S. Sakunthala Madhavendra

Hydrodechlorination of chlorobenzene on Nb2O5-supported Pd catalysts influence of microwave irradiation during preparation on the stability of the catalyst

Catalytic hydrodechlorination of chlorobenzene was studied on Pd/Nb2O5 catalysts prepared by the conventional and the microwave heating techniques. The catalysts were characterized by X-ray diffraction (XRD), BET surface area, hydrogen chemisorption and scanning electron microscopy (SEM). The time-on-stream studies reveal that the microwave-irradiated catalyst exhibits better resistance towards deactivation than the conventionally prepared catalyst. Microwave irradiation also seems to be preferable than the high-temperature reduction adopted to increase the particle size. The microwave-irradiated catalyst also shows higher residual activity than the electrically heated catalyst at all reaction temperatures studied. This is attributed to the formation of larger particles of palladium which is in conformity with the basic observation made in the literature that hydrodechlorination is more facile on low-dispersed Pd catalysts.

Furanoid sugar amino acid based peptidomimetics: well-defined solution conformations to gel-like structures

Abstract Furanoid sugar amino acid based peptide and a dimer fold into pseudo β-turn-like structures in DMSO-d6 with intramolecular H-bonds between LeuNH and sugarOH. In CDCl3, they display a repeating β-turn-type secondary structure at lower concentrations and start to form aggregates that gradually turn into excellent organogels as the concentrations are increased, a phenomenon observed for the first time in sugar amino acid containing peptides.

Hydrodechlorination of chlorobenzene over MgO MODIFIED Pt/Al2O3 CATALYSTS

Al 2 O 3 was modified with MgO and was used as support in the preparation of platinum catalysts. The prepared catalysts were characterised by Scaning electron microscope (SEM), X-ray diffraction (XRD), chemisorption of H 2 and BET surface area and were tested for their activity in hydrodechlorination of chlorobenzene. The investigations show that support modification reduces catalyst deactivation remarkably. The catalysts are also found to be active and selective for the hydrodechlorination of chlorobenne reaction.

Effect of preparation method on the dispersion and activity of V2O5–Al2O3 catalysts

Al2O3-supported 12 wt% V2O5 catalysts were prepared by physically grinding both the oxides (solid–solid wetting) and by wet impregnation techniques. The physical mixtures (PM) were treated under two different conditions – calcination in the presence of dry oxygen and wet oxygen. The catalysts were characterized by x-ray diffraction, scanning electron microscopy, electron spin resonance and oxygen and carbon dioxide chemisorptions. Vanadia dispersion of the physical mixture calcined in the presence of wet oxygen was found to be very similar to that of the V2O5/Al2O3 catalyst prepared by the standard impregnation method. Methanol partial oxidation activities of these catalysts were also comparable.

Structural characterization and water turbidity removing efficacy of Portulaca mucilage–alginate (PMA) beads

AbstractThe focus of the present study includes the isolation, characterization, and a correlation of water clarification efficacy of mucilage from Portulaca oleracea leaves, a food-grade polysaccharide and its encapsulated calcium alginate beads. The characterization of mucilage powder was conducted for its physical and chemical properties. Portulaca mucilage was encapsulated in calcium alginate to develop Portulaca mucilage–alginate (PMA) beads. The developed beads were characterized by scanning electron microscopy, energy dispersive X-ray analysis, thermo gravimetric analysis, differential scanning calorimetric analysis, and fourier transform infrared spectroscopy techniques to study various physicochemical aspects. Efficiency of PMA beads for water clarification in low as well as high turbid water was investigated. Percentage turbidity removal was found to be 97 and 87%, respectively, in high and low turbid waters. Efficiency of recycled beads was also studied. Mucilage and PMA beads showed varied sur...