Optimization Of Preparation Process And Performance Evaluation Of Graphene Based Aerogels

The preparation process of graphene based aerogels was optimized,which made the process conditions and preparation methods be more suitable for industrial production.The properties of the aerogels were also improved.The internal pore structure,elasticity,hydrophobicity and static adsorption capacity of the prepared graphene aerogels were measured.The kinetic adsorption parameters of the aerogels prepared were determined with water containing emulsified diesel oil.The law followed in the adsorption process was investigated.Pure graphene aerogel?PGA?can be prepared by raw materials of low purity graphene oxide?dGO?and sol-gel method?SG?.The density in air for PGA is about 8.09 mg·cm^-3,which belongs to ultra-light material,and the hydrophobic angle is 103.8°;PGA has good compression elasticity,maximum strain of 65%without damage of the internal structure can be achieved.PGA has a certain adsorption effect on methylene blue,and the static saturated adsorption capacities for n-hexane,gasoline,diesel,toluene and carbon tetrachloride are all related to the internal pore structure and the density of the organic matter,which can be reused by burning regeneration.The adsorption process of PGA for emulsified diesel oil in water follows quasi-second-order kinetics,and the adsorption rate increases with the increase of temperature.The adsorption activation energy is E_a=18.73kJ·mol^-1,and the adsorption process is divided into three stages under different temperatures:PGA adsorption in marcropores pores and internal diffusion between mesopore and small pore.The adsorption rate of the first stage is the largest and the initial adsorption behavior is weak and moderate in the first stage of the internal macroporous diffusion and the small pore diffusion.The carboxyl carbon nanotube-graphene composite aerogel was prepared by hydrothermal reduction method.When the mass ratio of GO to CNTs-COOH was 3:1,the composite aerogel showed the best properties.The apparent morphology and elasticity of the aerogels obtained are optimal.The density of the composite aerogels is about 9.64mg·cm^-3.Through observation of scanning electron microscopy?SEM?,it can be concluded that GO and CNTs-COOH have been successfully reduced and assembled into three dimensional aerogel pore structure.The adsorption capacity of CGA on emulsified diesel oil in water increased rapidly in the first 6 minutes and reached adsorption equilibrium after 0.5 h.The equilibrium adsorption capacity increased with the increase of temperature under 298K³28K.The adsorption process followed the quasi-second-order kinetic model.The apparent activation energy of the system is E_a=7.10kJ·mol^-1.The adsorption of emulsified oil can be divided into external surface adsorption process and internal pore adsorption process by means of intraparticle diffusion model analysis.A graphene aerogel VGA,which can be dried under normal pressure,was prepared by two-step reduction and ethanol post-treatment.The material has a regular mesh structure and can be compressed to a strain of 80%without being destroyed.The density is about 15.05mg·cm^-3,and the static adsorption capacity for straight-run diesel reached 58.18 g·g^-1.