Preparation Of Superhydrophobic Plant Fiber Sponge And Its Application In Oil-water Separation

With the rapid development of economy and industry,the problem of pollution of water resources and ecological environment caused by the discharge of oily wastewater and offshore crude oil spill has drawn wide attention from all over the world.Physical adsorption method is considered as the most promising oil treatment method because of its high efficiency,high adsorption capacity and selective collection of oil pollution.However,the materials used currently have the shortcomings of complicated preparation process,easy to cause secondary pollution to the environment and failure to highly viscous crude oil.Therefore,there is an urgent need to find an adsorbent material with high oil absorption rate,environmentally friendly and capable of adsorbing high viscosity oil.Plant fiber is a natural biomass material that is inexpensive,biodegradable and meets the requirements of sustainable development.In addition,given the temperature-sensitive characteristic of crude oil,the use of photothermal effect can effectively reduce its viscosity and improve the flowability.This study proposes to develop a plant fiber sponge with photothermal conversion effect and compression resilience,and apply it to oil adsorption and recovery.The main research contents are as follows:（1）To prepare hydrophobic plant fiber porous materials,this study firstly prepared plant fiber porous materials（PFS）by liquid mechanical foaming method using plant fibers as raw materials.Then,three-dimensional porous plant fiber sponge with hydrophobic properties（PFS@HMDS）was prepared by soaking-steam treatment process using TEOS,hexamethyldisiloxane（HMDS）and ammonia as modifiers.It was concluded that the PFS@HMDS prepared by HMDS treatment time of 2 h had the best hydrophobicity with water contact angle up to 141^o.The PFS@HMDS was used for oil-water separation tests and showed high oil adsorption capacity（15-40 g/g）,demonstrating its potential application in oil-water separation.（2）The graphene oxide-plant fiber porous material with three-dimensional mesh structure was prepared by using plant fiber as raw material and graphene oxide（GO）as modifier.Then,the reduced graphite oxide（r GO）and HMDS synergistically modified plant fiber sponges（PFS@r GO@HMDS）were prepared using NH₃-HMDS steam and high temperature thermal reduction treatment techniques.Due to the excellent mechanical properties and light absorption of r GO,the prepared PFS@r GO@HMDS sponges have excellent hydrophobicity（water contact angle of 145^o）,compressive resilience,and photothermal conversion properties,where the temperature on material surface can reach to 70^oC under one solar illumination.（3）Using PFS@r GO@HMDS sponge as adsorbent material,it presents a great adsorption capacity（27.3-52 g/g）for oil and organic solvents in oil adsorption recovery tests,especially for 52 g/g in crude oil.Due to the excellent photothermal conversion performance of PFS@r GO@HMDS sponge,the heat on the surface of the material can be effectively conducted downward,making it can heat up the high viscosity crude oil at the bottom of the material and promote its adsorption rapidly and effectively under the light condition.Experimentally,the adsorption rate of crude oil by the sponge under illumination is 25 times higher than that under no illumination.With the aid of a miniature diaphragm pump,it was also able to adsorb and recover oil from oil-water solutions in a sustained manner.In this paper,an oil adsorption material with compressive resilience and light absorption was prepared using plant fibers,which solved the problems of low adsorption rate,difficult to degradation and recovery of traditional oil adsorption materials,and provided technical support and theoretical reserve for the industrialization of materials for efficient cleanup of offshore oil spills in the future.