Engineering Minute

Engineering Minute – Squeezable Wooden Sponge

A new report published in American Chemical Society Nano (ACS nano) details a new sponge made out of wood, specifically designed to soak up oil. The sponge was designed to be reusable in that it still maintains absorbency even after many cycles of squeezing and absorbing. The main application of the wooden sponge would be cleaning up oil spills and other environmental disasters where water sources can easily be contaminated and the effects disastrous for the environment.



From the American Chemical Society article "Over the years, scientists have developed numerous techniques to clean up oily water, from gravity separation to burning to bioremediation. But many of these methods suffer from limitations, such as low efficiency, secondary pollution and high cost. More recently, researchers have explored 3D porous materials, such as aerogels or sponges, based on various building blocks including synthetic polymers, silica or cellulose nanofibers. However, these are often difficult to fabricate, lack mechanical robustness or are made from nonrenewable, nondegradable materials. Xiaoqing Wang and colleagues wanted to develop a sponge made from wood — a renewable resource — that would absorb oil and tolerate repeated squeezing without structural failure."


The wooden sponge was constructed by removing lignin and hemicellulose in natural balsa wood, leaving behind a cellulose skeleton. The skeleton was then modified with a hydrophobic coating designed to attract oil, but not water.  In testing, the sponge was able to absorb between 16 to 41 times its own weight, depending on the oil it was absorbing, leaving behind pure water. It also was able to endure a minimum of ten cycles of oil absorption and squeezing it out. The wooden sponge is currently being incorporated into an oil-collection device that continuously separates oil from water.


Read more about the squeezable wood sponge at the American Chemical Society.