The device is an example of how smart technology can be devised to help address some of the long-standing problems faces by humans. The Earth is made up of over two-thirds water, but most of this water is unusable due to its high salt content and most methods of desalination are not cost effective or they require larger, industrial sized pieces of equipment which makes them unsuitable for small-scale enterprises, like most farms.
Desalination refers to the removal of salts and minerals from a target substance; this can relate to soil or to water. Most commonly desalination is described in relation to saltwater (water that contains a significant concentration of dissolved salts), where the object is to desalinate the water in order to produce water suitable for human consumption or irrigation. The target water is most commonly sea water, which has a salinity of roughly 35,000 ppm, equivalent to 35 grams of salt per one liter (or kilogram) of water.
The desalination device comes from the Penn State Materials Research Institute. The device is a graphene-based membrane for clean water solutions. It can also be used for protein separation, wastewater treatment and pharmaceutical and food industry applications. Graphene is an allotrope of carbon in the form of a two-dimensional, atomic-scale, hexagonal lattice. The material is light-weight, very strong and with good filterable properties. Graphene has the property of rejecting salt from solutions it comes into contact with.
The device, marketed initially at the agricultural sector, is based on a spray-on technology. This is used to coat a mixture of graphene oxide and few-layered graphene in solution onto a a membrane made from polysulfone modified with polyvinyl alcohol. The membrane can withstand an intense cross-flow, high pressure and chlorine exposure. The membrane is considered to be ‘smart’ because it can work with a range of different pollutants, not used salt, in different environments and adapat accordingly.
The device has been described in the journal Nature Nanotechnology, in a peer reviewed paper titled “Effective NaCl and dye rejection of hybrid graphene oxide/graphene layered membranes.”
