Preparation And Oil-water Separation Application Of PH-responsive Superwetting Materials

The sustainable development of modern industry and the frequent occurrence of marine oil spills have had a significant impact on water resources,prompting people to develop advanced technologies or materials for solving oily wastewater.With the deepening of research,intelligent switchable wettability materials have attracted much attention,and there has been certain research and development in the field of oil-water separation.The preparation of such smart materials is inseparable from the construction of rough structures and the introduction of switchable wettability response substances.It can be seen from the reported studies that special wettability materials have been used in the purification of oily wastewater,the separation of oil-water mixture,the cleaning of surface oil spills and other aspects,and achieved remarkable achievements.However,such materials still face some problems,such as harsh processing conditions,expensive raw materials and reagents,simple and single applications.Therefore,using simple and economical methods to prepare low-cost multi-functional intelligent materials will be very popular.In this paper,common and easily available fabrics,sponges,and cottons are selected as substrates,and by introducing substances with p H-responsive functional groups,a multifunctional superwetting material that can transform wettability is prepared.The main research contents of this paper include the following three parts:(1)The fabric and sponge are modified by silica particles,3-aminopropyltriethoxysilane,methyl methacrylate and 3-(trimethoxysilyl)propyl acrylate to prepare the p H-responsive superwetting material.The wettability of the as-obtained material can be reversibly transformed between superhydrophilicity and superhydrophobicity,which can be driven by gravity to separate various oil-water mixtures(especially oil/water/oil mixture)with excellent separation efficiency and flux.In addition,phenol is separated from mixed organic system by chemical reaction,which is rarely reported in the previous literatures,providing a new idea for separating organics.It also offers excellent durability and chemical stability under harsh conditions.Meanwhile,it overcomes the pollution of traditional fluorinated compounds to the environment.(2)Acrylic acid,tridecyl methacrylate and vinyl trimethoxysilane are in situ polymerized on the fabric surface,and two kinds of micro-nano particles(silica and magnesium oxide)that can improve the roughness are added to produce a p H-sensitive multifunctional fabric with controlled wettability,good mechanical durability and excellent reusability.It can successfully separate different oil/water mixtures through two separation devices(vertical type and T-type),demonstrating high permeation flux and excellent separation efficiency.It also allows rapid in situ separation of multiple oil/water/oil mixtures.More importantly,the designed small oil collectors can capture the oil in the water.In addition,the obtained superwetting fabric is capable of separating immiscible organic solvents.(3)The cotton with adjustable wettability is modified by stearic acid and dodecyl trimethoxysilane.Based on the adjustable wettability of the resulting cotton,it can intelligently separate two types of oil/water mixtures,involving layered oil/water mixtures and surfactant-stabilized emulsions,with remarkable separation efficiency.Meanwhile,high speed and high efficiency in situ purification of oily wastewater driven by negative pressure has been successfully achieved.More interestingly,thanks to the photocatalytic properties of Ti O₂,the prepared cotton can also be used to degrade water-soluble dyes.