Preparation Of Graphene-Carboxymethyl Cellulose Aerogels And Their Performance Evaluation

As a three-dimensional macroscopic carbon material,graphene aerogel has great application potential in the field of environmental remediation due to its characteristics of high porosity,low density and large specific surface area.At present,the forming drying of graphene aerogel is still dominated by supercritical drying and vacuum freeze drying,with high equipment requirements and long preparation cycle,which makes it difficult to produce on a large scale.Also,the related studies mostly focus on the preparation methods of bulk graphene aerogels,while few researches on the shape and pore size and size of aerogels,which limits the use of aerogels to some extent.In this paper,with graphite oxide(GO)as the main raw material,and some carboxymethyl cellulose(CMC)introduced,graphene/carboxymethyl cellulose composite bulk aerogel(HGA/CMC)and aerogel beads(GAs/CMC)were prepared through exploring the optimal process conditions under the environmental pressure.HGA/CMC and GAs/CMC were characterized by different characterization methods.The adsorption properties of HGA/CMC and GAs/CMC were evaluated with oil and organic dyes,respectively.The preparation scheme was optimized by investigating the effects of concentration of polydimethylsiloxane and impregnation time on HGA/CMC.The HGA/CMC under the optimal preparation conditions was characterized through SEM,XRD,FT-IR,Raman,XPS and microcomputer controlled electronic universal testing machine.It can be seen that most of the oxygen-containing functional groups were removed and assembled into a three-dimensional network structure after hydrothermal reduction.After 300 cycles of compression,it still maintains its intact morphology and excellent elasticity.HGA/CMC can use its pore volume to fill and absorb oil,and it shows excellent oil-water separation ability.It has good adsorption capacity for oil with different densities,floating oil on water,heavy oil on water bottom and emulsified oil in water.HGA/CMC can be recycled by mechanical extrusion and thermal desorption.The preparation scheme of GAs/CMC was optimized by investigating the effect of coagulating bath type,coagulating bath concentration and freezing treatment temperature,etc.According to the analysis of the above characterization methods,GAs/CMC has rich pore structure and excellent mechanical properties.After 200 times of compression,no damage was observed which means that it has good elasticity.The removal rate of methylene blue(MB)from water by GAs/CMC was close to 100%,and the removal rate remained at about 90% after 30 times of ethanol regeneration and adsorption.Langmuir adsorption isothermal model and pseudo-second-order kinetic model are more suitable to describe the adsorption process.The mechanism of MB adsorption by GAs/CMC mainly depends on electrostatic interaction.The temperature,p H and initial concentration of MB solution all can affect its equilibrium adsorption capacity.When the pore size and particle size of GAs/CMC were reduced,the equilibrium adsorption capacity of MB increased.GAs/CMC can not only absorb oil by its pore volume,but also accumulate oil by the interspaces between aerogel beads.The larger the particle size,the larger the amount of oil by accumulation.