Energy from the Nanofluidic Transport of Water through Nanochannels between Packed Silica Spheres
mediaposted on 28.08.2019, 17:34 by Kundan Saha, Jumi Deka, Kalyan Raidongia
Efficient harvesting of electrokinetic-streaming-potential requires a trade-off between high flow-rate and nanofluidic confinement. To attain the best out of these parameters, we have developed a periodic network of tetrahedral and octahedral voids interconnected through fine biconical nanofluidic channels by close-packing nearly monodisperse silica spheres of diameters 285, 620, 1000, 1750, and 2900 nm. The interstices of close-packed silica spheres (diameter 285 to 1750 nm) simultaneously exhibit surface-charge-governed ionic conductivity and fast flow of water. The power density harvested from streaming water was found to be increasing with increased diameter of the close-packed spheres up to 1750 nm (151 mWm–2), and to be decreasing with further rise in the sphere diameter. The power density was found to be dependent on the mass loading of the silica spheres, contact area of the electrodes, and pH of the streaming water. Pretreatment of the silica spheres with concentrated nitric acid further enhanced the efficiency of the energy harvesting through streaming potential. Harvesting of streaming potential from packed silica spheres was found to be a convenient way of obtaining energy from water flowing through the household water taps, as they can be connected in a series to add up energy generated in multiple devices.