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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] more...

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] more...

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] more...

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-Cpt>3N4/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] more...

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] more...

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] more...

Response surface methodology (RSM) and central composite design have been applied to describe and optimize photocatalytic degradation of azo pyridone dye using TiO2, Hpt>2O2, 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] more...