Super-hydrophilic/Water Super-oleophobic Modified Membrane For Efficient Oil-water Separation

Simple,new and environmentally friendly materials and methods were used for oil-water separation,using a uniform coating of PVA/chitosan/SiO₂ composite coating on the surface of polyurethane sponge and cotton fabric with glutaraldehyde to achieve superhydrophilic/underwater superhydrophobic.These new types of modified sponge and cotton fabric can be used not only to continuously separate different oil-water mixtures,but also to have superior corrosion resistance and to separate oily wastewater from acidic,alkaline and high-concentration salt solutions.The surface roughness was characterized by using a scanning electron microscope,the good thermal stability was characterized by thermogravimetric analyzer,and the superhydrophilicity was characterize by contact angle meter.In addition,the materials exhibit excellent reusability and can be reused more than 10 times.The separation efficiency of oil and water on cotton fabric is still as high as 99.5%,the flux is 4200Lm^-2h^-1,and the separation efficiency on polyurethane sponge is as high as 99.3%,the flux is 3600 Lm^-2h^-1.Therefore,such simple,efficient,economical and environmentally friendly materiasls have broad prospects in practical applications.At the same time,a superhydrophilic/underwater superhydrophobic polyacrylamide/TiO₂ composite membrane was prepared by using a simple impregnation method on cotton fabric as the base material.And the effect of coating wettability,morphology and stability of different mass ratios of polyacrylamide and TiO₂ were studied.The novel membrane can be used for efficient oil-water separation.It can not only separate various mixtures of oil and water,the separation efficiency is above 99%,and the flux is as high as 4980 Lm^-2h^-1,but also separate mixtures of different pH values and different concentrations of NaCl solution and oil with high separation efficiency.The membrane also has high thermal stability and reusability.It can be reused 10 times and the separation efficiency can still be up to 99%.It is therefore also a new,efficient,green and easy to application material.