A team of engineers recently developed a method for utilizing graphene oxide sheets to obtain clean drinkable water. The technique basically includes a highly efficient method for utilizing solar energy to heat up dirty water up to boiling level leading to the creation of purified steam which is then collected and consumed safely. The basic idea behind this technique is a very simple one. Whenever water is boiled, the microbes that cause intestinal issues for humans are killed. So, when steam is collected and allowed to condense, the collected water is safe to drink.
However, the biggest issue faced with solar-steam techniques is their inefficiency. Lots and lots of energy gets wasted when the complete volume of water is boiled. So what’s the solution to this problem. The most simple solution is to confine heat energy to the line that demarcates air and water, through this you are just heating the relevant evaporation surface. These engineers found a way for heat localization with the help of a bilayered biofoam. The material is constituted by bacterial nanocellulose (BNC) along with reduced graphene oxide (RGO). this bilayer structure was created by growing a bacteria called Gluconacetobacter using graphene oxide flakes as catalysts.
A member of this team, Srikanth Singamaneni says, “The process is extremely simple. The beauty is that the nanoscale cellulose fiber network produced by bacteria has an excellent ability to move the water from the bulk to the evaporative surface while minimizing the heat coming down and the entire thing is produced in one shot. You have a bi-layered structure with light-absorbing graphene oxide filled nanocellulose at the top and pristine nanocellulose at the bottom”
Using this biofoam bilayer is a very simple job. All you need to do is spread the sheet of this material over dirty water and rest will be done by sunlight. The top most layers of this sheet will capture heat from sun rays while the bottom layer of pure BNC will abstract water from below keeping it safe from heat above. Singamaneni further adds, “When you suspend this entire thing on water, the water is actually able to reach the top surface where evaporation happens. Light radiates on top of it and it converts into heat because of the graphene oxide—but the heat dissipation to the bulk water underneath is minimized by the pristine nanocellulose layer.”
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