A superhydrophobic material based on an industrial solid waste for oil/water separation

In this study, we employed phosphogypsum, an important solid waste of the phosphorus chemical industry, to prepare a superhydrophobic material for oil/water separation using sodium metasilicate and stearic acid as the chemical modifiers through a facile method. This superhydrophobic material has rough micro-nano structure with low surface energy and possesses an average water contact angle of 151.5 degrees as well as an average water sliding angle of 1.8 degrees, showing extremely low adhesion to water. Due to its superhydrophobicity and superoleophilicity, this material can separate various oil/water mixtures with high separation efficiencies in the range from 92% to 97% by means of a simple apparatus driven by gravity. Additionally, the superhydrophobic material has high resistance to acidic solution and repeated separation, showing the reliability for harsh conditions and long-term use. This superhydrophobic material prepared based on industrial solid waste is a good example of waste valorization.