Search Results (353)

Composites consisting of NaX and Na-LTA zeolites and mesoporous silica in different ratios were successfully synthesized from coal fly ash and rice husk, and subsequently modified with Ni and Mn using the incipient wetness impregnation method. The initial composite and the modified materials were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), N₂ physisorption, temperature-programmed reduction (TPR–TGA) and X-ray photoelectron spectroscopy (XPS). The formation of finely dispersed Ni, Fe spinel nanoparticles was registered in the Ni- and NiMn-containing catalysts. The presence of Mn has a favorable effect on the Ni dispersion. The support composition, including zeolite phases and the content of mesoporous silica phase, effects the formation of catalytically active metallic species for CO₂ hydrogenation to methane. The formation of Fe⁰ and FeNi₃ crystalline phases was detected for the reduced catalysts. Additionally, 3D printing technology was applied for the macrostructuring of the catalyst prior to the modification of the powdered supports with metal precursors, aiming to enhance their catalytic performance. The stabilization of Fe⁰ and FeNi₃ phase dispersion in the 3D-printed samples is beneficial for long-term catalytic performance. The advantage of the 3D-printed catalyst was demonstrated, showing its higher CO₂ consumption rate relative to the external geometric surface area compared to its powder analogue. Full article

Metal–organic framework (MOF) powders possess remarkable adsorption capabilities, yet their practical application is severely hampered by poor processability, difficult recovery, and high mass-transfer resistance. Here, we report a green and rapid two-stage strategy for constructing UiO-66-NH₂ self-assembled aerogels with a bimodal micro-/mesoporous architecture. A brief thermal pretreatment (130 °C, 3 h) is used solely for precursor activation, after which the critical MOF crystallization and in situ self-assembly are driven under ambient conditions via ultrasonic cavitation (900 W, 15–60 min). This protocol simultaneously drives the nucleation, crystallization, and self-assembly of UiO-66-NH₂ nanocrystals into a monolithic, self-supporting architecture, thereby replacing the conventional prolonged high-temperature solvothermal MOF crystallization with a rapid room-temperature process. The sonication time critically governs the structural evolution, transforming initially amorphous aggregates into well-defined regular octahedral nanocrystals that form an interconnected framework. The optimized aerogel (UNA-T60) exhibits an exceptional specific surface area (1196.9 m² g⁻¹) and a synergistic bimodal pore structure comprising intrinsic micropores and intercrystalline mesopores. This architecture enables rapid mass transfer and active-site accessibility, resulting in a maximum Congo Red (CR) adsorption capacity of 660.56 mg g⁻¹, with kinetics conforming to the pseudo-second-order model (R² > 0.999). The robust monolithic structure endows the material with outstanding reusability, retaining 90.8% of its initial adsorption capacity after four regeneration cycles. This work presents a paradigm-shifting approach for the sustainable fabrication of pure MOF aerogels, offering a promising solution for advanced dye wastewater treatment. Full article

Hybrid nanocomposites composed of dendritic fibrous nanosilica (DFNS) identified as KCC-1 and resorcinol–formaldehyde (RF) resin were synthesized via the polymer-assisted deposition (PAD) method for the incorporation of Ni and Fe in mono- and bimetallic configurations. The RF resin enabled uniform dispersion Fe-based and Ni-based nanoparticles through coordination with functional groups, while KCC-1 provided a high-surface-area, mesoporous support. A comprehensive structural and chemical characterization confirmed the formation of hematite in the Fe-based system; NiO and metallic Ni in the Ni-based material; and FeO, NiO and metallic Ni in the bimetallic composite, in the form of well-dispersed metal nanoparticles between 3–6 nm. Although a reduction in BET surface area was observed due to resin and metal loading, all nanocomposites retained mesoporous structures with Type IV isotherms and H3-type hysteresis, suitable for catalytic applications. The nanocomposites exhibited structural stability up to 800 °C under N₂, with a total mass loss of 12–14% dominated by moisture desorption below 100 °C (~8–11%) and minor surface group degradation at higher temperatures. These findings demonstrate the potential of the PAD method for fabricating functional hybrid materials with improved metal dispersion. Full article

In the era of global energy transition, the development of third-generation photovoltaic technologies, such as dye-sensitized solar cells, has emerged as a paramount challenge in materials engineering. This study is dedicated to the synthesis and implementation of graphene quantum dots as eco-friendly sensitizers within DSSC architectures. The GQDs were synthesized via a microwave-assisted hydrothermal route using biodegradable organic precursors, providing a “green” alternative to conventional, toxic heavy-metal-based materials. The nanocrystalline structure and optoelectronic properties of the sensitizer were verified through UV-Vis and visual photoluminescence assessment. A focal point of this research was the optimization of the GQD concentration on the mesoporous surface of the titanium dioxide photoanode. Measurements were conducted utilizing a custom-designed experimental setup integrated with 3D-printed (FDM) components and an Arduino microcontroller, ensuring precise data acquisition under controlled illumination conditions (405–625 nm). The results indicated an optimal operational point at a fivefold dilution of the stock solution (0.4 g/dm³), which yielded the highest open-circuit voltage ($V_{\mathrm{oc}}$) of 545.4 mV under UV irradiation. The decline in photovoltaic performance observed at higher concentrations was attributed to excessive nanostructure agglomeration, which effectively blocked the mesopores of the semiconductor. Furthermore, the demonstrated high chemical capacitance of the system imparts electrochemical capacitor-like characteristics to the cell, enabling energy stabilization under fluctuating illumination. To elucidate the underlying sensitization mechanisms at the atomic level, computational simulations were conducted utilizing the MACE machine-learning potential and the GFN2-xTB semi-empirical method. The theoretical models revealed that the formation of stable covalent Ti–O–C bridges (chemisorption) is imperative for establishing strong interfacial electronic coupling. Solvation models and molecular dynamics (MD) at 300 K confirmed the thermodynamic and operational robustness of the hybrid system in an aqueous electrolyte. Ultimately, this combined experimental and theoretical work conclusively demonstrates that graphene quantum dots represent an efficient, highly stable, and non-toxic alternative to classic molecular dye sensitizers. Full article

Dealloyed nanoporous metals have a unique bicontinuous solid/void structure that provides a sizable surface area and outstanding electrical conductivity, making them attractive candidates for use in a range of applications. But for many of these applications, the utilization of an engineered hierarchical porous network topology that promotes and optimizes mass transport would be quite advantageous. We present a soft template approach for the routine fabrication of hierarchical multimodal nanoporous gold monolith (hm-NPG). This self-supporting framework composed of multimodal porosity is produced employing a synergistic mix of metal reduction, templating, annealing, and chemical dealloying. This method provides for the simultaneous optimization of active surface area and mass transport in a porous metal electrode. It is reliable, simple, economical, accessible, and environmentally friendly. The procedure should be scalable and can produce hm-NPG for use in applications such as biosensing, energy systems, biofiltration, and catalysis. The material visually displays two visibly unique structural length scales that range from the macroporous network structure (average pore size of 0.58 ± 0.29 μm) to the mesoporous pore/ligament morphology (average pore size of 37 ± 10 nm) as determined by SEM analysis. Modification by self-assembly with lipoic acid (LA) gave a coverage of 5.12 × 10¹⁴ molecules/cm² of the hm-NPG surface, according to calculations made using thermogravimetric analysis (TGA) data. Following the dealloying procedure, a compositional study of the np-Au monolith using EDS revealed that it was almost 98.2 atomic % gold. The specific surface area of the hm-NPG was found to be 7.84 ± 0.01 m²/g (n = 3) through analysis utilizing the Brunauer–Emmett–Teller (BET) multi-point surface area method applied to krypton adsorption isotherms. BET analysis using N₂ adsorption isotherms and the Barrett–Joyner–Halenda (BJH) pore distribution analysis gives strong evidence for the additional presence of micropores of diameter 2–3 nm, thus making the material likely trimodal. Full article

The development of reusable nanomaterials for the extraction of trace-metals from complex matrices remains challenging because strong metal-chelating functionalities often hinder desorption and regeneration, whereas weaker binding sites compromise selectivity and enrichment efficiency. This limitation has been addressed by designing a ligand-engineered fibrous mesoporous silica nanomaterial (Van-KCC-1) via the integration of the unique structural features of KCC-1 with an o-vanillin-derived Schiff-base chelator. The material was synthesized throughout the chemical grafting of 3-aminopropyltriethoxysilane (APTES) onto fibrous mesoporous silica KCC-1, followed by condensation with 3-methoxy-2-hydroxybenzaldehyde (o-vanillin). The successfulness of functionalization and Schiff-base formation were confirmed by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). The radially oriented fibrous channels of KCC-1 provide a highly accessible surface that remains available for interaction with the targeted ions even after chemical modification. This architecture facilitates rapid mass transfer and efficient utilization of binding sites, while the incorporated Schiff-base ligand introduces imine, phenolic, and methoxy donor groups capable of selectively and reversibly coordinating Ni(II) and Cd(II). The resulting balance between adsorption strength and desorption efficiency enables both effective metal capture and sorbent reusability. More importantly, the study demonstrates how KCC-1 can serve as a versatile nanosilica scaffold for the incorporation of tailored chelating ligands without sacrificing structural accessibility. The functionalized nanomaterial was evaluated as a dispersive solid-phase extraction (DSPE) sorbent coupled with inductively coupled plasma optical emission spectrometry (ICP-OES). Under optimized conditions, linear ranges of 0.035–50 μg L⁻¹ for Ni(II) and 0.058–50 μg L⁻¹ for Cd(II) were obtained, with limits of detection of 0.011 and 0.019 μg L⁻¹, respectively. The method exhibited excellent precision (relative standard deviation ≤ 3.6%) and recoveries of 92.00–98.83% in certified reference materaisl (NIST CRM 1643d), mineral water, tap water and synthetic wastewater. In addition, the nanochelator has retained more than 87% of its initial sorption efficiency after six adsorption–desorption cycles and showed minimal interference from common coexisting ions. These findings establish Van-KCC-1 as an efficient, selective, and reusable DSPE sorbent in the determination of trace-metals while highlighting the broader potential of fibrous mesoporous silica KCC-1 as a platform for the rational design of next-generation chelated nanomaterials. Full article

This review is devoted to the occurrence, extraction, structural characterization and catalytic applications of vanadyl porphyrins present in heavy crude oils and petroleum residues. Vanadyl porphyrins represent the major vanadium-containing compounds in petroleum systems and play a dual role as both catalyst poisons during refining processes and valuable precursors for functional catalytic materials. Particular attention is devoted to recent advances in extraction technologies, including solvent extraction, ionic liquids, deep eutectic solvents, functionalized adsorbents and chelating agents. Process intensification approaches such as ultrasound- and microwave-assisted extraction, are also discussed as promising strategies for improving extraction efficiency and selectivity. Furthermore, recent developments in petroleum characterization using FTICR-MS, EPR, HYSCORE and LA-ICP-MS techniques are reviewed, providing insights into metalloporphyrin speciation, oxidation states, and distribution within complex petroleum matrices. Beyond their traditional role in catalyst deactivation, vanadyl porphyrins have emerged as attractive precursors for catalytic materials applied in oxidation reactions, photocatalysis, oxidative desulfurization, wastewater treatment and selective organic synthesis. The development of hybrid catalytic systems based on mesoporous silica, graphene oxide, carbon nanotubes, polymer matrices, and metal–organic frameworks has significantly improved catalyst stability, activity and recyclability. Current challenges related to the selective extraction, preservation of metalloporphyrin structure and catalytic performance evaluation are also discussed. Overall, this review provides an integrated perspective on the recovery, characterization and valorization of vanadyl porphyrins for sustainable petroleum upgrading and environmental applications. Full article

A novel mesoporous XAD-based adsorbent (A336/XAD-7) was produced by impregnating the ionic liquid A336 into the pores of XAD-7 resin and used to separate tin(IV) and cadmium(II) from high-level liquid waste (HLLW). The as-produced material was characterized by SEM-EDS, TG-DSC, and N₂ adsorption–desorption isotherms, which revealed a well-developed open pore structure, high loading capacity, and large specific surface area. Adsorption performance analysis showed that in 4 M HCl solution, the experimental saturated adsorption capacity qexp of A336/XAD-7 for Sn(IV) and Cd(II) were 39.51 mg/g and 34.18 mg/g, respectively, with equilibrium reached within 120 min. Among ten coexisting metal ions (Sn⁴⁺, Cd²⁺, Co²⁺, Ni²⁺, Cu²⁺, Eu³⁺, Y³⁺, Ca²⁺, Mg²⁺, Al³⁺) in HLLW, A336/XAD-7 exhibited excellent selectivity for Sn(IV) under high acidity, with a separation factor (SF_Sn/others) of 13.13. Column experiments further evaluated the dynamic separation of Sn(IV) from simulated HLLW using A336/XAD-7, achieving an enrichment factor greater than 7. XPS spectra indicated that the adsorption mechanism involved anion exchange between A336/XAD-7 and the complex anions SnCl₆²⁻ and CdCl₄²⁻. This work demonstrates the application potential of A336/XAD-7 for HLLW treatment and provides valuable guidance for the efficient separation of other metal ions. Full article

The excessive emission of greenhouse gases (CO₂, CH₄, SF₆, and CF₄.) is a primary driver of global climate change, making the development of efficient adsorption and separation technologies critically important for achieving carbon reduction goals. Metal–organic frameworks (MOFs) have attracted considerable attention in this field due to their crystalline porous structures, ultrahigh surface areas, and tunable pore architectures. However, pristine MOFs face significant bottlenecks including poor water stability, high bed pressure drops caused by their powdered form, and limited mass transfer, which severely hinder their industrial application. The integration of MOFs with functional materials such as carbon materials, polymers, metal oxides, and porous SiO₂ offers a synergistic strategy to overcome these limitations. Carbon materials provide hydrophobic barriers and mesoporous transport channels, polymers enhance processability and mechanical strength, metal oxides introduce basic sites for enhanced chemisorption, and MOF-on-MOF heterostructures enable atomic-level interfacial integration and pore synergy. This review systematically summarizes recent advances in MOF composites for the separation of CO₂, CH₄, and fluorinated greenhouse gases (SF₆, CF₄.), with an emphasis on design strategies, structure–performance relationships, and synergistic mechanisms across different composite types. Finally, the current challenges including scalable synthesis, long-term stability, and separation performance under realistic conditions are discussed, and future directions toward rational design and functional synergy for industrial carbon capture and fluorinated gas emission reduction are envisioned. Full article

Triethylamine (TEA), a widely used volatile organic compound (VOC), poses severe threats to environmental safety and human health upon accidental leakage, making the development of high-performance TEA detection techniques urgently needed. Herein, we report a Sn-based metal–organic framework (Sn-MOF) constructed from 4,5-dichloroimidazole ligands synthesized via a solvothermal approach. The resulting MOF-derived SnO₂ materials were obtained by calcination at 400–600 °C, yielding SnO₂ with tunable specific surface area and surface defect-site density. Structural and surface characterizations revealed that the materials consist of primary nanoparticles in the range of 10–50 nm, forming aggregated particles of 1–2 µm. The gas sensing performance toward TEA was systematically evaluated. The SnO₂-400 °C sensor exhibited the highest response (S = 85.0) to 100 ppm TEA at 190 °C, with a low detection limit of 1 ppm, superior selectivity, good repeatability, and excellent long-term stability. The observed performance variation was attributed to the combined effects of specific surface area, abundant defect-associated surface sites, and suitable mesoporous structure. This work not only provides a high-performance TEA sensor for industrial and food safety monitoring but also offers a rational strategy for designing MOF-derived metal oxide gas sensors with tailored microstructures and surface defect chemistry. Full article

To efficiently degrade tetracycline (TC) antibiotic pollution, cobalt-based (Co-OMCs/F) and cobalt–copper bimetallic ((Co+Cu)-OMCs/F) monolithic mesoporous carbon catalysts were synthesized using resorcinol–formaldehyde resin as a carbon precursor, with hexamethylenetetramine (HMT) and formaldehyde (CH₂O) as crosslinking agents, followed by high-temperature carbonization under N₂. The materials were characterized by XRD, SEM-EDX, HRTEM, and EPR. Key factors-metal loading, PMS concentration, initial pH, and flow rate-were investigated for their effects on TC degradation. Degradation mechanisms and stability were assessed via radical quenching and continuous-flow cycling tests. Results show optimal performance at a cobalt loading of 0.6 g. Compared to CH₂O, HMT favors a three-dimensional interconnected mesoporous carbon framework with uniform metal distribution and high crystallinity. Under conditions of 25 mg/L TC, 0.33 mmol/L PMS, pH 7, and 2 mL/min flow rate, the (Co+Cu)-OMCs/F (HMT) catalyst achieved ~93% TC degradation over 9 h of continuous operation, and 95% after three reuse cycles, significantly outperforming the single-metal Cu-OMCs/F catalyst. Radical quenching and EPR identified superoxide radicals (·O₂⁻) as the dominant active species (~78% contribution), with sulfate radicals (SO₄^·−), hydroxyl radicals (·OH), and singlet oxygen (¹O₂) playing synergistic roles. The synergistic Co-Cu bimetallic effect, combined with the confinement effect of the mesoporous carbon support and HMT-induced uniform nucleation, endows the catalyst with high activity and long-term stability. This work provides a theoretical basis for designing efficient, reusable, monolithic mesoporous carbon-based PMS activation catalysts for advanced antibiotic wastewater treatment. Full article

Nitrogen and phosphorus are the primary pollutants responsible for eutrophication in water bodies, and their effective removal is crucial for water environmental protection. Biochar, owing to its porous structure and surface functional groups, exhibits excellent adsorption performance for nitrogen and phosphorus, which can be significantly enhanced through metal modification. In this study, magnetic biochar (MBC) was prepared from spent mushroom substrate via FeCl₃ impregnation and microwave pyrolysis, and its adsorption performance for NH₄⁺ and PO₄³⁻ was systematically evaluated. The physicochemical properties of MBC were characterized using scanning electron microscopy, thermogravimetric analysis, specific surface area and pore structure analysis, vibrating sample magnetometry, and Fourier transform infrared spectroscopy. The results showed that the saturated magnetization of MBC was 7.86 emu/g, the specific surface area was 37 m²/g, and the material exhibited a mesoporous structure with high thermal stability. The adsorption process followed pseudo-second-order kinetics, and the mechanisms involved electrostatic interactions, surface complexation, and pore filling. Isotherm studies indicated that the maximum adsorption capacities of MBC for NH₄⁺ and PO₄³⁻ were 16.25 mg/g and 14.99 mg/g, respectively. Thermodynamic analysis revealed that the adsorption of NH₄⁺ was exothermic, whereas that of PO₄³⁻ was endothermic. Furthermore, MBC maintained an adsorption efficiency of up to 93% after ten adsorption–desorption cycles, demonstrating excellent reusability. Full article

Mercury contamination in water poses severe environmental and health risks, requiring efficient and sustainable removal strategies. In this study, rice husk (RH), rice husk-derived materials, including rice ash (RHA), and Mobil Composition of Matter No. 41 (MCM-41) were evaluated as adsorbents for Hg(II) removal in aqueous systems. Among the tested materials, MCM-41 exhibited superior adsorption performance, achieving up to 98% Hg(II) removal under optimal conditions (pH 6.8, 3 g L⁻¹ of adsorbent, and a pollutant concentration of 0.90 mg L⁻¹). Adsorption followed a pseudo-second-order kinetic model and was best described by the Langmuir isotherm, indicating monolayer adsorption. The maximum adsorption capacity reached 0.80 mg g⁻¹. Thermodynamic analysis revealed that the process was spontaneous and exothermic, primarily governed by coordination interactions and hydrogen bonding with surface silanol groups. The adsorbent’s applicability was further assessed in distilled water, synthetic industrial wastewater, and river water. Although high removal efficiencies were maintained, a decrease was observed in complex matrices due to competition from coexisting ions. Reusability tests demonstrated that MCM-41 retained its performance over four adsorption cycles. Environmental safety was evaluated through ecotoxicological and microbiological assays. Daphnia magna exhibited high sensitivity to Hg(II) (EC₅₀ values of 0.0220 mg L⁻¹ at 24 h and 0.0158 mg L⁻¹ at 48 h), while treated samples showed improved germination indices of Lactuca sativa, particularly in distilled and river water. However, residual toxicity persisted in industrial wastewater matrices. Overall, rice husk-derived MCM-41 is a promising and sustainable adsorbent for Hg(II) removal, though further optimization is needed to mitigate residual toxicity in complex water matrices. Full article

Ordered mesoporous carbons have emerged as versatile supports for Fischer–Tropsch catalysts due to their high surface area, tunable pore architectures, and chemical stability. However, the influence of active-metal identity on product selectivity within a common carbon framework remains insufficiently understood, particularly when Fe and Co are compared under rigorously identical conditions. To address this aspect, we prepared Fe- and Co-based catalysts with comparable nominal metal loadings supported on CMK-5 carbon material and evaluated their structural, surface, and catalytic properties. Comprehensive characterization revealed distinct metal-dependent behaviors, and catalytic testing between 423 and 598 K at 2 MPa showed that the catalyst CMK-5(Co10) exhibited substantially higher activity, whereas CMK-5(Fe10) provided a more stable product distribution and exclusively paraffinic C₂–C₃ products across the studied temperature range. In contrast, CMK-5(Co10) displayed a pronounced temperature-dependent selectivity, with increasing methane formation and the emergence of olefinic C₂–C₃ species at intermediate and high temperatures. Chain-growth probabilities were consistent with these trends. Complementary Density Functional Theory and Kinetic Monte Carlo analyses indicated stronger binding of carbonaceous intermediates on Fe clusters and more accessible C–C coupling pathways on Co clusters. Together, these results clarify how active-metal identity governs selectivity within a shared CMK-5 architecture and provide guidelines for designing carbon-supported Fischer–Tropsch catalysts with controlled product distributions. Full article

With the rapid development of the edible fungus industry, the environmental pressure and resource waste caused by the massive generation of fungal residue have become increasingly prominent. Meanwhile, heavy metal wastewater pollution and the growing demand for clean energy pose dual challenges to sustainable development. This study focuses on Auricularia cornea var. Li. fungal residue, exploring the establishment of a multi-level resource utilization pathway integrating “porous carbon material preparation—heavy metal adsorption—photocatalytic hydrogen evolution.” Firstly, the Auricularia cornea var. Li. residue-based porous carbon material was examined by combining hydrothermal carbonization, activation and slow pyrolysis. In optimal conditions, the porous carbon obtained yielded a surface area of 675.56 m²/g and formed a composite pore structure consisting of micropores with coexisting micropore and mesopore. Secondly, we performed batch adsorption experiments to study the effects of solution pH, adsorbent dosage and contact time and the adsorption behavior via fitting adsorbing kinetic models. Under optimal conditions, Cd(II) removal efficiency reached 92.36% and an equilibrium adsorption capacity of 92.47 mg/g. We used Cd(II) adsorbed porous carbon as a cadmium source and converted into a CdS photocatalyst using a hydrothermal sulfidation process. The CdS prepared using sodium sulfide as a sulfur source gave an average hydrogen evolution rate of 668.01 μmol·g⁻¹·h⁻¹ and showed higher photocatalytic performance for water splitting to produce hydrogen. Full article