Cellulose acetate superhydrophobic coatings for efficient oil–water separation using a combination of electrostatic spraying and chemical vapor deposition

Abstract

The efficient and simple separation of oil–water mixtures has been a global challenge due to the growing problem of oily wastewater. To address this issue, various materials with special wetting properties and functionality have been developed in the past decades for oil–water separation. In this study, a superhydrophobic cellulose acetate (CA) functional coating was prepared by electrostatic spraying of CA and chemical vapor deposition of methyltrichlorosilane (MTCS) on a stainless steel mesh (SSM). Water contact angle in air (WCA) of the resulting coating is154° or more, and oil under water contact angle (UWOCA) is 0°. Simultaneously, the separation flux of the resulting coating for oil–water mixtures is as high as 23977.77 L·m−2·h−1, with separation efficiencies exceeding 99%. Due to its excellent water repellency, the CA functional coating can effectively separate oil and water, and can be easily dried for continuous use. Furthermore, the CA functional coating exhibits good stability in salt solutions and acidic environments, making it an ideal material for addressing oily wastewater challenges.Highlights The coating obtained by electrostatic spraying and CVD was superhydrophobic. The separation flux and separation efficiencies of coatings is 23977.77 L·m−2·h−1 and 99%. Coatings remain stable under polar environment conditions (pH = 2–12 and NaCl = 1–3 mol/L).