Fabrication of novel magnetically separable visible-light-driven photocatalysts through photosensitization of Fe 3 O 4 /ZnO with CuWO 4

Degradation of high-concentration Rhodamine-B using Cu-doped ZnO/Fe3O4 nanocomposites and assessment of its toxicity

This study was conducted to fabricate effective photocatalysts in the degradation of high concentrations of Rhodamine-B (RhB), to make the photocatalysts recyclable, and to determine the toxicity of the wastewater resulting from the degradation of RhB. Nanoparticles were synthesized by the hydrothermal method and magnetic nanocomposites by the thermal reflux method. The synthesized nanomaterials were characterized by SEM, EDX, Mapping, XRD, FTIR, UV-Vis, Zeta-potential, DLS, and bandgap energy analysis. The photocatalytic activity was performed under visible sunlight and in the presence of the variables of pollutant percentage, nanomaterial dose, pollutant concentration, and reaction time. Using 13 different groups, the toxicity of the synthesized nanomaterials, RhB and the resulting effluent was investigated through oxidative stress parameters and pathology of the liver, kidney, and testis tissues of the Syrian mice. The results showed that nanomaterials have a 1-100 nm diameter, high purity, and uniform distribution. Adding Cu dopant reduced the size of nanomaterials, reduced the bandgap energy, and increased their photocatalytic activity. The highest degradation efficiency of RhB, corresponding to 1.5 M% Cu doped ZnO and 1.0 M% Cu doped ZnO/Fe3O4, was 96, and 94 %, respectively. Using nanomaterials after four times decreased the photocatalytic activity of nanomaterials by 12-14 %. The highest toxicity was related to RhB group, then nanocomposites containing Fe3O4 followed by other types of nanomaterials. The toxicity of the dye decomposition effluent was lower than the group of pesticide toxins and nanomaterials. The difference in oxidative stress parameters between the studied groups was significant (p < 0.05). 1.5 M% Cu doped ZnO and 1.0 M% Cu doped ZnO/Fe3O4 had the highest photodegradation efficiency. The toxicity of the effluent resulting from the decomposition of RhB was lower than the toxicity of RhB itself.

A New Sensitive Fluorescence Sensor and Photocatalyst for Determination and Degradation of Sodium Valproate Using g-C3N4@Fe3O4@CuWO4 Nanocomposite and FCCD Optimization

In this research, carbon nitride nanocomposite coupled with Fe3O4 and CuWO4 was thermally synthesized and characterized by different techniques, including SEM, TEM, XRD, EDX, and FTIR. Due to sodium valproate's luminescence quenching of this nanocomposite, a reliable, accurate, sensitive, selective, and fast-acting sodium valproate assay was proposed. Optimization of this fluorescent sensor was carried out by the FCCD approach. In the optimum conditions, the plot of sodium valproate concentration versus nanocomposite fluorescence emission showed a linear response (R2 = 0.9918), with a range of 0-0.55 µM, the limit of detection (S/N = 3) equal to 0.85 nM and limit of qualification equal to 2.82 nM. Photocatalytic activity of g-C3N4@Fe3O4@CuWO4 (40%) nanocomposite exhibited a good potency to sodium valproate degradation. Active species of degradation including superoxide radicals, holes, and hydroxyl radicals were investigated using ammonium oxalate, benzoquinone, and 2-propanol to identify the mechanism of photodegradation action. The activity of benzoquinone in the photocatalytic process led to a reduction in the rate of analyte degradation, which indicates the prominent role of superoxide radicals compared to other species in the degradation process. The degradation rate of the analyte using the Fenton reagent was found to be around two times more than in the Fenton reagent-free process. The possible mechanism for the fluorescence sensor and photocatalytic degradation reaction was also discussed.

Functionalized magnetic nanostructured composites and hybrids for photocatalytic elimination of pharmaceuticals and personal care products

Due to rapid urbanization and globalization, an enormous use of pharmaceuticals and personal care products (PPCPs) has resulted their excessive release in water bodies leading to several environmental issues. This release into the environment takes place via household sewage, hospital effluents, manufacturing units and landfill sites etc. The pharmaceuticals and personal care products (PPCPs) are recently listed as emerging contaminants having many adverse effects towards aquatic life, human beings, and the whole ecosystem. The alarming threats of PPCPs demand efficient methods to cope up their hazardous impacts. The conventional wastewater remediations are not specifically designed for the removal of PPCPs and hence, they require advanced technologies and materials for their elimination to ensure water safety. Among various methods employed so far, photocatalysis is considered to be one of the most cost effective and eco-friendly method but it requires a suitable candidate as a photocatalyst. Thanks to the magnetic nanocomposites which have improved the limitations (poor stability, agglomeration, and difficult separation, etc.) of classically used nanomaterials. Magnetic nanocomposites contain at least one component having magnetic properties making their separation easy from the aqueous media after the photodegradation phenomenon. These can be further functionalized with other materials to obtain maximum advantage as photocatalyst. Few examples of such functionalized nanocomposites are inorganic material based magnetic nanocomposites, carbon based magnetic nanocomposites, biomaterial based magnetic nanocomposites, metal-organic framework based magnetic nanocomposites and polymer based magnetic nanocomposites etc. This review covers the global environmental issue of water pollution especially with respect to the PPCPs, their occurrence in aqueous environment and toxic effects on living beings. A comprehensive discussion of the recently reported functionalized magnetic nanocomposites for the photocatalytic removal of PPCPs from water is the main aim of this review. The synthetic/morphological approaches of various functionalized magnetic composites and their mechanism of action are also elaborated. The possible research challenges in the field of magnetic nanocomposites and future research directions are discussed to apply magnetic nanocomposites for wastewater treatment in near future.

LED-light-activated photocatalytic performance of metal-free carbon-modified hexagonal boron nitride towards degradation of methylene blue and phenol

The present study outlines the transformation of non-photoresponsive hexagonal boron nitride (HBN) into a visible-light-responsive material. The carbon modification was achieved through a solid-state reaction procedure inside a tube furnace under nitrogen atmosphere. In comparison to HBN (bandgap of 5.2 eV), the carbon-modified boron nitride could efficiently absorb LED light irradiation with a light harvesting efficiency of ≈90% and a direct bandgap of 2 eV. The introduction of carbon into the HBN lattice led to a significant change in the electronic environment through the formation of C-B and C-N bonds which resulted in improved visible light activity, lower charge transfer resistance, and improved charge carrier density (2.97 × 1019 cm-3). This subsequently enhanced the photocurrent density (three times) and decreased the photovoltage decay time (two times) in comparison to those of HBN. The electronic band structure (obtained through Mott-Schottky plots) and charge trapping analysis confirmed the dominance of e-, O2 -•, and •OH as dominant reactive oxygen species. The carbon modification could effectively remove 93.83% of methylene blue (MB, 20 ppm solution) and 48.56% of phenol (10 ppm solution) from the aqueous phase in comparison to HBN which shows zero activity in the visible region.

Biogenic Photo-Catalyst TiO2 Nanoparticles for Remediation of Environment Pollutants

This article reports a benign environmentally friendly fabrication method of titanium dioxide (TDO) nanoparticles (named TDO NPs3, TDO NPs5, and TDO NPs8) using aqueous extract of durva herb waste. This synthesis process avoids use of harmful substances and persistent chemicals throughout the order and enables us to control the size of the nanomaterials. Characterization of TDO nanoparticles was analyzed by ultraviolet-visible spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The morphological nature of the TDO samples was inspected by transmission electron microscopy, which indicated that the TDO NPs3, TDO NPs5, and TDO NPs8 were spherical in shape, with average sizes of 5.14, 12.54, and 29.61 nm, respectively. The stability of TDO nanoparticles was assessed using thermogravimetric analysis and dynamic light scattering analysis. These samples could be used for degradation of polluting industrial textile dyes, such as methylene blue (MB) and rhodamine B (Rh-B). Remarkably, the TDO NPs3 sample (5.14 nm size) exhibits a noticeable degradation of the MB dye in a shorter time period (50 min) than the TDO NPs8 sample with a size of 29.61 nm (120 min). The TDO NPs3 sample was also tested for degradation of Rh-B dye, showing high degradation efficiency over a short period of time (60 min). In contrast, the TDO NPs8 sample showed degradation of the Rh-B dye in 120 min. The effect of the dye concentration and the catalyst dose to remove dye pollutants has also been investigated. The synthesized TDO NPs act as exceptional catalysts for the degradation of dyes, and they are promising materials for the degradation of industrial polluting dyes.

Apple-like Zinc-Oxide Mesocrystals as Robust and Versatile Photocatalysts for Efficient Degradation of Eight Different Organic Dyes

The discovery of efficient photocatalysts is a promising key approach to solve the environmental crisis caused by hazardous organic dyes. Herein, we have for the first time created ZnO mesocrystals with a novel apple-like morphology. We have developed a one-pot biomineralization route to synthesize ZnO nanostructures at room temperature by using the rod-like protein collagen as the template. The shape of ZnO mesocrystals can be conveniently tuned from fusiform-like and kiwi-like to orange-like, apple-like, and snack-like structures. The apple-like ZnO mesocrystals show a significantly better photodegradation efficiency than the commercial ZnO powder as well as other nanostructured ZnO materials for both rhodamine B (RhB) and methyl orange (MO). Furthermore, the apple-like zinc-oxide mesocrystals can degrade all of the tested eight different types of organic dyes (RhB, rhodamine 6G, methylene blue, Coomassie brilliant blue R250, BPB, MO, Li Chunhong S, and carmine) simply under the exposure of sunlight, demonstrating their superior photodegradation prowess, environmental amiability, and energy-saving features. The novel robust and versatile photocatalyst has greatly advanced our abilities for the elimination of organic dyes. The green, one-pot strategy provides a convenient method for the construction of novel metal-oxide nanostructures with promising applications in environmental protection.

AgI/CuWO4 Z-scheme photocatalyst for the degradation of organic pollutants: Experimental and molecular dynamics studies

While the knowledge of the adsorption properties of components of a composite heterogeneous photocatalyst is critical to its applicability to a particular reaction, there has been little research in this direction. The present research is on the development of AgI/CuWO₄ nanocomposites that photocatalytically degraded ciprofloxacin and rhodamine B in an aqueous medium under visible light irradiation. The nanocomposites were prepared by a step-wise precipitation protocol. XPS analysis and active species trapping experiments demonstrated that the photocatalysis proceeded by a Z-scheme mechanism. Large scale aqueous medium molecular dynamics simulations showed that oxygen and CIP adsorb on the AgI part, while water interacts intensely with the CuWO₄ component. Information from experimental and molecular dynamics studies was combined to arrive at the photocatalysis mechanism.

Magnetic ZnO Crystal Nanoparticle Growth on Reduced Graphene Oxide for Enhanced Photocatalytic Performance under Visible Light Irradiation

Magnetite zinc oxide (MZ) (Fe₃O₄/ZnO) with different ratios of reduced graphene oxide (rGO) was synthesized using the solid-state method. The structural and optical properties of the nanocomposites were analyzed using transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis/DRS), and photoluminescence (PL) spectrophotometry. In particular, the analyses show higher photocatalytic movement for crystalline nanocomposite (MZG) than MZ and ZnO nanoparticles. The photocatalytic degradation of methylene blue (MB) with crystalline ZnO for 1.5 h under visible light was 12%. By contrast, the photocatalytic activity for MZG was more than 98.5%. The superior photocatalytic activity of the crystalline nanocomposite was detected to be due to the synergistic effect between magnetite and zinc oxide in the presence of reduced graphene oxide. Moreover, the fabricated nanocomposite had high electron-hole stability. The crystalline nanocomposite was stable when the material was used several times.

Hydrothermal Synthesis of the CuWO4/ZnO Composites with Enhanced Photocatalytic Performance

Photocatalytic technology aiming to eliminate organic pollutants in water has been rapidly developed. In this work, we successfully synthesized CuWO₄/ZnO photocatalysts with different weight ratios of CuWO₄ through facile hydrothermal treatment. Crystal structures, forms, and optical properties of these as-prepared materials were investigated and analyzed. 3% CuWO₄/ZnO showed the optimum photodegradation efficiency toward methylene blue under the irradiation of simulated sunlight for 120 min, the degradation rate of which was 98.9%. The pseudo-first-order rate constant of 3% CuWO₄/ZnO was ∼11.3 and ∼3.5 times bigger than that of pristine CuWO₄ and ZnO, respectively. Furthermore, the material exhibited high stability and reusability after five consecutive photocatalytic tests. In addition, free radical capture experiments were conducted and the possible mechanism proposed explained that the synergistic effect between CuWO₄ and ZnO accelerates the photodegradation reaction. This work provides a feasible technical background for the efficient and sustainable utilization of photocatalysts in wastewater control.

Ionic Liquid-assisted Preparation of Two-dimensional ZnO/Fe3O4 Nano-composites and their Application in Polysubstituted Pyrroles Synthesis

AIMS AND OBJECTIVE

Ionic liquids are a suitable medium for stabilization and preparation of catalytic systems.

MATERIALS AND METHODS

The two-dimensional (2D) ZnO/Fe3O4 nanocomposites were synthesized using ionic liquid [OMIM]Br as a stabilizer and soft template. The nanocomposites were characterized via FTIR, XRD, VSM and SEM analysis.

RESULT

The catalytic activity of these composites was evaluated using a multicomponent reaction of primary amines, acetylacetone, and 2-bromoacetophenone.

CONCLUSION

2D ZnO/Fe3O4 as a recyclable and green catalyst showed excellent catalytic performance for the preparation of poly-substituted pyrroles.

Enhanced sonocatalytic degradation of organic dyes from aqueous solutions by novel synthesis of mesoporous Fe3O4-graphene/ZnO@SiO2 nanocomposites

Fe₃O₄-graphene/ZnO@mesoporous-SiO₂ (MGZ@SiO₂) nanocomposites was synthesized via a simple one pot hydrothermal method. The as-obtained samples were investigated using various techniques, as follows: scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and specific surface area (BET) vibrating sample magnetometer (VSM), among others. The sonocatalytic activities of the catalysts were tested according to the oxidation for the removal of methylene blue (MB), methyl orange (MO), and rhodamine B (RhB) under ultrasonic irradiation. The optimal conditions including the irradiation time, pH, dye concentration, catalyst dosage, and ultrasonic intensity are 60min, 11, 50mg/L, 1.00g/L, and 40W/m², respectively. The MGZ@SiO₂ showed the higher enhanced sonocatalytic degradation from among the three dyes; furthermore, the sonocatalytic-degradation mechanism is discussed. This study shows that the MGZ@SiO₂ can be applied asa novel-design catalyst for the removal of organic pollutants from aqueous solutions.

Fe3O4–Ag2WO4: facile synthesis, characterization and visible light assisted photocatalytic activity

Photo-generated charge carriers are effectively separated on a magnetic nano-composite (Fe₃O₄–Ag₂WO₄) surface under visible light irradiation.

Facile preparation of novel quaternary g-C3N4/Fe3O4/AgI/Bi2S3 nanocomposites: magnetically separable visible-light-driven photocatalysts with significantly enhanced activity

In this paper, we successfully fabricated quaternary g-C₃N₄/Fe₃O₄/AgI/Bi₂S₃ nanocomposites with various weight percents of Bi₂S₃, as novel magnetically separable visible-light-driven photocatalysts, using a facile refluxing method at 96 °C.