Super-Wetting Material Design Based On The Candle Soot Template And Its Application In Oil-Water Separation

The oily wastewater produced by industrial production and human life not only pollutes the water source and destroy the ecological environment,but also threatens human life and health.However,traditional oil degradation methods have the disadvantages of damaging soil structure,producing secondary pollution and high cost.How to treat oily wastewater in an efficient and environmentally friendly way is of great significance to protect the environment and recover resources.At the same time,it is also a major problem that needs to be solved in the field of oil-water separation worldwide.Inspired by nature,researchers have prepared oil-water separation materials with superwetting surfaces based on the synergistic mechanism of surface rough structures and chemical groups,but most of the reported materials suffered from complicated preparation steps,high costs,toxic reagents and poor mechanical stability,which seriously limit their promotion and application in the field of oil-water separation.As a convenient,high efficiency,green and inexpensive method for the preparation of super-wetting surfaces,the candle soot template method has obvious advantages in the preparation of oil-water separation materials,thus attracting widespread attention from scholars and industries at home and abroad.Therefore,two different types of superhydrophobic-superoleophilic and superhydrophilic-underwater superoleophobic oil-water separation meshes were prepared in this project based on candle soot template idea,and the specific contents and results are as follwos:(1)Superhydrophobic-superoleophilic mesh based on candle soot template.100-mesh stainless steel mesh was used as the base material,of which nano silica(NS)rough structures were constructed on the surface by candle soot template method.Then the mesh surface was modified by polydimethylsiloxane(PDMS)with low surface energy to prepare NS-PDMS mesh with superhydrophobic-superoleophilic properties,and a series of performance studies were carried out on NS-PDMS mesh.The water contact angle of NS-PDMS mesh over 150°,and the sliding angle was about 3°,which demonstrates the excellent superhydrophobic properties of NS-PDMS mesh.In addition,water droplets,soy sauce,coffee and other liquids can slide off the surface of NS-PDMS mesh easily,showing its excellent self-cleaning performance.In the oil-water separation experiment,the separation efficiencies of NS-PDMS mesh for different oil-water mixtures were all above 99%,and the separation efficiency remained stable in the acid,alkali,saline and cold water.Even after being soaked in saline and organic solvents for a long time,NS-PDMS mesh still maintained efficient oil-water separation ability,showing its excellent chemical stability.During sand blasting experiments,the surface of NS-PDMS mesh still had high surface roughness even after being damaged by sand,and after re-modifying with PDMS,NS-PDMS mesh was able to gain the ability of superhydrophobicity and oil-water separation,showing the value of reutilization.(2)Superhydrophilic-underwater superoleophobic mesh based on candle soot template.The composite structure of nano silica-calcium alginate(NS-CA)hydrogel was built via candle soot template and dip-coating methods on the surface of 100-mesh stainless steel mesh,and NS-CA mesh with superhydrophilic-underwater superoleophobic was prepared.The underwater contact angle of oil droplet was 160° and the underwater oil sliding angle was about 1° on NS-CA mesh surface.The adhesion force to vegetable oils and organic solvents was close to 0 ?N.NS-CA mesh had excellent separation efficiency and water flux for vegetable oils and organic solvents.NS-CA mesh exhibited excellent and stable oil-water separation performance in acid,alkali,saline,high and low temperature environments.NSCA mesh has stable oil-water separation performance even after being immersed in saline for5 days,showing excellent chemical stability.After 20 cycles separation experiments,the oilwater separation efficiency of NS-CA mesh only decreased by 1%.During sand blasting experiments,the separation efficiency of the NS-CA mesh had no obvious change even after2 kg sand blasting,which exhibited excellent mechanical stability.