Graphite Essay

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Graphene is a single thin strongly packed layer of pure carbon atoms that are joined together in a hexagonal honeycomb matrix. In more comprehensive expression, it is a carbon allotrope arranged in a flat sp2 bonded atoms with a very small molecule bond length (0.142 nm). Graphite is formed by the arrangement of graphene layers on top of each other, with tiny inter planar gaps (0.335 nm) (Cohen-Tanugi and Grossman, 2012).
This quite novel material has progressed rapidly toward scaling up production of 30 in graphene membranes (Bae et al., 2010). The tiny thickness of graphene, i.e. one atomic layer, and its enhanced tensile strength (Lu and Huang, 2009), could allow accelerated water transport, low pressure supplies, and flexible array of operating conditions, and also, could be considered among the potential advantages of graphene compared to current RO membranes.
Although the matter of fact that the one atomic layer of graphene is impermeable to all gases and liquids (Bunch et al., 2008; Leenaerts et al., 2008) (Fig. 3A), there are many researchers are trying to explorer the ability of this material to develop a membrane, due to the currently mass production of graphene (Geim, 2009). Also, nanopores could be induced within the unsaturated carbon atoms in the structure of graphene, which exist at the chemically passivized pore edge. Lately, experimental procedures for introducing nanopores in graphene have been widely explored and rapid developments were achieved. Initial methods based on electron beam exposure were conducted, however the most modern approaches using helium ion beam drilling, diblock copolymer templating and chemical etching were performed to realize higher dense precise porosity distribution (Bell et al., 2009...

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...r material could be produced, either by the layer-by-layer self-assembly method (LbL) or through mixing it with polymers (H. Kim et al., 2010; Potts et al., 2011; Xu et al., 2009; Yang et al., 2013).
GO is verified to be a nano-material with amphiphilic nature, as the water molecules are adsorbed initially at the hydrophilic terminal (hydroxides), then quickly diffused among the hydrophobic carbon core, developing a water channel that improve permeation flux. Once water molecules infiltrate over the GO layers, they built up to arise a single layer configuration that drives the consecutive layers apart from each other, resulting in the increase of the d-spacing (Hung et al., 2014). The unique properties of GO-based water desalination membrane could open the door of opportunities to overcome the challenges, in order to make clean water easily reached around the earth.

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