Graphene for Water Desalination

Water, one of the world’s most abundant and highly demanded resources for sustaining life, agriculture, and industry, is being contaminated globally or is unsafe for drinking, creating a need for new and better desalination methods. Current desalination methods have high financial, energy, construction, and operating costs, resulting in them contributing to less than 1% of the world’s reserve water supplies. Advances in nanoscale science and engineering suggest that more cost effective and environmentally friendly desalination process using graphene is possible.
Our group has chosen to research this application of graphene for better water desalination, focusing on current desalination limitations and how graphene’s structure-processing-properties paradigm make it well suited to advance desalination’s efficiency.
Currently, most desalination plants run by making use of a process known as reverse osmosis by forcing water with high salt concentration through filters at high pressures to remove salt. This process requires enormous pressures, huge operating costs, and filters require nearly constant maintenance and monitoring to avoid clogging. What if there was a better, more efficient way to do this same desalination process? Current research has shown that graphene can do this same reverse osmosis process, only better.
Graphene consists of a single atom thick layer of carbon atoms bonded in a hexagonal honeycomb structure. This thinness allows for high diffusion fluxes, and therefore high water permeability. Graphene also has a high tensile stiffness of 150,000,000psi, allows it to withstand high pressures when water is forced through at high fluxes. While costs to produce graphene are still high, they have been decreasing rapidly. For example, MIT has pioneered a new way to produce graphene using a chemical technique that breaks graphite into graphene sheets, optimizing the quality of graphene for desalination while decreasing the time, money, and labor involved in production.
As salty water flows through graphene membranes, engineered pores of a size .8-1.6nm allow water molecules to pass through while stopping the passage of salt molecules. Benefits of swapping graphene membranes with current membranes used in desalination plants include decreased energy costs, less maintenance, higher salt rejection rates, greater water flow and permeability, and decreased cost of construction of desalination plants.
With our focus on graphene for water desalination, seek to compare the benefits as well as drawbacks, and better understand if the structure and processing of graphene produces the properties ideal for this application.
References

1 Desalination gets a graphene boost. (n.d.). Retrieved April 11, 2017, from
http://news.mit.edu/2015/desalination-gets-graphene-boost-jeffrey-grossman-1102

2Water desalination using nanoporous single-layer graphene. March 23, 2017. Retrieved April 10, 2017, from http://www.nature.com/nnano/journal/v10/n5/full/nnano.2015.37.html

3Graphene sieve turns seawater into drinking water. (n.d.). Retrieved April 10, 2017, from https://phys.org/news/2017-04-graphene-sieve-seawater.html

4Water Desalination across Nanoporous Graphene. (n.d.) Retrieved April 10, 2017, from http://www.rle.mit.edu/gg/wp-content/uploads/2016/03/03_WaterDesalination.pdf

5Nanotechnology applications for desalination: A report for the joint water use & desalination task force. Retrieved April 10, 2017, from http://prod.sandia.gov/techlib/access-control.cgi/2010/108355.pdf

6Desalination by reverse osmosis. (n.d.). Retrieved April 11, 2017, from https://www.oas.org/dsd/publications/Unit/oea59e/ch20.htm

7Novel nanomaterials for water desalination technology. Retrieved April 10, 2017, from http://web.mit.edu/lienhard/www/papers/conf/COHEN-TANUGI-IEEE-SusTech-2013.pdf

8Graphene. (n.d.) Retrieved April 10, 2017, from https://www.graphenea.com/pages/graphene#.WOaOANIrLb0

9Ultrapure Deionized Water Services and Reverse Osmosis Systems. (n.d.). Retrieved April 10, 2017, from, http://puretecwater.com/reverse-osmosis/what-is-reverse-osmosis

10Saline water: Desalination. (n.d.). Retrieved April 11, 2017, from https://water.usgs.gov/edu/drinkseawater.html

Видео Graphene for Water Desalination канала Intro to Materials Science--Guided Inquiry (UVa)