Facile preparation of colorful liquid marbles and liquid marbles used in water pollutant detection

Liquid marbles are drops coated with a hydrophobic powder. Different liquid marbles can be easily distinguished by the diverse color appearance. Here, we first demonstrate colorful liquid marbles, which were encapsulated with colored superhydrophobic stearate powders. A simple method was used to generate colorful superhydrophobic stearate powders via chemical reactions between sodium stearate and inorganic salts. In addition, the contact angle meter was used to monitor the horizontal profiles of liquid marbles to investigate the lifetime of liquid marbles on the stainless steel surface at room conditions. More important, we have described a proof of qualitative detection of oil pollution and measured the minimum detection limit of some water-soluble pollutants by liquid marbles.