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.

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 Green Nanotechnologies for Innovative Purifications of Water: Synthesis of the Nanoparticles from Renewable Sources.

Polluting the natural water resources is a serious global issue, which is confirmed by the fact that today at least 2 billion people consume water from contaminated sources. The conventional wastewater treatment methods cannot effectively remove the persistent pollutants (e.g., drugs, organic dyes, pesticides) from the aqueous environment. Heterogeneous photocatalysis is a promising and sustainable alternative for water remediation. It is based on the interaction between light irradiation and the semiconductors (e.g., TiO2, ZnO) as photocatalysts, but these compounds, unfortunately, have some disadvantages. Hence, great attention has been paid to the nanotechnology as a possible way of improvement. Nanomaterials have extraordinary properties; however, their conventional synthesis is often difficult and requires a significant amount of dangerous chemicals. This concise topical review gives recent updates and trends in development of sustainable and green pathways in the synthesis of nanomaterials, as well as in their application for water remediation. In our review we put emphasis on the eco-friendly, mostly plant extract-based materials. The importance of this topic, including this study as well, is proved by the growing number of publications since 2018. Due to the current serious environmental issues (e.g., global warming, shortage of pure and quality water), it is necessary for the traditional TiO2 and ZnO semiconductors to be replaced with the harmless, non-toxic, and more powerful nanocomposites as photocatalysts. Not only because of their higher efficiency as compared to the bulk semiconductors, but also because of the presence of biomolecules that can add up to the pollutant removal efficiency, which has been already confirmed in many researches. However, despite the fact that the application of heterogeneous photocatalysis together with green nanotechnology is absolutely the future in water purification, there are some challenges which have to be overcome. The exact effects of the biomolecules obtained from plants in the synthesis of nanoparticles, as well as in the photocatalytic processes, are not exactly known and require further investigation. Furthermore, heterogeneous photocatalysis is a well-known and commonly examined process; however, its practical use outside the laboratory is expensive and difficult. Thus, it has to be simplified and improved in order to be available for everyone. The aim of our review is to suggest and prove that using these bio-inspired compounds it is possible to reduce human footprint in the nature.

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.

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+ > ●OHads > ●OHbulk. Finally, several intermediates that were formed during the photocatalytic treatment of mesotrione were identified.