Study On The Surface Carboxyl Functionalization Of PEI-SiO₂material And Its Adsorption Properties

In this paper, two kinds of new materials were prepared: IDA-PEI/SiO₂ and GIY-PEI/SiO₂, through grafting carboxyl groups and controlling the grafting amount to improve the adsorption capacity of the silica gel. Then adsorption properties of these two different new materials were researched. Therefore, this paper mainly included two parts:On the one hand, IDA-PEI/SiO₂’s preparation and adsorption properties were studied by means of the orthogonal experiments and condition experiments. The best preparation conditions were explored, which was 3g PEI-SiO₂, 100 m L mixed solution of ethanol and distilled water in which the volume ratio was 3:1, 1.92 g sodium chloroacetate, 5m L triethylamine at the reaction temperature of 80℃ for 8 hours. The infrared spectrum analysis ensured that the new material was IDA-PEI/SiO₂. Effects of p H, initial concentration, and temperature on adsorption of IDA-PEI/SiO₂ were also researched, and the results showed that with the increase of solution’s p H、initial concentration and adsorption temperature, the IDA-PEI/SiO₂’s adsorption capacity for Mn2+ was increased. By means of fitting adsorption isothermal curve, the results showed that Langmuir and Freundlich isothermal equation could be better described the process of IDA-PEI/SiO₂ material adsorption manganese. Thermodynamic data of the adsorption process △ H0>0 showed the adsorption process of IDA-PEI/SiO₂ materials was an endothermic process; △S0>0 showed the adsorption process of IDA-PEI/SiO₂ materials was an entropy increase process; △G0<0 showed the adsorption process of IDA-PEI/SiO₂ materials was an spontaneous process; Between 303K³33K, |△H0|<|T△S0|,which showed that the adsorption process of IDA-PEI/SiO₂ materials was controlled by the entropy change, not the enthalpy change. Kinetic studies displayed that the process of IDA-PEI/SiO₂ adsorption Mn2+ was a chemical adsorption and a heterogeneous diffusion process, and was controlled by membrane diffusion and intraparticle diffusion.On the other hand, GIY-PEI/SiO₂’s preparation and adsorption properties were investigated. By using the same method, the best preparation conditions were explored, which was 3g PEI-SiO₂, 100 m L mixed solution of ethanol and distilled water in which the volume ratio was 3:1, 1.92 g sodium chloroacetate, 5m L triethylamine at the reaction temperature of 30℃ for 4 hours. Effects of p H, initial concentration and temperature on adsorption of GIY-PEI/SiO₂ were researched, and the results showed that with the increase of solution’s p H, initial concentration, adsorption temperature, the GIY-PEI/SiO₂’s adsorption capacity for Cu2+ was increased. By means of fitting adsorption isothermal curve, the results exhibited that the process of GIY-PEI/SiO₂ material adsorption copper could only be described by Langmuir isothermal equation. Thermodynamic data of the adsorption process △H0>0 showed the adsorption process of GIY-PEI/SiO₂ materials was an endothermic process; △S0>0 demonstrated the adsorption process of GIY-PEI/SiO₂ materials was an entropy increase process; △G0<0 showed the adsorption process of GIY-PEI/SiO₂ materials was an spontaneous process; Between 303K³33K, |△H0|<|T△S0|,which showed that the adsorption process of GIY-PEI/SiO₂ materials was controlled by the entropy change, not the enthalpy change. Kinetic studies displayed that the process of GIY-PEI/SiO₂ adsorption Cu2+ was a chemical adsorption, and controlled by membrane diffusion and intraparticle diffusion.