This paper presents an effective hydrothermal route to decorate various types of anodic 1D TiO 2 nanotubes (TiO 2 NTs) with magnetite nanoparticles (Fe 3 O 4 NPs), yielding a magnetically guidable and active photocatalyst. A unique portfolio of TiO 2 NTs including single-tube, single-walled, and double-walled ones was used. Optimal conditions for uniform decoration of these nanotubes by Fe 3 O 4 NPs (two different loadings) using a wet chemical synthesis based on an oleate hydrothermal approach were found. The resulting TiO 2 NTs@Fe 3 O 4 NPs were shown to be superparamagnetic at room temperature, to have a stable connection of NPs to NTs, and to have good magnetic response under an external applied magnetic field. The as-prepared materials were used as magnetically guidable photocatalyst for the decomposition of a model dye (methylene blue). Fe 3 O 4 NPs enhanced the photocatalytic activity of TiO 2 NTs under visible light. In principle, TiO 2 NTs@ Fe 3 O 4 NPs could be used as magnetically guidable drug delivery system with photoinduced drug release.

It is well known that the hydrodechlorination (HDC) of chlorinated aromatic contaminants in aqueous effluents enables a significant increase in biodegradability. HDC consumes a low quantity of reactants producing corresponding non-chlorinated and much more biodegradable organic compounds. Two commonly used precious metals free Al alloys (Raney Al-Ni and Devarda’s Al-Cu-Zn) were compared in reductive action in an alkaline aqueous solution. Raney Al-Ni alloy was examined as a universal and extremely effective HDC agent in a diluted aqueous NaOH solution. The robustness of Raney Al-Ni activity is illustrated in the case of HDC of polychlorinated aromatic compounds mixture in actual waste water. In contrast, Devarda’s Al-Cu-Zn alloy was approved as much less active for HDC of the tested chlorinated aromatic compounds, but with a surprisingly high selectivity on cleavage of C-Cl bonds in the meta and sometimes the ortho position in chlorinated aniline and sometimes chlorinated phenol structures. The reaction of both tested alloys with chlorinated aromatic compounds in the aqueous NaOH solution is accompanied by dissolution of aluminum. Dissolved Al in the alkaline HDC reaction mixture is very useful for subsequent treatment of HDC products by coagulation and flocculation of Al(OH)3 caused by simple neutralization of the alkaline aqueous phase after the HDC reaction.

A newly developed unique combination of direct microscopic and calorimetric measurements was used to study the crystal growth in amorphous selenium (a-Se) thin films (500 nm) deposited on Kapton tape and aluminum foil. The crystal growth rates (u r) microscopically determined in the 65–110 °C temperature range were similar to those for bulk selenium glass. The crystal growth kinetics was described in terms of the screw dislocation model with implemented temperature dependences of the growth activation energy E G and Ediger’s decoupling parameter ξ. Extensive analysis of the literature data on the crystal growth rates in thin selenium films revealed the dominant effect of the number and distribution of the dangling bonds of the [Se] n chains adjacent to the film/substrate interface. The seemingly scattered u r – T literature data were found to be consistent when the influences of impurities, substrate quality, illumination, and deposition conditions were accounted for. The macroscopic manifestation of the crystal growth in selenium thin films was observed by means of differential scanning calorimetry (DSC)the corresponding activation energies were similar to the E G values determined by optical microscopy; the Avrami equation with the implemented u r – T dependence was able to accurately describe the macroscopic DSC data. Additional DSC measurements for the selenium thin film scraped off the white glass substrate have shown that the above-T g annealing of such a material suppresses the crystallization, which can be interpreted as the evidence of the dominant growth from the mechanically activated crystallization centers.

No abstract

No abstract