Study shows how water dissolves stone, molecule by molecule

Dec 05, 2013
The dissolution process of a crystalline structure in water is shown: two bonded SiO4 -- molecules dissolve (top left), a quartz crystal (top right) and the computer-simulated surface of a dissolving crystalline structure (below). Credit: MARUM & Rice University

Scientists from Rice University and the University of Bremen's Center for Marine Environmental Sciences (MARUM) in Germany have combined cutting-edge experimental techniques and computer simulations to find a new way of predicting how water dissolves crystalline structures like those found in natural stone and cement.

In a new study featured on the cover of the Nov. 28 issue of the Journal of Physical Chemistry C, the team found their method was more efficient at predicting the dissolution rates of in water than previous methods. The research could have wide-ranging impacts in diverse areas, including water quality and planning, environmental sustainability, corrosion resistance and cement construction.

"We need to gain a better understanding of dissolution mechanisms to better predict the fate of certain materials, both in nature and in man-made systems," said lead investigator Andreas Lüttge, a professor of mineralogy at MARUM and professor emeritus and research professor in Earth science at Rice. His team specializes in studying the thin boundary layer that forms between minerals and fluids.

Boundary layers are ubiquitous in nature; they occur when raindrops fall on stone, water seeps through soil and the ocean meets the sea floor. Scientists and engineers have long been interested in accurately explaining how crystalline materials, including many minerals and stones, interact with and are dissolved by water. Calculations about the rate of these dissolution processes are critical in many fields of science and engineering.

This video is not supported by your browser at this time.
Credit: R. Arvidson/MARUM

In the new study, Lüttge and lead author Inna Kurganskaya, a research associate in Earth science at Rice, studied dissolution processes using quartz, one of the most common minerals found in nature. Quartz, or silicon dioxide, is a type of silicate, the most abundant group of minerals in Earth's crust.

At the boundary layer where quartz and meet, multiple chemical reactions occur. Some of these happen simultaneously and others take place in succession. In the new study, the researchers sought to create a computerized model that could accurately simulate the complex chemistry at the boundary layer.

"The new model simulates the dissolution kinetics at the with greater precision than earlier stochastic models operating at the same scale," Kurganskaya said. "Existing simulations rely on rate constants assigned to a wide range of possible reactions, and as a result, the total material flux from the surface have an inherent variance range—a plus or minus factor that is always there."

One reason the team's simulations more accurately represent real processes is that its models incorporate actual measurements from cutting-edge instruments and from high-tech materials, including glass ceramics and nanomaterials. With a special imaging technique called "vertical scanning interferometry," which the group at MARUM and Rice helped to develop, the team scanned the crystal surfaces of both minerals and manufactured materials to generate topographic maps with a resolution of a just a few nanometers, or billionths of a meter.

This is a computer-simulated surface of a dissolving quartz structure. Credit: MARUM & Rice University

"We found that dissolution rates that were predicted using rate constants were sometimes off by as much as two orders of magnitude," Lüttge said.

The new method for more precisely predicting dissolution processes could revolutionize the way engineers and scientists make many calculations related to a myriad of things, including the stability of building materials, the longevity of materials used for radioactive waste storage and more, he said.

"Further work is needed to prove the broad utility of the method," he said. "In the next phase of research, we plan to test our simulations on larger systems and over longer periods."

Explore further: Reaction performs differently in different size pores

More information: pubs.acs.org/doi/abs/10.1021/jp408845m

Related Stories

Reaction performs differently in different size pores

Nov 08, 2013

(Phys.org) —Predictive models of biogeochemical interactions in soils are more accurate and scalable if they consider the reaction chemistry that occurs in distinct soil pore structures, or domains, according ...

Ancient minerals: Which gave rise to life?

Nov 25, 2013

Life originated as a result of natural processes that exploited early Earth's raw materials. Scientific models of life's origins almost always look to minerals for such essential tasks as the synthesis of ...

How new substances form

Sep 19, 2013

Gas bubbles rise in a liquid. What looks like a bottle of sparkling mineral water actually is a type of reactor frequently used in industry – a bubble column. These reactors are found in laboratories and ...

Researchers find phosphate in more soluble form on Mars

Sep 02, 2013

(Phys.org) —A trio of researchers at the University of Nevada has found that phosphate found in minerals on Mars, is far more soluble than it is in natural Earth minerals. In their paper published in the ...

Recommended for you

Novel technique opens door to better solar cells

Apr 14, 2014

A team of scientists, led by Assistant Professor Andrivo Rusydi from the Department of Physics at the National University of Singapore's (NUS) Faculty of Science, has successfully developed a technique to ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

seilgu
1 / 5 (3) Dec 05, 2013
Does this Minecraft-isque program really require supercomputers?
Bob_60441
1 / 5 (3) Dec 05, 2013
I have to ask the question, one thing asked is how can I translate this information into an app? I really do appreciate knowledge for its own sake. But if it does not pay the bill's. Unless talking to yourself in the dark is something "noble". Only if you wish it.

More news stories

Better thermal-imaging lens from waste sulfur

Sulfur left over from refining fossil fuels can be transformed into cheap, lightweight, plastic lenses for infrared devices, including night-vision goggles, a University of Arizona-led international team ...

Researchers successfully clone adult human stem cells

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...