Modification conditions determine the surface topography and the active material phase composition of a catalyst.To study the influence of modification on a carbon-based sorbent,coconut husk activated carbon(AC)which ...Modification conditions determine the surface topography and the active material phase composition of a catalyst.To study the influence of modification on a carbon-based sorbent,coconut husk activated carbon(AC)which was activated using HNO_(3)and modified by FeSO4 and Fe(NO_(3))_(3)was examined.The pore textures and surface chemical characteristics of the carbon materials were examined by scanning electron microscopy(SEM),Brunner-Emmet-Teller(BET),X-ray diffraction(XRD)and Fourier transform infrared(FTIR)spectroscopy.The surface topography,the pore structure,active materials,and functional groups of AC,AC modificated by HNO3(HNO3/AC for short),and AC modificated by FeSO4 and Fe(NO3)3(Fe/AC for short)were systematically studied.Subsequently,the mechanism of modifying the conditions for the carbon materials was determined.Results showed that the surface micro topography of HNO3/AC became unsystematic and disordered.After modification with FeSO4,the ferriferous oxide was mainly present as a near-spherical crystal.Ferriferous oxides from Fe(NO_(3))_(3)modification mainly exhibited a plate shape.HNO_(3)modification could enlarge the pores but decrease the specific surface area of AC.FeSO_(4)modification resulted in a new net post structure in the pore canal of AC.Fe(NO_(3))_(3)modification caused the pore space structure to develop in the interior,and a higher calcination temperature was useful for ablation.The ash content of the AC was substantially reduced upon HNO_(3)modification.Upon FeSO_(4)modification,α-FeOOH,α-Fe_(2)O_(3)andγ-Fe_(2)O_(3)coexisted under the condition of a lower concentration of FeSO_(4)and a lower calcination temperature,and a higher FeSO_(4)concentration and calcination temperature generated moreα-Fe_(2)O_(3).The same Fe(NO_(3))_(3)modification and a higher calcination temperature were beneficial to the minor chipping formation ofγ-Fe_(2)O_(3).A higher Fe(NO_(3))_(3)loading produced a lower graphitization degree.HNO_(3)modification formed various new oxygen-containing functional groups and few nitrogen-containing groups.Based on the cover,FeSO_(4)and Fe(NO_(3))_(3)modification could decrease the oxygen-containing and nitrogen-containing functional groups.These results could optimize the modification condition and improve physical and chemical properties of carbon-based sorbents.展开更多
基金General Project of Science and Technology Plan of Yunnan Science and Technology Department,China(No.2019FB077)Open Fund of Key Laboratory of Ministry of Education for Metallurgical Emission Reduction and Comprehensive Utilization of Resources,China(No.JKF19-08)。
文摘Modification conditions determine the surface topography and the active material phase composition of a catalyst.To study the influence of modification on a carbon-based sorbent,coconut husk activated carbon(AC)which was activated using HNO_(3)and modified by FeSO4 and Fe(NO_(3))_(3)was examined.The pore textures and surface chemical characteristics of the carbon materials were examined by scanning electron microscopy(SEM),Brunner-Emmet-Teller(BET),X-ray diffraction(XRD)and Fourier transform infrared(FTIR)spectroscopy.The surface topography,the pore structure,active materials,and functional groups of AC,AC modificated by HNO3(HNO3/AC for short),and AC modificated by FeSO4 and Fe(NO3)3(Fe/AC for short)were systematically studied.Subsequently,the mechanism of modifying the conditions for the carbon materials was determined.Results showed that the surface micro topography of HNO3/AC became unsystematic and disordered.After modification with FeSO4,the ferriferous oxide was mainly present as a near-spherical crystal.Ferriferous oxides from Fe(NO_(3))_(3)modification mainly exhibited a plate shape.HNO_(3)modification could enlarge the pores but decrease the specific surface area of AC.FeSO_(4)modification resulted in a new net post structure in the pore canal of AC.Fe(NO_(3))_(3)modification caused the pore space structure to develop in the interior,and a higher calcination temperature was useful for ablation.The ash content of the AC was substantially reduced upon HNO_(3)modification.Upon FeSO_(4)modification,α-FeOOH,α-Fe_(2)O_(3)andγ-Fe_(2)O_(3)coexisted under the condition of a lower concentration of FeSO_(4)and a lower calcination temperature,and a higher FeSO_(4)concentration and calcination temperature generated moreα-Fe_(2)O_(3).The same Fe(NO_(3))_(3)modification and a higher calcination temperature were beneficial to the minor chipping formation ofγ-Fe_(2)O_(3).A higher Fe(NO_(3))_(3)loading produced a lower graphitization degree.HNO_(3)modification formed various new oxygen-containing functional groups and few nitrogen-containing groups.Based on the cover,FeSO_(4)and Fe(NO_(3))_(3)modification could decrease the oxygen-containing and nitrogen-containing functional groups.These results could optimize the modification condition and improve physical and chemical properties of carbon-based sorbents.
