I lived in India from 2010 to 2013. This was an unbelievable culture shock between my time in the States, with differences in school, food, culture, and sport. One of the things that fell under the radar for me was the difference in water availability. I had to use a filter, but I could still get a bath, I could still get good food, and I could live comfortably. This wasn’t the case right outside my bubble. Clean water was drying up by the day, and life 1 mile from me could mean a complete lack of steady, flowing water. There was a whole world around me without the most important resource for life.
The Global Problem:
Only 1% of all the water that is available on the planet can be consumed by humans safely. This means that 1.1 billion people worldwide lack steady access to water, and 2.7 billion find water scarce for at least one month of the year. According to the Global Water Institution, 700 million people worldwide could be displaced by intense water scarcity by 2030. If we can provide a cheap, steady flow of water, we alleviate these problems so we can have a better future.
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The best Desalination method
We can utilize the most plentiful source of water by two orders of magnitude with the desalination of seawater. In the previous graphic, 97 of those squares could become available through desalination. However, the common methods of desalination require too much energy: Both Reverse Osmosis and Solar Desalination requires too much energy. Therefore, we are left with the task of creating the best, cheapest solution.
Graphene Oxide Filters
Graphene can be used for the ion bombardment filters, due to its uniform shaping in hexagon ties. Selective tearing can allow water to pass through, while blocking larger items. On a large scale, however, this is impossible. Getting the exact amount of holes is something that cannot be done on an industrial scale. Graphite oxide can work here. The oxidation of geo sheets (pictured on right) leads to graphene oxide. Here, we’re close in using ion bombardment, but it is still not very practical on a large scale. We can, however, use layers of Graphite Oxide, water can be carried with capillary action, while the salt ions are blocked from entering.
To form these layers of Graphite Oxide, we have to utilize the process known as Hummer’s Method. The method is a four step process as followed:
- 100 g of Graphene + 50g of Sodium Nitrate are in 2.3 liters of Sulfuric Acid, with a temperature of 66 degrees Celsius
- The solution is then cooled to 0 degrees celsius.
- 300 grams of Potassium Permanganate are added to the solution and then stirred
- Water is incrementally added until a mixture of 32 liters is created, when it is then cleaned.
Creating a Filter:
Layers of GO are placed on top of one another. The space between layers of the filter has to be just large enough to fit water in, but small enough to block salt ions and other larger ions. A range of distances can fit here, anywhere from 6.4 to 9.8 angstroms. The filter’s distance can erode over time, meaning that salt ions could manage to get through. To fix that, epoxy can be added to fix the distance between layers for a long time. This filtration system can get rid of up to 97% of salts!
The solution is an effective one, but the biggest problem in water filtration and desalination isn’t addressed: cost. The cost of graphene is not cheap, and therefore the filters will be expensive. Creating graphene in a cheap, non-toxic way becomes the main issue.
Creating Cheap Graphene
Using a bottom up approach that has been tested in labs, we can create graphene easily and cheaply. By heating any carbon-containing material up to 3000 Kelvin, we can isolate graphene cheaply. Energy consumption would be around 7.2 kilojoules/gram, meaning that it is very cost effective.
Glass Fiber Membranes
The entire system doesn’t need to be with graphene. Keeping the core parts unchanged while changing the accessories would mean a large difference in cost without downgrading the machine itself. We can fuse together graphene and Teflon nano-particles into commercial glass-fiber membranes, utilizing graphene to its fullest. Teflon binds both glass and graphene together, making a filter with a customizable pore size.
We have made Graphene cheaper and more effective, therefore making water filters even better and cheaper. We have solved the biggest issue in water filtration; the cost.
For this project, we really want to make sure that no one is without water. We hope that this project can lead to a better world.
Better filtration through graphene, theoretically cheaper.
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