Nanotechnology Now - Press Release: Wood You Like Some Fresh Water? New treatment for wood makes a membrane to extract fresh water

Home > Press > Wood You Like Some Fresh Water? New treatment for wood makes a membrane to extract fresh water

A new treatment for wood could make renewable salt-separating membranes.

Abstract:
A membrane made of a sliver of wood could be the answer to renewable-sourced water cleaning. Most membranes that are used to distill fresh water from salty are made of polymers based on fossil fuels.

Wood You Like Some Fresh Water? New treatment for wood makes a membrane to extract fresh water

Princeton, NJ | Posted on August 5th, 2019

Inspired by the intricate system of water circulating in a tree, a team from Princeton University, the University of Maryland, and the University of Colorado Boulder, have figured out how to use a thin slice of wood as a membrane through which water vapor can evaporate, leaving behind salt or other contaminants.

Different from previous work the researchers demonstrated using wood for water filtration, the team chemically treated the wood to become hydrophobic, so that it more efficiently allows the water vapor through driven by a heat source like solar energy.

“This study discovered a new way of using wood materials’ unique properties as both an excellent insulator and water vapor transporter,” said Z. Jason Ren, a professor in environmental engineering who recently moved from CU Boulder to Princeton, who co-led the study.

“This work demonstrates another exciting energy/water application of nanostructured wood, as a high-performance membrane material,” said Liangbing Hu, a professor in materials science at the University of Maryland, College Park, and the other co-leader of the team that performed the study.

The researchers treat the wood so that it loses 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” is treated with silane, a compound used to make silicon for computer chips. 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. Silane is also used in solar cell manufacturing.

The membrane looks like a thin piece of wood, seemingly bleached white, that 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 is now free of large contaminants like salt.

To test it, the researchers distilled water through it and found that it performed 1.2 times better than a conventional membrane.

“The wood membrane has very high porosity, which promotes water vapor transport and prevents heat loss,” said first author Dianxun Hou, who was a student at CU Boulder.

Inventwood, a UMD spinoff company of Hu’s research group, is working on commercializing wood based nanotechnologies.

The research will be published in the journal Science Advances on August 2, 2019.

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