Search Results (235)

Moroccan oil shale ash (MOSA) represents an underutilized industrial by-product, particularly in the Rif region, where its high mineral content has often led to its neglect in value-added applications. This study highlights the successful conversion of MOSA into amorphous mesoporous silica (AS-Si) using a sol–gel process assisted by polyethylene glycol (PEG-6000) as a soft template. The resulting AS-Si material was extensively characterized to confirm its potential for environmental remediation. FTIR analysis revealed characteristic vibrational bands corresponding to Si–OH and Si–O–Si bonds, while XRD confirmed its amorphous nature with a broad diffraction peak at 2θ ≈ 22.5°. SEM imaging revealed a highly porous, sponge-like morphology composed of aggregated nanoscale particles, consistent with the nitrogen adsorption–desorption isotherm. The material exhibited a specific surface area of 68 m²/g, a maximum in the pore size distribution at a pore diameter of 2.4 nm, and a cumulative pore volume of 0.11 cm³/g for pores up to 78 nm. DLS analysis indicated an average hydrodynamic diameter of 779 nm with moderate polydispersity (PDI = 0.48), while a zeta potential of –34.10 mV confirmed good colloidal stability. Furthermore, thermogravimetric analysis (TGA) and DSC suggested the thermal stability of our amorphous silica. The adsorption performance of AS-Si was evaluated using methylene blue (MB) and ciprofloxacin (Cipro) as model pollutants. Kinetic data were best fitted by the pseudo-second-order model, while isotherm studies favored the Langmuir model, suggesting monolayer adsorption. AS-Si could be used four times for the removal of MB and Cipro. These results collectively demonstrate that AS-Si is a promising, low-cost, and sustainable adsorbent derived from Moroccan oil shale ash for the effective removal of organic contaminants from aqueous media. Full article

The conversion of CO₂ into CH₄ through the Sabatier reaction is one of the key processes that can reduce CO₂ emissions into the atmosphere. This work aims to develop Ni-Al aerogel-based thermo-photocatalysts with large specific surface areas prepared using a sol–gel method and subsequent supercritical drying in CO₂. Different Al/Ni molar ratios were selected for the development of the catalysts, characterized using ICP-OES, N₂ adsorption–desorption isotherms, XRD, H₂-TPR, TEM, UV-Vis DRS, and XPS techniques. Thermo-photocatalytic activity tests were performed in a photoreactor with two different light sources (λ = 365 nm, λ = 470 nm) at a temperature range from 300 °C to 450 °C and a pressure of 10 bar. The catalyst with the highest Ni loading (AG 1/3) produced the best catalytic results, reaching CO₂ conversion and CH₄ selectivity levels of 82% and 100%, respectively, under visible light at 450 °C. In contrast, the catalysts with the lowest nickel loading produced the lowest results, most likely due to their low amounts of active Ni. These results suggest that supercritical drying is an efficient method for developing active thermo-photocatalysts with high Ni dispersion, suitable for Sabatier reactions under mild reaction conditions. Full article

This paper presents the synthesis of La₂Ti₂O₇ nanoparticles by the sol–gel method starting from lanthanum nitrate and titanium alkoxide (noted as LTA). Subsequently, the lanthanum titanium oxide nanoparticles are modified with noble metals (platinum) using the chemical impregnation method, followed by a reduction process with NaBH₄. The comparative analysis of the structure and surface characteristics of the nanopowders subjected to thermal treatment at 900 °C is conducted using Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), ultraviolet-visible (UV–Vis) spectroscopy, as well as specific surface area and porosity measurements. The photocatalytic activity is evaluated in the oxidative photodegradation of ethanol (CH₃CH₂OH) under simulated solar irradiation. The modified sample shows higher specific surfaces areas and improved photocatalytic properties, proving the better conversion of CH₃CH₂OH than the pure sample. The highest conversion of ethanol (29.75%) is obtained in the case of LTA-Pt after 3 h of simulated solar light irradiation. Full article

High-entropy ceramics have gained wider attention due to their structural integrity and stability, which can be used in various functional applications. Especially, high-entropy oxides exhibit excellent thermal stability, particularly at high temperatures. Thermal barrier coating materials must demonstrate good thermal stability without any phase transformation or phase separation, which is critical in aerospace and energy conversion applications. To address this, we have prepared new high-entropy stannate pyrochlore oxide nanoparticles with the composition (Gd_0.2Nd_0.2La_0.2Pr_0.2Sm_0.2)₂Sn₂O₇ through a simple glycine-assisted sol–gel synthesis. The phase evolution was probed at different heat-treatment temperatures from 1000 °C to 1500 °C. Among the temperatures investigated, a single-phase pyrochlore oxide was formed from 1300 °C without any impurity or phase separation. The obtained nanoparticles were characterized using various techniques, including X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), nanoindentation, and dilatometry to investigate their physiochemical and mechanical properties. The Vickers hardness of high-entropy oxides is 4.2 ± 0.33 GPa, while a thermal expansion coefficient (TEC) of 8.7 × 10⁻⁶ K⁻¹ at 900 °C is calculated. The results show that the prepared high-entropy pyrochlore oxide can be a suitable candidate for thermal barrier coating. Full article

To develop eco-friendly low-temperature NH₃-SCR catalysts for the non-electric industry, a series of CeMn-modified Ba₂Ti₅O₁₂ catalysts were synthesized using the sol-gel method to achieve denitrification. Activity tests revealed that Ce-Mn-modified Ba₂Ti₅O₁₂ catalysts exhibit excellent low-temperature denitrification performance with a broad operational temperature window. Characterization through XRD, XPS, BET, NH₃-TPD, and EPR indicated that Ce-Mn modification enhances surface oxygen chemisorption and increases acidity, significantly improving NO_x reduction. Notably, the optimal catalyst achieved NO_x conversion rates exceeding 90% within the temperature range of 90 to 240 °C under a gas hourly space velocity (GHSV) of 28,000 h⁻¹. In particular, the coexistence of Ce and Mn species promotes the oxidation of NO to NO₂, facilitating the “fast SCR” reaction. The abundance of valence states further enhances the catalyst’s ultra-low-temperature NH₃-SCR denitration performance. Full article

Solid Fe catalysts supported on SiO₂ with Lewis and Brönsted acidity were synthesized using sol–gel methodology. FTIR spectroscopy, XRD, Raman spectroscopy, BET isotherms, and SEM characterized the materials. Subsequently, they were used to dehydrate xylose to obtain furfural. It was observed that increasing the metal loading from 0.5% to 1.5% by mass increases the selectivity of furfural up to 40.09%. In addition, the calcination temperature influenced the conversion because materials calcined at 450 °C presented higher xylose conversion than those calcined at 750 °C. Finally, the employed catalysts were active and effective in obtaining furfural from hydrolysates via hydrothermal treatments of a coffee crop’s residual biomass, producing an average of 9.11 mg/g of furfural per gram of biomass. Full article

Background/Objectives: The absence of standardized protocols for assessing in vitro drug release from nanocarriers poses significant challenges in nanoformulation development. This study evaluated three in vitro methods: sample and separate without medium replacement (independent batch), sample and separate with medium replacement, and a dialysis bag method, to characterize the release of rhodamine B from mesoporous silica nanoparticles (MSNs). Methods: Each method was examined under varying agitation conditions (shaking versus stirring). MSNs were synthesized via the sol-gel method, exhibiting a hydrodynamic diameter of 202 nm, a zeta potential of −23.5 mV, and a surface area of 688 m²/g, with a drug loading efficiency of 32.4%. Results: Release profiles revealed that the independent batch method exhibited a rapid initial burst followed by a plateau after 4 h, attributed to surface saturation effects. Conversely, the sample and separate with medium replacement method sustained the release up to 60% over 48 h, maintaining sink conditions. The dialysis method showed agitation-dependent variability, with magnetic stirring using a longer stir bar enhancing release. Kinetic analyses indicated first-order kinetics with non-Fickian diffusion. Conclusions: Overall, the results indicate that both the selection of the in vitro method and the agitation technique play a crucial role in determining the apparent drug release kinetics from nanocarriers. These findings highlight the critical role of experimental design in interpreting nanocarrier release kinetics, advocating for tailored protocols to improve reproducibility and in vitro–in vivo correlations in nanoformulation. Full article

Layered double hydroxides (LDHs), notable for their unique two-dimensional layered structures, have attracted significant research attention due to their exceptional versatility and promising performance in energy storage and conversion applications. This comprehensive review systematically addresses the fundamentals and diverse synthesis strategies for LDHs, including co-precipitation, hydrothermal synthesis, electrochemical deposition, sol-gel processes, ultrasonication, and exfoliation techniques. The synthesis methods profoundly influence the physicochemical properties, morphology, and electrochemical performance of LDHs, necessitating a detailed understanding to optimize their applications. In this paper, the role of LDHs in batteries, supercapacitors, and hydrogen production is critically evaluated. We discuss their incorporation in various battery systems, such as lithium-ion, lithium–sulfur, sodium-ion, chloride-ion, zinc-ion, and zinc–air batteries, highlighting their structural and electrochemical advantages. Additionally, the superior pseudocapacitive behavior and high energy densities offered by LDHs in supercapacitors are elucidated. The effectiveness of LDHs in hydrogen production, particularly through electrocatalytic water splitting, underscores their significance in renewable energy systems. This review paper uniquely integrates these three pivotal energy technologies, outlining current innovations and challenges, thus fulfilling a critical need for the scientific community by providing consolidated insights and guiding future research directions. Full article

Porous nanocrystalline lanthanum perovskite La-Fe-O (LaFeO₃) powders were synthesized by the sol–gel self-combustion method, using polyvinyl alcohol as the colloidal medium. The perovskite structure of the material, without secondary phases, was obtained at a calcination temperature of 900 °C for 40 min. The obtained powder was tested for catalytic activity at moderate temperatures (50–550 °C) for ethanol, methanol, acetone, benzene, and Pb-free gasoline vapors. Catalytic combustion begins at quite low temperatures (60–200 °C), compared to normal combustion, and this can be attributed to the nanometric crystallites, the large specific surface area, and the presence of iron cations with different valences, Fe³⁺/Fe²⁺, resulting from the method we used to obtain the material. The degree of conversion reaches values of over 99% for acetone and ethanol vapors at a temperature of 270 °C and 310 °C, respectively, and over 97% for methanol vapors at a temperature of 330 °C. The degree of conversion for Pb-free gasoline and benzene reaches somewhat lower values, over 88% at much higher temperatures, 470 °C and 550 °C, respectively. The lanthanum perovskite catalyst, LaFeO₃, obtained by the presented preparation method, can be recommended for the combustion of acetone, ethanol, and methanol vapors. The performance of this catalyst is remarkable and can be compared to that of a catalyst containing noble metals in its composition. Full article

Nickel-doped titanium dioxide (NIT) with different nickel contents (0.1–1.0 wt%) was prepared via the sol–gel method, combined with mechanical ball milling. X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–Vis diffuse reflectance spectroscopy (DRS) were employed to characterize the crystalline structure, morphological characteristics, and optical properties of the samples. The photocatalytic activity was evaluated through the photocatalytic degradation of methylene blue (MB) under visible light and nitric oxide (NO) under simulated sunlight. The XRD results show that all the catalysts retain the anatase phase, confirming that nickel doping does not alter the crystalline structure of TiO₂. NIT catalysts exhibited a plate-like morphology due to the ball milling treatment of the precursors. The DRS analysis revealed that nickel modification induced a redshift in the absorption edge of TiO₂ and enhanced the visible-light absorption. The photocatalytic tests demonstrated that 0.5 wt% NIT and 0.7 wt% NIT exhibited the highest photocatalytic activity for MB degradation, achieving degradation rates of 93.1% and 91.4% after 60 min, respectively. Moreover, 0.7 wt% NIT showed the optimal NO conversion efficiency of 45.4% after 30 min. The improved photocatalytic performance of the sample is attributed to enhanced visible-light absorption, reduced charge recombination, and a high specific surface area. This study provides a facile strategy for synthesizing Ni-doped TiO₂ nanoplates based on the sol–gel method, which is scalable in regard to the industrial production of efficient photocatalysts. Full article

As an environmentally friendly and clean energy technology, solar-driven interfacial evaporation technology has attracted wide attention. However, organic pollutants can easily pollute distilled water during the evaporation of wastewater. In this work, we report a strategy of N-TiO₂/C solar absorption with a low bandgap (2.33 eV), excellent light absorption ability, and high photothermal conversion efficiency (48.2%). Black N-TiO₂/C was prepared by the sol-gel method in the presence of hexamethylenetetramine as a source of nitrogen and carbon. The simultaneous N doping and C with superior photothermal effect rapidly increased the surface temperature of the material, reduced the recombination rate of electrons and holes, and improved the photocatalytic activity, showing great potential for solar thermal energy conversion. The prepared solar absorbent and polyurethane (PU) were mixed evenly to form a porous N-TiO₂/C/PU (NTCP) foam for purifying water. The evaporator produced clean water at a rate of 1.73 kg m⁻² h⁻¹ under the simulated sunlight of 1 sun irradiation. Meanwhile, the evaporator simultaneously photodegraded methylene blue (MB) and rhodamine B (RhB) underwater at a removal rate > 90%. The bifunctional solar water evaporation device combining photocatalytic and photothermal effects holds great potential for water purification. Full article

The auto-thermal reforming (ATR) of acetic acid is an effective hydrogen production method, but it suffers from catalyst deactivation by coking. Sm-promoted layered La₂NiO₄ perovskite catalysts were synthesized via the sol–gel method and its catalytic performance in the ATR of HAc was further evaluated. The characterization results demonstrate that the incorporation of Sm into the lattice of La₂NiO₄ perovskite led to the formation of Ni-La-Sm-O species, inducing crystal defects in the perovskite structure which could promote the gasification of coking precursors. Additionally, Sm regulated the reduction characteristics of La₂NiO₄, resulting in the formation of highly dispersed nickel nanoparticles upon the hydrogen reduction, which increased the number of active sites available for acetic acid conversion. Consequently, a stable reactivity without obvious coking was obtained over a Ni_0.42La_0.7Sm_0.36O_2.01±δ catalyst within the ATR of Hac. The hydrogen yield reached 2.53 mol-H₂/mol-HAc along with the complete conversion of acetic acid. Full article

SO₂ emissions are a major source of air pollution, and the catalytic reduction of SO₂ to elemental sulfur by CO represents a promising solution. This study investigates the effects of Fe doping and pre-sulfurization on the catalytic performance of LaCoO₃ perovskite catalysts. A series of Fe-doped LaCoO₃ perovskites were synthesized via the sol–gel method and evaluated for the catalytic reduction of SO₂ by CO. The results showed that LaCo_0.8Fe_0.2O₃ exhibited the highest catalytic performance, achieving 84.0% SO₂ conversion at 500 °C. The oxygen-free sulfurization (OFS) treatment compared with oxygen-assisted sulfurization (OAS) treatment significantly enhanced the activity, reaching a SO₂ conversion of 95.9% from 80.0% at 450 °C with the lower byproduct generation. Characterization analyses demonstrated that the OFS treatment facilitated the formation of active sulfur species and oxygen vacancies on the catalyst surface while also enhancing the adsorption capacity of the catalyst for the reactant gases. These factors were identified as key contributors to the improved catalytic performance, driven by the combination of redox and carbonyl sulfide (COS) intermediate mechanism. The findings suggest that the OFS treatment is an effective strategy to improve the catalytic reduction of SO₂ by CO, offering a more environmentally friendly solution for SO₂ emission control through resource utilization. Full article

Currently, there is an increasing demand for advanced materials that can address the needs of tissue engineering and have the potential for use in treatments targeting tumor cells, such as black bioactive materials in photothermal therapy. Thus, 3D fibrous scaffolds of black 45S5 bioactive glass were produced using the air-heated solution blow spinning (A-HSBS) technique, with polyvinylpyrrolidone (PVP) serving as a spinning aid and an oxygen vacancy-inducing agent. Glass powder with the same composition was synthesized via the sol-gel route for comparison. The samples were characterized using thermogravimetric analysis, X-ray diffraction, FTIR spectroscopy, and scanning electron microscopy, along with in vitro tests using simulated body fluid (SBF), phosphate-buffered saline (PBS), and TRIS solution. The results showed that PVP enhanced oxygen vacancy formation and stabilized the scaffolds at 600 °C. Doping with Zn and Mg ions reduced crystallization while significantly increasing the fiber diameters. Scaffolds doped with Zn exhibited lower degradation rates, delayed apatite formation, and hindered ionic release. Conversely, Mg ions facilitated greater interaction with the medium and rapid apatite formation, completely covering the fibers. The scaffolds showed no cytotoxicity in the MTT assay at concentrations of up to 200 µg/mL for HaCat cells and 0.8 mg/mL for L929 cells. This study demonstrated the effectiveness of using PVP in the production of black bioactive glass scaffolds, highlighting their potential for bone regeneration. Full article

The emergence of bismuth molybdate (Bi₂MoO₆) as a promising visible-light catalyst has prompted researchers to increasingly focus on its investigation. To elucidate the impact of different preparation methods on the morphology and photocatalytic properties of Bi₂MoO₆, samples were synthesized via solvothermal, in situ conversion, solution combustion, precipitation, and sol-gel techniques. The physicochemical properties of Bi₂MoO₆ were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), particle size analysis (PSA), fluorescence, and photocurrent measurements. The materials’ ability to degrade Rhodamine B (RhB) was evaluated. The results demonstrated that the crystallinity, morphology, bandgap width, and photogenerated carrier recombination of Bi₂MoO₆ varied significantly depending on the preparation method. Among these methods, the solvothermal route proved most effective, yielding Bi₂MoO₆ with the highest photocatalytic activity, achieving 97.5% RhB degradation within 25 min of light exposure. The low photogenerated carrier recombination rate was attributed to the large specific surface area and narrow bandgap (2.71 eV). This study provides valuable insights into preparing Bi₂MoO₆ with enhanced photocatalytic properties. Full article