Search Results (45)

Free-standing copper oxide (Cu₂O)-copper hydroxide (Cu(OH)₂) nanocomposites with enhanced catalytic and antibacterial functionalities were synthesized on copper mesh using a green method based on spinach leaf extract and glycerol. EDX, SEM, and TEM analyses confirmed the chemical composition and morphology. The resulting Cu2O-Cu(OH)₂@Cu mesh exhibited notable hydrophobicity, achieving a contact angle of 137.5° ± 0.6, and demonstrated the ability to separate thick oils, such as HD-40 engine oil, from water with a 90% separation efficiency. Concurrently, its photocatalytic performance was evaluated by the degradation of methylene blue (MB) under a weak light intensity of 5 mW/cm², achieving 85.5% degradation within 30 min. Although its application as a functional membrane in water treatment may raise safety concerns, the mesh showed significant antibacterial activity against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria under both dark and light conditions. Using the disk diffusion method, strong bacterial inhibition was observed after 24 h of exposure in the dark. Upon visible light irradiation, bactericidal efficiency was further enhanced—by 17% for S. aureus and 2% for E. coli. These findings highlight the potential of the Cu₂O-Cu(OH)₂@Cu microfibers as a multifunctional membrane for industrial wastewater treatment, capable of simultaneously removing oil, degrading organic dyes, and inactivating pathogenic bacteria through photo-assisted processes. Full article

The textile industry encounters serious environmental challenges from wastewater with persistent organic pollutants, demanding sustainable solutions for remediation. Herein, we report a novel green synthesis of flexible BiOBr@PZT nanocomposite membranes via electrospinning and successive ionic layer adsorption and reaction (SILAR) for visible-light-driven photocatalytic degradation. The hierarchical structure integrates leaf-like BiOBr nanosheets with PAN/ZnO/TiO₂ (PZT) nanofibers, forming a Z-scheme heterojunction. This enhances the separation of photogenerated carriers while preserving mechanical integrity. SILAR-enabled low temperature deposition ensures eco-friendly fabrication by avoiding toxic precursors and cutting energy use. Optimized BiOBr@PZT-5 shows exceptional photocatalytic performance, achieving 97.6% tetracycline hydrochloride (TCH) degradation under visible light in 120 min. It also has strong tensile strength (4.29 MPa) and cycling stability. Mechanistic studies show efficient generation of O₂⁻ and OH radicals through synergistic light absorption, charge transfer, and turbulence-enhanced mass diffusion. The material’s flexibility allows reusable turbulent flow applications, overcoming rigid catalyst limitations. Aligning with green chemistry and UN SDGs, this work advances multifunctional photocatalytic systems for scalable, energy-efficient wastewater treatment, offering a paradigm that integrates environmental remediation with industrial adaptability. Full article

Microwave-assisted synthesis presents a promising method for enhancing the formation of nanocomposites due to its rapid heating and uniform energy distribution. In this study, we successfully fabricated polyethersulfone–zinc-oxide (PES-ZnO) nanocomposite membranes by exposing PES/ZnCl₂/DMF dope solutions to microwave radiation. Before synthesizing the membranes, zinc-oxide nanoparticles (ZnO-NPs) were optimized in an organic phase using microwave radiation to ensure effective nanoparticle formation. The synthesis of ZnO-NPs in DMF solvent was validated through UV–Vis spectroscopy, X-ray diffraction (XRD), and Dynamic Light Scattering (DLS). We examined the surface morphology and roughness of the PES-ZnO membranes through Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). Moreover, we assessed the membranes’ hydrophilicity, permeability, and physicochemical properties through contact-angle measurements, pure water flux tests, water uptake assessments, and porosity tests. Energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) verified the successful integration of ZnO nanoparticles (ZnO-NPs) into the membrane matrix. The results indicate that including ZnO-NPs significantly improves the membrane’s permeability and hydrophilicity. The nanocomposite membranes exhibited high dye rejection efficiency, with ZnO-NPs facilitating photocatalytic self-cleaning properties. Antibacterial tests also demonstrated a substantial inhibition of common bacteria, suggesting enhanced resistance to biofouling. This research highlights the potential of microwave-assisted PES-ZnO nanocomposite membranes as effective and sustainable solutions for wastewater treatment, offering scalable applications along with added benefits of antifouling, self-cleaning, and antibacterial properties. Full article

Novel AB-Polybenzimidazole (AB-PBI)/TiO₂ nanocomposite membranes have been prepared using a synthetic green chemistry approach. Modified Eaton’s reagent (methansulfonic acid/P₂O₅) was used as both reaction media for microwave-assisted synthesis of AB-PBI and as an efficient dispersant of partially agglomerated titanium dioxide powders. Composite membranes of 80 µm thickness have been prepared by a film casting approach involving subsequent anti-solvent inversion in order to obtain porous composite membranes possessing high sorption capacity. The maximal TiO₂ filler content achieved was 20 wt.% TiO₂ nanoparticles (NPs). Titania particles were green synthesized (using a different content of Mentha Spicata (MS) aqueous extract) by hydrothermal activation (150 °C), followed by thermal treatment at 400 °C. The various methods such as powder X-ray diffraction and Thermogravimetric analyses, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and Energy-dispersive X-ray spectroscopy, Electronic paramagnetic resonance, Scanning Electron Microscopy and Transmission Electron Microscopy have been used to study the phase and surface composition, structure, morphology, and thermal behavior of the synthesized nanocomposite membranes. The photocatalytic ability of the so-prepared AB-Polybenzimidazole/bio-TiO₂ membranes was studied for decolorization of Reactive Black 5 (RB5) as a model azo dye pollutant under UV light illumination. The polymer membrane in basic form, containing TiO₂ particles, was obtained with a 40 mL quantity of the MS extract, exhibiting the highest decolorization rate (96%) after 180 min of UV irradiation. The so-prepared AB-Polybenzimidazole/TiO₂ samples have a powerful antibacterial effect on E. coli when irradiated by UV light. Full article

The advancement of pharmaceutical science has resulted in the development of numerous tailor-made compounds, i.e., pharmaceuticals, tuned for specific drug targets. These compounds are often characterized by their low biodegradability and are commonly excreted to a certain extent unchanged from the human body. Due to their low biodegradability, these compounds represent a significant challenge to wastewater treatment plants. Often, these compounds end up in effluents in the environment. With the advancement of membrane technologies and advanced oxidation processes, photocatalysis in particular, a synergistic approach between the two was recognized and embraced. These hybrid advanced water treatment processes are the focus of this review, specifically the removal of pharmaceuticals from water using a combination of a photocatalyst and pressure membrane process, such as reverse osmosis or nanofiltration employing photocatalytic nanocomposite membranes. Full article

This study investigates the modification of polyethersulfone (PES) membranes with 1 wt% titanium dioxide (TiO₂), zirconium dioxide (ZrO₂) and a nanocomposite of TiO₂/ZrO₂. The aim was to efficiently remove Rhodamine B (RhB) from water using a threefold approach of adsorption, filtration and photodegradation. Among the modified membranes (TiO₂, ZrO₂ and TiO₂/ZrO₂), the TiO₂/ZrO₂-PES nanocomposite membrane showed a better performance in rejection of RhB than other membranes with the rejection efficiency of 96.5%. The TiO₂/ZrO₂-PES membrane was found to possess a thicker selective layer and reduced mean pore radius, which contributed to its improved rejection. The TiO₂/ZrO₂ nanocomposite membrane also showed high bulk porosity and a slightly lower contact angle of 69.88° compared to pristine PES with a value of 73°, indicating an improvement in hydrophilicity. Additionally, the TiO₂/ZrO₂-PES nanocomposite membrane demonstrated a relatively lower surface roughness (Sa) of 8.53 nm, which offers the membrane antifouling properties. The TiO₂/ZrO₂-PES membrane showed flux recovery ratio (FRR), total fouling (R_t), reversible fouling (R_r) and irreversible fouling (R_ir) of 48.0%, 88.7%, 36,8% and 52.9%, respectively. For the photocatalytic degradation performance, the removal efficiency of RhB followed this order TiO₂ > TiO₂/ZrO₂ > ZrO₂ (87.6%, 85.7%, 67.8%). The tensile strength and elongation were found to be compromised with the addition of nanoparticles and nanocomposites. This indicates the necessity to further modify and optimise membrane fabrication to achieve improved mechanical strength of the membranes. At low pressure, the overall findings suggest that the TiO₂/ZrO₂ nanocomposite has the potential to offer significant improvements in membrane performance (water flux) compared to other modifications. Full article

Methylene blue (MB) is a dye hazardous pollutant widely used in several industrial processes that represents a relevant source of water pollution. Thus, the research of new systems to avoid their environmental dispersion represents an important goal. In this work, an efficient and sustainable nanocomposite material based on green gold nanoparticles for MB water remediation was developed. Starting from the reducing and stabilizing properties of some compounds naturally present in Lambrusco winery waste (grape marc) extracts, green gold nanoparticles (GM-AuNPs) were synthesized and deposited on a supporting membrane to create an easy and stable system for water MB decontamination. GM-AuNPs, with a specific plasmonic band at 535 nm, and the modified membrane were first characterized by UV–vis spectroscopy, X-ray diffraction (XRD), and electron microscopy. Transmission electron microscopy analysis revealed the presence of two breeds of crystalline shapes, triangular platelets and round-shaped penta-twinned nanoparticles, respectively. The crystalline nature of GM-AuNPs was also confirmed from XRD analysis. The photocatalytic performance of the modified membrane was evaluated under natural sunlight radiation, obtaining a complete disappearance of MB (100%) in 116 min. The photocatalytic process was described from a pseudo-first-order kinetic with a rate constant (k) equal to 0.044 ± 0.010 min⁻¹. The modified membrane demonstrated high stability since it was reused up to 20 cycles, without any treatment for 3 months, maintaining the same performance. The GM-AuNPs-based membrane was also tested with other water pollutants (methyl orange, 4-nitrophenol, and rhodamine B), revealing a high selectivity towards MB. Finally, the photocatalytic performance of GM-AuNPs-based membrane was also evaluated in real samples by using tap and pond water spiked with MB, obtaining a removal % of 99.6 ± 1.2% and 98.8 ± 1.9%, respectively. Full article

Carbon-based functional nanocomposites have emerged as potent antimicrobial agents and can be exploited as a viable option to overcome antibiotic resistance of bacterial strains. In the present study, graphitic carbon nitride nanosheets are prepared by controlled calcination of urea. Spectroscopic measurements show that the nanosheets consist of abundant carbonyl groups and exhibit apparent photocatalytic activity under UV photoirradiation towards the selective production of singlet oxygen. Therefore, the nanosheets can effectively damage the bacterial cell membranes and inhibit the growth of bacterial cells, such as Gram-negative Escherichia coli, as confirmed in photodynamic, fluorescence microscopy, and scanning electron microscopy measurements. The results from this research highlight the unique potential of carbon nitride derivatives as potent antimicrobial agents. Full article

We have developed an innovative thin-film nanocomposite membrane that contains cellulose acetate (CA) with small amounts of TiO₂-decorated graphene oxide (GO) (ranging from 0.5 wt.% to 2 wt.%) sandwiched between two polytetrafluoroethylene (PTFE)-like thin films. The PTFE-like films succeeded in maintaining the bulk porosity of the support while increasing the thermal and chemical robustness of the membrane and boosting the catalytic activity of TiO₂ nanoparticles. The membranes exhibited a specific chemical composition and bonding, with predominant carbon–oxygen bonds from CA and GO in the bulk, and carbon–fluorine bonds on their PTFE-like coated sides. We have also tested the membranes’ photocatalytic activities on azithromycin-containing wastewaters, demonstrating excellent efficiency with more than 80% degradation for 2 wt.% TiO₂-decorated GO in the CA-GO-TiO₂/PTFE-like membranes. The degradation of the azithromycin formulation occurs in two steps, with reaction rates being correlated to the amount of GO-TiO₂ in the membranes. Full article

Polyvinylidene fluoride (PVDF) membranes were coated with TiO₂ and TiO₂-Ag to enhance their efficiency for oil-in-water emulsion separation. The photocatalytic activities of the two modified membranes and their filtration performances were compared in detail. The significantly enhanced photocatalytic activity of the TiO₂-Ag composite was proved using a methyl orange (MO) solution (c = 10⁻⁵ M) and a crude oil emulsion (c = 50 mg·L⁻¹). The TiO₂-Ag-coated membrane reduced the MO concentration by 87%, whereas the TiO₂-modified membrane reached only a 46% decomposition. The photocatalytic reduction in the chemical oxygen demand of the emulsion was also ~50% higher using the TiO₂-Ag-coated membrane compared to that of the TiO₂-coated membrane. The photoluminescence measurements demonstrated a reduced electron/hole recombination, achieved by the Ag nanoparticle addition (TiO₂-Ag), which also explained the enhanced photocatalytic activity. A significant improvement in the oil separation performance with the TiO₂-Ag-coated membrane was also demonstrated: a substantial increase in the flux and flux recovery ratio (up to 92.4%) was achieved, together with a notable reduction in the flux decay ratio and the irreversible filtration resistance. Furthermore, the purification efficiency was also enhanced (achieving 98.5% and 99.9% COD and turbidity reductions, respectively). Contact angle, zeta potential, scanning electron microscopy (SEM), and atomic force microscopy (AFM) measurements were carried out to explain the results. SEM and AFM images revealed that on the TiO₂-Ag-coated membrane, a less aggregated, more continuous, homogeneous, and smoother nanolayer was formed due to the ~50% more negative zeta potential of the TiO₂-Ag nanocomposite compared to that of the TiO₂. In summary, via Ag addition, a sufficiently hydrophilic, beneficially negatively charged, and homogeneous TiO₂-Ag-coated PVDF membrane surface was achieved, which resulted in the presented advantageous filtration properties beyond the photocatalytic activity enhancement. Full article

The worldwide increase of multidrug-resistant Gram-negative bacteria is a global threat. The emergence and global spread of Klebsiella pneumoniae carbapenemase- (KPC-) producing Klebsiella pneumoniae represent a particular concern. This pathogen has increased resistance and abilities to persist in human reservoirs, in hospital environments, on medical devices, and to generate biofilms. Mortality related to this microorganism is high among immunosuppressed oncological patients and those with multiple hospitalizations and an extended stay in intensive care. There is a severe threat posed by the ability of biofilms to grow and resist antibiotics. Various nanotechnology-based strategies have been studied and developed to prevent and combat serious health problems caused by biofilm infections. The aim of this review was to evaluate the implications of nanotechnology in eradicating biofilms with KPC-producing Klebsiella pneumoniae, one of the bacteria most frequently associated with nosocomial infections in intensive care units, including in our department, and to highlight studies presenting the potential applicability of TiO₂ nanocomposite materials in hospital practice. We also described the frequency of the presence of bacterial biofilms on medical surfaces, devices, and equipment. TiO₂ nanocomposite coatings are one of the best long-term options for antimicrobial efficacy due to their biocompatibility, stability, corrosion resistance, and low cost; they find their applicability in hospital practice due to their critical antimicrobial role for surfaces and orthopedic and dental implants. The International Agency for Research on Cancer has recently classified titanium dioxide nanoparticles (TiO₂ NPs) as possibly carcinogenic. Currently, there is an interest in the ecological, non-toxic synthesis of TiO₂ nanoparticles via biological methods. Biogenic, non-toxic nanoparticles have remarkable properties due to their biocompatibility, stability, and size. Few studies have mentioned the use of nanoparticle-coated surfaces as antibiofilm agents. A literature review was performed to identify publications related to KPC-producing Klebsiella pneumoniae biofilms and antimicrobial TiO₂ photocatalytic nanocomposite coatings. There are few reviews on the antibacterial and antibiofilm applications of TiO₂ photocatalytic nanocomposite coatings. TiO₂ nanoparticles demonstrated marked antibiofilm activity, but being nano in size, these nanoparticles can penetrate cell membranes and may initiate cellular toxicity and genotoxicity. Biogenic TiO₂ nanoparticles obtained via green, ecological technology have less applicability but are actively investigated. Full article

In this study, a mixed-matrix method was used to prepare PVDF polymeric membranes with different amounts of TiO₂ P25 photocatalyst embedded, which were employed in filtration processes in the presence of UV radiation (LED, peak emission at 375 nm) to eliminate two aqueous micropollutants (MPs) used as model compounds (venlafaxine and metoprolol). The obtained membranes were characterized to gain insights into their texture, morphology, composition, and other catalyst-related properties that could affect the photocatalytic filtration process. For that purpose, N₂ adsorption–desorption, contact angle, SEM-EDX, thermal analysis, FTIR, XPS, UV-vis DRS, and PL spectroscopy were used. Filtration tests were carried out in continuous mode using a dead-end filtration cell to evaluate the performance of the prepared membranes in removing the selected MPs. Experiments were performed both in ultrapure water and a secondary effluent from a municipal wastewater treatment plant. It was found that the synthesized membranes could effectively remove the target MPs in ultrapure water, achieving up to 99% elimination. Such process performance decreased drastically in the secondary effluent with removals below 35%. Carbonate/bicarbonate ions in the secondary effluent were identified as the main scavenging substances. Thus, after the partial removal of carbonate/bicarbonate ions from the secondary effluent, the removal of MPs achieved was above 60%. Full article

For environmental remediation, it is significant to design membranes with good mechanical properties and excellent photocatalytic activity. In this work, RGO/TiO₂ membranes with heterogeneous structures and good photocatalytic efficiency were synthesized using the method of electrospinning combined with a thermal treatment process. In the binary nanocomposites, RGO was tightly adhered to TiO₂ fibers and by simply adjusting the loading of RGO, the strength and modulus of the fibrous membranes were improved. Notably, the RGO-permeated TiO₂ fibers exhibited 1.41 MPa in tensile strength and 140.02 MPa in Young’s modulus, which were 705% and 343% of the original TiO₂ fibers, respectively. Benefiting from the enhanced light response and the homogeneous and compact heterogeneous structure, the synthesized RGO/TiO₂ membranes displayed good antibacterial performance with a photocatalytic inactivation rate of 6 log against E. coli within 60 min. This study offers a highly efficient alternative to inactivate E. coli for the synthesis of TiO₂-based membranes. Full article

Multifunctional membrane technology has gained tremendous attention in wastewater treatment, including oil/water separation and photocatalytic activity. In the present study, a multifunctional composite nanofiber membrane is capable of removing dyes and separating oil from wastewater, as well as having antibacterial activity. The composite nanofiber membrane is composed of cellulose acetate (CA) filled with zinc oxide nanoparticles (ZnO NPs) in a polymer matrix and dipped into a solution of titanium dioxide nanoparticles (TiO₂ NPs). Membrane characterization was performed using transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and Fourier transform infrared (FTIR), and water contact angle (WCA) studies were utilized to evaluate the introduced membranes. Results showed that membranes have adequate wettability for the separation process and antibacterial activity, which is beneficial for water disinfection from living organisms. A remarkable result of the membranes’ analysis was that methylene blue (MB) dye removal occurred through the photocatalysis process with an efficiency of ~20%. Additionally, it exhibits a high separation efficiency of 45% for removing oil from a mixture of oil–water and water flux of 20.7 L.m⁻² h⁻¹ after 1 h. The developed membranes have multifunctional properties and are expected to provide numerous merits for treating complex wastewater. Full article