This array of water droplets illustrates how salt slows ice formation. The large condensed water droplet in the center contains a single crystal of sodium chloride. An array of smaller condensed water droplets surrounds it. Rukmava Chatterjee, a PhD candidate at the University of Illinois at Chicago, studies anti-icing systems. Chatterjee added a single sodium chloride crystal to a plate cooled to –15 °C. The air around the plate was room temperature and humid. As vapor from the air condensed on the plate, the central drop remained liquid for about 3 h, while the smaller drops froze after about 20 min. Chatterjee captured this image in grayscale at 100× magnification; he adjusted the hue and saturation to give it a violet tint. Deicing is critical for safe winter driving, but rock salt can have detrimental effects on the environment. Chatterjee’s doctoral work focuses on coating salt with a polymer membrane so that it still slows freezing but is not released into the environment.
Submitted by Rukmava Chatterjee
Do science. Take pictures. Win money. Enter our photo contest here.
Related C&EN content: