Gas bubble formation of filaments from sedimented graphene oxide

Abstract

Gas bubbles that were generated in freshly prepared graphene oxide (GO) solution were found to float up as oblate shapes and travelled in the same way as they would when created in water. Gas bubbles, that were produced from the sediment of GO solution that was stood for 120 h, however, floated upward with a fine filament present in their wake while still retaining the oblate form. With bubbles that were 5 and 10 μL in volume, their average vertical speeds of 0.4 m/s could be maintained via significantly lower lateral displacements compared with similar sized gas bubbles created in water, notwithstanding that the shape aspect ratio fluctuations remained throughout. This behavior could be accounted for by a proposed mechanistic model in which the superhydrophilic and conversely superaerophobic GO particles (with contact angles of 4° ± 0.8°), that began encapsulating the liquid-gas interface as soon as the bubble was formed at the tip, prevented a typical pinch-off from occurring. This produced a thin filament with elastic properties brought along by the upward floating bubble. Rising gas bubbles, released from sedimented GO that was mixed with iron powder were found to create, under the influence of a magnet, fine structures that attached to the side of a container. These structures have the potential to be applied for environmental remediation.