-fractal dimension Ds ∼ 2.6, as inferred from small-angle X-ray scattering (SAXS) and nitrogen adsorption data.