Wednesday, November 30, 2016

Glowing crystals can detect, cleanse contaminated drinking water

Glowing crystals can detect, cleanse contaminated drinking water: Tiny, glowing crystals designed to detect and capture heavy-metal toxins such as lead and mercury could prove to be a powerful new tool in locating and cleaning up contaminated water sources. Motivated by publicized cases in which high levels of heavy metals were found in drinking water in Flint, Mich., and Newark, N.J., a science team led by researchers at Rutgers University used intense X-rays at Lawrence Berkeley National Laboratory (Berkeley Lab) to probe the structure of the crystals they developed and learn how they bind to heavy metals.

The crystals function like miniature, reusable sensors and traps, and are known as luminescent metal-organic frameworks, or LMOFs. One type of LMOF that the team tested was found to selectively take up more than 99 percent of mercury from a test mixture of heavy and light metals within 30 minutes, according to recent results published in Applied Materials and Interfaces. No other MOFs have performed as well in this dual role of detecting and capturing, or "adsorbing," toxic heavy metals, the team reported.

Simon Teat, a Berkeley Lab staff scientist, studied individual LMOF crystals, each measuring about 100 microns (millionths of a meter), with X-rays at the lab's Advanced Light Source (ALS). Using diffraction patterns produced as the X-ray light struck the LMOF samples, Teat applied software tools to map their three-dimensional structure with atomic resolution. The ALS is one of just a few synchrotron X-ray light sources in the world that have dedicated experimental stations for chemical crystallography studies of crystallized chemical compounds such as MOFs.