Preliminary studies of photocatalytic activity of gypsum plasters containing TiO₂ co-modified with nitrogen and carbon

The conducted studies were focused on the development of the gypsum material exhibiting self-cleaning properties. To this end, the raw gypsum was mixed with unique TiO2-based photocatalysts, previously modified by nitrogen and/ or carbon doping. The photocatalytic activity of the obtained gypsum plasters was evaluated trough the degradation of model organic compound (Reactive Red 198) under UV-vis irradiation. The impact of the photocatalysts presence on the physicochemical properties of the obtained gypsum plasters was evaluated. Furthermore, the role of non-metals presence on the photocatalytic properties of the TiO2 was determined. It was confirmed that the addition of N,C co-modified titanium dioxide into gypsum bestows this material with self-cleaning properties. The highest dye removal rate was displayed by the gypsum plaster containing optimal amount (10 wt%) of co-modified TiO2/N,C photocatalyst, after 20 hours of UV-vis irradiation

NOx photocatalytic degradation on gypsum plates modified by TiO2-N,C photocatalysts

In presented studies the photocatalytic decomposition of NOx on gypsum plates modified by TiO2-N,Cphotocatalysts were presented. The gypsum plates were obtained by addition of 10 or 20 wt.% of different types of titanium dioxide, such as: pure TiO2 and carbon and nitrogen co-modified TiO2 (TiO2-N,C) to gypsum. TiO2-N,C photocatalysts were obtained by heating up the starting TiO2 (Grupa Azoty Zakłady Chemiczne Police S.A) in the atmosphere of ammonia and carbon at the temperature: 100, 300 i 600ºC. Photocatalyst were characterized by FTIR/DRS, UVVis/DR, BET and XRD methods. Moreover the compressive strength tests of modified gypsum were also done. Photocatalytic activity of gypsum plates was done during NOx decomposition. The highest photocatalytic activity has gypsum with 20 wt.% addition of TiO2-N,C obtained at 300ºC

Influence of the calcination of TiO2-reduced graphite hybrid for the photocatalytic reduction of carbon dioxide

In this work, a conversion of carbon dioxide (CO2) into methane, carbon monoxide, as well as hydrogen was investigated. The TiO2/rGO photocatalysts were prepared by two steps: solvothermal method and calcination at 500, 800, and 1000 degrees C in an argon atmosphere. The obtained samples were characterized by X-ray diffraction (XRD), UV-vis diffuse reflection spectroscopy (UV-vis/DRS), N2 adsorption-desorption and analysis of carbon content. The activity of photocatalysts was evaluated in the photocatalytic reduction of CO2. The TiO2/rGO-10 without calcination showed the highest activity toward CO2 conversion. It was found that all samples after rGO modification exhibited good activity toward H2 generation with high selectivity. The enhanced photocatalytic performance was attributed mainly to the presence of graphene due to its excellent electron transport/collection ability.Web of Science380403

E. coli Inactivation by High-Power Impulse Magnetron Sputtered (HIPIMS) Cu Surfaces

This study reports HIPIMS-sputtered samples of Cu-particulate films with currents at 6 and 60 amps leading to E. coil inactivation. The Cu coverage and nanoparticle structure of the fibers is reported by TEM. Evidence is presented of redox processes in the Cu taking place during E. coil inactivation and the buildup of intermediate species resulting from the bacterial oxidation. Cu is deposited on the polyester in the form of Cu(2)O and CuO as observed by XPS. During the bacterial oxidation, the CuO on the polyester after 30 min decreases from 84 to 70%. After longer bacterial inactivation times, the CuO oxidizes again increases its presence to 94% when the bacterial inactivation has been completed within 90 min. The broadening of the O-C=O signal during E. coli inactivation suggests direct interaction of Cu with carboxylic groups. The surface atomic concentration of 0, Cu, and C was determined within the E. coli inactivation time. The E. coil inactivation occurred within 90 min on Cu-nanoparticulate films sputtered for 61 s at 60 amps being 28 nm thick. This Cu-layer thickness is equivalent to 140 layers with a content of 1.4 x 10(17) atoms Cu/cm(2), and the sputtering proceeded with deposition rate of 2.3 x 10(15) atoms/cm(2)s. The values found for the rugosity indicate that the texture of the Cu-nanoparticulate film is smooth. R(q) values and the R(a) were similar before and after the E. coil inactivation, providing further evidence of the stability of the Cu-nanoparticulate films during the bacterial inactivation process. The Cu-loading percentage required in the Cu-nanoparticulate films sputtered by HIPIMS to inactivate E. coil completely was about three times lower compared with DCMS-sputtered Cu-nanoparticulate films. This indicates a substantial Cu-metal savings within the preparation of antibacterial films

Comparison of Methods for Evaluation of the Bactericidal Activity of Copper-Sputtered Surfaces against Methicillin-Resistant Staphylococcus aureus.

Bacteria can survive on hospital textiles and surfaces, from which they can be disseminated, representing a source of health care-associated infections (HCAIs). Surfaces containing copper (Cu), which is known for its bactericidal properties, could be an efficient way to lower the burden of potential pathogens. The antimicrobial activity of Cu-sputtered polyester surfaces, obtained by direct-current magnetron sputtering (DCMS), against methicillin-resistant Staphylococcus aureus (MRSA) was tested. The Cu-polyester microstructure was characterized by high-resolution transmission electron microscopy to determine the microstructure of the Cu nanoparticles and by profilometry to assess the thickness of the layers. Sputtering at 300 mA for 160 s led to a Cu film thickness of 20 nm (100 Cu layers) containing 0.209% (wt/wt) polyester. The viability of MRSA strain ATCC 43300 on Cu-sputtered polyester was evaluated by four methods: (i) mechanical detachment, (ii) microcalorimetry, (iii) direct transfer onto plates, and (iv) stereomicroscopy. The low efficacy of mechanical detachment impeded bacterial viability estimations. Microcalorimetry provided only semiquantitative results. Direct transfer onto plates and stereomicroscopy seemed to be the most suitable methods to evaluate the bacterial inactivation potential of Cu-sputtered polyester surfaces, since they presented the least experimental bias. Cu-polyester samples sputtered for 160 s by DCMS were further tested against 10 clinical MRSA isolates and showed a high level of bactericidal activity, with a 4-log(10) reduction in the initial MRSA load (10(6) CFU) within 1 h. Cu-sputtered polyester surfaces might be of use to prevent the transmission of HCAI pathogens