Search results for "Aqueous suspension"
showing 10 items of 12 documents
Home-prepared anatase, rutile, and brookite TiO2 for selective photocatalytic oxidation of 4-methoxybenzyl alcohol in water: reactivity and ATR-FTIR …
2009
5th European Meeting on Solar Chemistry and Photocatalysis -- OCT 04-08, 2008 -- Palermo, ITALY
Photoreduction of carbon dioxide to formic acid in aqueous suspension: a comparison between phthalocyanine/TiO2 and porphyrin/TiO2 catalysed processes
2014
Composite materials prepared by loading polycrystalline TiO2 powders with lipophilic highly branched Cu(II)- and metal-free phthalocyanines or porphyrins, which have been used in the past as photocatalysts for photodegradative processes, have been successfully tested for the efficient photoreduction of carbon dioxide in aqueous suspension affording significant amounts of formic acid. The results indicated that the presence of the sensitizers is beneficial for the photoactivity, confirming the important role of Cu(II) co-ordinated in the middle of the macrocycles. A comparison between Cu(II) phthalocyanines and Cu(II) porphyrins indicated that the Cu(II)- phthalocyanine sensitizer was more e…
Design of enzyme-mediated controlled release systems based on silica mesoporous supports capped with ester-glycol groups
2012
[EN] An ethylene glycol-capped hybrid material for the controlled release of molecules in the presence of esterase enzyme has been prepared. The final organic-inorganic hybrid solid S1 was synthesized by a two-step procedure. In the first step, the pores of an inorganic MCM-41 support (in the form of nanoparticles) were loaded with [Ru(bipy) 3]Cl 2 complex, and then, in the second step, the pore outlets were functionalized with ester glycol moieties that acted as molecular caps. In the absence of an enzyme, release of the complex from aqueous suspensions of S1 at pH 8.0 is inhibited due to the steric hindrance imposed by the bulky ester glycol moieties. Upon addition of esterase enzyme, del…
A dihydrogen arsenate-mediated supramolecular network: crystal structure and magnetic properties of {[(bipy)Cu(μ-H2AsO4)(H2AsO4)]2}n
2002
Treatment of an aqueous suspension of Cu(OH)2 and 2,2′-bipyridine (bipy) with either Na2HAsO4·7H2O (1∶1∶2) or As2O5 (1∶1∶1) yields single crystals of {[(bipy)Cu(μ-H2AsO4)(H2AsO4)]2}n, 1, on standing. The solid-state structure of 1 consists of a three dimensional supramolecular network, supported by a combination of coordination covalent, hydrogen bonding and face-to-face π–π interactions. Variable temperature magnetic susceptibility measurements reveal very weak antiferromagnetic coupling between Cu(II) centres across the dihydrogen arsenate bridges (J = −0.58 cm−1).
Photocatalytic Partial Oxidation of 5-hydroxymethyl-2-furfural Under UV and Natural Solar Irradiation in Aqueous Suspension of K Containing C3N4
2020
Background: The influence of the potassium metal cation on the graphitic carbon nitride (g-C3N4) photocatalyst has been studied in the partial oxidation of 5-hydroxymethyl-2-furfural (HMF) to 2,5-furandicarboxaldehyde (FDC). Objective: The aim of this study was to understand if the presence of K in C3N4 could increase the oxidative conversion of HMF to high added value species. Methods: Two sets of photocatalysts were prepared by following two different methodologies. In both series of the materials, the precursor of C3N4 was melamine with different types of the K containing species including KCl and KOH in one case and KNO3 alone in the other case. However, for both series of photocatalys…
Heterogeneous Photocatalysis and Photoelectrocatalysis: From Unselective Abatement of Noxious Species to Selective Production of High-Value Chemicals
2015
Heterogeneous photocatalysis and photoelectrocatalysis have been considered as oxidation technologies to abate unselectively noxious species. This article focuses instead on the utilization of these methods for selective syntheses of organic molecules. Some promising reactions have been reported in the presence of various TiO2 samples and the important role played by the amorphous phase has been discussed. The low solubility of most of the organic compounds in water limits the utilization of photocatalysis. Dimethyl carbonate has been proposed as an alternative green organic solvent. The recovery of the products by coupling photocatalysis with pervaporation membrane technology seems to be a…
Polycrystalline TiO2 impregnated with cardanol-based porphyrins for the photocatalytic degradation of 4-nitrophenol
2004
Hydrogenated cardanol (3-n-pentadecylphenol), a renewable organic resource obtained by vacuum distillation of roasted “cashew nut shell liquid” (CNSL), a by-product of the cashew industry, has been used to synthesize novel lipophilic porphyrins. Polycrystalline TiO2 impregnated with these novel “cardanol-based” porphyrins as sensitizers has been investigated in the photodegradation of 4-nitrophenol (4-NP) in aqueous suspension. The results indicated that the presence of the sensitizer enhances the photoactivity of polycrystalline bare TiO2 in the process. The activating effect was higher in the case of the Cu-complex.
Selective Gree-Syntheses of Flavour-Molecules through TiO2 Photocatalysis in Aqueous Suspension
2013
To make a glass—avoid the crystal
2016
Colloidal model systems allow for a flexible tuning of particle sizes, particle spacings and mutual interactions at constant temperature. Colloidal suspensions typically crystallize as soon as the interactions get sufficiently strong and long-ranged. Several strategies have been successfully applied to avoid crystallization and instead produce colloidal glasses. Most of these amorphous solids are formed at high particle concentrations. This paper shortly reviews experimental attempts to produce amorphous colloidal solids using strategies based on topological, thermodynamic and kinetic considerations. We complement this overview by introducing a (transient) amorphous solid forming in a thoro…
The structure of gas-filled n-butyl-2-cyanoacrylate (BCA) polymer particles
1995
Abstract The structure of gas-filled poly-[n-butyl-2-cyanoacrylate] (BCA) particles has been demonstrated by negative staining with uranyl acetate, platinum-carbon shadowing of air-dried material and thin sectioning of the aqueous suspension of BCA particles, embedded in water-soluble melamine resin. The polymer shell of the hollow particles possesses a globular outer surface and a smoother inner surface.