Preparation Of Coal-based Superhydrophilic Material And Its Application In Oil/Water Separation

With the rapid development of industry,fossil energy sources,mainly oil and coal,have been developed and used on a large scale.However,these fossil energy sources will inevitably produce oily wastewater in the process of mining,transportation and use.If wastewater is discharged into rivers and lakes without treatment,it will affect the normal life activities of animals and plants at least,and severely damage the water ecosystem and bring huge disasters to the living organisms in it.Therefore,how to quickly and efficiently separate and purify oily wastewater has become an urgent problem to be solved at this stage.Superhydrophilic materials have become one of the most popular materials for treating oily wastewater due to their superhydrophilicity,underwater superoleophobicity and excellent separation stability.For oily wastewater,oil and water mainly exist in the form of oil-water mixture,slick oil and oil-water emulsion.In this thesis,aiming at these three types of oily wastewater,a superhydrophilic material that can quickly and efficiently treat oily wastewater has been prepared using rich coal in Xinjiang as the raw material and electrospinning as the main preparation method.The specific work content is as follows:1.Aiming at the separation of oil-water mixture,a superhydrophilic coal-based carbon fiber membrane with a sandwich structure was prepared by electrospinning and hydrothermal methods.The membrane material has the ability to adaptively separate light（heavy）oil/water mixtures.After testing,the separation flux of this material can reach4458Lm^-2h^-1(3176Lm^-2h^-1),and it can still maintain a separation effectiveness of more than 99（97）%after 50 separation cycles.2.Aiming at the separation of slick oil,by adjusting the volume of the spinning solution of the hydrophilic layer during the electrospinning process,a Janus membrane with one hydrophilic side and another hydrophobic side is prepared.The hydrophilic surface of this Janus membrane allows the membrane material to be immersed in water,the hydrophobic surface can keep the material on the water surface without sinking.This feature not only gives the Janus membrane the ability to separate heavy oil-water mixtures,but also gives the material the ability to absorb slick oil on the water surface,which helps the membrane material to solve floating problems.Ideas and methods are provided for the problem of oil cleaning.3.Aiming at the separation of oil-water emulsion,a coal-based carbon microsphere with bowl-shaped structure was prepared by electrospray method.The high surface energy and special groove structure of this microsphere give it the ability to separate oil-water emulsions,and the maximum separation volume of oil-water emulsions can reach 591mLg^-1.In addition,the material is also recyclable.After five separation cycles,the separation amount can still reach more than 97% of the first time,indicating that the material has excellent recyclability.Aiming at various types of oily wastewater,this thesis uses coal as the raw material to prepare superhydrophilic materials with oil-water separation ability by electrospinning,which is expected to be used in the treatment of oily wastewater in the future.