Although a large percentage of the Earth’s surface is covered in water, most of it is undrinkable. Removing the salt, compounds and microbes that make it unsafe to drink could expand the world’s supply of safe drinking water and address many human health concerns.
Desalination is an important technology that could help accomplish this, and now, engineers in China have demonstrated a new, relatively simple design for a solar still with high efficiency and low cost. In a new design, researchers from Dalian Maritime University in China developed a unit that can float on top of seawater, efficiently absorb solar energy and use that heat to evaporate the water.
The unit itself consists of three layers: the bulk is a polyethylene foam that helps it float and acts like a thermal insulator. The outside of the foam is wrapped in airlaid paper, an absorbent material used in disposable diapers that wicks water up towards the upper surface. The top face is coated in titanium nitride oxide (TiNO).
This unit is eventually placed in a solar still – a transparent plastic container with a sloped roof, which catches the condensing fresh water and directs it to be collected. In tests, the team found that the new solar still has a solar-to-water efficiency of 46 percent. Also, the team found that no salt layer buildup was formed, suggesting that the pores wick salt away and dump it back in the seawater.
The research was published in the journal AIP Advances. Chao Chang was the lead author of the study.