Synthesis of 2-methylpiperazine by photocatalytic reaction in a non-aqueous suspension of semiconductor-zeolite composite catalysts

Adsorption of Dye from Wastewater onto ZnO Nanoparticles-Loaded Zeolite: Kinetic, Thermodynamic and Isotherm Studies

The adsorption process of methylene blue (MB) and its removal from aqueous solution at initial pollutant concentration range of 1–7 ppm was investigated. Zeolite-A (Z) and its ZnO-loaded species (Z/ZnO) were prepared via microwave technique from natural resource and applied for dye removal. The loading of ZnO was governed by the cation exchange property of zeolite, followed by calcination. Experimentally, Z and Z/ZnO were tested using X-ray Diffraction (XRD), Fourier-Transform Infrared (FTIR), Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDX) and N2 adsorption-desorption. The examined parameters such as concentration of dye, contact time, ZnO dose and solution pH were traversed. Three isothermal models were analyzed. Kinetic studies indicated that, the adsorption of MB matched with pseudo-second order model. The maximum removal efficiency at pH 3, increased from 67.8% for Z to 94.8% for Z/ZnO modified with 3% ZnO loads (Z/ZnO(3%)). Parameters such as ΔH, ΔS, ΔG, S* and Ea were thermodynamically calculated. Langmiur isotherm and pseudo-second order models were the best fitting for the obtained data. The results indicated that, the adsorption of MB dye is spontaneous and endothermic, the removal efficiency is favored by increasing the temperature. ZnO-zeolite has much higher adsorption capacity for eliminating MB dye than that of the un-loaded zeolite.

Synthesis and optical properties of phenanthromidazole derivatives for organic electroluminescent devices

The external quantum efficiency roll-off may be due to triplet–triplet annihilation (TTA) and triplet–polaron annihilation (TPA).

Photocatalysis with TiO2 Applied to Organic Synthesis

Titanium dioxide is a versatile heterogeneous catalyst. Absorption of light by a TiO2 particle leads to the formation of an electron–hole pair. Electron transfer from or to the particle induces redox reactions. Although mainly applied in the context of environmental chemistry, these processes are also used to selectively transform organic compounds. Oxidations and reductions have been carried out. Applications to the synthesis of heterocycles have been reported. Many C–C bond formation reactions have been performed. Owing to adsorption of the substrates or by different surface modifications, visible light can be used to excite the catalytic system, which generates mild reaction conditions.

Selective formation of benzo[c]cinnoline by photocatalytic reduction of 2,2′-dinitrobiphenyl using TiO2 and under UV light irradiation

Photocatalytic reduction of 2,2′-dinitrobiphenyl (25 μmol) using P25-TiO₂ under an argon atmosphere and 20 h UV light irradiation selectively produced 23.8 μmol of benzo[c]cinnoline (95%), and 2,2′-biphenyldiamine (5%).

Nano rutile TiO2 catalysed synthesis of (E)-4-(2-(1-(4-chlorophenyl)-1H-phenanthro[9,10-d]imidazol-2-yl)vinyl)-N,N-dimethylaniline and its interaction with super paramagnetic nanoparticles

The synthesis of (E)-4-(2-(1-(4-chlorophenyl)-1H-phenanthro[9,10-d]imidazol-2-yl)vinyl)-N,N-dimethylaniline (CPPIVI) has been carried out using TiO₂ (R) as catalyst under solvent free conditions and characterized by NMR spectral studies.

Biodiesel production from used cooking oil by two-step heterogeneous catalyzed process

The present study demonstrates the production of biodiesel from used cooking oil containing high free fatty acid by a two-step heterogeneously catalyzed process. The free fatty acids were first esterified with methanol using a 25 wt.% TPA/Nb(2)O(5) catalyst followed by transesterification of the oil with methanol over ZnO/Na-Y zeolite catalyst. The catalysts were characterized by XRD, FT-IR, BET surface area and CO(2)-TPD. In the case of transesterification the effect of reaction parameters, such as catalyst concentration, methanol to oil molar ratio and reaction temperature, on the yield of ester were investigated. The catalyst with 20 wt.% ZnO loading on Na-Y exhibited the highest activity among the others. Both the solid acid and base catalysts were found to be reusable for several times indicating their efficacy in the two-step process.

Green oxidations: titanium dioxide induced tandem oxidation coupling reactions

The application of titanium dioxide as an oxidant in tandem oxidation type processes is described. Under microwave irradiation, quinoxalines have been synthesized in good yields from the corresponding alpha-hydroxyketones.

Zeolite Mediated Reactions: Mechanistic Aspects and Environmental Applications

An overview is presented of basic research and applications for the use of zeolites in environmentally-related topics. The use of these materials to promote oxidation reactions, and other catalytic processes is surveyed along with ship-in-a-bottle synthesis of particular zeolite-encapsulated catalysts. Methods for probing the surfaces of zeolites using spin-probes and ESR detection are mentioned. The ability of some thermally activated zeolites to produce spontaneously radical cations by single-electron oxidation of organic molecules is reviewed. The issue of the degree of acidity of H-zeolites is discussed, which demonstrates them not to be super-acids. Some ESR determinations of the adsorption of NOx species onto selected zeolites are reviewed and the use of zeolites to catalyse desulfurisation of hydrocarbons is considered. Finally, there is mention made of the use of zeolites to catalyse hydrodechlorination of CFC's and other organic chlorine-containing compounds. Surfactant-modified zeolites (SMZ) for use as polyfunctional decontamination agents are further discussed. Theoretical methods, e.g. Density Functional Theory (DFT), are finding their own application to studying the mechanisms of reactions that are mediated by zeolites as is shown throughout.

Photocatalysis: a promising route for 21st century organic chemistry

One of the main goals of 21st century chemistry is to replace environmentally hazardous processes with energy efficient routes allowing to totally avoid the use and production of harmful chemicals and to maximise the quantity of raw material that ends up in the final product. Selective photocatalytic conversions will play a major role in this evolution and this account shows how photocatalysis is offering an alternative green route for the production of organics.