Study reveals how salt and other contaminants affect ice adhesion

Study reveals how salt and other contaminants affect ice adhesion
by Clarence Oxford
Los Angeles CA (SPX) Dec 05, 2023

As the winter season approaches in the United States, the perennial challenge of dealing with ice becomes more prominent. While ice accumulation is a common annoyance, delaying flights and making roads treacherous, a recent study from the University of Illinois Chicago (UIC) offers fresh perspectives on this frozen foe. Researchers at UIC have delved into the nature of ice's stickiness, particularly when it contains everyday contaminants such as salt, soap, and alcohol.

The study, led by Sushant Anand, an associate professor of mechanical and industrial engineering at UIC, moves beyond the traditional scope of ice research. "Be it dirty sidewalks or the hull of Arctic-going marine ships, there's always impurities there," Anand explains. This reality prompted the investigation into how these compounds influence ice's adhesion to surfaces.

In a novel approach, Anand's laboratory prepared ice samples with varying concentrations of contaminants and tested their adherence to different industrial materials. Contrary to what might be expected, the team discovered that impure ice often adheres less strongly than pure water ice under certain conditions. This difference in stickiness was attributed to the way water freezes when it contains impurities, particularly the formation of a quasi-liquid layer at the ice-solid interface.

To explore this phenomenon further, Anand collaborated with UIC colleague Subramanian Sankaranarayanan and his group at UIC/Argonne National Laboratory. Using molecular dynamics simulations, they examined how impure water behaves as it freezes, noting that contaminants are expelled and accumulate at the base of the ice, forming a liquid layer that reduces stickiness.

Graduated PhD student Rukmava Chatterjee, the first author of the paper, highlighted the potential applications of this research: "These insights could lead to the design of next-generation winterization techniques that slowly release contaminants to promote facile ice shedding."

The study also addressed a puzzling question: If small concentrations of salt reduce ice stickiness, why do Arctic ships still struggle with ice formation? The researchers found that the rate of water freezing plays a crucial role. Slower freezing processes lead to the isolation or expulsion of contaminants, resulting in purer and stronger ice, while faster freezing traps the contaminants within the ice, weakening its adhesion.

"Our study represents just the tip of the iceberg, opening new lines of investigation of how impure ice adheres with widespread implications across multiple disciplines," Anand remarked, underlining the broader relevance of their findings.

The UIC team, including Rajith Unnikrishnan Thanjukutty, Christopher Carducci, Arnab Neogi, Suman Chakraborty, Vijay Prithiv Bathey Ramesh Bapu, and Suvo Banik, has contributed to a better understanding of ice behavior in real-world conditions. This research not only enhances our knowledge of ice physics but also paves the way for practical solutions in areas ranging from transportation to maritime operations, where ice management is a crucial concern.

Research Report:Adhesion of impure ice on surfaces!