Remote Site Production of Sterile Purified Water from Available Surface Water

Ultrathin Cellulose Voronoi-Nanonet Membranes Enable High-Flux and Energy-Saving Water Purification

Creating a desirable porous membrane with high-flux and energy-saving properties for the purification of water containing submicron-sized contaminants, especially pathogenic microbes, is of great significance, yet a great challenge. Herein, we demonstrate a facile methodology to construct an innovative membrane with continuous cellulose Voronoi-nanonet structures via nonsolvent-induced phase separation. This approach enables cellulose Voronoi nanonets to tightly weld with electrospun nanofibrous substrates by controlling the solvent-nonsolvent mutual diffusion process. The resultant membranes exhibit integrated properties of small pore size (0.23 μm), high porosity (90.7%), good interconnectivity, and ultrathin thickness (∼600 nm, 2 orders of magnitude thinner than the conventional microfiltration membrane). As a result, the prepared membranes can effectively intercept submicron particles (∼0.3 μm) with robust rejection efficiency (>99.80%) and ultrahigh permeation flux (maximum of 8834 L m^-2 h^-1) under an extremely low driving pressure (≤20 kPa). More importantly, prominent bacterial rejection efficiency with a log reduction value (LRV) of 8.0 (overcoming the previous limitation of LRV <7) and outstanding antifouling function are also achieved for the membranes. The successful fabrication of such a versatile membrane may provide new insights into the development of next-generation high-performance separation materials for various applications.

An ultrathin bacterial cellulose membrane with a Voronoi-net structure for low pressure and high flux microfiltration

Developing a porous membrane to effectively remove sub-micron sized contaminants from water while maintaining a high permeate flux with energy-saving properties is of great significance but extremely challenging. Herein, we describe a feasible strategy to create a bacterial cellulose (BC) membrane with a continuous Voronoi-net structure via combining evaporation-induced self-assembly with chemical cross-linking. This presented approach allows micro-length BC nanofibers to self-assemble in the electrospun polyacrylonitrile (PAN) nanofibrous frameworks to form stable and continuous Voronoi-like nanonets, endowing the obtained membrane with small pore size, stable pore structure, high porosity, favourable interconnectivity, and ultrathin membrane thickness. By virtue of these unique structural advantages and superhydrophilicity from BC Voronoi-like nanonets, the resulting membrane exhibits integrated performances of high rejection efficiency (>99.63%) for 0.3 μm TiO2 microparticles, robust permeate flux (5541 L m-2 h-1) at a low driving pressure of 20 kPa, intriguing reusability, excellent bacterial rejection efficiency (log reduction value of 8.2), and promising antifouling function to bacteria. It is expected that the proposed strategy can provide a facile approach for the development of next-generation high performance microfiltration membranes.