Effects of varying SiO2 content on the superhydrophilic properties of PAM/CSn semi-IPN hydrogels and their applications in oil-water and emulsion separation

Hydrogels have become a focal point in oil-water separation technologies owing to their pronounced hydrophilicity and manageable viscosity. However, traditional hydrogels often suffer from subpar physical and mechanical strength. Our research introduces a semi-interpenetrating network (Semi-IPN) hydrogel composed of polyacrylamide and chitosan network (PAM/CSn), distinguished by both physical and chemical cross-linking to boost mechanical robustness. Experimental results demonstrate that polyacrylamide/chitosan network-SiO 2 @stainless steel mesh (PAM/CSn-SiO 2 @SSM) not only displays exceptional superoleophobic properties underwater (OCA >150°) but also maintains over 99 % separation efficiency across >20 cycles in diverse conditions including acidic, alkaline, and saline environments. In addition, the composite coating excelled in self-cleaning of viscous oils and in oil-in-water emulsion oil removal (92 %). Compared with previous polyacrylamide (PAM) hydrogels, our composite coating also possesses corrosion resistance to acids and alkalis and excellent ability to separate oil-water mixtures in harsh environments. These findings underscore the substantial potential of polyacrylamide/chitosan network-SiO 2 @stainless steel mesh (PAM/CSn-SiO 2 @SSM) composites in enhancing oil-water separation techniques.