BEIJING, June 3 (Xinhuanet) -- A mat of nanowires
that feels like paper and can absorb up to 20 times its weight in oil could be
an important tool in cleaning up oil spills and other organic pollutants,
scientists announced Monday.
MIT researchers and colleagues
say they have created a membrane that can be recycled many times for future
use and that allows recovery of the oil itself.
"What we found is that we can make 'paper' from an
interwoven mesh of nanowires that is able to selectively absorb hydrophobic
liquids ¡ª oil-like liquids ¡ª from water," said Francesco Stellacci, an associate
professor in the Department of Materials Science and Engineering and leader of
the work.
In addition to its environmental applications, the
nanowire paper could also impact filtering and the purification of water, said
Jing Kong, an assistant professor of electrical engineering in the Department of
Electrical Engineering and Computer Science and one of Stellacci's colleagues on
the work. She noted that it could also be inexpensive to produce because the
nanowires of which it is composed can be fabricated in larger quantities than
other nanomaterials.
The new material appears to be completely impervious
to water.
"Our material can be left in water a month or two,
and when you take it out it's still dry," Stellacci said. "But at the same time,
if that water contains some hydrophobic contaminants, they will get absorbed."
Made of potassium manganese oxide, the nanowires are
stable at high temperatures. As a result, oil within a loaded membrane can be
removed by heating above the boiling point of oil. The oil evaporates and can be
condensed back into a liquid. The membrane ¡ª and oil ¡ª can be used again.
Two key properties make the system work. First, the
nanowires form a spaghetti-like mat with many tiny pores that make for good
capillarity, or the ability to absorb liquids. Second, a water-repelling coating
keeps water from penetrating into the membrane. Oil, however, isn't affected,
and seeps into the membrane.
(Agencies)
