The Preparation Of Reduced Graphene Sponge And Its Applications In Oil Removal

Oil leakage is greatly harmful to the ecological environment,and the recovery is quite slow,so it has been regarded as the most important pollution nowadays.Currently,the remediation of oil pollution is a hot topic in environment protection.Graphene has unique structure and properties to form 3D porous and hydrophobic structure,thus has natural priorities in adsorbing oil pollutants.To apply graphene in oil adsorption,it is urgent to develop economic and high-performance technology for reduced graphene and the adsorption performance of graphene adsorbents should be tested.In this thesis,we adopted hydrothermal method,vapor hydrazine hydrate reduction method,and liquid hydrazine hydrate reduction to reduce graphene oxide(GO),the reduced graphene sheets that either self-assembled into 3D porous structure or deposited on porous polyester staple,and the reduced graphene sponge was obtained with high capacity for oil adsorption.We simplified the preparation protocol,developed more environmental friendly method,and provided new concepts for graphene environmental nanotechnology and high-performance adsorbents for oil remediation.First,using glucose as the reducing reagent,GO was reduced under hydrothermal condition to prepare reduced graphene sponge.The sample was characterized,tested in adsorbing oils under simulated conditions and regenerated.The hydrazine hydrate vapor was used for the reduction of GO and ultra-light graphene sponge was obtained.The adsorption of oils on ultra-light graphene sponge was tested.Finally,we used hydrazine hydrate and glucose as reducing reagents to prepare graphene/polyester staple composites,and tested its adsorption capacity.By performing aforementioned experiments,the main results were obtained as showing below.1)Using glucose as the reducing reagent,graphene sponge was prepared by the hydrothermal reduction of GO for oil removal.Graphene sheets were reduced byglucose during the hydrothermal treatment and formed 3D porous structure.GS efficiently adsorbed organic solvents and oils with competitive adsorption capacities.GS was able to treat pollutants in pure liquid form and also in the simulated seawater.GS could be easily regenerated by evaporating or burning.After 10 cycles,the adsorption capacity still retained 77% by evaporating and 87% by burning.B)Using vapor reduction method,graphene sponge was prepared and the ultra-high adsorption performance was observed in treating oils and organic solvents.GO was lyophilized and reduced by steamy hydrazine hydrate to produce VPRGS.VPRGS had huge capacity for oils and organic solvents(72-224 g/g).In particular,the adsorption capacity for crude oil reached 165 g/g,suggesting that VPRGS could be applied in oil leakage treatment.VPRGS could treat pollutants both in pure liquid form and in the simulated sea water,where the hydrophobic nature of VPRGS allowed the floating of VPRGS on simulated sea water.VPRGS could be easily regenerated without obvious capacity loss up to 9 cycles.C)Using hydrazine hydrate or glucose as reducing reagents,graphene/polyester staple composites were prepared with low cost and high adsorbing capacity.GO was in situ reduced in the presence of polyester staple by hydrazine hydrate or glucose to form GPSC.GPSC efficiently adsorbed oils and organic solvents with high adsorption capacities.Demonstrations of treating pure oils and those in simulated sea water by GPSC were successfully performed.Due to the loose structure,GPSC adsorbed crude oil quickly with an adsorption capacity of 52 g g-1.During the regeneration,the adsorption capacity of GPSC retained around 78% of the initial capacity up to 9cycles.