With funding from the Army Research Office, part of the Army Research Laboratory at the U.S. Army combat capability development command, researchers at the University of Rochester have developed a new type of aluminum panel that can concentrate solar energy more effectively to evaporate and purify contaminated water.
Dr. Evan runnerstrom, aro project manager, said: "the army and its soldiers are running on water, so they are particularly interested in the research of basic materials, which may lead to advanced technologies for producing drinking water." The combination of super wicking and light absorbing properties of these aluminum surfaces can achieve passive or low-power water purification to better maintain soldiers on the battlefield. "
The researchers have developed a laser processing technology that turns conventional aluminum pitch black, making it highly absorbent and super wicking (it draws water cores up hillsides to resist gravity). Then they used this super absorbent and super core absorbent aluminum for solar water purification.
A technology in nature sustainability uses femtosecond (ultrashort) laser pulses to etch the surface of ordinary aluminum plates. When the aluminum plate is immersed in water at an angle facing the sun, a layer of water is pulled upward on the metal surface. At the same time, the blackened surface retains nearly 100% of the energy it absorbs from the sun to heat water quickly. Finally, the structure of wicking surface changes the intermolecular bond of water, which further improves the efficiency of evaporation process.
"These three things together make the technology run better than the ideal device at 100% efficiency," said Professor Guo Chunlei, an optics professor at the University of Rochester "It's a simple, durable, and cheap way to solve the global water crisis, especially in developing countries."
Laboratory experiments have shown that this method can reduce the presence of all common pollutants (such as detergents, dyes, urine, heavy metals and glycerol) to safe drinking levels.
Guo said the technology could also be useful in water shortage and desalination projects in developed countries to alleviate water shortages in arid areas.
For a long time, it has been considered that boiling with sunlight is a way to eliminate microbial pathogens and reduce deaths caused by diarrhea infection. However, boiling water can not eliminate heavy metals and other pollutants.
Solar water purification; however, since evaporated water becomes gaseous and then condensed and collected, almost all impurities are forgotten, so these pollutants can be greatly reduced.
The most common method of solar water evaporation is volume heating, which heats a lot of water, but only the top layer can evaporate. This is obviously inefficient, because only a small part of the heat is used, Guo said.
A more effective method, called interfacial heating, places floating multilayer absorbent and wicking material on top of the water, so only water near the surface needs to be heated. But all available materials must float horizontally on the water and not directly face the sun. In addition, the available wicking materials will be quickly blocked by the pollutants left by evaporation, and the materials need to be replaced frequently.
The aluminum panel, developed by the researchers, avoids these difficulties by pumping a thin layer of water from the reservoir and placing it directly on the surface of a solar absorber for heating and evaporation.
"In addition, because we use slotted surfaces, it's very easy to clean just by spraying," Guo said "The biggest advantage is that the angle of the panel can be continuously adjusted so that it faces the sun directly when it rises, and then moves in the sky before setting, so as to maximize energy absorption."