Titanic acid nanotubes(H_(2)Ti_(2)O_(4)(OH)_(2))were surface-modified with cetyl alcohol through dehydration reaction because of existence of Ti–OH.The modified nanotubes were characterized by transmission electron m...Titanic acid nanotubes(H_(2)Ti_(2)O_(4)(OH)_(2))were surface-modified with cetyl alcohol through dehydration reaction because of existence of Ti–OH.The modified nanotubes were characterized by transmission electron microscopy(TEM),Fourier Transform Infrared(FT-IR)spectrometry and pho-toluminescence(PL)spectra.The results indicate that the modified nanotubes can be easily dis-persed into organic solvent such as chloroform and toluene in contrast with the unmodified nanotubes,which makes it easier to be assembled by LB technique.Moreover,the Ti-O-CH_(2)(CH_(2))_(14)CH_(3) on the surface of the nanotubes can hinder the adsorption of water and consequently the photoluminescence property of the nanotubes can be stabilized.Even though kept in humid condition or in air for a long time,the modified nanotubes also maintain the special photoluminescence property in the visible region.展开更多
The effects of pH,contact time and natural organic ligands on radionuclide Eu(Ⅲ) adsorption and mechanism on titanate nanotubes(TNTs) are studied by a combination of batch and extended X-ray absorption fine structure...The effects of pH,contact time and natural organic ligands on radionuclide Eu(Ⅲ) adsorption and mechanism on titanate nanotubes(TNTs) are studied by a combination of batch and extended X-ray absorption fine structure(EXAFS) techniques.Macroscopic measurements show that the adsorption is ionic strength dependent at pH < 6.0,but ionic strength independent at pH > 6.0.The presence of humic acid(HA) /fulvic acid(FA) increases Eu(Ⅲ) adsorption on TNTs at low pH,but reduces Eu(Ⅲ) adsorption at high pH.The results of EXAFS analysis indicate that Eu(Ⅲ) adsorption on TNTs is dominated by outer-sphere surface complexation at pH < 6.0,whereas by inner-sphere surface complexation at pH > 6.0.At pH < 6.0,Eu(Ⅲ) consists of ～ 9 O atoms at REu?O ≈ 2.40 in the first coordination sphere,and a decrease in NEu-O with increasing pH indicates the introduction of more asymmetry in the first sphere of adsorbed Eu(Ⅲ).At long contact time or high pH values,the Eu(Ⅲ) consists of ～2 Eu at REu-Eu ≈ 3.60 and ～ 1 Ti at REu-Ti ≈ 4.40 ,indicating the formation of inner-sphere surface complexation,surface precipitation or surface polymers.Surface adsorbed HA/FA on TNTs modifies the species of adsorbed Eu(Ⅲ) as well as the local atomic structures of adsorbed Eu(Ⅲ) on HA/FA-TNT hybrids.Adsorbed Eu(Ⅲ) on HA/FA-TNT hybrids forms both ligand-bridging ternary surface complexes(Eu-HA/FA-TNTs) as well as surface complexes in which Eu(Ⅲ) remains directly bound to TNT surface hydroxyl groups(i.e.,binary Eu-TNTs or Eu-bridging ternary surface complexes(HA/FA-Eu-TNTs)).The findings in this work are important to describe Eu(Ⅲ) interaction with nanomaterials at molecular level and will help to improve the understanding of Eu(Ⅲ) physicochemical behavior in the natural environment.展开更多
Transition element substituted titanic acid nanotubes were fabricated by a hydrothermal method using transition elements (Cr, Mn, Fe, Co, Ni, Cu) doped anatase TiO2 nanopowders as precursors. The properties of product...Transition element substituted titanic acid nanotubes were fabricated by a hydrothermal method using transition elements (Cr, Mn, Fe, Co, Ni, Cu) doped anatase TiO2 nanopowders as precursors. The properties of products were characterized by SEM, TEM, XRD, EDX and Raman spectroscopy. The photodegradation performances of transition elements substituted titanic acid nanotubes for methylene blue were studied. The results show that the photocatalytic activities of Co, Fe and Cr substituted titanic acid nanotubes were increased to different extent, while the photocatalytic activities of Cu, Ni and Mn substituted titanic acid nanotubes were decreased evidently, indicating that these ions were poison to photocatalysts.展开更多
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.90306010 and 20371015)State Key Basic Research'973'Plan of China(Grant No.2002CCC02700).
文摘Titanic acid nanotubes(H_(2)Ti_(2)O_(4)(OH)_(2))were surface-modified with cetyl alcohol through dehydration reaction because of existence of Ti–OH.The modified nanotubes were characterized by transmission electron microscopy(TEM),Fourier Transform Infrared(FT-IR)spectrometry and pho-toluminescence(PL)spectra.The results indicate that the modified nanotubes can be easily dis-persed into organic solvent such as chloroform and toluene in contrast with the unmodified nanotubes,which makes it easier to be assembled by LB technique.Moreover,the Ti-O-CH_(2)(CH_(2))_(14)CH_(3) on the surface of the nanotubes can hinder the adsorption of water and consequently the photoluminescence property of the nanotubes can be stabilized.Even though kept in humid condition or in air for a long time,the modified nanotubes also maintain the special photoluminescence property in the visible region.
基金supported by the National Natural Science Foundation of China(20907055,20971126 & 21077107)the National Basic Research Program of China(2007CB936602 & 2011CB933700)
文摘The effects of pH,contact time and natural organic ligands on radionuclide Eu(Ⅲ) adsorption and mechanism on titanate nanotubes(TNTs) are studied by a combination of batch and extended X-ray absorption fine structure(EXAFS) techniques.Macroscopic measurements show that the adsorption is ionic strength dependent at pH < 6.0,but ionic strength independent at pH > 6.0.The presence of humic acid(HA) /fulvic acid(FA) increases Eu(Ⅲ) adsorption on TNTs at low pH,but reduces Eu(Ⅲ) adsorption at high pH.The results of EXAFS analysis indicate that Eu(Ⅲ) adsorption on TNTs is dominated by outer-sphere surface complexation at pH < 6.0,whereas by inner-sphere surface complexation at pH > 6.0.At pH < 6.0,Eu(Ⅲ) consists of ～ 9 O atoms at REu?O ≈ 2.40 in the first coordination sphere,and a decrease in NEu-O with increasing pH indicates the introduction of more asymmetry in the first sphere of adsorbed Eu(Ⅲ).At long contact time or high pH values,the Eu(Ⅲ) consists of ～2 Eu at REu-Eu ≈ 3.60 and ～ 1 Ti at REu-Ti ≈ 4.40 ,indicating the formation of inner-sphere surface complexation,surface precipitation or surface polymers.Surface adsorbed HA/FA on TNTs modifies the species of adsorbed Eu(Ⅲ) as well as the local atomic structures of adsorbed Eu(Ⅲ) on HA/FA-TNT hybrids.Adsorbed Eu(Ⅲ) on HA/FA-TNT hybrids forms both ligand-bridging ternary surface complexes(Eu-HA/FA-TNTs) as well as surface complexes in which Eu(Ⅲ) remains directly bound to TNT surface hydroxyl groups(i.e.,binary Eu-TNTs or Eu-bridging ternary surface complexes(HA/FA-Eu-TNTs)).The findings in this work are important to describe Eu(Ⅲ) interaction with nanomaterials at molecular level and will help to improve the understanding of Eu(Ⅲ) physicochemical behavior in the natural environment.
文摘Transition element substituted titanic acid nanotubes were fabricated by a hydrothermal method using transition elements (Cr, Mn, Fe, Co, Ni, Cu) doped anatase TiO2 nanopowders as precursors. The properties of products were characterized by SEM, TEM, XRD, EDX and Raman spectroscopy. The photodegradation performances of transition elements substituted titanic acid nanotubes for methylene blue were studied. The results show that the photocatalytic activities of Co, Fe and Cr substituted titanic acid nanotubes were increased to different extent, while the photocatalytic activities of Cu, Ni and Mn substituted titanic acid nanotubes were decreased evidently, indicating that these ions were poison to photocatalysts.
