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ZnFe photocatalysts have been increasingly investigated for water remediation due to the high demands in this field, such as activity, toxicity, cost, and stability. The presented study was focused on the simple, safe, non-toxic, and eco-friendly synthesis and characterization of ZnFe-mixed metal oxides in correlation with their functional properties. Photocatalytic performance of these materials was evaluated by rhodamine B photodegradation under simulated solar light irradiation. The synthesized mixed oxides contained hexagonal wurtzite ZnO as the predominant phase, whereas, after thermal treatment, the formation of the spinel-structured ZnFe2O4 phase was observed. The photocatalysts with the additional spinel phase and thermally treated at 300°C and 500°C exhibited superior photocatalytic activity probably due to the highest amount of the ZnFe2O4 spinel phase, favourable mesoporous structure, and an optimal energy band gap of ∼2.30 eV that initiated higher light-harvesting efficiency. The rhodamine B photodegradation followed zero-order kinetics, indicating complete coverage of active sites by the pollutant substrate. Additionally, photocatalysts showed the highest efficiency at the natural pH (6.8), being in accordance with green synthesis principles. Simple, green route assembling synthesis method, high photodegradation efficiency, and good reusability make these ZnFe-mixed oxides great candidates for potential application in practical wastewater treatments.

In recent decades, the rising wastewater output from industrial pollution has inflicted severe harm on both surface and groundwater, leading to substantial environmental damage. The elimination of harmful, toxic materials and wastewater remediation are pressing global concerns and pose a formidable challenge for scientists worldwide. Heterogeneous photocatalysis has been recognized as a promising, effective, energy-free, and eco-friendly process capable of completely degrading various organic pollutants. Finding a material that simultaneously satisfies various thermodynamic and kinetic criteria, coupled with good thermal- and photo-stability, is a challenging task necessitating the modification of existing materials or the synthesis of new ones to meet the required standards. This present study comprehensibly elaborates on different approaches to the modification of various photocatalytic systems, both organic and inorganic, in order to obtain more efficient and feasible catalysts for practical applications. In addition, the current status of the application of photocatalysts in dye wastewater treatment is summarized, projecting the future direction for wastewater management by photocatalytic processes. [ABSTRACT FROM AUTHOR]

The presented study was focused on the simple, eco-friendly synthesis of composite hydrogels of crosslinked carboxymethyl cellulose (CMC)/alginate (SA) with encapsulated g-C3N4 nanoparticles. The structural, textural, morphological, optical, and mechanical properties were determined using different methods. The encapsulation of g-C3N4 into CMC/SA copolymer resulted in the formation of composite hydrogels with a coherent structure, enhanced porosity, excellent photostability, and good adhesion. The ability of composite hydrogels to eliminate structurally different dyes with the same or opposite charge properties (cationic Methylene Blue and anionic Orange G and Remazol Brilliant Blue R) in both single- and binary-dye systems was examined through adsorption and photocatalytic reactions. The interactions between the dyes and g-C3N4 and the negatively charged CMC/SA copolymers had a notable influence on both the adsorption capacity and photodegradation efficiency of the prepared composites. Scavenger studies and leaching tests were conducted to gain insights into the primary reactive species and to assess the stability and long-term performance of the g-C3N4/CMC/SA beads. The commendable photocatalytic activity and excellent recyclability, coupled with the elimination of costly catalyst separation requirements, render the g-C3N4/CMC/SA composite hydrogels cost-effective and environmentally friendly materials, and strongly support their selection for tackling environmental pollution issues. [ABSTRACT FROM AUTHOR]

Use of broken honeycomb-like expanded perlite as support for magnesium modified nickel catalysts in process of partial hydrogenation of sunflower oil was studied. By the use of the precipitation-deposition method, two groups of precursors were synthesized: different Ni/SiO2 mole ratios with constant Mg/Ni mole ratio 0.1, and different Mg/Ni mole ratios with constant Ni/SiO2 mole ratio 0.25. Characterizations of precursors were done (scanning electron microscopy, diffuse reflectance UV–Vis, infrared spectroscopy, N2-physisorption, temperature programmed reduction (TPR) and He-pycnometry) to determine the material differences, considering the change in morphology, structure, texture and reducibility with overall Ni and Mg content. In addition, TPR and hydrogen chemisorption were performed in order to estimate the temperature reduction range of supported precursors and the dispersion degree of nickel in reduced precursors, respectively. The interaction between Ni2+ and perlite support was established. Different reducibility and dispersion were obtained as a function of Ni/SiO2 and Mg/Ni mole ratios. After the precursor’s reduction and paraffin oil impregnation, the obtained catalysts were tested in a sunflower oil hydrogenation reaction. Catalyst activity was monitored through the decrease of the refractive index and hydrogen consumption that gave the insight that the influence on catalyst activity represents the accessibility of triacylglycerols and not always the hydrogen determined dispersion degree. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 45001]

Montmorillonite (Mt) and acid modified montmorillonite (MtA) were tested as nicotine adsorbents. The samples were characterized using FT-IR spectroscopy and low temperature nitrogen physisorption. Nicotine adsorption was performed with respect to contact time, pH and initial nicotine concentration. The kinetics of adsorption obeyed the pseudo-second-order kinetics. The optimal pH values for nicotine adsorption were 6 and 9 for Mt and MtA, respectively. The isotherms related to adsorption on Mt at pH = 6 and 9 as well as for MtA at pH=6 were best fitted with Sips isotherm model, while adsorption onto MtA at pH=9 obeyed Langmuir isotherm model. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 45001]

This study was carried out at the Danube River and its tributaries during the Joint Danube Survey 4 (JDS4) expedition. Three freshwater benthic species were used to estimate the quantity of microplastics (MPs): Corbicula spp., Limnodrilus hoffmeisteri (Claparede, 1862), and Polypedilum nubeculosum (Meigen, 1804). Following the kick and sweep technique, individuals were sampled using a hand net or dredge. In order to estimate the number of MP particles/individual particles/g wet body mass, the body mass and total length of all specimens were measured. Alkaline (Corbicula spp. and L. hoffmaisteri) and enzymatic (P. nubeculosum) protocols were performed for tissue degradation. All samples were filtered through glass microfiber filters (mesh size 0.5 µm). The particles were photographed, measured, and counted. A total of 1904, 169, and 204 MPs were isolated from Corbicula spp., L. hoffmaisteri, and P. nubeculosum, respectively. To confirm the chemical composition of isolated MPs, a subsample of 46 particles of the fragmented particles from 14 sampling sites was analysed via µ-ATR-FTIR spectroscopy analysis. The particles were characterised as polycarbonate (PC), polyethylene terephthalate (PET), polypropylene–polyethylene copolymer (PP-PE), nylon (polyamide-PA) and cellophane, with the domination of PET. [ABSTRACT FROM AUTHOR]

The visible-light-active heterojunctions based on TiO2 were extensively investigated due to their wide range of energy and environment applications. In this study, g-C3N4/titanate heterojunction photocatalyst was successfully prepared by a simple one-step calcination route from melamine and hydrothermally prepared titanates. The photocatalyst was characterized by different physicochemical methods, e.g., X-ray diffraction (XRD), scanning electron microscopy (SEM), and N2 physisorption analysis. The photocatalytic efficiency of synthesized photocatalyst was evaluated by single and simultaneous degradation of methylene blue (MB) and orange G (OG) dyes under solar and visible light irradiation. The photocatalyst exhibited improved visible light activity due to the efficient separation of photogenerated charge carriers and enhanced visible light absorption. The degradation of MB was examined under different reaction conditions to assess the influence of initial MB concentration, catalyst loading, and pH on the degradation kinetics. Dye degradation study in the single and binary dye systems revealed that adsorption was limiting step that governs the pollutant degradation order. Radical trapping experiments were performed using different types of scavengers to highlight the difference in photochemical reactions and mechanism of MB and OG dye degradation under different light irradiation. Comparison of the reaction pathways under visible and solar light irradiation supported with determined bandgap edges and photoluminescence (PL) analysis suggested that the g-C3N4/titanate heterojunction belonged to the type II heterojunction. [ABSTRACT FROM AUTHOR]

Polymer supported catalysts with different contents of metal ions where synthesized by wet impregnation of the degassed support from ethanolic solutions of cobalt(II) nitrate. Amacroreticular copolymer of poly-4-vinylpyridine with divinylbenzene was used as the support. The prepared catalysts were tested in the partial oxidation of cyclohexane to cyclohexanol and cyclohexanone. Activity tests were performed in a stainless steel, laboratory scale, stirred autoclave, in the semi batch regime under isothermal and non-isothermal conditions. Isothermal experiments where performed at 170 °C for 120 min. In the non-isothermal conditions. isothermal experiments where performed at 170 °C for 120 min. In the non-isothermal experiments, a constant heating rate of 0.3 degree/min was used in the range between 110 °C and 170 °C. Non-linear, least-squares analysis with the simplex optimization method and numerical simulation of the reaction model in each iterative step was used for the kinetic characterization of the process in a non-stationary, semi-batch regime. Apparent rate constants were obtained as an invariant measure of the catalytic system. Anon-linear effect of the content of metal ions on the reaction rate and on the ratio of the yield of the products was observed, which is attributed to a complex interactions between the reaction medium and the heterogeneous catalyst, including a catalyst-inhibition effect.

In this work hydrogen production activity of a series of the nickel-loaded, nitrogen-doped titanate-based photocatalysts was tested by water splitting reaction in isopropanol-water mixture. The utilization of ammonium ions during catalyst synthesis and subsequent calcination led to successful formation of nitrogen-doped nanotubular titanates with lower sodium content, favored titanate-to-anatase transformation and enhanced textural, morphological and interface properties. The photocatalytic tests revealed that hydrogen production activity of nitrogen-doped titanates is ten times higher compared to nitrogen-free titanates. The presence of highly photoactive anatase phase, improved anatase crystallinity and lower amount of sodium ions are found to be decisive factors for increased hydrogen production activity. The optimal nickel loading was determined and the variation in photocatalytic activity with reduction temperature was explained. Stability tests gave quantitative analysis of the effects of reaction products accumulation and photocorrosion on the catalyst deactivation. [Display omitted] • Alkaline hydrothermal method was used for synthesis of nanotube catalysts support. • Solar light driven hydrogen evolution over Ni loaded N doped titanate catalyst. • Ion exchange of Na + ions by NH 4 + ions favor titanate to anatase phase transition. • Preservation of textural and morphological properties at higher contact temperature. • Identifying different catalytic sites for dye degradation and hydrogen evolution. [ABSTRACT FROM AUTHOR]

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We have studied processes of gold ion implantation in polyethylene (PE) by theoretical chemistry methods. Car–Parrinello molecular dynamics (CPMD) simulations of collisions and following chemical kinetics considerations lead to the conclusion that chemical bonds between gold atoms and PE chains are formed. We have identified and characterized by a DFT method various stable structures with C–Au, C–Au–C, C–Au–H and C–Au…H2 types of chemical bonds. The binding energies (BE) of C–Au bonds are as high as 227 kJ mol−1 and the bond analysis reveals a covalent bonding character. For the experimental detection of these structures in gold implanted PE, we predicted characteristic infra-red (IR) frequencies. The C–Au stretching vibrational modes lie around 500 cm−1. Other characteristic frequencies lie in a band between 730 cm−1 and 1500 cm−1. [ABSTRACT FROM AUTHOR]

Poly(glycidyl methacrylate- co-ethylene glycol dimethacrylate) (poly(GMA- co-EGDMA) macroporous copolymer decorated with silver nanoparticles was prepared by a modification of poly(GMA- co-EGDMA) in the reaction with arginine, and consequent reduction of silver ions with amino groups. The mercury intrusion porosimetry, transmission electron microscopy, X-ray diffraction, UV-vis reflection spectroscopy, and inductively coupled plasma atomic emission measurements were used to characterize obtained composite. The coordination of silver nanoparticles to the poly(GMA- co-EGDMA) copolymer was studied using infrared spectroscopy. Time dependence and concentration dependence of the antimicrobial efficiency of composite were tested against Gram-negative bacteria Escherichia coli, Gram-positive bacteria Staphylococcus aureus, and fungus Candida albicans. The composite ensured maximum reduction of both bacteria, while the fungi reduction reached satisfactory 96.8%. Preliminary antimicrobial efficiency measurements using laboratory flow setup indicated potential applicability of composite for wastewater treatment. POLYM. COMPOS., 38:1206-1214, 2017. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The interfacial charge transfer (ICT) complex formation is a simple procedure to bring optical absorption of wide-bandgap oxide materials in the visible spectral range, crucial for enhancing their use in photo-driven reactions. The optical absorption of the prepared ICT complexes between ZnO and five different colorless benzene derivatives is red-shifted compared to pristine ZnO nanopowder. The density functional theory (DFT) calculations provided realistic energy level alignment in hybrid systems. Also, the DFT-calculated infrared spectra support the binding structures derived based on experimental measurements of free and adsorbed ligands onto ZnO surfaces. The photocatalytic performance of prepared hybrids was evaluated using photocatalytic hydrogen generation in the water-splitting reaction. The ZnO nanopowders modified with catechol and caffeic acid have over 50% higher hydrogen production rate than pristine ZnO, displaying steady hydrogen production under long-run working conditions. • Interfacial charge transfer complexes (ICT) between ZnO and benzene derivatives were prepared. • The visible-light-responsive ZnO-based ICT complexes were formed. • The density functional theory (DFT) calculations for ICT complexes were done. • The water-splitting reaction was used to test the photocatalytic performance of prepared hybrids. [ABSTRACT FROM AUTHOR]

Response surface methodology (RSM) and central composite design have been applied to describe and optimize photocatalytic degradation of azo pyridone dye using TiO2, H2O2, and simulated sun light. The mutual interactions between three independent variables, viz. H2O2 concentration, irradiation time, and TiO2 content were obtained. The results revealed that the most influential variables under selected reaction conditions were irradiation time and TiO2 content. The optimized conditions for the photocatalytic degradation of azo pyridone dye were as follows: H2O2 concentration: 130.5 mg/L, irradiation time: 54.8 min, and TiO2 content: 2.48 g/L. Under these conditions, the maximum decolorization efficiency of 96.43% was achieved. This experimental value was in good agreement with the predicted one, which proved the validity of the model. Operation cost analysis indicated that irradiation time had the major influence on total process cost. The RSM based on the central composite design was shown to be a successful technique for the optimization of the decolorization efficiency of azo pyridone dye and can be very helpful in improving the process economic feasibility. TOC analysis showed that the dye could be effectively mineralized during photocatalytic degradation. [ABSTRACT FROM AUTHOR]