The burning of coal may be falling out of favor as a means of generating heat and electricity, but that doesn't mean the material no longer has any valuable uses. According to a new study, it could be utilized in the desalination of seawater.
In a project led by Assoc. Prof. Andrea Fratalocchi, a team at Saudi Arabia's King Abdullah University of Science and Technology (KAUST) explored the use of a material known as carbonized compressed powder (CCP). It is created by grinding coal or charcoal into a powder, then compressing that powder back into a solid which is more porous than the original material – it can also be molded to a desired shape.
The KAUST team combined CCP with natural cotton fibers, producing a 20 x 20-cm (7.8-in) block which was then placed within a 34 x 34-cm (13.4-in) seawater-containing container, with the bottom of the block touching the surface of the water.
While sunlight heated the black surface of the block, the absorbent fibers drew water in from the sides. When that liquid water reached the hot surface of the block, it turned to steam which rose and condensed on the inside of a transparent pyramid-shaped cover. That condensation then trickled down the sloped cover and was collected as fresh, drinkable water within a trough.
The seawater's salt content remained behind within the CCP. A simple rinse with more seawater was sufficient to remove most of it, so the material could be reused multiple times. According to the scientists, the CCP's desalination rate per unit of raw material is two to three times higher than that of any other solar desalination system.
KAUST has now partnered with Dutch startup PERA to commercialize the technology. The material may see its first use in a pilot plant in Brazil, where it will be utilized to desalinate brackish water for the production of drinking and cooking water.
"CCP is abundant in nature and low-cost, as well as lightweight, versatile and highly scalable from a fabrication point of view," says postdoctoral student Marcella Bonifazi, who is part of the research team. "The device produced fresh water for around one-third the cost of current state-of-the-art solar desalination technologies."
A paper on the study was recently published in the journal Advanced Sustainable Systems.
Source: KAUST