Study On The Preparation Of Superhydrophilic/Superoleophobic Materials And Their Oil/Water Separation Performance

Oil/water separation materials based on superwettability surfaces have become a research hotspot of functional materials,due to their advantages of low cost,high efficiency,and environmental friendliness,and they are of great significance in many aspects such as oil spill cleaning,oily wastewater treatment,and oil extraction.Superhydrophilic/superoleophobic surfaces with "abnormal" wettability are the most ideal choice for oil/water separation,but they are rarely reported.Although some research groups have prepared the surfaces,there are still many problems such as expensive raw materials and reagents,poor mechanical stability,and single function.To address these challenges,we have prepared a series of superhydrophilic/superoleophobic materials and then systematically studied their performance.The main research results are as follows:(1)A remote-controllable superhydrophilic/superoleophobic magnetic sponge was prepared by combining magnetic nanoparticles,fluorine groups and hydrophilic units on the sponge.The sponge can be used as a reusable water sorbent scaffold,and remotely controlled by magnets to collect dispersed water from light or heavy oil without absorbing any oil.The sponge can also be separate the water from oil/water mixtures and oil-in-water emulsions selectively,when fixed into a cone funnel.(2)We prepared a superhydrophilic/superoleophobic titanium dioxide coating with photocatalytic activity.The reversible wetting transition between superoleophobic state and slippery state was realized by water wetting and removing water alternatively.Under UV irradiation,the organic dyes on the surface of the coating and the water polluted by organic dyes were removed with its photocatalytic ability.At the same time,the coating was sprayed on copper mesh and other materials to achieve efficient and stable oil/water separation.(3)A superhydrophilic/superoleophobic shell powder coating was prepared by crushing the discarded shells and chemically modifying.The on-demand separation of oil/water mixtures,emulsions and immiscible organic liquids was realized by changing their wettability through ethanol response.Moreover,the obtained shell powder had good adsorption capacity for organic dyes during the separation process.(4)A polyvinyl alcohol(PVA)composite hydrogel coating was developed,which exhibited excellent oil resistance in air and water.This enhanced oil repellency was still retained after hand-bending,water-jetting and even 1000 cycles of sand abrasion,demonstrating mechanical robustness.Application of the PVA hydrogel-coated copper mesh was demonstrated to separate oil/water and oily mixtures,with separation efficiency being greater than 98%.