Researchers have developed an inexpensive and eco-friendly steam generator to desalinate and purify water using sunlight. The rate of steam production is four to five times higher than that of direct water evaporation.
The steam generator consists of an aerogel that contains a cellulose-based structure decorated with the organic conjugated polymer PEDOT:PSS. The polymer has the ability to absorb the energy in sunlight in the infrared part of the spectrum where much of the Sun’s heat is transported. The aerogel has a porous nanostructure, which means that large quantities of water can be absorbed into its pores. A 2-mm layer of this material can absorb 99 percent of the energy in the Sun’s spectrum.
A porous and insulating floating foam is also located between the water and the aerogel so that the steam generator is kept afloat. The heat from the Sun vaporizes the water, while salt and other materials remain behind. The durable aerogel can be cleaned in, for example, salt water so that it can be used again immediately. This can be repeated many times. The water that passes through the system by evaporation becomes very high-quality drinking water.
All the materials are eco-friendly — the system uses nanocellulose and a polymer that has a very low impact on the environment and people. Very small amounts of material are used; the aerogel is made up of 90 percent air.