Water droplets on superhydrophobic material

Water droplets cannot soak into a bed of cotton topped by a coating composed partially of eggshells. Credit: J. He et al./Adv. Eng. Mater.

Biomaterials

An eggshell mixture that sheds water and shrugs off punishment

A layer of this eco-friendly substance could prevent corrosion and ice build-up.

Researchers have used eggshells to create a waterproof material that can withstand radiation, corrosive liquids and other abuse.

Eggshells are inexpensive, readily available and eco-friendly, unlike the ingredients of many previously developed water-repellent materials. Jinmei He, Mengnan Qu and their colleagues at Xi’an University of Science and Technology in China obtained eggs from local supermarkets, ground up the shells and mixed them with stearic acid. By combining the mixture with zinc oxide particles, the researchers created a solid substance that sheds water even after exposure to harsh treatment, such as ultraviolet irradiation and prolonged scraping by sandpaper.

The group’s invention can be used as a coating to keep surfaces clean and prevent corrosion and ice build-up. Although water does not penetrate the material, oil does. That could make the material useful in filters for treating oily wastewater.