Researchers figure out a way to create zeolite nanosheets with better filtration properties

Oct 07, 2011 by Bob Yirka report

(PhysOrg.com) -- Michael Tsapatsis and colleagues at the University of Minnesota have devised a means for overcoming the problem of grouping that occurs during the exfoliation stage when producing zeolites which results in deformed structures in the framework which then leads to holes in the material that are larger than the pores needed to capture whatever is being filtered. The team has published its results in Science.

Zeolites are materials that are traditionally used as absorbents, but can also be used as a sieve or filter to separate or collect materials found in other materials. In the case of very small materials, scientists would like to create very small sieves to separate molecules from one another. Unfortunately, thus far, their efforts to create so-called zeolite nanosheets have proved rather fruitless as the processes used so far tend to result in the creation of holes in the sheet that are too large to capture the desire molecules.

The approach up to now has involved making layered and its other component, ITQ-1, then blending the two by melting them together. The result is a that has two unique kinds of nanosheets called MWW and MFI. It’s at this stage where things go wrong. To get the zeolites, the polystyrene in the mix must be removed and attempts to do so have resulted in bent or curled sheets, which won’t work because it causes grouping or bunching which results in the development of that aren’t of the desired size.

Tsapatsis and his team used the first process but went another way with the second. To separate out the polystyrene, they used sound waves in the water soluble liquid toluene and a centrifuge and wound up with flaky crystal type nanosheets that are not only flat, but have just the right amount of thickness.

The resultant product can be used to separate as a sieve or as a membrane barrier in both research and industrial applications and Tsapatsis writes that he believes the same process can be used to create other types of zeolites, though he can’t say with any confidence how effective they may actually be. As always, further research will have to be done to find out.

Explore further: Thinnest feasible nano-membrane produced

More information: Dispersible Exfoliated Zeolite Nanosheets and Their Application as a Selective Membrane, Science 7 October 2011:
Vol. 334 no. 6052 pp. 72-75 DOI:10.1126/science.1208891

ABSTRACT
Thin zeolite films are attractive for a wide range of applications, including molecular sieve membranes, catalytic membrane reactors, permeation barriers, and low-dielectric-constant materials. Synthesis of thin zeolite films using high-aspect-ratio zeolite nanosheets is desirable because of the packing and processing advantages of the nanosheets over isotropic zeolite nanoparticles. Attempts to obtain a dispersed suspension of zeolite nanosheets via exfoliation of their lamellar precursors have been hampered because of their structure deterioration and morphological damage (fragmentation, curling, and aggregation). We demonstrated the synthesis and structure determination of highly crystalline nanosheets of zeolite frameworks MWW and MFI. The purity and morphological integrity of these nanosheets allow them to pack well on porous supports, facilitating the fabrication of molecular sieve membranes.

Related Stories

New zeolite is discovered

Oct 18, 2006

A Spanish-led team of geologists has reported discovering a porous material with a new, highly open framework structure.

Exploring the possibilities for zeolites

Apr 05, 2011

Some people collect stamps and coins, but when it comes to sheer utility, few collections rival the usefulness of Rice University researcher Michael Deem's collection of 2.6 million zeolite structures.

Hunting for new zeolites

Nov 02, 2009

In all the world, there are about 200 types of zeolite, a compound of silicon, aluminum and oxygen that gives civilization such things as laundry detergent, kitty litter and gasoline. But thanks to computations ...

Atom-thick sheets unlock future technologies

Feb 03, 2011

(PhysOrg.com) -- A new way of splitting layered materials, similar to graphite, into sheets of material just one atom thick could lead to revolutionary new electronic and energy storage technologies.

Recommended for you

Thinnest feasible nano-membrane produced

Apr 17, 2014

A new nano-membrane made out of the 'super material' graphene is extremely light and breathable. Not only can this open the door to a new generation of functional waterproof clothing, but also to ultra-rapid filtration. The ...

Wiring up carbon-based electronics

Apr 17, 2014

Carbon-based nanostructures such as nanotubes, graphene sheets, and nanoribbons are unique building blocks showing versatile nanomechanical and nanoelectronic properties. These materials which are ordered ...

Making 'bucky-balls' in spin-out's sights

Apr 16, 2014

(Phys.org) —A new Oxford spin-out firm is targeting the difficult challenge of manufacturing fullerenes, known as 'bucky-balls' because of their spherical shape, a type of carbon nanomaterial which, like ...

User comments : 0

More news stories

'Exotic' material is like a switch when super thin

(Phys.org) —Ever-shrinking electronic devices could get down to atomic dimensions with the help of transition metal oxides, a class of materials that seems to have it all: superconductivity, magnetoresistance ...

Innovative strategy to facilitate organ repair

A significant breakthrough could revolutionize surgical practice and regenerative medicine. A team led by Ludwik Leibler from the Laboratoire Matière Molle et Chimie (CNRS/ESPCI Paris Tech) and Didier Letourneur ...

LinkedIn membership hits 300 million

The career-focused social network LinkedIn announced Friday it has 300 million members, with more than half the total outside the United States.

Magnitude-7.2 earthquake shakes Mexican capital

A powerful magnitude-7.2 earthquake shook central and southern Mexico on Friday, sending panicked people into the streets. Some walls cracked and fell, but there were no reports of major damage or casualties.