Novel magnetically retrievable In2O3/MoS2/Fe3O4 nanocomposite materials for enhanced photocatalytic performance

Novel MoS2-In2O3-WS2 (2D/3D/2D) ternary heterostructure nanocomposite material: Efficient photocatalytic degradation of antimicrobial agents under visible-light

Fabrication of ternary composited photocatalytic nanomaterials with strong interaction is vital to deriving the fast charge separation for efficient photodegradation of organic contaminants in wastewater under visible light. In this work, novel ternary 2D/3D/2D MoS2-In2O3-WS2 multi-nanostructures were synthesized using facile hydrothermal processes. XRD, FTIR, and XPS results confirmed the phase, functional groups, and element composition of pure MoS2, MoS2-In2O3, and MoS2-In2O3-WS2 hybrids. UV-DRS spectra of the MoS2-In2O3-WS2 ternary hybrid indicate maximum absorption in the visible light range with a band-gap energy value of 2.4 eV. The surface of the 2D WS2 nanosheet structure tightly blends and densely disperses 2D MoS2 nanosheets and 3D In2O3 nanocubes. This confirmed the formation of the MoS2-In2O3-WS2 ternary hybrid in the form of 2D/3D/2D multi-nanostructures, which is also indicated from SEM and HR-TEM images. The synthesized MoS2-In2O3-WS2 ternary hybrid showed maximum photocatalytic activity under visible-light for antimicrobial agents such as triclosan (TCS) and trichlorocarban (TCC). The photocatalytic activity of TCS was revealed to be 95% at 90 min, while that of TCC was 93% at 100 min. The reusability and stability tests of the prepared MoS2-In2O3-WS2 ternary hybrid after four consecutive photocatalytic cycles were analyzed by FTIR and SEM, which indicated that the prepared ternary hybrid was very stable. Overall results suggested that the developed MoS2-In2O3-WS2 (2D/3D/2D) multi-nanostructures are environmentally friendly and low-cost nanocomposites as a potential photocatalyst for the removal of antimicrobial agents from wastewater.

Removal of Cu(II) by sodium hexametaphosphate and nano zero-valent iron modified calcium bentonite: characteristic, adsorption performance and mechanism

Cu (II) is a toxic heavy metal commonly identified in groundwater contaminants. Bentonite-based cutoff wall is the most used method in isolating and adsorbing contaminants, while the bentonite in it easily to fail due to Cu(II) exchange. This study synthesized a novel material through the modification of calcium bentonite (CaB) utilizing sodium hexametaphosphate (SHMP) and nano zero-valent iron (NZVI). The characteristics, adsorption performance, and mechanism of the NZVI/SHMP-CaB were investigated comprehensively. The results showed that SHMP can disperse CaB and reduce flocculation, while NZVI can be further stabilized without agglomeration. The best adsorption performance of NZVI/SHMP-CaB could be obtained at the dosage of 2% SHMP and 4% NZVI. The NZVI/SHMP-CaB exhibited an outstanding removal efficiency of over 60% and 90% at a high Cu(II) concentration (pH = 6, Cu(II) = 300 mg/L) and acidic conditions (pH = 3-6, Cu(II) = 50 mg/L), respectively. The adsorption of Cu(II) by NZVI/SHMP-CaB followed a pseudo-second-order kinetic model, and fitting results from the Freundlich isothermal model suggested that the adsorption process occurred spontaneously. Besides the rapid surface adsorption on the NZVI/SHMP-CaB and ion exchange with interlayer ions in bentonite, the removal mechanism of Cu(II) also involved the chemical reduction to insoluble forms such as Cu0 and Cu2O. The generated FePO4 covered the surface of the homogenized NZVI particles, enhancing the resistance of NZVI/SHMP-CaB to acidic and oxidative environments. This study indicates that NZVI/SHMP-CaB is a promising alternative material which can be used for heavy metal removal from contaminated soil and water.

Fiberglass cloth coated by coffee ground waste-derived carbon quantum dots/titanium dioxide composite for removal of caffeine and other pharmaceuticals from water

Coffee ground waste from the coffee beverage preparation is mainly discarded and consequently ends up in landfill, which cause the contamination of caffeine in various environmental compartments. This study focuses on the upcycling of coffee-ground waste to carbon quantum dots (CQDs) for use as a modifying material to improve the visible light activity of titanium dioxide (TiO₂). The CQD solution was synthesized by hydrothermal method, which has an average size of 2.80 ± 0.63 nm. The CQDs/TiO₂ photocatalysts were prepared by combining CQD solutions at various amounts with sol-gel TiO₂ and then coated on the fiberglass cloths (FGCs). The photocatalytic application mainly focuses on the removal of caffeine from the water. The photocatalytic experiment was preliminary run in a simple batch reactor under visible light. The 5CQDs/TiO₂ coated FGC (5 mL of CQD solution/g of Ti-based on sol-gel) showed the best performance, and it was selected for the removal of caffeine and other pharmaceuticals (i.e., carbamazepine and ibuprofen) in the recirculating reactor. The removals of caffeine, carbamazepine, and ibuprofen after irradiation for 9 h were 82%, 88%, and 84%, respectively. The residual concentrations were significantly lower than the reported toxicity levels based on specific species. The changes in total organic carbon were observed, indicating the mineralization of pharmaceuticals in water. The 5CQDs/TiO₂ coated FGC showed good flexible performance. No obvious loss of activity was observed for five runs. The actual wastewater from the coffee pot cleaning process was also tested. The removal was 80% for caffeine and 86% for color in the unit of the American Dye Manufacturers Institute (ADMI).

Enhanced photocatalytic degradation performance of In2O3/g-C3N4 composites by coupling with H2O2

Environmental pollution by organic pollutants poses a great threat to the ecosystem and human development. Solar-powered catalytic oxidation technology can solve the existing energy and pollution crisis. Hence, in this work, cubic nano-In₂O₃ modified g-C₃N₄ composite was synthesized by in situ calcination, then it was coupled with hydrogen peroxide for the degradation of antibiotic under visible light. The results of SEM and XPS showed that In₂O₃ and g-C₃N₄ were closely combined. The catalytic oxidation efficiency of the antibiotic doxycycline was greatly improved when the as-prepared compound was coupled with hydrogen peroxide, and 88.2% of doxycycline was degraded within 80 min. By designing the active species inhibition test, it was found that a large number of hydroxyl radicals were generated in the system after adding hydrogen peroxide, which accelerated the degradation of the target. Hydrogen peroxide not only acts as a source of hydroxyl radical, but also as an active electron acceptor, which promotes the separation of photogenerated electron-hole pairs in the composite photocatalyst. Therefore, the double oxidation system formed by In₂O₃/g-C₃N₄ coupled with hydrogen peroxide can degrade the target at a higher rate. This work provided a research basis for the synthesis of In₂O₃ with regular morphology and simplified synthesis of In₂O₃/g-C₃N₄, and explored the practicability of the coupling method of double advanced oxidation for pollutant degradation.

Molybdenum Disulfide-Based Nanomaterials for Visible-Light-Induced Photocatalysis

Visible-light-responsive photocatalytic materials have a multitude of important applications, ranging from energy conversion and storage to industrial waste treatment. Molybdenum disulfide (MoS₂) and its variants exhibit high photocatalytic activity under irradiation by visible light as well as good stability and recyclability, which are desirable for all photocatalytic applications. MoS₂-based materials have been widely applied in various fields such as wastewater treatment, environmental remediation, and organic transformation reactions because of their excellent physicochemical properties. The present review focuses on the fundamental properties of MoS₂, recent developments and remaining challenges, and key strategies for tackling issues related to the utilization of MoS₂ in photocatalysis. The application of MoS₂-based materials in visible-light-induced catalytic reactions for the treatment of diverse kinds of pollutants including industrial, environmental, pharmaceutical, and agricultural waste are also critically discussed. The review concludes by highlighting the prospects of MoS₂ for use in various established and emerging areas of photocatalysis.

Adsorptive and photocatalytic remediation of hazardous organic chemical pollutants in aqueous medium: A review

The provision of clean water is still a major challenge in developing parts of the world, as emphasized by the United Nation Sustainable Development Goals (SDG 6), and has remained a subject of extensive research globally. Advancements in science and industry have resulted in a massive surge in the amount of industrial chemicals produced within the last few decades. Persistent and emerging organic pollutants are detected in aquatic environments, and conventional wastewater treatment plants have ineffectively handled these trace, bioaccumulative and toxic compounds. Therefore, we have conducted an extensive bibliometric analysis of different materials utilized to combat organic pollutants via adsorption and photocatalysis. The classes of pollutants, material synthesis, mechanisms of interaction, merits, and challenges were comprehensively discussed. The paper highlights the advantages of various materials used in the removal of hazardous pollutants from wastewater with activated carbon having the highest adsorption capacity. Dyes, pharmaceuticals, endocrine-disrupting chemicals, pesticides and other recalcitrant organic pollutants have been successfully removed at high degradation efficiencies through the photocatalytic process. The photocatalytic degradation and adsorption processes were compared by considering factors such as cost, efficiency, ease of application and reusability. This review will be good resource material for water treatment professionals/scientists, who may be interested in adsorptive and photocatalytic remediation of organic chemicals pollutants.

Hydrothermal synthesis of novel heterostructured Ag/TiO2 /CuFe2 O4 nanocomposite: Characterization, enhanced photocatalytic degradation of methylene blue dye, and efficient antibacterial studies

In this work, we reported the successful synthesis of novel Ag/TiO₂ /CuFe₂ O₄ ternary nanocomposite by hydrothermal technique by using TiO₂ /CuFe₂ O₄ binary nanocomposite precursor that was also prepared by hydrothermal treatment by using TiO₂ nanoparticles and CuFe₂ O₄ nanoparticles synthesized via sol-gel method. The synthesized nanomaterials were accessed for their morphological, structural, and optical properties. X-ray diffraction (XRD) study reveals the formation of pure Ag/TiO₂ /CuFe₂ O₄ ternary nanocomposite in which the Ag, TiO₂ , and CuFe₂ O₄ are in anatase, spinal, and cubic crystal phases, respectively. Transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) analyses of Ag/TiO₂ /CuFe₂ O₄ ternary nanocomposite indicated granule-shaped morphology with bright spots of silver. The existence of Ti, O, Cu, Fe, and Ag without any other elements in the energy-dispersive X-ray spectroscopy (EDS) spectra of the prepared ternary nanocomposite depict its purity and its polycrystalline nature was confirmed by its selected area electron diffraction (SAED) pattern. The ternary nanocomposite was utilized for the methylene blue dye degradation with an optimum dose of 1.00 g/100 ml under ultraviolet (UV) light; the enhanced photocatalytic activity of the composite is attributed mainly due to the appreciable magnitudinal difference of positive charge of the valence band and negative charge of the conduction band of TiO₂ and CuFe₂ O₄ ; meanwhile, the interfacially placed Ag acts as a sink for the elections. Also, the ternary nanocomposite showed satisfactory antibacterial activities. PRACTITIONER POINTS: The prepared ternary nanocomposite showed effective results in dye degradation and satisfactory antibacterial property. The concentration of methylene dye has decreased considerably in every degradation process which was accessed through UV-vis studies. The highest degradation by using the ternary nanocomposite archived at pH = 6 Appreciable antibacterial activity was achieved against a few Gram-positive strains and Gram-negative strains of bacteria. This research activity can open a broad area of research towards textile dye degradation and antibacterial studies.

Features of structure, magnetic state and electrodynamic performance of SrFe12-xInxO19

Indium-substituted strontium hexaferrites were prepared by the conventional solid-phase reaction method. Neutron diffraction patterns were obtained at room temperature and analyzed using the Rietveld methods. A linear dependence of the unit cell parameters is found. In³⁺ cations are located mainly in octahedral positions of 4f_VI and 12 k. The average crystallite size varies within 0.84–0.65 μm. With increasing substitution, the T_C Curie temperature decreases monotonically down to ~ 520 K. ZFC and FC measurements showed a frustrated state. Upon substitution, the average and maximum sizes of ferrimagnetic clusters change in the opposite direction. The M_r remanent magnetization decreases down to ~ 20.2 emu/g at room temperature. The M_s spontaneous magnetization and the k_eff effective magnetocrystalline anisotropy constant are determined. With increasing substitution, the maximum of the ε^/ real part of permittivity decreases in magnitude from ~ 3.3 to ~ 1.9 and shifts towards low frequencies from ~ 45.5 GHz to ~ 37.4 GHz. The maximum of the tg(α) dielectric loss tangent decreases from ~ 1.0 to ~ 0.7 and shifts towards low frequencies from ~ 40.6 GHz to ~ 37.3 GHz. The low-frequency maximum of the μ^/ real part of permeability decreases from ~ 1.8 to ~ 0.9 and slightly shifts towards high frequencies up to ~ 34.7 GHz. The maximum of the tg(δ) magnetic loss tangent decreases from ~ 0.7 to ~ 0.5 and shifts slightly towards low frequencies from ~ 40.5 GHz to ~ 37.7 GHz. The discussion of microwave properties is based on the saturation magnetization, natural ferromagnetic resonance and dielectric polarization types.