Search Results (21)

Contaminants of emerging concern (CECs), including pharmaceuticals and perfluorinated compounds, pose a growing threat to water quality due to their persistence and resistance to conventional treatment methods. In this context, photocatalytic processes capable of promoting both oxidative and reductive transformations have attracted increasing attention. This study explores the synthesis and performance of a SnS₂-TiO₂ heterojunction photocatalyst, designed to facilitate such reactions under solar and UV-A light. The composite was synthesized via the hydrothermal method and thoroughly characterized for its morphological, structural, surface, and semiconducting properties. The results confirmed the formation of a type-II heterojunction with improved visible-light absorption and suppressed charge recombination. Photoelectrochemical measurements indicated enhanced charge separation and favorable band-edge alignment for reductive processes. Photocatalytic experiments with amoxicillin (AMX) and perfluorooctanoic acid (PFOA) revealed distinct degradation behaviors: AMX was predominantly degraded via superoxide-mediated reductive pathways, whereas PFOA exhibited limited transformation, likely proceeding via a combination of oxidative and reductive mechanisms. While overall removal efficiencies were moderate, this study highlights the role of band structure engineering and heterojunction design in tailoring photocatalytic behavior. The SnS₂-TiO₂ system serves as a promising platform for further development of composite materials to address the challenge of CECs in water treatment. Full article

This research presents the synthesis of Fe-doped ZnS nanocomposites via a chemical route, exploring their photocatalytic activity against amoxicillin (AMX) and evaluating their hydrogen production potential. The synthesized nanocomposites were characterized by several state-of-the-art analytical techniques, such as XRD, SEM, PL, UV adsorption, Raman, TEM, and AFM. The photocatalytic performance revealed significant degradation of AMX under optimal conditions. Specifically, Fe-doped ZnS nanocomposites achieved a degradation efficiency of 94% within 120 min at a photocatalyst dosage of 110 mg. The pristine ZnS nanoparticles exhibited a hydrogen production rate of 23.6 µmol·g⁻¹·h⁻¹, whereas Fe doping substantially enhanced this rate to 526.6 µmol·g⁻¹·h⁻¹ under optimized conditions. The optimal temperature for hydrogen production was 200 °C, with maximum efficiency at pH 7. Furthermore, the recyclability tests demonstrated that the photocatalyst maintained a considerable hydrogen production rate over multiple cycles, underscoring its potential for commercial nanotechnology and environmental science applications. Full article

Novel photocatalysts were synthesized through the association of carbon quantum dots (CQDs) with commercial (P25) titanium dioxide (TiO₂) by sonication. The resulting TiO₂/CQDs composite was then incorporated into the polyamide 66 (PA66) biopolymer nanofibers using the electrospinning technique, considering a composite nanoparticles-to-polymer ratio of 1:2 in the electrospinning precursor solution. The produced nanofibers presented suitable morphology and were tested for the photocatalytic degradation under simulated solar radiation of 10 mg L⁻¹ of amoxicillin (AMX) and sulfadiazine (SDZ), in phosphate buffer solution (pH 8.06) and river water, using 1.5 g L⁻¹ of photocatalyst. The presence of the photocatalyst increased the removal of AMX in phosphate buffer solution by 30 times, reducing the AMX degradation half-life time from 62 ± 1 h (without catalyst) to 1.98 ± 0.06 h. Moreover, SDZ degradation half-life time in phosphate buffer solution was reduced from 5.4 ± 0.1 h (without catalyst) to 1.87 ± 0.05 h in the presence of the photocatalyst. Furthermore, the PA66/TiO₂/CQDs were also efficient in river water samples and maintained their performance in at least three cycles of SDZ photodegradation in river water. The presented results evidence that the produced photocatalyst can be a promising and sustainable solution for antibiotics’ efficient removal from water. Full article

A series of composites was prepared starting from five types of LDHs, which were then exchanged with three types of metallo-phthalocyanines, and, in the end, magnetic nanoparticles were attached. In the case of LDHs containing Fe, characterization data showed that there was a partial oxidation from Fe²⁺ to Fe³⁺. Samples containing evident LDH structures performed better in general than the ones containing iron oxide mixtures, the composites being more active towards amoxicillin removal compared with ampicillin removal. The nature of the phthalocyanine did not have such a great influence, although some differences in the activity were observed. The removal was a combination between adsorption and photocatalytic degradation. The best composites for this application were those based on Mg_0.325Fe_0.325Al_0.25-LDH prepared by co-precipitation in the presence of NaOH and Na₂CO₃. They presented high adsorption capacity in 10 min and, at the same time, high photocatalytic activity for both amoxicillin and ampicillin. Full article

Amoxicillin (AMX) is utilized in the treatment of several infectious diseases, and its concentration in wastewater has increased quite significantly over the years, posing high health hazards for humans and other living organisms. Investigations are in progress globally to eliminate AMX and other related pollutants using several methods that include adsorption, photolysis, photocatalytic degradation, photoelectrocatalytic degradation, and electrochemical conversion. AMX can be eliminated efficiently from the environment using photodegradation, either by photolysis or a photocatalytic process. Several types of semiconductor NMs have been used to eliminate AMX and other related drugs present in wastewater. This review spans the photodegradation studies conducted during the years 2018–2024 to degrade and eliminate AMX in aquatic systems. Several studies have been reported to eliminate AMX from different water streams. These studies are categorized into TiO₂-containing and non-TiO₂-based catalysts for better comparison. A section on photolysis is also included, showing the use of UV alone or with H₂O₂ or PS without using any nanomaterial. A tabulated summary of both types of catalysts showing the catalysts, reaction conditions, and degradation efficiency is presented. Researchers have used a variety of reaction conditions that include radiation types (UV, solar, and visible), pH of the solution, concentration of AMX, number of nanomaterials, presence of other additives and activators such as H₂O₂ as oxidant, and the influence of different salts like NaCl and CaCl₂ on the photodegradation efficiency. TiO₂ was the best nanomaterial found that achieved the highest degradation of AMX in ultraviolet irradiation. TiO₂ doped with other nanomaterials showed very good performance under visible light. WO₃ was also used by several investigators and found quite effective for AMX degradation. Other metal oxides used for AMX elimination were derived from molybdenum, zinc, manganese, copper, cerium, silver, etc. Some researchers have used UV and/or visible irradiation or sunlight, without using solid catalysts, in the presence of oxidants such as H₂O₂. A summarized description of earlier published reviews is also presented. Full article

The present research work describes the synthesis and characterization of CuO/SiO₂ for coating-perforated 304 stainless steel (SS) substrates to degrade methylene blue and amoxicillin under visible light irradiation. The foregoing photocatalytic system was achieved through the coprecipitation method by adding pure CuO to a SiO₂ sol at 1:5, 1:10, and 1:15 molar ratios. The conditions for carrying out the depositions on the SS substrates (three per substrate) involved an immersion rate of 90 mm/min with a drying time of 20 min at 120 °C. The XRD technique confirmed the presence of the SiO₂ amorphous phases and CuO monoclinic systems in the coatings, with a particle size distribution ranging from 0.5 to 2.5 μm (with an average of 1.26 ± 0.06 μm). As for SEM, it revealed a homogeneous coating surface without cracks. The produced photoactive CuO/SiO₂ coatings were capable of degrading methylene blue (98%) at 1500 min and amoxicillin (55%) at 450 min. Full article

Efficient compositions for the selective detection of ethanol gas and the removal of organic contaminants were realized by codoping of (Gd, Nb) and (Gd, Mo) ions into TiO₂. TiO₂, Ti_0.96Gd_0.01Nb_0.03O₂, and Ti_0.96Gd_0.01Mo_0.03O₂ samples were prepared by a coprecipitation method. For all compositions, a crystalline anatase phase of TiO₂ was detected. Compared to pure TiO₂, the absorption edges of Ti_0.96Gd_0.01Nb_0.03O₂ and Ti_0.96Gd_0.01Mo_0.03O₂ samples were red-shifted, further broadening towards visible light. The morphological studies demonstrate that the grains of TiO₂ were more refined after (Gd, Nb) and (Gd, Mo) codoping. The photocatalytic efficiency of the Ti_0.96Gd_0.01Mo_0.03O₂ catalyst for degrading 20 mg/L reactive yellow 145, brilliant green, and amoxicillin was 98, 95, and 93% in 90 min, respectively. The reusability experiments indicate that the Ti_0.96Gd_0.01Mo_0.03O₂ catalyst had high stability during reuse. The high photocatalytic activity of the Ti_0.96Gd_0.01Mo_0.03O₂ catalyst was correlated to the broad visible-light absorption and effective separation of electron–hole pairs by Gd³⁺ and Mo⁶⁺ cations. The gas sensing characteristic is reflected by the high sensitivity of the Ti_0.96Gd_0.01Nb_0.03O₂ sensor to ethanol gas in the presence of different gases at 275 °C. The obtained results indicated that the (Gd, Mo) mixture could more effectively induce the photocatalytic properties of TiO₂ while (Gd, Nb) dopants were the best for reinforcing its sensing characteristics. Full article

Zeolite Y samples with microporous and hierarchical structures containing Ti–Ni and Ti–Co oxides were obtained as active photocatalysts. Different Ti amounts (5, 10% TiO₂) were supported, followed by the loading of Ni or Co oxides (5%). X-ray diffraction evidenced the presence of TiO₂ as an anatase. N₂ adsorption–desorption results showed type IV isotherms for hierarchical zeolite Y samples, and a combination of type IV and I isotherms for zeolite Y samples. UV–Vis diffuse reflectance spectra showed a shift in the absorption band to visible with increasing Ti loading and especially after Co and Ni addition. A significant effect of the support was evidenced for Ti and its interaction with Co/Ni species. The zeolite Y support stabilized Ti in the 4+ oxidation state while hierarchical zeolite Y support favored the formation of Ti³⁺ species, Ni⁰ and Ni²⁺ and the oxidation of Co to 3+ oxidation state. Photocatalytic activity, under UV and visible light irradiation, was evaluated by the degradation of amoxicillin, used as a model test. The photocatalytic mechanism was investigated using ethanol, p-benzoquinone and KI as ·OH and ·O₂⁻ radicals and hole (h⁺) scavengers. The best results were obtained for the immobilized Ni-Ti species on the hierarchical zeolite Y support. Full article

The present work reports the synthesis of efficient Ti–Au/zeolite Y photocatalysts by different processing of aluminosilicate gel and studies the effect of titania content on the structural, morphological, textural, and optical properties of the materials. The best characteristics of zeolite Y were obtained by aging the synthesis gel in static conditions and mixing the precursors under magnetic stirring. Titania (5, 10, 20%) and gold (1%) species were incorporated in zeolite Y support by the post-synthesis method. The samples were characterized by X-ray diffraction, N₂-physisorption, SEM, Raman, UV–Vis and photoluminescence spectroscopy, XPS, H₂-TPR, and CO₂-TPD. The photocatalyst with the lowest TiO₂ loading shows only metallic Au on the outermost surface layer, while a higher content favors the formation of additional species such as: cluster type Au, Au¹⁺, and Au³⁺. A high TiO₂ content contributes to increasing the lifetime of photogenerated charge careers, and the adsorption capacity of the pollutant. Therefore, an increase in the photocatalytic performances (evaluated in degradation of amoxicillin in water under UV and visible light) was evidenced with the titania content. The effect is more significant in visible light due to the surface plasmon resonance (SPR) effect of gold interacting with the supported titania. Full article

In this work, we report the synthesis of Mn-doped Cu₂O nanoparticles using aloe vera leaves extract. X-ray diffraction data revealed that the Mn-doped Cu₂O crystals have a cubic crystal structure. The surface morphology of the as-synthesized catalyst indicated truncated octahedral and spherical-like shapes. The photocatalytic activity of the catalyst is efficient at pH 9, initial concentration of amoxicillin 15 mg/L, and photocatalyst dosage 1 g/L under sunlight irradiation. 92% of amoxicillin was degraded in the presence of Mn-doped Cu₂O. The enhancement in photocatalytic performance is due to the incorporation of Mn, which delays the rapid recombination rate by trapping the photogenerated electron. Therefore, Mn-doped Cu₂O could remove pharmaceuticals from pharmaceutical factory and hospital wastes. Full article

New photocatalysts were obtained by immobilization of titanium and gold species on zeolite Y, hierarchical zeolite Y, MCM-48 and KIT-6 supports with microporous, hierarchical and mesoporous cubic structure. The obtained samples were characterized by X-ray diffraction (XRD), N₂-physisorption, scanning and transmission electron microscopy (SEM/TEM), diffuse reflectance UV–Vis spectroscopy (DRUV-Vis), X-ray photoelectron spectroscopy (XPS), Raman and photoluminescence spectroscopy. The photocatalytic properties were evaluated in degradation of amoxicillin (AMX) from water, under UV (254 nm) and visible light (532 nm) irradiation. The higher degradation efficiency and best apparent rate constant were obtained under UV irradiation for Au-TiO₂-KIT-6, while in the visible condition for the Au-TiO₂-MCM-48 sample containing anatase, rutile and the greatest percent of Au metallic clusters were found (evidenced by XPS). Although significant values of amoxicillin degradation were obtained, total mineralization was not achieved. These results were explained by different reaction mechanisms, in which Au species act as e⁻ trap in UV and e⁻ generator in visible light. Full article

Easy and cost-efficient modifications of titanium dioxide nanoparticles that improve their efficiency in the visible light domain represent a continuous and challenging research topic. In addition, the effect of graphene on the overall photocatalytic process is still debated. Consequently, herein, we prepared a series of TiO₂ nanoparticle-based composites with different copper oxide mass content (1–3%) and co-doped with graphene of different oxidation degrees. Different characterization techniques were used to analyze the structural and physico-chemical properties of the obtained composites: Scanning Electron Microscopy (SEM)/Transmission Electron Microscopy (TEM)/Energy-dispersive X-ray spectroscopy (EDX) analysis, X-ray powder diffraction (XRD), Fourier-transformed infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The photocatalytic performance was evaluated by the degradation of methylene blue under both UVA and visible light irradiation. The nanocomposites show very good photocatalytic activity independent of the presence of reduced graphene oxide, due to the Cu₂O/CuO-TiO₂ heterojunctions. This finding has been confirmed by the very efficient visible-light-driven degradation of amoxicillin and ciprofloxacin. Full article

Special attention has recently been paid to surface-defective titanium dioxide and black TiO₂ with advanced optical, electrical, and photocatalytic properties. Synthesis of these materials for photodegradation and mineralization of persistent organic pollutants in water, especially under visible radiation, presents interest from scientific and application points of view. Chemical reduction by heating a TiO₂ and NaBH₄ mixture at 350 °C successfully introduced Ti³⁺ defects and oxygen vacancies at the surface of TiO₂, with an increase in the photocatalytic degradation of amoxicillin—an antibiotic that is present in wastewater due to its intense use in human and animal medicine. Three TiO₂ samples were prepared at different annealing temperatures to control the ratio between anatase and rutile and were subjected to chemical reduction. Electron paramagnetic resonance investigations showed that the formation of surface Ti³⁺ defects in a high concentration occurred mainly in the anatase sample annealed at 400 °C, contributing to the bandgap reduction from 3.32 eV to 2.92 eV. The reduced band gap enhances visible light absorption and the efficiency of photocatalysis. The nanoparticles of ~90 m²/g specific surface area and 12 nm average size exhibit ~100% efficiency in the degradation of amoxicillin under simulated solar irradiation compared with pristine TiO₂. Mineralization of amoxicillin and by-products was over 75% after 48 h irradiation for the anatase sample, where the Ti³⁺ defects were present in a higher concentration at the catalyst’s surface. Full article

Due to the release of active pharmaceutical compounds in wastewater and their persistence in the environment, dangerous consequences can develop in the aquatic and terrestrial organisms. Chitosan/Ag/TiO₂ 3D printed scaffolds, at different Ag nanoparticle concentrations (10, 100, 1000 ppm) are investigated here as promising materials for photocatalytic degradation under the UV–Vis irradiation of pharmaceutical compounds in wastewater. As target drugs, amoxicillin, paracetamol and their 1:1 mix were selected. Ag nanoparticles increase the photocatalytic efficiency of the system based on titanium dioxide embedded in the chitosan scaffold: in the presence of Chitosan/Ag₁₀₀/TiO₂, the selected pharmaceuticals (PhCs), monitored by UV–Vis spectroscopy, are completely removed in about 2 h. The photodegradation products of the PhCs were identified by Liquid Chromatography–Mass Spectroscopy and assessed for their toxicological impact on six different bacterial strains: no antibacterial activity was found towards the tested strains. This new system based on Ag/TiO₂ supported on 3D chitosan scaffolds may represent an effective strategy to reduce wastewater pollution by emerging contaminants. Full article

Dye sensitization on semiconductor catalyst TiO₂ was performed with four different metallophthalocyanine (MPc) derivates (M: Zn, Cu, Co, and Si) using a modified sol-gel method. MPc derivatives were loaded on TiO₂ at 1% mass ratio aiming to increase its photocatalytic action and to shift the light absorption to higher UV region (365 nm). Non-ionic surfactant Triton X-100 (TX-100) was used to obtain a homogenous and mesa pore catalyst structure. The prepared catalysts were characterized by FT-IR, XRD, and SEM to determine the crystal and surface structural properties of nanocomposites. The nanocomposites were used for photocatalytic removal and degradation of Cr(VI) and amoxicillin (AMX) as model pollutants. Photocatalytic reduction capacities of the catalysts were tested for Cr(VI) (10 mg/L) and AMX (20 mg/L) aqueous solutions. ZnPc-TiO₂ catalyst was successful for Cr(VI) photoreduction since all Cr(VI) ions in the solution were successfully removed. Presence of TX-100 in the sol-gel synthesis of ZnPc-TiO₂ had a positive effect by increasing the Cr(VI) removal rate to 97.93% after 150 min exposure period. Prepared catalysts were also tested for photodegradation of AMX, applying similar procedures. In general, all catalysts exhibited low degradation rates under the studied condition but more effective with 254 nm UV light (50.38%). Neither surface modification with TX-100 nor MPc sensitization provided significant degradation of AMX. Full article