May 25, 2004
Nanoparticles clean up arsenic
Researchers at Oklahoma State University, US, have used nanoparticles of zinc oxide to remove arsenic from water, even though bulk zinc oxide cannot absorb arsenic. They produced the zinc oxide in a porous aggregate form that was suitable for water treatment.
“Nanoparticles have already been demonstrated to have useful absorption and catalytic properties but there wasn’t a way to take advantage of them in the real world due to their small size,” researcher Satish Kuriyavar told nanotechweb.org. “For example, in a water treatment column they would simply suspend and flow away with the water or clog any filter that might be used to keep them in place.”
According to Kuriyavar, he and his colleagues found a way to make spherical aggregates of nanoparticles that have a similar size and shape to the resin beads already used in water purification. “Indeed they are made from ion-exchange resins,” he said.
To create the aggregates, the researchers loaded cationic exchange resins with zinc ions. Then they fired them: the result was spherical nanoparticulate zinc oxide spheres.
“In the case of arsenic, our zinc oxide product could best be used in at-the-tap water purification devices,” said Kuriyavar. “However, our process can be used to create a large range of metal, metal oxide, and metal sulphide nanoparticle aggregates that could be used in a number of pollution-prevention, water-treatment and catalytic applications.”
Now the team plans to study the surface chemistry of zinc oxide nanoparticles to understand why they absorb arsenic when the bulk material does not. “We also intend to pursue the application of zinc oxide nanoparticles as a catalyst for an industrial process, and to develop sorbants for lead, based on the pyrolysis of ion-exchange resins,” said Kuriyavar.
The researchers reported their work at the American Chemical Society meeting in Anaheim in April.
About the author
Liz Kalaugher is editor of nanotechweb.org.