TECH­NOL­OGY

NANO-SPONGES TO THE RES­CUE!

Guru Magazine - - In The News - Au­thor: Ross Harper

Oh no! I’ve spilled my wine! Be a dear and pass me that carbon nan­otube. I’ll ad­mit, it’s not the first thing you think of when it comes to mop­ping up spills, but tiny tubes made of a sheet one carbon atom thick may soon be the an­swer to a whole host of clean­ing jobs. As the name sug­gests, carbon nan­otubes (CNTs) are small… re­ally small. They’re ‘nanoscopic’ to be pre­cise! Since their dis­cov­ery in the 1960s, CNTs have adopted a va­ri­ety of roles – from flat screen TVs and so­lar pan­els to carbon fi­bre bike frames, and even nerve re­gen­er­a­tion ther­a­pies. CNTs have taken the world of sci­ence and in­dus­try by storm, and now they prom­ise to help the en­vi­ron­ment by clean­ing up pol­lu­tion. Is there noth­ing th­ese lit­tle guys won’t do? Clever Ital­ian chaps at the Univer­sity of Roma have led the way in mak­ing this new type of CNT su­per­sponge by chang­ing the way CNTs are nor­mally made. To the com­pli­cated man­u­fac­tur­ing process, they have added a key new in­gre­di­ent – sul­phur – which has let them syn­the­sise longer tubes than be­fore, fash­ion­ing

them into a por­ous sponge-like struc­ture. In tests, th­ese 2×2cm mini-sponges were able to se­lec­tively ab­sorb up to 3.5 times more toxic sub­stances from wa­ter than all pre­vi­ous ef­forts. They were also able to hold an amount of veg­etable oil up to 150 times their ini­tial weight – mean­ing a small 7 gram sponge could eas­ily soak up your one litre bot­tle of olive oil. Now that’s got to come in handy dur­ing any kitchen-based fi­asco! But the real ap­pli­ca­tions are to en­vi­ron­men­tal clean-up ini­tia­tives. Af­ter, let’s say, an oil spill, th­ese new CNT sponges could be re­leased into the wa­ter, se­lec­tively grab­bing all the nasty tox­ins. “OK,” I hear you sneer, “but then what, smart guy? You’ve just re­placed free-float­ing tox­ins with tox­in­filled sponges. Idiot!” That’s true (and a lit­tle harsh). How­ever, the im­por­tant thing is that th­ese CNT sponges con­tain iron… iron is mag­netic… mag­nets can be used to pull stuff to­wards you… see where I’m go­ing with this? Af­ter send­ing out the CNT troops, they can be re­trieved far more eas­ily than other wa­ter-clean­ing op­tions avail­able by us­ing good old-fash­ioned mag­nets. Then, like any sponge, they can sim­ply be squeezed out and used again. Per­fect. The next step is to fig­ure out a way to pro­duce th­ese CNT sponges on a com­mer­cial scale. (If a 550,000-ton oil tanker bites the dust, you’re go­ing to need a lot of sponges.) The other thing to be ab­so­lutely sure of is that the sponges them­selves aren’t toxic to any wildlife. All things be­ing well, we should soon have a new tool in the fight against dirty wa­ter, and, more im­por­tantly to you and me, an ef­fec­tive way to get red wine out of the car­pet.

Ref­er­ence:

A three-di­men­sional carbon nan­otube net­work for wa­ter treat­ment

BE­LOW: A scan­ning elec­tron mi­cro­graph of carbon

nan­otube bun­dles.

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