Polymer Nanotrap Incarcerates Mercury

A thiol-modified porous polymer that snatches up mercury(II) like gangbusters has set a new standard for trapping the toxic metal for wastewater treatment and environmental cleanups (Nat. Commun. 2014, DOI: 10.1038/ncomms6537). A research team led by Shengqian Ma of the University of South Florida made the nanotrap by preparing a known porous organic polymer that consists of a three-dimensional network of tetraphenylmethylene units. The team grafted mercury-chelating thiol groups onto phenyl rings throughout the polymer by adding chloromethyl substituents followed by treatment with sodium bisulfide. The team used the material to reduce the mercury concentration in water test samples from 10 ppm to less than 0.4 ppb, a level below the U.S. drinking water standard of 2 ppb. Afterward, the researchers washed the polymer with hydrochloric acid to recover the mercury and regenerate the material so it could be reused. Overall, the polymer nanotrap removes more than 1 g of mercury per gram of polymer from contaminated water samples, outperforming other sorbent materials such as silica, carbon, and metal-organic frameworks. The researchers have filed a patent and continue to explore the material for removing mercury, lead, and cadmium from flue gases and wastewater.