Nano Lett. 13, 4288–4293 (2013)

Current methods of disinfecting water, such as membrane filtration and ultraviolet disinfection, have high financial and energy costs; cheaper methods, such as adding chlorine, have been found to produce carcinogenic by-products. Electroporation, a technique often used in molecular biology, is an alternative method that works by applying a strong electric field, damaging the cell membranes of bacteria and viruses and causing death. However, the high external voltage required has implications in terms of cost, energy consumption and safety.

Yi Cui and colleagues at Stanford University have now developed a nanosponge filtration device, which incorporates nanomaterials into a commercial polyurethane sponge to achieve efficient disinfection by electroporation. Carbon nanotubes are added to the sponge to make it conductive and silver nanowires are added to create a large number of nanoscale tips. The tips increase the strength of the electric field that can be generated by several orders of magnitude compared with an electric field generated by flat surfaces.

The researchers evaluated the performance of the nanosponge using water sources containing various model bacteria and a model virus. Inactivation of the microorganisms increased with rising external voltage, with over 99% of bacteria and viruses inactivated at 10 V and 20 V, respectively. Additionally, no harmful by-products were formed during the process and the energy consumption at 10 V was 100 J l−1 compared with more than 500 J l−1 for membrane filtration.