Study On The Preparation And Adsorption Performance Of Porous Go/Polyurea Monolith

Porous monolith is one of the most ideally suitable materials to remove pollutants from water as the following reasons: the problem that traditional adsorbent materials is difficult to be removed after adsorption has been solved;porous monolith has the larger specific surface area and pore volume;aperture size and distribution range of porous monolith can be varied by controlling the molding methods and production processing;surface characters of porous monolith can be determined by raw material selection and further surface modification.However,nowadays the methods which are used to prepare porous monoliths structures usually require highly costs and complicated processes.Therefore,the large-scale industrialization production and application are both limited.In the view of these facts,developing a facile,economical synthetic method to synthesize porous monoliths architectures has a great significance on both scientific researches and practical applications.In this paper,porous polyurea monolith is simple and convenient preparation under centrifugal force via the reaction between TDI and “green” vapor,which replaces the expensive and toxic amines.Meanwhile,the influences of different processing conditions on the structures and properties of porous monolith are investigated.The results show that the amounts of triethylamine and water vapor,reaction temperature,and the concentration of TDI solution affect the gel time of polyurea respectively.Triethylamine and reaction temperature also affect the pore structure and micro morphology of polyurea porous materials.Moreover,centrifugal moulding is an effective method to form the whole block structure.Monolith materials with different pore structures could be prepared by effecting of different centrifugal forces on the fluid flows in the reaction system.Furthermore,the pore structure of material is affected by TDI concentration directly.And in this research,BET surface area reaches the maximum value of 267.96 m2/g when the concentration of TDI is 0.70 mol/L and the centrifugal speed is 3000 rpm.The TDI concentration also affects on internal microscopic structure,surface property,shrinkage rate,compressive strength and internal hydrogen bond of porous polyurea monolith.TDI covalently grafts onto the surface of GO,and then others active isocyanate groups remain upon the GO surface.In order to obtain the largest amounts of the isocyanate groups on surface of TDI-r GO,the optimal temperature and equilibrium time of reaction are 75 ? and 5 h respectively.When TDI grafts onto the surface of GO,the reduction reaction process of GO occurs at the same time.Moreover,grafting TDI onto the surface of GO enhances the thermal stability of GO and the surface of TDI-r GO changes from hydrophilic to hydrophobic.GO/polyurea porous monolith is prepared in the same method as porous polyurea monolith by adding TDI-r GO as a reinforcement.The results show that the isocyanate groups of TDI-r GO are reacted completely after adding into GO/polyurea porous monolith.TDI-r GO connects with polyurea through chemical bond to form a whole block structure.The amount of GO affects the BET surface area of GO/polyurea porous monolith.The addition of GO could shorten the gel time of polyurea,reduce the linear shrinkage of GO/polyurea porous monolith and improve the mechanical properties of the porous monolith material.More importantly,the fluid flows of reaction system under centrifugal force can be further influenced by adding GO,which leads to affecting the pore structure of materials.Compared with the porous polyurea monolith,GO/polyurea porous monolith is with the narrower pore size distribution,the larger amounts of mesoporous structure and the bigger BET surface area.The BET surface area of GO/polyurea porous monolith reaches the maximum value of 308.74 m2/g when the concentration of TDI is 0.70 mol/L.GO/polyurea porous monolith exhibits high hydrophobic due to the influence of internal microstructure.The absorptions of oily adsorbates by polyurea and GO/polyurea porous monoliths are also investigated in this thesis.The maximum adsorption capacity of monoliths can be achieved at 50 ? and the p H values of 7.The adsorption capacity increases with enlarging of BET surface area and pore volume of monoliths.Polyurea and GO/polyurea porous monoliths exhibit fast adsorption rate for low viscosity oily adsorbates,excellent water oil separation ability and recyclability.Meanwhile they have high adsorption capacity for common organic solvents and oils with adsorption capacities of more than 10 times as weight as themselves.