Sonication effect on graphene oxide (GO) membranes for water purification applications

Recent literature indicates the use of graphene oxide (GO), derived from 2D material graphene as being the active material in membranes for water purification and desalination applications, mainly because of it exhibiting unique properties including high mechanical strength, excellent chemical stability, strong hydrophilicity, and excellent anti-fouling properties (Dreyer et al 2010 Chem. Soc. Rev. 39 228, Dikin et al 2007 Nature 448 457 and Koinuma et al 2012 J. Phys. Chem. C 116 19822). In the current study, graphene oxide has been synthesized using well established Hummer's method and thereafter utilized as membranes on porous PVDF (polyvinylidene fluoride) support for water purification applications. The effect of sonication time (5 to 60 min) during preparation of graphene oxide membrane has been investigated vis-à-vis water purification abilities of the developed membranes. Related characterizations like dynamic light scattering (DLS), Raman spectroscopy, ultraviolet-visible light (UV-vis) spectroscopy, x-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) have been employed for examining the effect of sonication for the observed enhancement in water purification of the GO-membranes. Specifically, Raman spectroscopy is seen to indicate enhancement of defect states with an increase in sonication time. GO-membrane's interlayer spacing is also noted to undergo a change as confirmed by XRD analysis. Membrane developed with 10 min of sonication time is noted to exhibit an augmented dye rejection capability due to formation of a compact and ordered structure.