Praseodymium incorporated AIPO-5 molecular sieves for aerobic oxidation of ethylbenzene.

PrAlPO-5 with (Al + P)/Pr ratios of 25, 50, 75 and 100 molecular sieves were successfully synthesized by hydrothermal method. These molecular sieves were characterised using XPS, TPD-NH3, ex-situ pyridine adsorbed IR, TPR, TGA, 27Al and 31P MAS-NMR and ESR studies. The incorporation of praseodymium in the framework of AlPO-5 was confirmed by XRD, DRS UV-vis and 27Al and 31P MAS-NMR analysis. ESR spectrum showed the presence of adsorbed oxygen. The nature and strength of acid sites were identified by ex-situ pyridine adsorbed IR and TPD-NH3. The BET surface area was found to be in the range of 238-272 m2 g(-1). The catalytic activity of the molecular sieves was tested for the liquid phase aerobic oxidation of ethylbenzene. Acetophenone was found to be the major product with more than 90% ethylbenzene conversion. ICP-OES analysis revealed the presence of praseodymium intact in the framework of AlPO-5 up to five cycles.

A novel magnetic Fe3O4/SiO2 core-shell nanorods for the removal of arsenic.

A novel magnetic Fe3O4 core-shell nanorods (MCSNs) were synthesized by crosslinking amine functionalized Fe3O4@SiO2 core-shell nanoparticles with 1,2-bromochloroethane. These nanorods were then protonated with dilute HCl. The MCSNs nanorods were characterized using FT-IR, N2 adsorption, VSM, SEM and TEM. The surface area of MCSNs nanorods was found to be 335 m2/g, which is higher than bare iron oxide and amine functionalized Fe3O4@SiO2. These nanorods were used simultaneously as ion-exchanger and adsorbent for the removal of arsenic from aqueous solution. It exhibited high adsorption capacity for arsenic. The kinetic study revealed that adsorption equilibrium attained within five min. The adsorbed arsenic on the nanorods were removed by magnetic separation and regenerated by acid treatment. The percentage removal of arsenic was more than 99%. Such nanorods can be used to remove not only arsenic but also other anions from potable water.

Visible-light active mesoporous ce incorporated TiO2 for the degradation of 4-chlorophenol in aqueous solution.

Efficient visible-light active mesoporous Ce incorporated TiO2 nanoparticles have been prepared by sol-gel method using Pluranic P123 as the structure directing agent. Low angle XRD and BET analysis revealed the mesoporous nature of the nanoparticles. The incorporation of Ce4+ into TiO2 and Ti4+ into CeO2 is evident from the slight shift in their respective XRD patterns. XPS results exhibited +4 oxidation state for Ce and Ti ions. UV-DRS analysis of Ce incorporated TiO2 demonstrated red shift in the absorbance spectrum of TiO2, which is mainly due to the formation of Ce impurity states below the conduction band edge of TiO2. The photocatalytic activity of mesoporous Ce incorporated TiO2 nanoparticles has been evaluated in the degradation of 4-chlorophenol in aqueous solution under solar light illumination. Pure mesoporous TiO2 showed poor visible-light activity due to its small absorption of sun light. Mesoporous Ce incorporated TiO2 photocatalysts exhibited the highest photocatalytic activity compared to pristine mesoporous TiO2 and CeO2. The incorporation of Ce4+ in TiO2 played a major role in the enhancement of photocatalytic activity under sun light.

Sol-gel synthesis of mesoporous mixed Fe2O3/TiO2 photocatalyst: application for degradation of 4-chlorophenol.

Photosensitization of TiO2 with other transition metal oxides can extend its light absorption property in the visible region. Such materials could emerge as excellent catalysts for solar photocatalytic degradation. In the present study mesoporous Fe2O3/TiO2 (10, 30, 50, 70 and 90 wt% Fe2O3) photocatalysts were synthesized by sol-gel process and characterized using different techniques. The XRD patterns exhibited the presence of mesoporous structure and isomorphic substitution of Fe(3+) in TiO2 at low Fe(3+) loading and Ti(4+) in Fe2O3 at high Fe(3+) loading. The XPS results revealed the presence of Ti(4+) and Fe(3+) in Fe2O3/TiO2 materials. The DRS UV-vis spectra showed a shift in the band gap excitation of TiO2 to longer wavelength, thus illustrating incorporation of Fe(3+) in TiO2. In addition, free TiO2 and Fe2O3 particles were also present. Their photocatalytic activity was tested for the degradation of 4-chlorophenol in aqueous medium using sunlight. The activity of the catalysts followed the order: meso-30 wt% Fe2O3/TiO2>meso-10 wt% Fe2O3/TiO2>meso-50 wt% Fe2O3/TiO2>meso-70 Fe2O3/TiO2>meso-90 wt% Fe2O3/TiO2>meso-Fe2O3>meso-TiO2. This order concluded that mesoporous Fe2O3/TiO2 could be an active catalyst for pollutant degradation, as TiO2 with framework Fe(3+) and photosensitization with free Fe2O3 were involved in the activity.