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Characterization of organic matter in four sediments in the influence area of wastewater discharges was carried out by both chemical and thermal analysis in order to assess their pollution level. Oxidisable organic carbon and organic matter were calculated by the standard methodology in laboratory. Thermogravimetry (TG), between 50 and 900° C, was simultaneously performed in oxidizing conditions on ground sediments samples after three different pretreatments. Linear regression adjust of thermal analysis results versus chemical parameters provides the better Pearson's coefficients, leading to the best coefficients for weight loss in 250-400° C temperature range versus oxidisable organic carbon and organic matter at 360°C, respectively. These results demonstrated the utility of thermoanalysis technique for the evaluation of the organic matter content of fresh sediments. [ABSTRACT FROM AUTHOR]

The optical properties of 5wt% Fe 3 O 4 -TiO 2 thin films were evaluated in detail with the aim of proposing a mechanism for solar photocatalytic processes and highlighting the advantages over the use of bare TiO 2 . The results showed that the incorporation of 5wt% Fe 3 O 4 enhanced the optical properties by a redshift to a wavelength in the visible range, reducing the anatase/rutile band gap energy from 3.2 eV to 2.8 eV. Photoluminescence studies reveal a superior separation efficiency of photoexcited electron-hole pairs when Fe 3 O 4 nanoparticles (NPs) are present in the photocatalyst. X-ray photoelectron spectroscopy spectra confirm the presence of Fe 3 O 4 and existence of a chemical bonding between TiO 2 and Fe 3 O 4 NPs. Moreover, in this study, a mechanism of solar photocatalytic processes involving Fe 3 O 4 -TiO 2 thin films is proposed and it is supported by experimental results. Finally, solar photocatalytic experiments were carried out, indicating that the effectiveness for the removal of the selected pharmaceutical is considerably improved when the composite material is used as catalyst. Furthermore, it was demonstrated that the photocatalytic activity of the prepared Fe 3 O 4 -TiO 2 thin films depends on their thickness, achieving the highest pharmaceutical removal yields using the 2 µm thick sample. The stability and reusability of the catalyst was confirmed studying the photocatalytic activity over three cycles., Competing Interests: The authors declare no conflict of interest.

Fe 3+ -TiO 2 (Fe-TiO 2 ) thin films were successfully prepared using a "sandwich" approach. TiO 2 NPs were doped with different Fe 3+ content (0.05%, 0.1%, 0.2% molar ratio), and the modified TiO 2 NPs were deposited on glass flat support by dip coating.Structural, morphological, optical, and photocatalytic properties of Fe-TiO 2 thin films were studied. XPS spectra confirm the presence of Ti, Fe, O, and defective -OH groups at the material surface. The Fe 2p spectrum demonstrates the existence of Fe 3+ . SEM images indicate that the incorporation of Fe 3+ deforms in some degree the homogeneity of the TiO 2 system. Additionally, incorporation of Fe 3+ ions to the network creates an impurity band near the VB due to the oxygen vacancies, resulting in the reduction of the effective optical band gap. Photocatalytic activity of fabricated thin films in the elimination of sulfamethoxazole (SMT) follows pseudo first-order kinetics. The highest SMT removal yields were achieved using the sample with 0.05%Fe. Additionally, the use of greater thicknesses improves the removal performance. However, material detachment limits the maximum usable value around 6 µm.Finally, stability and reusability of catalysts were confirmed studying the photocatalytic activity over three cycles and evaluating that no Fe 3+ leaching occurred., (© 2021. The Author(s).)

An increasing number of promising applications for future technology is arising from size constraints in nanoparticles (NPs) and from the chemical manipulation of their surfaces. In this work, we analyse the finite-size and surface effects on polyacrylic acid-coated Fe(3)O(4) NPs and oleic acid-coated gamma-Fe(2)O(3) NPs by studying their magnetization curves at different temperatures. The measured thermal dependence of the saturation magnetization is no longer explained by the typical T(3/2) Bloch law, yielding higher values than those expected for its exponent. When incorporated in polymeric matrixes to form magnetic transparent nanocomposites, the oleic acid-coated gamma-Fe(2)O(3) NPs also deviate from Bloch's law, but following the opposite trend observed in free coated NPs.