THE NEW SCHOOL OF IONICS

WATER BEHAVIOR DISCOVERED ANEW

Who knew there was more to know about the basics of water? Well, one group of researchers, at least.

Scientists at the University of Cambridge and the Max Planck Institute for Polymer Research tweaked the process of determining how electrolyte solutions, like saltwater, interface with the air.

They discovered behavior that is much different than what has been understood, and taught, to date.

It has to do with how water molecules align at saltwater surfaces during processes such as evaporation. That alignment is specific, and has implications for climate science and understanding how human behavior impacts the planet.

The study, “Surface stratification determines the interfacial water structure of simple electrolyte solutions,” was published in the journal, Nature Chemistry.

Their more complex method of studying various electrolyte solutions and how they behave where water and air meet, produced results that are being called revolutionary, and a paradigm shift in our understanding of environmental processes and atmospheric chemistry models.

We don’t need to fully understand the science to see how their findings change things up, but here’s a shot at an explanation, from a layperson’s perspective.

Until now, scientific findings upheld the theory that ions in saltwater molecules form an electrical double layer, orientating all the molecules in one direction.

Not the case, according to these researchers, who demonstrated that both positively and negatively charged ions were depleted in the transition from water to air.

And there’s more.

Ions in simple electrolytes can orient molecules in both upward and downward directions.

In case you were wondering, the scientists’ tweak was to the traditional method of measuring the strength of molecular vibrations at water/air interfaces; vibrational sum-frequency generation (VSFG). Their advanced version of that, heterodyne-detected (HD)-VSFG, uses computer modeling to eliminate the need to interpret data for things like determining if the vibration signals are positive or negative.

What does this mean?

According to co-first study author, Dr. Yair Litman, of the Yusuf Hamied Department of Chemistry at Cambridge and the Max Planck Institute for Polymer Research, the findings show a big difference in what was previously believed about a simple electrolyte’s surface and the way the ions are distributed. Above the predominate, bulk salt solution is an ion-rich layer topped by several layers of pure water.

It all boils down to a better, molecular-level understanding of liquid interfaces.

At the Max Planck Institute, (which has produced 29 Nobel Prize winners) Professor Mischa Bonn leads the Molecular Spectroscopy department, and offers insight into the practical applications, suggesting that applying their research methods to study solid/liquid interfaces has potential for applications in batteries and other energy storage.

Solid/air, liquid/air, and probably a lot of other interfaces are everywhere, making them a big piece of the environmental puzzle. Ions are electrically charged, and other groundbreaking research is leading to ways to turn those tiny bits of power into an energy source for external applications.

Also contributing to the study were Kuo-Yang Chiang at the Research Takakazu Seki and Yuki Nagata, all at the Max Planck Institute for Polymer Research.