These Tiny Glowing Crystals Could Detect Toxins, Clean Contaminated Drinking Water

A team led by researchers at Rutgers University developed tiny, glowing crystals that are designed to detect and capture heavy-metal toxins, such as lead and mercury, in drinking waters.

Their discovery, described in a paper published in the journal Applied Materials and Interfaces, could become the latest powerful tool to be used in locating and cleaning up contaminated water sources, just like the drinking waters in Flint, Michigan and Newark, New Jersey.

The crystals known as luminescent metal-organic frameworks, or LMOFs, function like miniature, reusable sensors and traps for heavy-metal toxin contaminating water supplies. The researchers noted that there are no other MFOs have the dual role of detecting and capturing toxic heavy metals.

"Others had developed MOFs for either the detection of heavy metals or for their removal, but nobody before had really investigated one that does both," said Jing Li, a chemistry professor at Rutgers University and lead author of the study, in a press release.

The research team discovered that one type of LMOF can selectively take up more than 99 percent of mercury from a test mixture of heavy and light metals in 30 minutes. Using X-ray at Berkeley Lab's Advanced Light Source (ALS) and applied software tools, the researchers were able to map a three-dimensional structure of the crystal with atomic resolution.

The researchers found that the crystals contain carbon, hydrogen, oxygen, nitrogen and zinc atoms that framed large, open channels. These holes in the framework of the LMOFs allow heavy metals to enter to the open channels and chemically bind to the MOFs.

The LMOFs were also discovered to be selective of their targets. The researchers observed that the crystals bind strongly to mercury and lead, while binding weakly to lighter metals in the water, such as magnesium and calcium. The researchers noted that the LMOFs can also be recycled, surviving three cycles of collecting, cleaning and reusing before showing signs of degradation.

With their findings, the researchers noted that further studies of the LMOFs are still needed. However, the result of their current study can still be considered as promising in the field.