Washington, May 31 : Researchers at MIT (Massachusetts Institute of Technology) have developed a mat of nanowires, with the touch and feel of paper, which could be an important new tool in the cleanup of oil and other organic pollutants.
According to the scientists, they have created a membrane that can absorb up to 20 times its weight in oil, and can be recycled many times for future use. The oil itself can also be recovered.
"What we found is that we can make 'paper' from an interwoven mesh of nanowires that is able to selectively absorb hydrophobic liquids-oil-like liquids-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, according to 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.
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," said Stellacci. "But at the same time, if that water contains some hydrophobic contaminants, they will get absorbed," he added.
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. he oil evaporates, and can be condensed back into a liquid. The membrane-and oil-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. econd, a water-repelling coating keeps water from penetrating into the membrane. Oil, however, isn't affected, and seeps into the membrane.
The membrane is created by the same general technique as its low-tech cousin, paper.
"We make a suspension of nanowires, like a suspension of cellulose (the key component of paper), dry it on a non-sticking plate, and we get pretty much the same results," said Stellacci.
According to Joerg Lahann of the University of Michigan, "Stellacci and co-workers have provided an example of a nanomaterial that has been rationally designed to address a major environmental challenge."