Silica and montmorillonite-supported silica nanoparticles were prepared via an acid one step sol-gel process. The synthesized solids were characterized using XRD, FTIR, TEM and N2 adsorption. The effect of preparing t...Silica and montmorillonite-supported silica nanoparticles were prepared via an acid one step sol-gel process. The synthesized solids were characterized using XRD, FTIR, TEM and N2 adsorption. The effect of preparing temperatures on the structure and properties of the silica nanoparticles were studied. The results show that the increase of annealing temperature from 25 to 200℃, don’t change amorphous state of silica. While for montmorillonite-supported silica the clay platelets are delaminated during the sol-gel process. TEM results showed that the average particle size of silica is increased by increasing temperature due to the particle sintering and the clay-silica nanoparticles possessed core–shell morphology with diameter of 29 nm. The surface area measurements showed that by increasing annealing temperature the surface area was decreased due to aggregation of particle. The clay-silica sample showed lower average pore width than that of the silica prepared at 200℃ indicating that it has a macropores structure. The adsorption efficiency of the prepared samples was tested by adsorption of protoporphyrin IX. The highest adsorption efficiency was found for SiO2 prepared at 200℃. Temkin model describe the equilibrium of adsorption of protoporphyrin IX on caly-silica nanoparticles under different conditions.展开更多
In this study, a modified silica gel surface with a hydrophobic ionic liquid (SG-1,10-PhenanNTf2) was used as an adsorbent for a selective extraction of coumarin prior to its determination by use of high performance l...In this study, a modified silica gel surface with a hydrophobic ionic liquid (SG-1,10-PhenanNTf2) was used as an adsorbent for a selective extraction of coumarin prior to its determination by use of high performance liquid chromatography. Results demonstrated that SG-1,10-PhenanNTf2 phase had a good adsorption capacity up to 85.29 mg?g?1, high selectivity, good site accessibility and fast binding kinetics toward coumarin. The adsorption capacity for coumarin was improved by 62.33% with the SG-1,10-PhenanNTf2 phase as compared to activated silica gel. Adsorption isotherm data displayed that the adsorption process was mainly monolayer on a homogeneous adsorbent surface, confirming the validity of Langmuir adsorption isotherm model. The adsorption of coumarin on the SG-1,10-PhenanNTf2 phase was accomplished after only 60 min contact time. Results of kinetic models showed that the adsorption of coumarin on the SG-1,10-PhenanNTf2 phase obeyed a pseudo second-order kinetic model. Finally, the efficiency of this methodology was confirmed by applying it to real water samples.展开更多
A ternary Sm（ Ⅲ ） complex with salicylate （sal-） and o-phenanthroline （phen） was synthesized and incorporated in silica matrix by sol-gel method. The luminescence behavior of the complex in silica gel was studi...A ternary Sm（ Ⅲ ） complex with salicylate （sal-） and o-phenanthroline （phen） was synthesized and incorporated in silica matrix by sol-gel method. The luminescence behavior of the complex in silica gel was studied compared with that of the pure complex by means of emission, excitation spectra and thermogravimetic analysis. The results indicate that the fluorescence intensity ratio of the ^4G5/2→^6H9/2 transition to the ^4G5/2→^6H5/2 transition in silica gel doped with Sm（sal）3 （phen） is lower than that of the pure Sm（sal）3（phen）. The thermal stability of Sm（sal）3（phen） is enhanced greatly by the introduction of the complex into silica matrix. An isolated and chemical inert environment of the complex appears to be responsible for the thermal stability enhancement in silica gel.展开更多
In the process of synthesis of nanometer SiC precursors with sol-gel of SiO2 and lignin , the products of all sizes required can be controlled by the concentration of reac-t ants , pH, temperature, reaction and ageing...In the process of synthesis of nanometer SiC precursors with sol-gel of SiO2 and lignin , the products of all sizes required can be controlled by the concentration of reac-t ants , pH, temperature, reaction and ageing time , and so on . The best conditions in this research are : the concentration of Na2SiO3 and organic matters are 4. 50% and 26.4% respectively, pH = 3.3 , T = 65℃ , ageing time is 30min , dried at 150 ℃ , the size of SiC precursors is about 2.0μm .展开更多
Under different annealing temperatures, Eu 3+ doped SiO 2 gel and glass were prepared by sol gel method, and the structure and luminescent properties were studied with excitation spectra, emission spectra, IR ...Under different annealing temperatures, Eu 3+ doped SiO 2 gel and glass were prepared by sol gel method, and the structure and luminescent properties were studied with excitation spectra, emission spectra, IR and DTA TG. The results show that the fluorescent intensity tends to get stable when concentration of Eu 3+ doped is above 1 86 % (mass fraction) most water absorbed by the gel was removed at 300 ℃, and that the emission spectrum of Eu 3+ , with peaks at 614, 588, 577 nm, is due to 5D 0→ 7F 2, 5D 0→ 7F 1, 5D 0→ 7F 0 transitions, and the excitation peaks at 318, 362, 380, 393, 412 and 462 nm were observed. These results illustrate that the temperature range of 300～500 ℃ is critical for the structure conversion from gel to glass, and the fluorescence is strongly quenched by water.展开更多
SiO2 aerogels were produced from tetraethyl orthosilicate （TEOS） as silicon resources,ethanol as solvent and watery HCl or ammonia by sol-gel method and surface modification at ambient pressure.Scanning electronic m...SiO2 aerogels were produced from tetraethyl orthosilicate （TEOS） as silicon resources,ethanol as solvent and watery HCl or ammonia by sol-gel method and surface modification at ambient pressure.Scanning electronic microscopy,Fourier transform infrared spectrometer （FT-IR）,pore size distribution measurement,packing density and some other experiment methods were used to characterize the morphology and pore structure and other properties of the silica aerogels.The results show that the silica aerogels have a typical nano-porous microstructure with hydrophobic property.It was discovered that SiO2 aerogels have better properties when the preparation condition is as following the watery HCl concentration is 1%,the aging reagent is CH3CHOHC4H9,the aging time is 20 d,the volume concentration of trimethylchlorosilane （TMCS） in hexane is 6% and the surface modification time is 24 h.展开更多
文摘Silica and montmorillonite-supported silica nanoparticles were prepared via an acid one step sol-gel process. The synthesized solids were characterized using XRD, FTIR, TEM and N2 adsorption. The effect of preparing temperatures on the structure and properties of the silica nanoparticles were studied. The results show that the increase of annealing temperature from 25 to 200℃, don’t change amorphous state of silica. While for montmorillonite-supported silica the clay platelets are delaminated during the sol-gel process. TEM results showed that the average particle size of silica is increased by increasing temperature due to the particle sintering and the clay-silica nanoparticles possessed core–shell morphology with diameter of 29 nm. The surface area measurements showed that by increasing annealing temperature the surface area was decreased due to aggregation of particle. The clay-silica sample showed lower average pore width than that of the silica prepared at 200℃ indicating that it has a macropores structure. The adsorption efficiency of the prepared samples was tested by adsorption of protoporphyrin IX. The highest adsorption efficiency was found for SiO2 prepared at 200℃. Temkin model describe the equilibrium of adsorption of protoporphyrin IX on caly-silica nanoparticles under different conditions.
文摘In this study, a modified silica gel surface with a hydrophobic ionic liquid (SG-1,10-PhenanNTf2) was used as an adsorbent for a selective extraction of coumarin prior to its determination by use of high performance liquid chromatography. Results demonstrated that SG-1,10-PhenanNTf2 phase had a good adsorption capacity up to 85.29 mg?g?1, high selectivity, good site accessibility and fast binding kinetics toward coumarin. The adsorption capacity for coumarin was improved by 62.33% with the SG-1,10-PhenanNTf2 phase as compared to activated silica gel. Adsorption isotherm data displayed that the adsorption process was mainly monolayer on a homogeneous adsorbent surface, confirming the validity of Langmuir adsorption isotherm model. The adsorption of coumarin on the SG-1,10-PhenanNTf2 phase was accomplished after only 60 min contact time. Results of kinetic models showed that the adsorption of coumarin on the SG-1,10-PhenanNTf2 phase obeyed a pseudo second-order kinetic model. Finally, the efficiency of this methodology was confirmed by applying it to real water samples.
基金Project supported bythe Science and Research Planning Project of Zhejiang Provincial Education Department (0424XP18)
文摘A ternary Sm（ Ⅲ ） complex with salicylate （sal-） and o-phenanthroline （phen） was synthesized and incorporated in silica matrix by sol-gel method. The luminescence behavior of the complex in silica gel was studied compared with that of the pure complex by means of emission, excitation spectra and thermogravimetic analysis. The results indicate that the fluorescence intensity ratio of the ^4G5/2→^6H9/2 transition to the ^4G5/2→^6H5/2 transition in silica gel doped with Sm（sal）3 （phen） is lower than that of the pure Sm（sal）3（phen）. The thermal stability of Sm（sal）3（phen） is enhanced greatly by the introduction of the complex into silica matrix. An isolated and chemical inert environment of the complex appears to be responsible for the thermal stability enhancement in silica gel.
文摘In the process of synthesis of nanometer SiC precursors with sol-gel of SiO2 and lignin , the products of all sizes required can be controlled by the concentration of reac-t ants , pH, temperature, reaction and ageing time , and so on . The best conditions in this research are : the concentration of Na2SiO3 and organic matters are 4. 50% and 26.4% respectively, pH = 3.3 , T = 65℃ , ageing time is 30min , dried at 150 ℃ , the size of SiC precursors is about 2.0μm .
文摘Under different annealing temperatures, Eu 3+ doped SiO 2 gel and glass were prepared by sol gel method, and the structure and luminescent properties were studied with excitation spectra, emission spectra, IR and DTA TG. The results show that the fluorescent intensity tends to get stable when concentration of Eu 3+ doped is above 1 86 % (mass fraction) most water absorbed by the gel was removed at 300 ℃, and that the emission spectrum of Eu 3+ , with peaks at 614, 588, 577 nm, is due to 5D 0→ 7F 2, 5D 0→ 7F 1, 5D 0→ 7F 0 transitions, and the excitation peaks at 318, 362, 380, 393, 412 and 462 nm were observed. These results illustrate that the temperature range of 300～500 ℃ is critical for the structure conversion from gel to glass, and the fluorescence is strongly quenched by water.
基金Sponsored by the National Research Fund for Fundamental Key Projects (2002CB211800)Project of Beijing Key Laboratory of Environmental Science and Engineering (SYS100070416)
文摘SiO2 aerogels were produced from tetraethyl orthosilicate （TEOS） as silicon resources,ethanol as solvent and watery HCl or ammonia by sol-gel method and surface modification at ambient pressure.Scanning electronic microscopy,Fourier transform infrared spectrometer （FT-IR）,pore size distribution measurement,packing density and some other experiment methods were used to characterize the morphology and pore structure and other properties of the silica aerogels.The results show that the silica aerogels have a typical nano-porous microstructure with hydrophobic property.It was discovered that SiO2 aerogels have better properties when the preparation condition is as following the watery HCl concentration is 1%,the aging reagent is CH3CHOHC4H9,the aging time is 20 d,the volume concentration of trimethylchlorosilane （TMCS） in hexane is 6% and the surface modification time is 24 h.
