Preparation of SiO2/chitosan composite coating on stainless steel mesh for efficient and stable oil/water separation

In recent years, the application of underwater superoleophobic coatings in the field of oil/water separation has received increasing attention, and chitosan (CS) coatings have become a research hotspot due to their advantages of hydrophilicity, non-toxicity, biodegradability, and antibacterial properties. In this work, a SiO2/CS underwater superoleophobic composite coating was prepared on 304 stainless steel mesh by a simple dip-coating method. The underwater oil droplet contact angle (OCA) of the SiO2/CS coating was 151.2 degrees, and the oil droplet showed a stable underwater Cassie state on the coating. The stainless steel mesh with SiO2/CS coating could effectively separate different kinds of oil/water mixtures, and the separation efficiency for the kerosene/ water mixture was 99.2 %. After 20 cycles of separation, the separation efficiency was more than 98 %, indicating that the SiO2/CS coating had excellent recycling performance. In addition, the prepared underwater superoleophobic coating exhibited excellent long-term stability, acid and alkali resistant stability and UV resistant stability. This SiO2/CS coating has promising practical application, which could expand the use of underwater superoleophobic coatings.