Search Results (756)

Aguama (Bromelia pinguin L.), a plant belonging to the Bromeliaceae family, possesses a rich content of organic compounds historically employed in traditional medicine. This research focuses on the sustainable synthesis of ZnO nanoparticles via an eco-friendly route using 1, 2, and 4% of Aguama peel extract. This method contributes to environmental sustainability by reducing the use of hazardous chemicals in nanoparticle production. The optical properties, including the band gap, were determined using the TAUC model through Ultraviolet–Visible Spectroscopy (UV–Vis). The photocatalytic activity was evaluated using three widely studied organic dyes (methylene blue, methyl orange, and rhodamine B) under both solar and UV radiation. The results demonstrated that the ZnO nanoparticles, characterized by a wurtzite-type crystalline structure and particle sizes ranging from 68 to 76 nm, exhibited high thermal stability and band gap values between 2.60 and 2.91 eV. These nanoparticles successfully degraded the dyes completely, with methylene blue degrading in 40 min, methyl orange in 70 min, and rhodamine B in 90 min. This study underscores the potential of Bromelia pinguin L. extract in advancing sustainable nanoparticle synthesis and its application in environmental remediation through efficient photocatalysis. Full article

The oxidation of organic pollutants in water is the most reported application of a Titanium dioxide (TiO₂) photocatalyst. During the last decade, photoreduction with TiO₂ has also been explored but simultaneous capabilities for unmodified TiO₂ have not been reported yet. Here, we reported on the fabrication of TiO₂ nanorods using hydrothermal treatment and compared the effect of two different TiO₂ powders as the starting material: P-25 and TiO₂ sol–gel (N-P25 and N-TiO₂, respectively) which were further calcined at 400 °C (N-P25-400 and N-TiO₂-400). XPS and XRD analyses confirmed the presence of sodium and hydrogen titanates in N-P25, but also an anatase structure for N-TiO₂. The specific surface area of the calcined samples decreased compared to the dried samples. Photocatalytic activity was evaluated using phenol and methyl orange for degradation, whereas 4-nitrophenol was used for photoreduction. Irradiation of the suspension was performed under UV light (λ = 254 nm). The results demonstrated that the nanorods calcined at 400 °C were more photoactive since methyl orange (20 ppm) degradation reached 86% after 2 h, when N-TiO₂-400 was used. On the other hand, phenol (20 ppm) was completely degraded by the presence of N-P25-400 after 2 h. Photoreduction of 4-nitrophenol (5 ppm) was achieved by the N-TiO₂-400 during the same period. These results demonstrate that the presence of Ti³⁺ and the source of TiO₂ have a significant effect on the photocatalytic activity of TiO₂ nanorods. Additionally, the removal of methylene blue (20 ppm) was performed, demonstrating that N-TiO₂ exhibited a high adsorption capacity for this dye. Full article

With the increasing demand for eco-friendly water treatment solutions, the development of novel photocatalysts such as calcium polyanion (Ca-POM) plays a vital role in mitigating industrial wastewater pollution. In this research, calcium polyanion, H₆₀N₆Na₂Ca₂W₁₂O₆₀ (Ca–POM), was successfully synthesized via a self-assembly reaction from metal-oxide subunits. The synthesized Ca–POM was verified to have a polycrystalline structure with a broad size distribution, with an average particle diameter of approximately 623.62 nm. Powder X-ray diffraction (XRD) analysis confirmed the polycrystalline structure of the Ca–POM, with a calculated band gap energy of 3.29 eV. The photocatalytic behavior of the Ca-POM sample was tested with two model dyes, methylene blue (MB) and methyl orange (MO). The reaction mixture was then exposed to ultraviolet (UV) irradiation for durations ranging from 20 to 140 min. The synthesized cluster demonstrated photocatalytic efficiency (PCE%) values of 81.21% for MB and 25.80% for MO. This work offers a valuable basis for applying Ca–POM as a heterogeneous photocatalyst for treating industrial wastewater organic pollutants and highlights the potential of Ca–POM in sustainable water treatment applications. Full article

In this work, the mechanical properties of hydrogels based on linear polyethyleneimine (PEI) chemically crosslinked with ethyleneglycoldiglycidyl ether (EGDE) were improved by the ionic crosslinking with sodium tripolyphosphate (TPP). To this end, the quaternization of the nitrogen atoms present in the PEI structure was conducted to render a network with a permanent positive charge to interact with the negative charges of TPP. The co-crosslinking process was studied by ¹H high-resolution magic angle spinning (¹H HRMAS) NMR and X-ray photoelectron spectroscopy (XPS) in combination with organic elemental analysis and inductively coupled plasma mass spectrometry (ICP-MS). In addition, the mobility and confinement of water molecules within the co-crosslinked hydrogels were studied by low-field ¹H NMR. The addition of small amounts of TPP, 0.03 to 0.26 mmoles of TPP per gram of material, to the PEI-EGDE hydrogel resulted in an increase in the deformation resistance from 320 to 1080%, respectively. Moreover, the adsorption capacity of the hydrogels towards various emerging contaminants remained high after the TPP crosslinking, with maximum loading capacities (q_max) of 77, 512, and 55 mg g⁻¹ at pH = 4 for penicillin V (antibiotic), methyl orange (azo-dye) and copper(II) ions (metal ion), respectively. A significant decrease in the adsorption capacity was observed at pH = 7 or 10, with q_max of 356 or 64 and 23 or 0.8 mg g⁻¹ for methyl orange and penicillin V, respectively. Full article

Piezocatalytic materials have attracted widespread attention in the fields of clean energy and water treatment because of their ability to convert mechanical energy directly into chemical energy. In this study, γ-AlON particles synthesised using carbothermal reduction and nitridation (CRN) were used for the first time as a novel piezocatalytic material to degrade dye solutions under ultrasonic vibration. The γ-AlON particles exhibited good performance as a piezocatalytic material for the degradation of organic pollutants. After 120 min under ultrasonic vibration, 40 mg portions of γ-AlON particles in 50 mL dye solutions (10 mg/L) achieved 78.06%, 67.74%, 74.29% and 64.62% decomposition rates for rhodamine B (RhB), methyl orange (MO), methylene blue (MB) and crystal violet (CV) solutions, respectively; the fitted k values were 13.35 × 10⁻³, 10.79 × 10⁻³, 12.09 × 10⁻³ and 8.00 × 10⁻³ min⁻¹, respectively. The piezocatalytic mechanism of γ-AlON particles in the selective degradation of MO was further analysed in free-radical scavenging activity experiments. Hydroxyl radicals (•OH), superoxide radicals (•O₂⁻), holes (h⁺) and electrons (e⁻) were found to be the main active substances in the degradation process. Therefore, γ-AlON particles are an efficient and promising piezocatalytic material for the treatment of dye pollutants. Full article

This study analyzes the elemental and oxide compositions of three selected agricultural residues—Dried Pawpaw Leaves (DPL), Kola Nut Pod (KNP), and Sweet Orange Peel (SOP)—for their potential as heterogeneous catalysts. Energy Dispersive X-ray (EDX) analysis identified calcium (25%) and potassium (29%) as the primary elements in DPL and KNP, with calcium oxide (CaO) and potassium oxide (K₂O) as the dominant oxides. SOP had a similar composition but lacked vanadium. Calcined residues were analyzed at temperatures ranging from 500 °C to 900 °C using X-ray Fluorescence (XRF), revealing stable silicon dioxide (SiO₂) content and temperature-dependent variations in CaO and K₂O, indicating their catalytic potential for transesterification processes. Scanning Electron Microscopy (SEM) showed non-uniform, spongy microstructures, enhancing the surface area and catalytic efficiency. Fourier Transform Infrared Spectroscopy (FTIR) identified functional groups essential for catalytic activity, such as hydroxyls, methyl, and carboxyl. X-ray Diffraction (XRD) confirmed the presence of crystalline phases like calcium carbonate and calcium oxide, crucial for catalytic performance. Experimental biodiesel production using a mixture of the calcined residues (33.33% each of KNPA, SOPA, and DPLA) resulted in the highest biodiesel yield at 65.3%. Model summary statistics, including R² (0.9824) values and standard deviations (0.0026), validated the experimental design, indicating high precision and prediction accuracy. These results suggest that the selected agricultural residues, when calcined and mixed properly, can serve as effective heterogeneous catalysts, with significant implications for biodiesel production, supporting previous research on the importance of calcium in catalytic processes. Full article

This research examined the elimination of methyl orange (MO) utilizing a novel magnetic biochar adsorbent (MLPB) derived from lemon peels via an impregnation-pyrolysis method. Material characterization was conducted using SEM, XRD, TGA, FTIR, and nitrogen adsorption isotherms. SEM-EDX analysis indicates that MLPB is a homogeneous and porous composite comprising Fe, O, and C, with iron oxide uniformly dispersed throughout the material. Also, MLPB is porous with an average pore diameter of 4.65 nm and surface area value (111.45 m²/g). This study evaluated pH, MO concentration, and contact time to analyze the adsorption process, kinetics, and isothermal behavior. Under optimal conditions, MLPB was able to remove MO dye from aqueous solutions with an efficiency of 90.87%. Results showed optimal MO removal at pH 4, suggesting a favorable electrostatic interaction between the adsorbent and dye. To ascertain the adsorption kinetics, the experimental findings were compared using several adsorption models, first- and second-orders, and intra-particle diffusion. According to the findings, the pseudo-second-order model described the adsorption kinetic promoting the formation of the chemisorption phase well. Modeling of intra-particle diffusion revealed that intra-particle diffusion is not the only rate-limiting step. A study involving isothermal systems showed that Langmuir is a good representation of experimental results; the maximum adsorption capacity of MLPB was 17.21 mg/g. According to the results, after four cycles of regeneration, the produced magnetic material regained more than 88% of its adsorption ability. Full article

The root bark extract of the Maerua oblongifolia plant in the green synthesis of titanium dioxide nanoparticles (TiO₂ NPs) for photocatalytic degradation of toxic pollutants and antibacterial activities was implemented in this study. The root bark extract served as a novel capping and reducing agent for the first time. Characterization of the TiO₂ NPs was conducted by using visual observation, ultraviolet visible spectrometry (UV-Vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) techniques, confirming their successful synthesis. The TiO₂ NPs exhibited maximum absorbance at 323 nm and an average particle size of 19.58 nm; the conjugations and existences of Ti-O and OH vibrational bands were revealed by the FTIR spectrum. The photocatalytic activities of the TiO₂ NPs were investigated by using solar irradiation as an energy source for aqueous solutions of methyl orange (MO) and methylene blue (MB) dyes. The TiO₂ NPs showed strong photocatalytic activities by degrading 97.23% MB and 91.8% MO under optimized conditions. Degradation behavior was investigated by isotherms and kinetics models, with the Langmuir isotherms (R²: 0.996, 0.979) and Langmuir–Hinshelwood (R²: 0.998, 0.997) highest correlation coefficients for MB and MO, respectively. Moreover, the antibacterial efficacy of the green-synthesized TiO₂ NPs and the results indicated higher antibacterial activities on Gram-negative bacteria (27 ± 0.52). Full article

Monascus species are known to produce various secondary metabolites with polyketide structures, including Monacolins, pigments, and citrinin. This study investigates the effects of 5-azacytidine on Monascus M1 and RP2. The dry weight, red, yellow, and orange pigment values, and Monacolin K yield of both Monascus strains were measured, and their hyphae observed through electron microscopy. The experimental group showed higher dry weights and pigment values than the control group for both strains. However, Monacolin K production increased substantially only for Monascus M1. Electron micrographs revealed surface wrinkles and large protrusions in both strains after 5-azacytidine treatment. As a potent DNA methylation-promoting agent, 5-azacytidine is very useful for epigenetic and cancer biology studies and for studying secondary metabolism in fungi. Full article

A comprehensive analysis of the volatile components of 11 different cherry tomato pastes (Tesco Extra, Orange, Zebra, Yellow, Round Netherland, Mini San Marzano, Spar truss, Tesco Sunstream, Paprikakertész, Mc Dreamy, and Tesco Eat Fresh) commercially available in Hungary was performed. In order to ensure the reliability and accuracy of the measurement, the optimal measurement conditions were first determined. SPME (solid-phase microextraction) fiber coating, cherry tomato paste treatment, and SPME sampling time and temperature were optimized. CAR/PDMS (carboxen/polydimethylsiloxane) fiber coating with a film thickness of 85 µm is suggested at a 60 °C sampling temperature and 30 min extraction time. A total of 64 common compounds was found in the prepared, mashed cherry tomato samples, in which 59 compounds were successfully identified. Besides the already published compounds, new, cherry tomato-related compounds were found, such as 3 methyl 2 butenal, heptenal, Z-4-heptenal, E-2-heptenal, E-carveol, verbenol, limonene oxide, 2-decen-1-ol, Z-4-decen-1-al, caryophyllene oxide, and E,E-2,4-dodecadienal. Supervised and unsupervised classification methods have been used to classify the tomato varieties based on their volatiles, which identified 16 key components that enable the discrimination of the samples with a high accuracy. Full article

Steam explosion (STEX) of peel from commercially juice-extracted oranges was used to convert peel pectin into pectic oligosaccharides (POSs). Surprisingly uniform populations, based on the polydispersity index (PDI; weight-average molecular weight (M_w)/number-average molecular weight (M_n)) of POSs, were obtained from the Hamlin and Valencia varieties of Citrus sinensis. The POSs from Hamlin and Valencia peel had PDI values of (1.23 ± 0.01, 1.24 ± 0.1), respectively. The M_w values for these samples were 14.9 ± 0.2 kDa for Hamlin, and 14.5 ± 0.1 kDa for Valencia, respectively. The degree of methyl-esterification (DM) was 69.64 ± 3.18 for Hamlin and 65.51 ± 1.61 for Valencia. The composition of the recovered POSs was dominated by galacturonic acid, ranging from 89.1% to 99.6% of the major pectic sugars. Only the Hamlin sample had a meaningful amount of rhamnose present, indicating the presence of an RG I domain. Even so, the Hamlin sample’s degree of branching (DBr) was very low (2.95). Full article

The catalytic reduction of organic pollutants in water is a critical environmental challenge due to the persistent and hazardous nature of compounds like azo dyes and nitrophenols. In this study, we synthesized nanostructured CuO/TiO₂ catalysts via a combustion technique, followed by calcination at 700 °C to achieve a rutile-phase TiO₂ structure with varying copper loadings (5–40 wt.%). The catalysts were characterized using X-ray diffraction (XRD), attenuated total reflectance-Fourier transform infrared (ATR–FTIR) spectroscopy, thermogravimetric analysis-differential thermal analysis (TGA–DTA), UV-visible diffuse reflectance spectroscopy (DRS), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDS). The XRD results confirmed the presence of the crystalline rutile phase in the CuO/TiO₂ catalysts, with additional peaks indicating successful copper oxide loading onto TiO₂. The FTIR spectra confirmed the presence of all the functional groups in the prepared samples. SEM images revealed irregularly shaped copper oxide and agglomerated TiO₂ particles. The DRS results revealed improved optical properties and a decreased bandgap with increased Cu content, and 4-Nitrophenol (4-NP) and methyl orange (MO), which were chosen for their carcinogenic, mutagenic, and nonbiodegradable properties, were used as model organic pollutants. Catalytic activities were tested by reducing 4-NP and MO with sodium borohydride (NaBH₄) in the presence of a CuO/TiO₂ catalyst. Following the in situ reduction of CuO/TiO₂, Cu (NPs)/TiO₂ was formed, achieving 98% reduction of 4-NP in 480 s and 98% reduction of MO in 420 s. The effects of the NaBH₄ concentration and catalyst mass were investigated. The catalysts exhibited high stability over 10 reuse cycles, maintaining over 96% efficiency for MO and 94% efficiency for 4-NP. These findings demonstrate the potential of nanostructured CuO/TiO₂ catalysts for environmental remediation through efficient catalytic reduction of organic pollutants. Full article

Four new glycosides of polyhydroxysteroids, ceramasterosides A, B, D, and E (1–4), and two previously known compounds, ceramasteroside C₁ (5) and attenuatoside B-I (6), were isolated from an extract of a deep-sea sea star species, the orange cookie star Ceramaster patagonicus. The structures of 1–4 were elucidated by the extensive NMR and ESIMS methods. Steroid monoglycosides 1 and 2 had a common 3β,6α,8,15β,16β-pentahydroxysteroid nucleus and a C–29 oxidized stigmastane side chain and differed from each other only in monosaccharide residues. Ceramasteroside A (1) contained 3-O-methyl-4-O-sulfated β-D-xylopyranose, while ceramasteroside B (2) had 3-O-methyl-4-O-sulfated β-D-glucopyranose, recorded from starfish-derived steroid glycosides for the first time. Their biological activity was studied using a model of lipopolysaccharide-induced (LPS) inflammation in a SIM-A9 murine microglial cell line. During the LPS-induced activation of microglial cells, 1, 3, and 5, at a non-toxic concentration of 1 µM, showed the highest efficiency in reducing the production of intracellular NO, while 4 proved to be most efficient in reducing the extracellular nitrite production. All the test compounds reduced the LPS-induced malondialdehyde (MDA) production. The in vitro experiments have demonstrated, for the first time, the antioxidant activity of the compounds under study. Full article

Currently, several organic dyes found in wastewater cause severe contamination problems for flora, fauna, and people in direct contact with them. This research proposes an alternative for the degradation of polluting dyes using ZnO nanoparticles (NPs) synthesized by an ecological route using leaf and root extracts of Ambrosia ambrosioides as a reducing agent (with a weight/volume ratio = 4%). Scanning Electron Microscopy (SEM) was used to determine the morphology, showing an agglomeration of cluster-shaped NPs. Using Transmission Electron Microscopy (TEM), different sizes of NPs ranging from 5 to 56 nm were observed for both synthesized NPs. The composition and structure of the nanomaterial were analyzed by infrared spectroscopy (FT-IR) and X-ray diffraction (XRD), showing as a result that the NPs have a wurtzite-like crystalline structure with crystallite sizes around 32–37 nm for both samples. Additionally, the bandgap of the NPs was calculated using Ultraviolet Visible Spectroscopy (UV–Vis), determining values of 2.82 and 2.70 eV for the NPs synthesized with leaf and root, respectively. Finally, thermogravimetric analysis demonstrated that the nanoparticles contained an organic part after the green synthesis process, with high thermal stability for both samples. Photocatalytic analysis showed that these nanomaterials can degrade four dyes under UV irradiation, reaching 90% degradation for methylene blue (MB), methyl orange (MO) and Congo red (CR) at 60, 100 and 60 min, respectively, while for methyl red (MR) almost 90% degradation was achieved at 140 min of UV irradiation. These results demonstrate that it is effective to use Ambrosia ambrosioides root and leaf extracts as a reducing agent for the formation of ZnO NPs, also evidencing their favorable application in the photocatalytic degradation of these four organic dyes. Full article

In this study, porous activated carbon was produced from coffee waste and used as an effective adsorbent for the removal of humic acid (HA) from seawater and methyl orange (MO) dye from aqueous solutions. Phosphoric acid H₃PO₄ was used as an activating agent for the chemical activation of these agricultural wastes. The characterization of the activated carbon obtained using a scanning electron microscope (SEM), Fourier-transform infrared (FTIR) spectroscopy analysis, X-ray diffraction (XRD) and the Brunauer–Emmett–Teller (BET) method revealed that the activated carbon products exhibited high porosity and the formation of various functional groups. The effects of different parameters were examined using batch adsorption experiments, such as the adsorbent masses, pH, initial pollutant concentration and contact time. The results show that the performance increased with an increased adsorbent mass (up to 0.25 g/L) and decreased initial concentration of the adsorbent tested. On the other hand, this study clearly showed that the adsorption efficiency of the MO on the raw spent coffee grounds (SCGs) waste was around 43%, while no removal was observed for the humic acid. The experiments demonstrated that the activated carbon synthesized from the used coffee grounds (the efficiency was compared with commercial activated carbon (CAC) with a difference of 13%) was a promising alternative to commercially available adsorbents for the removal of humic acid from seawater. To understand and elucidate the adsorption mechanism, various isothermal and kinetic models were studied. The adsorption capacity was analyzed by fitting experimental data to these models. The experimental data for methyl orange dyes were analyzed using Langmuir and Freundlich isothermal models. The Freundlich isotherm model provided a superior fit to the equilibrium data, as indicated by a higher correlation coefficient (R²) than that of the Langmuir model. The maximum adsorption was observed at pH 3. The Freundlich adsorption capacity was found to be 333 mg/g adsorbent. The PAC showed a high adsorption capacity for the MO and HA. The PAC showed the highest adsorption capacities for the HA and MO compared with the other adsorbents used (SCGs and CAC) and would be a good material to increase the adsorption efficiency for humic acid removal in the seawater pretreatment process. In addition, the prepared AC BET surface area was 520.40 m²/g, suggesting a high adsorption capacity. This makes the material potentially suitable for various applications that require a high surface area. These results indicate that high-quality sustainable activated carbon can be efficiently produced from coffee waste, making it suitable for a wide range of adsorbent applications targeting various pollutants. Full article