By Peak Johnson
They operate like miniature, reusable sensors and traps and are known as luminescent metal-organic frameworks (LMOFs). These crystals are designed to detect and capture heavy metal toxins such as lead and mercury.
Motivated by publicized cases in which strong levels of heavy metals were located in drinking water in Flint, MI, and Newark, NJ, a science team led by researchers at Rutgers University used “intense X-rays at Lawrence Berkeley National Laboratory to inspect the structure of the crystals they developed and learn how they bind to heavy metals,” according to Berkeley Lab’s website.
According to recent results published in Applied Materials and Interfaces, one type of LMOF that the researchers 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.
The team reported to Berkeley Labs that no other LMOFs performed as well “in this dual role of detecting and capturing, or ‘adsorbing,’ toxic heavy metals.”
Simon Teat, a Berkeley Lab staff scientist, studied individual LMOF crystals, that measured about 100 microns, with X-rays at the lab’s Advanced Light Source.
By using what is known as diffraction patterns to produce X-ray light, “Teat applied software tools to map their three-dimensional structure with atomic resolution.” He was then able to find “a patterned, grid-like 3-D structure containing carbon, hydrogen, oxygen, nitrogen, and zinc atoms that framed large, open channels.”
Jing Li, a chemistry professor at Rutgers University who spearheaded the research, believes a next step could be to “explore lower-cost and more durable LMOFs that could last for more cycles, and researchers could also pursue the development of water filters by blending the LMOFs with polymers to create solid film.”
“These filters could be used to capture on a larger scale,” Li said, per Berkeley Labs.
Li’s team is interested in testing performance on actual contaminated water sources if it can obtain the funding to do so.