Efficient Filters Produced From Carbon Nanotubes Through Rensselaer Polytechnic Institute-Banaras Hindu University Collaborative Research
Filters remove nano-scale germs from water, heavy
hydrocarbons from petroleum
Aligned multiwalled nanotubes of the filter wall
(scale 100 micrometers).
Troy, N.Y. — Researchers at Rensselaer Polytechnic Institute
and Banaras Hindu University (India) have devised a simple
method to produce carbon nanotube filters that efficiently
remove micro- to nano-scale contaminants from water and heavy
hydrocarbons from petroleum. Made entirely of carbon nanotubes,
the filters are easily manufactured using a novel method for
controlling the cylindrical geometry of the structure.
“The research demonstrates how to spray well-ordered nanotube
structures directly onto a substrate,” said Pulickel M. Ajayan,
professor of materials engineering at Rensselaer and one of the
authors of “Carbon Nanotube Filters,” which describes the
manufacture and application of the filters in the September
issue of Nature Materials. The work was supported in
part by the Center for the Directed Assembly of Nanostructures
at Rensselaer and the Ministry of Education in India.
The filters are hollow carbon cylinders several centimeters
long and one or two centimeters wide with walls just one-third
to one-half a millimeter thick. They are produced by spraying
benzene into a tube-shaped quartz mold and heating the mold to
900° C. The nanotube composition makes the filters strong,
reusable, and heat resistant, and they can be cleaned easily
“In the future, we hope to be able to spray, or print, a great
variety of nanotube structures directly onto substrates,”
Ajayan said. “This method provides a better way of creating
more interesting shapes and structures from nanotubes. By
adjusting the size and flow of the nozzle, we can define the
geometric structure of the nanotube form.”
Rensselaer researchers involved in the project are Saikat
Talapatra, a post-doctoral research associate at the Rensselaer
Nanotechnology Center; Robert Vajtai, a research scientist at
the center; and Ajayan. Researchers from Banaras Hindu
University in Varanasi, India, are O.N. Srivastava, professor
of physics; and Anchal Srivastava, lecturer.
The carbon nanotube filters offer a level of precision
suitable for different applications. The experiments
demonstrated the filters may be useful in producing high-octane
gasoline. They also can remove 25-nanometer-sized polio viruses
from water, as well as larger pathogens, such as E. coli and
Staphylococcus aureus bacteria. Moreover, the nanotube surfaces
of the filters may be chemically modified to create highly
ordered and chemically selective pore spaces for high-quality
separation of specific chemical mixtures. The researchers
believe this could make the filters adaptable to microfluidics
applications that separate chemicals in drug discovery.
Ajayan and colleagues plan to continue the development of
various macrostructure architectures from carbon nanotubes.
Their work is part of the ongoing research at the Rensselaer
Nanotechnology Center. The mission of the center is to
integrate research, education, and technology dissemination,
and serve as a national resource for fundamental knowledge and
applications, in directed assembly of nanostructures.
Contact: Robert Pini
Phone: (518) 276-6050