Using low-cost materials, academics from the University of Buffalo developed a solar-powered water purifier. The device could help to address global drinking water shortages, especially in developing areas and regions affected by natural disasters.
To conduct the research, the team built a small-scale solar still. The device, a “solar vapor generator,” cleans or desalinates water by using the heat converted from sunlight.
The sun evaporates the water. During the process, salt, bacteria, or other unwanted elements remain as the liquid moves into a gaseous state. The water vapor then cools and returns to a liquid state, where it is collected in a separate container without the salt or contaminants.
The still is made of expanded polystyrene foam and porous paper coated in carbon black. The foam , a common plastic, acts as a thermal insulator. Like a napkin, the paper absorbs water, while the carbon black absorbs sunlight and transforms the solar energy into heat used during evaporation.
The device converts water to vapor very efficiently. Only 12 percent of the available energy was lost during the evaporation process, a rate that the research team believes is unprecedented. The accomplishment is made possible, in part, because the device converts only surface water, which evaporated at 44 degrees Celsius.
Based upon test results, researchers believe the still is capable of producing 3 to 10 liters of water per day, which is an improvement over most commercial solar stills of similar size that produce 1 to 5 liters per day.
“The solar still we are developing would be ideal for small communities, allowing people to generate their own drinking water much like they generate their own power via solar panels on their house roof,” said Zhejun Liu, a visiting scholar at UB, PhD candidate at Fudan University and one the study’s co-authors.
Also: Learn how NASA aerogels support water purification.