Reusable Fe2O3/TiO2/PVC Photocatalysts for the Removal of Methylene Blue in the Presence of Simulated Solar Radiation

Currently, environmental pollution by various organic pollutants (e.g., organic dyes) is a serious, emerging global issue. The aqueous environment is highly exposed to the harmful effects of these organic compounds. Furthermore, the commonly applied conventional purification techniques are not sufficient enough. Heterogeneous photocatalysis and the photo-Fenton process are effective, low-cost and green alternatives for the removal of organic pollutants. In this study, different iron(III) oxide/titanium(IV) oxide/polyvinyl chloride (Fe₂O₃/TiO₂/PVC) nanocomposites in tablet form were investigated in the photodegradation of methylene blue (MB) under simulated sunlight, and their possible antibacterial effects were examined. The newly synthesized nanocomposites were characterized by scanning electron microscope, X-ray diffraction, UV-Vis diffuse reflectance spectroscopy, and Raman spectroscopy. The results showed a hematite crystal form in the case of Fe₂O₃₍₂₎ and Fe₂O₃ samples, while the Fe₂O₃₍₁₎ sample showed a combination of hematite and synthetic mineral akaganeite. The highest photocatalytic efficiency was achieved in the presence of Fe₂O₃/TiO₂/PVC, when 70.6% of MB was removed. In addition, the possible photo-cleaning and reuse of the mentioned photocatalyst was also examined. Based on the results, it can be seen that the activity did not decrease after five successive runs. Nanocomposites also exhibited mild antibacterial effects against the two tested Gram-positive bacteria (S. aureus and B. cereus).

Sustainable Removal of Tolperisone from Waters by Application of Photocatalysis, Nanotechnology, and Chemometrics: Quantification, Environmental Toxicity, and Degradation Optimization

Environmental pollution is an emerging global issue. Heterogenous photocatalytic degradation, which belongs to the advanced oxidation processes, is a promising sustainable technique for the removal of harmful pollutants (e.g., pharmaceuticals) from natural resources (surface and underground waters), as well as wastewaters. In our study, we examined the efficiency of photocatalytic degradation (with TiO₂ and ZnO as photocatalysts) of tolperisone hydrochloride (TLP) and the effect of TLP and its degradation intermediates on germination, photosynthetic capacity, and biomass production of wheat. According to the UFLC-DAD and LC-ESI-MS results, we found that the complete degradation of TLP can be reached after 60.83 min of UV irradiation using TiO₂ as a photocatalyst. Furthermore, we determined that germination, biomass production, and chlorophyll b (Chl b) were not related to the percentage of TLP after irradiation. Chlorophyll a (Chl a) (r = -0.61, p ≤ 0.05), Chl a+b (r = -0.56, p ≤ 0.05), and carotenoid (car) (r = -0.57, p ≤ 0.05) were strongly inversely (negatively) correlated with TLP, while Chl a+b/car (r = 0.36, p ≤ 0.05) was moderately (positively) related.

Rapid Removal of Organic Pollutants from Aqueous Systems under Solar Irradiation Using ZrO2/Fe3O4 Nanoparticles

Pure water scarcity is an emerging, all-around problem that globally affects both the life quality and the world's economy. Heterogeneous photocatalysis under solar irradiation is a promising technique for the organic pollutants (e.g., pesticides, drugs) removal from an aqueous environment. Furthermore, the drawbacks of commercially available photocatalysts can be successfully overcome by using innovative nanoparticles, such as ZrO₂/Fe₃O₄. Four ZrO₂/Fe₃O₄ nanopowders with a different mass ratio of ZrO₂ and Fe₃O₄ were synthesized using the chemical co-precipitation method. XRD analysis showed the presence of magnetite and hematite Fe-oxide phases in all samples. The content of the magnetite phase increased with the addition of 19% ZrO₂. The efficiency of the newly synthesized ZrO₂/Fe₃O₄ nanoparticles was investigated in the rapid removal of selected pollutants under various experimental conditions. Nevertheless, the influence of the water matrix on photocatalytic degradation was also examined. The obtained data showed that using ZrO₂/Fe₃O₄ nanosystems, an appropriate removal rate of the selected pesticides and pharmaceuticals can be reached after 120 min of solar irradiation. Further, the total organic carbon measurements proved the mineralization of the target emerging pollutants. ZrO₂/Fe₃O₄ nanoparticles are economically feasible, as their removal from the suspension can be easily achieved using affordable, environmentally-friendly magnetic separation.

Potential of TiO2 with Various Au Nanoparticles for Catalyzing Mesotrione Removal from Wastewaters under Sunlight

Nowadays, great focus is given to the contamination of surface and groundwater because of the extensive usage of pesticides in agriculture. The improvements of commercial catalyst TiO₂ activity using different Au nanoparticles were investigated for mesotrione photocatalytic degradation under simulated sunlight. The selected system was 2.43 × 10⁻³% Au–S–CH₂–CH₂–OH/TiO₂ (0.5 g/L) that was studied by transmission electron microscopy and ultraviolet-visible (UV-Vis) spectroscopy. It was found that TiO₂ particles size was ~20 nm and ~50 nm, respectively. The Au nanoparticles were below 10 nm and were well distributed within the framework of TiO₂. For 2.43 × 10⁻³% Au–S–CH₂–CH₂–OH/TiO₂ (0.5 g/L), band gap energy was 2.45 eV. In comparison to the pure TiO₂, addition of Au nanoparticles generally enhanced photocatalytic removal of mesotrione. By examining the degree of mineralization, it was found that 2.43 × 10⁻³% Au–S–CH₂–CH₂–OH/TiO₂ (0.5 g/L) system was the most efficient for the removal of the mesotrione and intermediates. The effect of tert-butanol, NaF and ethylenediaminetetraacetic acid disodium salt on the transformation rate suggested that the relative contribution of various reactive species changed in following order: h⁺ > ^●OH_ads > ^●OH_bulk. Finally, several intermediates that were formed during the photocatalytic treatment of mesotrione were identified.

[Antibiotic resistance of gram-negative bacteria isolated at a hospital intensive care unit]

The antibiotic sensitivity of Gram-negative facultatively pathogenic bacteria isolated between 1982-1986 in the respiratory intensive care unit of the 3rd department of pediatry of the "László" Hospital (Budapest) has been studied. Pseudomonas aeruginosa, Klebsiella, Acinetobacter calcoaceticus and Acinetobacter lwoffii were most frequently isolated both from the clinical samples (total 56.9%) and in samples obtained from hospital-hygienic check-examinations. 70-100% of the individual species was resistant to antibiotics used in Hungary. The gentamicin and tobramycin resistance of P. aeruginosa and A. lwoffii showed significant rate of increase. Favourable in vitro results were obtained only with ceftriaxon, ceftazidime, netilmicin and amikacin.

Origin and spread of Pseudomonas aeruginosa, Proteus and Klebsiella during twenty years in an infectious hospital

Bacteriological examinations carried out in an infectious hospital revealed that the occurrence of Pseudomonas and Proteus grew 4-fold, and the rate of Klebsiella positive cultures 3.5-fold between 1958 and 1977. On the other hand, the occurrence of Staphylococcus aureus decreased to the half since 1961. The occurrence of Gram-negative facultative pathogens started to increase in the surgical wards in the fifties and the rise lasted until the mid-sixties. Pseudomonas aeruginosa was the most frequent among them. In contrast, Escherichia coli dominated and P. aeruginosa was the least frequent in the non-surgical wards. Here the Gram-negative facultative pathogens showed a more rapid increase and the incidence of P. aeruginosa and Proteus kept rising throughout the whole examination period. When Gram-negative facultative pathogens of hospital origin were colonizing, the proportion of sick persons versus symptomless carriers was significantly higher than in the case of extrahospital colonization on the basis of the records of 300 P. aeruginosa, 300 Proteus and 300 Klebsiella positive patients. This proportion changed parallel with the rate of the strains of hospital origin. The number of patients who acquired P. aeruginosa, Proteus or Klebsiella extrahospitally, kept continuously rising between 1958 and 1971. Thus, the advance of Gram-negative facultative pathogens is due not ony to nosocomial causes.