Maryland, Princeton and Colorado Boulder University scientists have developed a new nanowood membrane for separating salt water from fresh water.
While most membranes are made of fossil fuel polymers, the new membrane features a thin slice of wood through which water vapor can evaporate, leaving behind salt and other contaminants.
“This work demonstrates another exciting energy/water application of nanostructured wood, as a high-performance membrane material,” notes Maryland University professor Liangbing Hu, who also co-led the study.
As part of their study, the scientists chemically treated the wood to become hydrophobic, increasing its efficiency in allowing water vapor through, while being driven by a heat source such as solar energy.
According to co-lead and CU Boulder professor Z. Jason Ren, the team has successfully proven wood’s unique properties not just as an excellent insulator, but also as a reliable water vapor transporter.
The researchers first treated the wood to make it lose its lignin – the part of the wood that makes it brown and rigid, and its hemicellulose – which weaves in and out between cellulose to hold it in place.
The resulting ‘nanowood’ was treated with silane, a compound used to make silicon for computer chips.
According to the scientists, the semiconducting nature of the compound maintains the wood’s natural nanostructures of cellulose, and clings less to water vapor molecules as they pass through.
The membrane which appears like a thin piece of wood bleached white, is suspended above a source of water vapor.
As the water heats and passes into the gas phase, the molecules are small enough to fit through the tiny channels lining the walls of the leftover cell structure.
Water collected on the other side of the membrane is free of large contaminants like salt.
According to the scientists, the new nanowood membrane performs 1.2 times better than a conventional membrane.
Image and content: University of Maryland