Photosynthesis of Au/TiO2 nanoparticles for photocatalytic gold recovery from industrial gold-cyanide plating wastewater

A series of Au_x/TiO₂ nanoparticles (NPs) with different gold loadings (x = 0.1-1.0 wt%) was synthesized by the photodeposition and then employed as photocatalysts to recover precious component from the industrial gold-cyanide plating wastewater. Effects of Au loading, catalyst dosage and types of hole scavenger on the photocatalytic gold recovery were investigated under ultraviolet-visible (UV-Vis) light irradiation at room temperature. It was found that different Au loadings tuned the light absorption capacity of the synthesized photocatalysts and enhanced the photocatalytic activity in comparison with the bare TiO₂ NPs. The addition of CH₃OH, C₂H₅OH, C₃H₈O, and Na₂S₂O₃ as a hole scavenger significantly promoted the photocatalytic activity of the gold recovery, while the H₂O₂ did not. Among different hole scavengers employed in this work, the CH₃OH exhibited the highest capability to promote the photocatalytic gold recovery. In summary, the Au_0.5/TiO₂ NPs exhibited the best photocatalytic activity to completely recover gold ions within 30 min at the catalyst dosage of 0.5 g/L, light intensity of 3.20 mW/cm² in the presence of 20 vol% CH₃OH as hole scavenger. The photocatalytic activity slightly decreased after the 5th cycle of recovery process, indicating its high reusability.

Photochemical Alkene Isomerization for the Synthesis of Polysubstituted Furans and Pyrroles under Neutral Conditions

A photochemical approach to polysubstituted heterocycles using UV-induced alkene isomerization is described. The method allows for the synthesis of disubstituted furans and pyrroles under mild and neutral conditions and also provides access to a class of trisubstituted furans pertinent to natural-product synthesis. The method has broad functional-group tolerance and many richly decorated heterocycles have been prepared incorporating functional groups that are unstable under Brønsted and Lewis acidic conditions.

Kinetics and Optimization of the Photocatalytic Reduction of Nitrobenzene

The photocatalytic reduction of nitrobenzene to aniline in alcoholic solutions appears as an interesting alternative to the classical hydration. However, little is known about the influence of reaction parameters on the kinetics of the reaction which were therefore studied herein. The effects of light intensity, catalyst concentration, initial concentration, and temperature were systematically investigated under more than 50 different conditions and accurately described with an appropriate kinetic model. The results show that the efficiency of the reaction is extremely high and apparent quantum yields of up to 142 % were observed under optimized conditions. Particularly interesting is the fact high efficiencies were also obtained at high reaction rates of up to 74.3 mM h-1. Overall these results demonstrate that heterogeneous photocatalytic reactions can be very efficient and productive at the same time and may therefore present a powerful tool in synthetic organic chemistry.

Rapid and morphology controlled synthesis of anionic S-doped TiO2 photocatalysts for the visible-light-driven photodegradation of organic pollutants

In recent years, growing concerned has been raised to the global problem of the drainage of organic pollutants into water steams.

Nitrogen-doped TiO2 microspheres with hierarchical micro/nanostructures and rich dual-phase junctions for enhanced photocatalytic activity

We successfully synthesized microspherical nitrogen-doped TiO₂ with hierarchical nano/microstructures, rich anatase TiO₂–TiO₂(B) phase junctions and a reduced band gap for the photo-degradation of dyes with improved photocatalytic activity.

Floating photocatalysts based on loading Bi/N-doped TiO2 on expanded graphite C/C (EGC) composites for the visible light degradation of diesel

Enhanced visible-light photocatalytic activity for degradation of diesel based on photocatalyst easy recycle.

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.

Review on modified N–TiO2 for green energy applications under UV/visible light: selected results and reaction mechanisms

Modifications of the activity, band structure, morphology, optical and electronic properties of N–TiO₂ for energy and environmental applications.

Recent advances in the synthesis of quinolines: a review

This review article gives information about the recent advances in the synthesis of quinoline derivatives by various eco-friendly, green and clean protocols.