Synthesis And Oil-water Separation Properties Of Functionalized Switchable Wettability Materials

Nowadays,with the excessive discharge of oil-contained wastewater and the frequent occurrence of oil spill accidents,it has caused serious harm to the ecological environment and human health.It is of great significance to design and develop multifunctional switchable wettability materials with low cost and simple operation in the field of oil-water separation.It has been reported that switchable wettability material can selectively carry out the"oil-removing" and "water-removing" types oil-water separation due to the wettability change under different external stimulations,so that to meet the various demands of oil-water separation occasions.In recent years,the switchable wettability material made great progress,but there are remain some issues that need to be overcome and make better in the synthesis process.For example:it involves some expensive and toxic heavy metal material,fluoro-carbon silame and organic solvent,the preparation process takes long time and requires strict conditions,and the material is vulnerable to limitation of the substrate,which means that it reduces industrial application to some extent.On the basis of the current research status,a multifunctional switchable wettability material is synthesized by using cheap and easy to obtain zinc oxide and silica particals as the main raw materials and adding common low surface energy material for modifcation.The preparation method is simple and easy,and does not need harsh reaction conditions,and avoids the shortcomings of traditional preparation methods.The major study contents of this thesis are as below:(1)A pH-responsive switchable wettability material is prepared by polymerizing silane with double-bond to introduce a special responsive group and then adding silica particles to form a rough structure.The prepared super-wetting material exhibited good pH-induced surface wetting transition and could be reversible between superhydrophobic and superhydrophilic for many times.Based on pH-responsive mechanism,it can control separate various oil-water mixtures on-demand(especially complex multiphase oil-water mixtures),showing admirable separation property.In addition,the prepared material can also exhibit excellent mechanical and chemical stability under harsh conditions.Moreover,the material can withstand a certain amount of carry-capacity when floating on the water due to its admirable water-repellent property.Meanwhile,the material also demonstrates wonderful self-cleaning property and low surface adhesion.Above all these advantages,we have reason to believe that simply prepared switchable wettability material with good chemical and mechanical stability has broad prospects in oil-water separation fields.(2)A switchable wettability material with pH-responsiveness was prepared by a simple and eco-friendly hydrolytic polycondensation method via selective modification with long-carbon chains and amino silanes and then using zinc oxide/silica particles to construct a rough structure.By virtue of the special surface wettability,the prepared material is capable of dealing with a variety of oil-water mixtures,showing superior separation performance and cycle separation performance.Moreover,the prepared material could maintain a stable surface wettability even after long-term work in harsh chemical environment or under rigorous mechanical abrasion,showing prominent durability,and can be applied to different substrates.Moreover,the material also has a certain load-capacity when floating on the water,also shows excellent self-cleaning performance and low surface adhesion property.(3)An ethanol-triggered and highly-stable superamphiphobic material with a switchable wettability has successfully prepared by using zinc oxide particles and organic silane via a simple coating method.The prepared superamphiphobic material could keep high-oil and high-water repellency after treating with various harsh conditions,including aqua regia,hydrochloric acid,sulfuric acid,saturate sodium hydroxide and sodium chloride solutions,ultraviolet exposure,different temperatures(-15?250?)and mechanical abrasion.In addition,the excellent corrosion resistance of the prepared material can be further demonstrated by electrochemical testing.Most importantly,the prepared superamphiphobic material demonstrates the switchable wettability by ethanol treatment,showing the transition from superamphiphobicity to superhydrophilicity/under-water superoleophobicity and superoleophilicity/under-oil superhydrophobicity,which shows high efficiency and high flux of oil-water separation.Moreover,the material can also separate mixtures of highly corrosive liquid and oil with outstanding separation performance.The prepared material has excellent self-cleaning and anti-fouling capabilities of water and oil,and low surface adhesion,which can effectively avoid the pollution of contaminants.All these advantages indicate that the prepared material can play an important role in solving the related severe conditions of marine oil pollution treatment and industrial wastewater treatment.