Fabrication Of Superhydrophobic Materials And Their Performance Study In Oil/Water Separation

Oil/water mixtures leaked from offshore crude oil and oily wastewater in industrial manufacturing brings huge challenges to the floating oil treatment,oil/water separation and degradation of oily contamination.As one of the biomimetic materials with special wettability,superhydrophobic materials play a significant role in the fields of surface self-cleaning,anti-corrosion,anti-fouling,fluid drag reduction and oil/water due to their unique hydrophobic and oleophilic interface properties.Aiming at oil/water separation and floating oil treatment,we employed the methods of in-situ growth and dip coating to prepare the superhydrophobic mesh and superhydrophobic PU sponge,respectively,and studied the preparation process,synthesis mechanism,material properties and oil/water separation application simultaneously.The research contents of this article are as follows:A piranha solution was used to hydroxylate the original stainless steel mesh to prepare a hydrophilic surface.Subsequently,by the means of crystal growth in situ and modification of low surface energy molecules,the superhydrophobic stainless steel mesh was obtained.The synergistic effect of Ni-Al LDHs with a flower-like hierarchical and substance with low surface energy is the key to achieving superhydrophobic properties.The water contact angle of the as-prepared mesh was156 °,and the sliding angle was 5 °,thereby achieving the self-cleaning function of the surface.Besides,the separation efficiencies of various oil/water mixtures are higher than 96.5%,as well as the ultra-high separation fluxes.Through repeated tests,ultrasonic and friction treatment,etching of acidic and alkaline solution,immersion of organic solvents and heat treatment,the as-prepared superhydrophobic mesh still maintains stable surface wettability and oil/water separation efficiencies.The rough polyurethane surface was prepared by oxidizing the original polyurethane sponge with Jones reagent.The Ni-Co LDOs were uniformly anchored onto the active surface by dip coating,so that low surface energy molecules can be successfully modified to the surface,thereby achieving superhydrophobicity.In addition,different reaction conditions and parameters are optimized in this paper.The as-prepared superhydrophobic PU sponge possessed the superb morphology with an ultra-high water contact angle of 157 °.Through the connection with a peristaltic pump,the superhydrophobic PU sponge can selectively separate the oil/water mixture under disturbance and non-disturbance conditions.Oil absorption test demonstrated that it can adsorb pure oil with 13-22.4 times of its own weight.After 50 cycles of oil absorption tests,the superhydrophobic PU sponge still maintain a stable oil absorption capacity value for all oil samples with different densities.Meanwhile,durability tests show that the superhydrophobic PU sponge has stability on structure and surface properties.The research in this paper expands the application of bimetal oxides on porous materials.This kind of superhydrophobic material that can be synthesized quickly and on a large scale provides an effective way for practical floating oil treatment and oil/water separation.