New Class of Carbon Nanotubes Shows Potential in Cleaning Polluted Waters

Researchers from the Rochester Institute of Technology developed a new class of reusable carbon nanotubes that could clean polluted waters more effectively than silicon gels and activated carbon, which are considered to be standard industry materials.

The study, published in the journal Environmental Science Water: Research and Technology, showed that enhanced single-walled carbon nanotubes could be the next-generation solution for toxic sludge and contaminated waters.

"This aspect is new -- taking knowledge of carbon nanotubes and their properties and realizing, with new processing and characterization techniques, the advantages nanotubes can provide for removing contaminants for water," said John-David Rocha, assistant professor in the School of Chemistry and Materials Science in RIT's College of Science and one of the authors of the study, in a press release.

Carbon nanotubes are storage units that are 50,000 times smaller than the width of a human hair. In order to create a single-walled carbon nanotube, the researchers first transformed graphite into a nanometer-type material known as graphene. A sheet of graphene is then rolled up to create single-walled carbon nanotubes.

The change in the material's physical properties alters its chemical structure and determines how it behaves. The rolling up of the graphene resulted to "one of the most heat conductive and electrically conductive materials in the world."

Using new techniques in manipulating tiny materials, the researchers isolated high-quality, single-walled carbon nanotubes and sorted them based on their semiconductive or metallic properties. The researchers then redistributed the pure carbon nanotubes into thin papers, which is quite similar to carbon-copy papers.

The researchers claim that their single-walled carbon nanotubes could act as an absorbent that can pull contaminants out of the water. They noted that the secret behind the filtration process of their new material is the dislike of carbon nanotubes to water. Water molecules could freely pass through the paper, while organic contaminants in the water stick to the nanotubes.