EAGER: A bio-inspired approach for enhancing lifetime of salts during icing and frost formation

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#1644815Anand, SushantInvestigating chemically enhanced salt particles with extended lifetime for ice and frost preventionIce formation on roads can have profound effects, including car accidents, traffic congestion, and billions of dollar losses in economic productivity. To date, the most viable solution worldwide is to use deicing salts on roads that suppress ice formation through freezing point depression. However, their usage also poses significant threats to our environment and economy. Nearly 43% of salt usage related to deicing highways (costing around $2.2 billion) in USA alone. Deicing salts increase the soil salinity near roads causing higher alkanity, increased moisture retention and loss of soil fertility, thus adversely affecting plant growth. The salt can also percolate through soil, ultimately reaching lakes and underground water systems where the increase in salinity can lead to significantly harmful effects on flora, aquatic/amphibious animals and our own drinking water supplies. Furthermore, deicing salts have serious consequences for our infrastructure by promoting corrosion of steel (e.g. in bridges, vehicles) or disintegration of concrete. This study proposes that the lifetime of salt can be increased by enhancing them with special environmentally friendly chemicals that can decrease the dissolution rate of salts while maintaining their deicing functionality. These studies will also lead to development of new understanding of the fundamentals of phase change of water to ice in the presence of a hygroscopic material (such as salt). The work will lead to development of a new class of deicing salts that will have significantly large lifetime compared to conventional salt and will be beneficial for both transportation safety and environmental sustainability.A salt particle can suppress ice formation due to two mechanisms - by depressing the freezing point of water, and by depressing the vapor supersaturation in its vicinity by acting as a "humidity sink". Chemically enhanced salt particles that may maintain their hygroscopic properties but also slow the leeching of salt molecules in the environment during dissolution will be prepared. Experiments will be performed to: (a) to fabricate chemically enhanced salt particles, and investigate scalable techniques for preparing such materials, (b) investigate the deicing delays through use of chemically enhanced salt particles compared to plain salt particles at different thermodynamic conditions (humidity levels, degree of subcooling), (c) investigate the salt leeching rate as a function of chemical properties and thermodynamic conditions. These tasks will be accomplished using combination of thermographic and optical techniques during in-situ observation of ice formation on the chemically enhanced salt particles. In addition to the development of a new type of deicing salt particles with enhanced lifetime, the proposed studies have the potential to shed new light on ice formation in presence of hygroscopic chemicals such as salts.