Search Results (2,999)

Novel fibrous cellulosic substrates impregnated with meta-polybenzimidazole (PBI)-stabilized carbon nanotubes/zinc oxide with different weight content of ZnO and with the use of dimethylacetamide as dispersant media. The pristine ZnO nanoparticle powder was prepared by plant extract-mediated synthesis using Vaccinium vitis-idaea L. The green synthesized ZnO possesses an average crystallite size of 15 nm. The formation of agglomerates from ZnO NPs with size 250 nm–350 nm in the m-PBI@CNTs/ZnO was determined. The prepared materials were investigated by PXRD analysis, XPS, SEM, EDS, AFM, and TEM in order to establish the phase and surface composition, structure, and morphology of the hybrids. The potential of the synthesized hybrid composites to degrade methylene blue (MB) dye as a model contaminant in aqueous solutions under UV illumination was studied. The photocatalytic results show that in the course of the photocatalytic reaction, the m-PBI@CNTs/ZnO 1:3 photocatalyst leads to the highest degree of degradation of the methylene blue dye (67%) in comparison with the other two studied m-PBI@CNTs/ZnO 1:1 and 1:2 composites (48% and 41%). The antibacterial activity of ZnO nanoparticles and the hybrid CNT materials was evaluated by the RMDA and the dynamic contact method, respectively. The profound antibacterial effect of the m-PBI@CNTs/ZnO hybrids was monitored for 120 h of exposition in dark and UV illumination regimes. The photocatalytic property of ZnO nanoparticles significantly shortens the time for bactericidal action of the composites in both regimes. The m-PBI@CNTs/ZnO 1:2 combination achieved complete elimination of 5.10⁵ CFU/mL E. coli cells after 10 min of UV irradiation. Full article

Effluent-containing dye molecules is a significant environmental hazard. An economical and energy-saving solution is needed to combat this issue for the purpose of environmental sustainability. In this study, Fe-Ni-Co-based trimetallic nanocomposite was synthesized using the coprecipitation method. Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), and Fourier Transform Infra-Red spectroscopy were conducted to explore the physical morphology, phase structure and functional groups of the synthesized catalyst. Among dyes, methyl orange is considered as a major contaminant in textile effluent. The current study focused on the degradation of methyl orange using a trimetallic Fe-Ni-Co-based nanocomposite. A central composite design in response surface methodology was employed to analyze the independent variables including dye concentration, catalyst dose, temperature, hydrogen peroxide, irradiation time, and pH. Dye degradation has been achieved up to 81% in 20 min at the lowest initial concentration (5 mg/L) in optimized conditions. Based on ANOVA, the predicted values were in great agreement with the actual values, signifying the applicability of response surface methodology in the photocatalytic decolorization of dyeing effluents. The results gained from this research demonstrated that the synthesis method of trimetallic nanocomposite (Iron Triad) is a cost-effective and energy efficient method that can be scaled up to a higher level for industrial application. Full article

This study aims to improve the photocatalytic properties of titanium dioxide nanorods (TNRs) and other related nanostructures (dense nanorods, needle-like nanorods, nanoballs, and nanoflowers) by modifying them with silver nanoparticles (AgNPs). This preparation is carried out using a two-step method: sol–gel dip-coating deposition combined with hydrothermal crystal growth. Further modification with AgNPs was achieved through the photoreduction of Ag⁺ ions under UV illumination. The investigation explores the impact of different growth factors on the morphological development of TiO₂ nanostructures by modulating (i) the chemical composition, the water:acid ratio, (ii) the precursor concentration involved in the hydrothermal process, and (iii) the duration of the hydrothermal reaction. Morphological characteristics, including the length, diameter, and nanorod density of the nanostructures, were analyzed using scanning electron microscope (SEM). The chemical states were determined through use of the X-ray photoelectron spectroscopy (XPS) technique, while phase composition and crystalline structure analysis was performed using the Grazing Incidence X-ray Diffraction (GIXRD) method. The results indicate that various nanostructures (dense nanorods, needle-like nanorods, nanoballs, and nanoflowers) can be obtained by modifying these parameters. The photocatalytic efficiency of these nanostructures and Ag-coated nanostructures was assessed by measuring the degradation of the organic dye rhodamine B (RhB) under both ultraviolet (UV) irradiation and visible light. The results clearly show that UV light causes the RhB solution to lose its color, whereas under visible light RhB changes into rhodamine 110, indicating a successful photocatalytic transformation. The nanoball-like structures’ modification with the active metal silver (TNRs 4 Ag) exhibited high photocatalytic efficiency under both ultraviolet (UV) and visible light for different chemical composition parameters. The nanorod structure (TNRs 2 Ag) is more efficient under UV, but under visible-light photocatalyst, the TNRs 6 Ag (dense nanorods) sample is more effective. Full article

The global challenge of sustainable and affordable wastewater treatment technology looms large as water pollution escalates steadily with the rapid pace of industrialization and population growth. The photocatalytic wastewater treatment is a cutting-edge and environmentally friendly technology that uses photons from light source to degrade and remove organic and inorganic contaminants from water. Thus, utilizing solar energy for photocatalytic wastewater treatment holds great promise as a renewable solution to alleviate pressures on the global water crisis. Employing solar concentrators to intensify sunlight for photocatalysis represents a promising avenue for future applications of a low-cost and rapid sustainable wastewater purification process. This groundbreaking approach will unveil fresh technological avenues for a cost-effective, sustainable, and swift wastewater purification process utilizing sunlight. This review article explores diverse solar concentrating systems and their potential applications in the wastewater treatment process. Full article

Density functional theory and a semi-empirical quantum chemical approach were used to evaluate the photocatalytic efficiency of ceria (CeO₂) combined with reduced graphene oxide (rGO) and graphene (GP) for degrading methylene blue (MB). Two main aspects were examined: the adsorption ability of rGO and GP for MB, and the separation of photogenerated electrons and holes in CeO₂/rGO and CeO₂/GP. Our results, based on calculations of the adsorption energy, population analysis, bond strength index, and reduced density gradient, show favorable energetics for MB adsorption on both rGO and GP surfaces. The process is driven by weak, non-covalent interactions, with rGO showing better MB adsorption. A detailed analysis involving parameters like fractional occupation density, the centroid distance between molecular orbitals, and the Lewis acid index of the catalysts highlights the effective charge separation in CeO₂/rGO compared to CeO₂/GP. These findings are crucial for understanding photocatalytic degradation mechanisms of organic dyes and developing efficient photocatalysts. Full article

Volatile organic compounds (VOCs) are representative indoor air pollutants that negatively affect the human body owing to their toxicity. One of the most promising methods for VOC removal is photocatalytic degradation using TiO₂. In this study, the addition of carbon black (CB) and heavy metal nanoparticles (NPs) was investigated to improve the efficiency of a TiO₂-based photocatalytic VOC decomposition system combined with ultrasonic atomization and ultraviolet irradiation, as described previously. The addition of CB and Ag NPs significantly improved the degradation efficiency. A comparison with other heavy metal nanoparticles and their respective roles are discussed. Full article

Peroxymonosulfate (PMS, SO₅²⁻)-based oxidation is an efficient pathway for degrading organic pollutants, but it still suffers from slow degradation efficiency and low PMS utilization. In this work, we report the preparation of porous Fe-doped g-C₃N₄ catalysts by one-step thermal polymerization using urea and transition metal salts as precursors and investigate the effect of atmosphere conditions (air and nitrogen) on the catalytic performance. Systematic characterizations show that Fe-doped g-C₃N₄ prepared in air (FeN_x-CNO) has a larger specific surface area (136.2 m² g⁻¹) and more oxygen vacancies than that prepared in N₂ (FeN_x-CNN, 74.2 m² g⁻¹), giving it more active sites to participate in the reaction. Meanwhile, FeN_x-CNO inhibits the recombination of photogenerated carriers and improves the light utilization. The redox cycling of Fe(III) and Fe(II) species in the photocatalytic system ensures the continuous generation of SO₅•⁻ and SO₄•⁻. Therefore, FeN_x-CNO can remove CBZ up to 96% within 20 min, which is 3.4 times higher than that of CNO and 3.1 times higher than that of FeN_x-CNN, and the degradation efficiency can still retain 93% after 10 cycles of reaction. This study provides an economical and efficient method for photocatalysis in the degradation of medicines in contaminated water. Full article

Indoor air quality determines the comfort, health, and wellbeing of people in buildings. Windows are the optimal elements for providing natural ventilation and fresh air, but the outside contains suspended particles that can be harmful in high concentrations. This work presents an openable and double-glazed façade component with a cavity that includes a series of slats that filter the air and depurate it by means of a photocatalytic reaction (TiO₂). This component integrates the functions of ventilation, solar protection, and air purification, which were analysed in the slat and the façade component to approve a preliminary design. To this end, it was applied to a specific case, a non-residential building at a latitude 41° N in a Mediterranean climate. The results show the optimal dimensions according to solar radiation and ventilation in this specific case and the method used to obtain them, along with the increase in the temperature of the incoming air with respect to the outside (10 °C). Finally, the results obtained from a photocatalytic coating sample show that the NOx degradation can be up to 9%. All these results confirm the applicability of this component in buildings and pave the way for further research. Full article

The literature shows that both in laboratory and in industrial conditions, the photocatalytic oxidation method copes quite well with degradation of most environmental toxins and pathogenic microorganisms. However, the effective utilization of photocatalytic processes for environmental decontamination and disinfection requires significant technological advancement in both the area of semiconductor material synthesis and its application. Here, we focused on the presence and “photocatalytic capability” of photocatalysts among soil minerals and their potential contributions to the environmental decontamination in vitro and in vivo. Reactions caused by sunlight on the soil surface are involved in its normal redox activity, taking part also in the soil decontamination. However, their importance for decontamination in vivo cannot be overstated, due to the diversity of soils on the Earth, which is caused by the environmental conditions, such as climate, parent material, relief, vegetation, etc. The sunlight-induced reactions are just a part of complicated soil chemistry processes dependent on a plethora of environmental determinates. The multiplicity of affecting factors, which we tried to sketch from the perspective of chemists and environmental scientists, makes us rather skeptical about the effectiveness of the photocatalytic decontamination in vivo. On the other hand, there is a huge potential of the soils as the alternative and probably cheaper source of useful photocatalytic materials of unique properties. In our opinion, establishing collaboration between experts from different disciplines is the most crucial opportunity, as well as a challenge, for the advancement of photocatalysis. Full article

Polymeric carbon nitride (PCN) is a kind of polymeric semiconductor that is widely popular in photocatalysis-related energy and environmental fields. However, the photocatalytic activity is still limited due to its poor conductivity and low charge separation efficiency. In this work, benzene rings were introduced to adjust the electronic structure of PCN, and then a PCN-based all-solid Z-scheme heterojunction was fabricated by combing multiwall carbon nanotubes (CNTs) and ferric oxide through precipitation and the in situ deposit method. Upon optimizing the ratio between PCN, CNTs, and Fe₂O₃, (PCN:CNTs:Fe₂O₃ = 10:1:3 by weight), the composites expressed superior photocatalytic degradation activity towards methylene blue (MB) and crystal violet (CV) compared with pristine PCN and Fe₂O₃. The MB degradation percentage achieved 90% in 75 min, and the CV up to 99.6% within 50 min. The Z-scheme mechanism was verified by band alignment and metal selective deposition. The CNTs in the heterojunction played the role of an electron shuttling mediator and hence improved charge separation efficiency. This work provides ideas for the construction of polymer-inorganic all-solid Z-scheme photocatalysts for practical applications. Full article

Carbon nitrides can form coordination compounds or metallic oxides in the presence of transition metals, depending on the reaction conditions. By adjusting the pH to basic levels for mild synthesis with metals, composites like g-C₃N₄-M(OH)_x (where M represents metals) were obtained for nickel (II) and manganese (II), while copper (II) yielded coordination compounds such as Cu-g-C₃N₄. These materials underwent spectroscopic and electrochemical characterization, revealing their photocatalytic potential to generate superoxide anion radicals—a feature consistent across all metals. Notably, the copper coordination compound also produced significant hydroxyl radicals. Leveraging this catalytic advantage, with band gap energy in the visible region, all compounds were activated to disinfect E. coli bacteria, achieving total disinfection with Cu-g-C₃N₄. The textural properties influence the catalytic performance, with copper’s stabilization as a coordination compound enabling more efficient activity compared to the other metals. Additionally, the determination of radicals generated under light in the presence of dicloxacillin supported the proposed mechanism and highlighted the potential for degrading organic molecules with this new material, alongside its disinfectant properties. Full article

Ag₃PO₄/g-C₃N₄ photocatalytic composites were synthesized via calcination and hydrothermal synthesis for the degradation of rhodamine B (RhB) in wastewater, and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and diffuse reflectance spectroscopy (DRS). The degradation of RhB by Ag₃PO₄/g-C₃N₄ composites was investigated to evaluate their photocatalytic performance and cyclic degradation stability. The experimental results showed that the composites demonstrated notable photocatalytic activity and stability during degradation. Their high degradation efficiency is attributed to the Z-scheme transfer mechanism, in which the electrons in the Ag₃PO₄ conduction band and the holes in the g-C₃N₄ valence band are annihilated by heterojunction recombination, which greatly limits the recombination of photogenerated electrons and holes in the catalyst and enhances the activity of the composite photocatalyst. In addition, measurements of photocurrent (PC) and electrochemical impedance spectroscopy (EIS) confirmed that the efficient charge separation of photo-generated charges stemmed from strong interactions at the close contact interface. Finally, the mechanism for catalytic enhancement in the composite photocatalysts was proposed based on hole and radical trapping experiments, electron paramagnetic resonance (EPR) analysis, and work function evaluation. Full article

Polyvinyl alcohol (PVA)/TiO₂/colloidal photonic crystal (CPC) films with photocatalytic properties are presented, where TiO₂ nanoparticles were introduced into the PVA gel network. Such PVA/TiO₂/CPC films possess three-dimensional periodic structures that are supported with a PVA/TiO₂ composite gel. The unique structural color of CPCs can indicate the process of material preparation, adsorption, and desorption. The shift of diffraction peaks of CPCs can be more accurately determined using fiber-optic spectroscopy. The effect of the PVA/TiO₂/CPC catalyst films showed better properties as the degradation of methylene blue (MB) by the PVA/TiO₂/CPC film catalyst in 4 h was 77~90%, while the degradation of MB by the PVA/TiO₂ film was 33% in 4 h, indicating that the photonic crystal structure was 2.3~2.7 times more effective than that of the bulk structure. Full article

Nanomaterials are widely used in several biomedical and environmental applications, due to their ideal properties. However, the synthetic and characterization procedure requires significant costs and has a negative environmental impact. Various methods are available in order to control the pre-synthesis design of the produced materials, predicting their behavior and minimizing the series of experiments. Multi-Criteria Decision-Making is proposed in this study in order to determine the best combination of the physicochemical parameters and to define the best alternative among fifteen different samples of nanostructured titanium dioxide. In particular, the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method was applied to achieve a final ranking of the available alternatives by avoiding several of the trials that would follow testing the biological effect and the photocatalytic degradation of organic pollutants. Thus, this approach helps us to stay environmentally and ethically correct, saving time, money, and energy and also providing an optimization of the nanomaterials that are developed. Full article

Photocatalysis is one of the most effective ways to solve environmental problems by solving pollutants. This article designed and prepared a conjugated system of 2,4,6-triaminopyrimidine-g-C₃N₄ (TAP-CN) to modify ZnO NWs. We systematically studied the photocatalytic performance of ZnO NWs modified with different ratios of TAP-CN. The results showed that 9 wt% TAP-CN-30/ZnO NWs had the best degradation effect on Rhodamine B dye. The degradation rate was 99.36% in 80 min. The excellent degradation performance was attributed to the TAP-CN conjugated system promoting photo-generated charge transfer. This work provided guidance for designing efficient composite catalysts for application in other renewable energy fields. Full article