A continuous-flow, coil-type photoelectrocatalytic microreactor for the degradation of caffeine was designed, assembled and characterized. Its main components are the photocatalytically active anode and the cathode coils, which are wrapped around a silica-glass rod and placed into a UV-transparent housing. The anode coil was prepared by anodic oxidation of the titanium coil, which leads to the formation of vertically aligned, titanium dioxide, nanotube arrays that exhibit a high photocatalytic activity and are rigidly attached to the titanium wire. The photocatalytic, electrocatalytic and photoelectrocatalytic activities of the assembled microreactor were measured systematically while changing the main parameters that affect the device’s efficiency. The most significant change in the microreactor’s design in terms of efficiency was to place the cathode coils on both sides of the anode coil, which resulted in the shortest time for complete degradation of the caffeine. When an applied anodic bias potential of 4 V was used in the most efficient microreactor design, 1 mL of the 40 mg/L caffeine was fully decomposed in 55 min.
COBISS.SI-ID: 30193703
Titanates are suitable for many applications such as oxygen sensing and tunable HTS (high temperature superconducting) microwave filters. The potential advantages of the nanostructured forms have been however scarcely explored compared to other oxides. In this work, the structural and electrical properties of individual iron-doped strontium titanate nanotubes (Fe:SrTiO3) grown by electrophoretic deposition (EPD) were assessed for the first time, showing high stability and reproducibility. This result paves the way to further development of more complex titanate-based devices, as for instance nanostructured oxygen STFO sensors. From experimental data, it was concluded that the polycrystalline form of Fe:SrTiO3 nanotubes is the major limitation to attain high photoconductivity gains when exposed to UV-light.
COBISS.SI-ID: 26818855
An ethanol biosensor based on alcohol dehydrogenase (ADH) attached to Au seeds decorated on magnetic nanoparticles (Fe3O4@Au NPs) is presented. ADH was immobilized on Fe3O4@Au NPs, which were subsequently fixed by a magnet on a carbon paste electrode modified with 5?% (m?:?m) MnO2. Optimum conditions for the amperometric determination of ethanol with the biosensor were as follows: working potential +0.1 V (vs. Ag/AgCl); supporting electrolyte: 0.1 M phosphate buffer solution at pH 6.8 containing 0.25 mM of the coenzyme (NAD+); working electrode: carbon paste with magnetically attached Fe3O4@Au NPs (0.012 mg?·?cm-2 electrode area) with immobilized alcohol dehydrogenase (120 units per cm2 of electrode area). Linearity between signal and concentration was found for the range from 0.1 to 2.0 M ethanol (r2=0.995) with a detection limit of 0.07 M, a sensitivity of 0.02 µA?·?mM-1?·?cm-2, a reproducibility of 4.0?% RSD, and a repeatability of 2.7?% RSD. The results for the determination of ethanol in alcoholic beverages showed good agreement with gas chromatography (GC) with recovery of 96.0?–?108.8?%.
COBISS.SI-ID: 29317415
Titanium dioxide (TiO2) rutile nanoparticles were synthesized at temperatures below 100 °C using a gel-sol process that provides control of the final particles’ characteristics, such as the nanoparticle size, morphology, crystal structure and crystallinity. The synthesized rutile nanoparticles were analyzed using X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the gel-sol process allows control over the final nanoparticle characteristics with the proper choice of reaction parameters. The most profound influence on the nanoparticles’ properties is achieved by the type and concentration of the acid used in the reaction mixture. The gel-sol synthesis resulted in anisotropic rutile nanoparticles that are 60–160 nm long, depending on the reaction parameters, and have an aspect ratio of about 5. A reaction mechanism is presented, explaining the influence of various reaction parameters on the characteristics of the TiO2 nanoparticles.
COBISS.SI-ID: 18903605