Search Results (4,187)

Contamination of heavy metals, particularly chromium from industrial activities, represents a critical challenge for public health and the environment. The aim of this study is to evaluate the adsorption performance of green mesoporous silica (GMS-24 h), synthesized through a sustainable process from industrial sodium silicate, and its derivative functionalized with amino groups (GMS-24 h–NH₂) for the removal of Cr(III) in aqueous systems. FTIR and CP–MAS NMR characterization confirmed the surface modification and textural property improvement of green mesoporous silica. The adsorption experiments, carried out under varying pH and Cr(III) concentration conditions, were fitted to the Langmuir and Freundlich models. The results showed that GMS-24 h reached a maximum capacity of 303 mg·g⁻¹ at pH 3, while GMS-24 h–NH₂ achieved 370 mg·g⁻¹ at pH 5. The evaluated adsorbents showed up to a 44% increase in efficiency. Preliminary kinetic studies indicated that the pseudo-second-order model accurately describes the process (R² > 0.99), with the rapid stabilization of the system. Diffusion analysis indicated combined mechanisms, with an additional chelation step (N → Cr) in GMS-24 h–NH₂. These findings suggest that GMS–NH₂ has the potential to be a sustainable and economical adsorbent for the remediation of wastewater from the tanning industry in León, Guanajuato, Mexico. Full article

The threats leading to the extinction of humanity accelerate the evolution and development of materials that are capable of providing conditions for preserving health and, implicitly, life. In our work, we developed drug delivery systems based on mesoporous silica which can deliver an antibiotic, bacitracin, in a more controlled manner. The synthesis of the FDU-12 was performed through a sol–gel method and alternatively functionalized with -NH₂ groups or with poly(N-acryloylmorpholine) chains. The loading of bacitracin was performed using the vacuum-assisted method we successfully used to load these mesoporous materials preferentially within the pores as proved by the TGA-DSC results. The release was performed in two types of simulated body fluid (SBF) and this process was evaluated with chromatographic method using UV detection. The obtained data were fitted in three mathematical models of kinetic drug release (Weibull model, Korsmeyer–Peppas model, and nonlinear regression). The antimicrobial evaluation demonstrated that bacitracin-loaded FDU-12 formulations exhibited strong activity against both reference and clinical Staphylococcus strains. At sub-inhibitory concentrations, all formulations significantly reduced microbial adherence and biofilm formation, although certain strain-dependent stimulatory effects were observed. Furthermore, exposure to sub-MIC levels modulated the production of soluble virulence factors (hemolysins, lipase, and amylase), in a formulation- and strain-dependent manner, underscoring the ability of surface-functionalized FDU-12 carriers to influence bacterial pathogenicity while enhancing antimicrobial efficacy. Full article

An inorganic–organic hybrid nano-adsorbent was prepared by chemical immobilisation of an organic Schiff base Cu (II) ion receptor, DHB ((E)-N-(1-(2-hydroxy-6-methyl-4-oxo-4H-pyran-3-yl) ethylidene) benzohydrazide), a selective dehydroacetic acid-based chemosensor, onto a mesoporous silica support. In order to prepare the sorbent, the silylating agent was anchored onto the silica. During this procedure, 3-Chloropropyl trimethoxy silane (CPTS) was attached to the surface, increasing hydrophobicity. By immobilising DHB onto the CPTS platform, the silica surface was activated, and as a result the coordination chemistry of the Schiff base generated a hybrid adsorbent with the capability to rapidly sequestrate Cu (II) ions from wastewater, as an answer to combat growing Waste Electrical and Electronic Equipment (WEEE) contamination in water supplies, in the wake of a prolonged consumerism mentality and boom in cryptocurrency mining. The produced hybrid materials were characterised by FTIR, proximate and ultimate analysis, nitrogen physisorption, PXRD, SEM, and TEM. The parameters influencing the removal efficiency of the sorbent, including pH, initial metal ion concentration, contact time, and adsorbent dosage, were optimised to achieve enhanced removal efficiency. Under optimal conditions (pH 7.0, adsorbent dosage 3 mg, contact time of 70 min, and 25 °C), Cu (II) ions were quantitatively sequestered from the sample solution; 93.1% of Cu (II) was removed under these conditions. The adsorption was found to follow pseudo-second-order kinetics, and Langmuir model fitting affirmed the monolayer adsorption. Full article

The heterogeneity of pore structure in deep coal reservoirs is a critical factor controlling the storage and transport capacity of coalbed methane (CBM). However, the fundamental control exerted by macrolithotypes remains inadequately quantified. This study systematically investigates the No. 8 coal seam of the Taiyuan Formation in the Daniudi gas field, Ordos Basin, using an integrated multi-technique approach including high-pressure mercury intrusion (HPMI), low-temperature N₂ adsorption (LTGA-N₂), and low-pressure CO₂ adsorption (LPGA-CO₂). Results reveal a consistent bimodal pore structure across all samples, dominated by well-developed micropores and macropores, whereas mesopores are relatively underdeveloped. More importantly, a clear macrolithotype control is established: as coal brightness decreases from bright to dull coal, the proportions of micropores and macropores decline significantly, leading to a substantial reduction in total pore volume and specific surface area. Fractal analysis further indicates that dull and semi-dull coals exhibit larger fractal dimensions, reflecting more complex pore structures and stronger heterogeneity compared to bright and semi-bright coals. This heterogeneity shows a positive correlation with ash and mineral contents, but a negative correlation with vitrinite and fixed carbon contents, suggesting that coal composition plays a primary governing role. These findings underscore that bright and semi-bright coals, with their superior micropore storage capacity and well-connected macropore networks, represent the most favorable targets for deep CBM exploration. This work establishes macrolithotype as a practical key indicator for reservoir quality assessment and production strategy optimization in deep CBM plays. Full article

Porous photocatalysts from agricultural waste, i.e., apricot and peach shell, with titanium dioxide were prepared by a carbonaceous method, the adsorption and photocatalytic degradation and its kinetics about methylene blue (MB) were studied systematically. The properties of the prepared composite sorbents were characterized using Brunauer–Emmett–Teller, surface area, scanning electron microscopy, and energy dispersive spectroscopy analyses. Several key factors, including radiation, pH, temperature, initial MB concentration, contact time, and sorbent dosage, as well as photocatalytic activity were investigated. All the waste-TiO₂ adsorbents showed improved adsorption and photodegradation performance compared to commercial charchoal-TiO₂. The produced materials presented high specific surface areas especially those derived from apricot shell-TiO₂ with a combination of type I and IV adsorption isotherms with a hysteresis loop indicating micro and mesopore structures. In addition, under UV radiation, the composite sorbents exhibited greater MB removal efficiency than non-radiated composite sorbents. The examined conditions have shown the best MB adsorption results at pH greater than 7.5, temperature 30 °C, contact time 120 min, initial concentration 0.5 mg/L MB, and sorbent dosage equal to 2.0 g/L C/MB. The total removal rate of MB is 98.5%, while the respective amount of commercial charcoal-TiO₂ is equal to 75.0%. The kinetic model that best describes the experimental data of MB degradation from the photocatalytic materials is the pseudo-second order model. In summary, this work highlights the effectiveness and feasibility of transforming agricultural waste into carbonaceous composite sorbent for the removal of cationic dyes from wastewater. Future work will involve scaling up the synthesis of the catalyst and evaluating its performance using bed reactors for industrial processes. Full article

Spent coffee grounds (SCG) are an abundant, carbon-rich residue that can be valorized through thermochemical conversion into biochar. Conventional CO₂ activation is typically performed in a two-step process, which is time- and energy-consuming. This study aims to evaluate whether a one-step CO₂-assisted pyrolysis can produce biochar with comparable or enhanced structural and textural properties while simplifying the process. We compare a two-step pyrolysis process followed by CO₂ activation with a one-step CO₂-assisted route for producing biochar from SCG. CO₂ treatment markedly increases surface area (from 9.8 m²∙g⁻¹ to 550.6–671.0 m²∙g⁻¹) and pore volume. FTIR and Boehm titration indicate depletion of oxygenated surface groups, while N₂ adsorption–desorption analyses and SEM reveal a more uniform micro/mesoporous texture for the one-step sample. Although fixed carbon decreases due to gasification, the one-step route delivers superior textural properties in a single thermal stage, reducing energy demand. These results highlight one-step CO₂-assisted pyrolysis as an efficient, scalable option for producing high-porosity biochar from coffee waste. Full article

Catalytic dry reforming of ethanol offers a sustainable pathway for syngas and hydrogen production through CO₂ utilization, though its efficiency depends heavily on the strategic synthesis of catalysts and the optimization of reaction parameters. This study employs Box–Behnken Design (BBD) and Response Surface Methodology (RSM) to optimize hydrogen yield from CO₂ reforming of ethanol over a Yttrium-promoted Ni-Co/MCM-41 catalyst. The catalyst was synthesized using sequential wet impregnation method and characterized for its physicochemical properties. The catalyst was tested in fixed-bed reactor using experimental data obtained from BBD considering the effects of temperature (550–700 °C), ethanol flowrate (0.5–1 mL/min) and CO₂ flowrate (15–30 mL/min) on the hydrogen yield. The experimental conditions were optimized using RSM quadratic model. The characterization revealed that the ordered mesoporous nature of the MCM-41 is maintained providing a high surface area of 597.75 m²/g for the catalyst. The addition of Yttrium as a promoter facilitates the formation of well crystallized nanoparticles. Maximum hydrogen yield of 85.09% was obtained at 700 °C, 20.393 mL/min and 0.877 mL/min for temperature, CO₂ and ethanol flowrate, respectively. The predicted hydrogen yield obtained is strongly correlated with the actual values as indicated by R² of 0.9570. Full article

Ionic liquids (ILs) have attracted considerable attention for light olefin separation owing to their negligible vapor pressure, excellent thermal stability, and tunable molecular structures. However, their intrinsically high viscosity severely restricts gas diffusion, leading to poor mass-transfer efficiency and limited separation performance in bulk form. Herein, we report the develop a high-performance adsorbent by immobilizing a silver-functionalized ionic liquid within ordered mesoporous MCM-41 to overcome the diffusion limitations of bulk ILs. The IL@MCM-41 composites were prepared via an impregnation–evaporation strategy, and their mesostructural integrity and textural evolution were confirmed by XRD and N₂ sorption analyses. Their C₂H₄/C₂H₆ separation performance was subsequently evaluated. The composite with a 70 wt% IL loading achieves a high C₂H₄ uptake of 25.68 mg/g and a C₂H₄/C₂H₆ selectivity of 15.59 in breakthrough experiments (298 K, 100 kPa). X-ray photoelectron spectroscopy results are consistent with the presence of reversible Ag⁺–π interactions, which governs the selective adsorption of C₂H₄. Additionally, the composite exhibits excellent thermal stability (up to 570 K) and maintains stable separation performance over 10 adsorption–desorption cycles. These IL@MCM-41 composites have significant potential for designing sorbent materials for efficient olefin/paraffin separation applications. Full article

This study investigates the activation mechanism of boron-doped carbon (BMC) catalysts for the degradation of the antibiotic sulfamethoxazole (SMX) via persulfate (PMS) activation. The catalysts were synthesized using a sequential double-melting calcination method, resulting in mesoporous carbon nanosheets characterized by hierarchical macro-mesopores and atomically dispersed dual active sites. Comprehensive characterization was performed using BET, SEM, TEM, FT-IR, XPS, XRD, and Raman techniques. The optimized BMC catalyst demonstrated excellent performance, achieving complete removal of sulfamethoxazole (100%) and a high mineralization rate (~90%) within 45 min. Mechanistic analysis, including electron paramagnetic resonance (EPR), revealed that the degradation predominantly follows a singlet oxygen (1O2)-dominated pathway. The system exhibited broad applicability to various pollutants, along with notable operational stability and robust resistance to common environmental interferents. Persulfate activation was primarily attributed to boron-active sites, while the hierarchical mesoporous structure facilitated both pollutant enrichment and catalytic efficiency. Full article

Deep coalbed methane (CBM) development in the Eastern Ordos Basin indicates that strong vertical heterogeneity within the Benxi Formation No. 8 thick coal seam can severely constrain well productivity. Here, twelve coal samples from two typical wells (W1: upper coal seams; W2: lower coal seams) were analyzed to quantify vertical variability in pore structure and its controls. Proximate and maceral analyses were combined with low-temperature N₂ adsorption (2–100 nm) and CO₂ adsorption (<2 nm) to characterize mesopores and micropores, respectively; mono-fractal and multifractal approaches were further applied to quantify pore-system heterogeneity. The results indicate that upper coal seams (W1) exhibit more developed micropores and stronger adsorption capacity, while the lower coal seams (W2) display more significant heterogeneity in pore structure, particularly at the micropore scale. Ash content is identified as the dominant control factor for vertical variations in pore characteristics, showing a negative correlation with both micropore and mesopore volumes, while coal rank and maceral composition exert secondary influences. A vertical zoning model has been established based on multiple parameters: the upper section is classified as a high-quality sweet-spot interval, whereas only localized layers in the lower section retain development potential. These findings can serve as a geological basis for optimizing target layer selection and fracturing design in deep coalbed methane wells. Full article

This study addresses the issues of poor stability and difficulty in recovery of free horseradish peroxidase (HRP) by developing a multi-level composite immobilized carrier that combines high loading capacity with long-term stability. The SiO₂@MnO₂@MAF-7 core–shell structured carrier was prepared via a solvothermal self-assembly method. Three immobilization strategies—adsorption, covalent cross-linking, and encapsulation—were systematically compared for their immobilization efficacy on HRP. The material structure was analyzed using techniques such as specific surface area analysis (BET), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) to characterize the material structure. Enzyme kinetic parameter determination experiments were conducted to systematically evaluate the performance advantages of the immobilized enzyme. BET analysis showed that SiO₂@MnO₂@MAF-7 had a specific surface area of 251.99 m²/g and a mesoporous area of 12.47 nm, and its HRP loading was 50.37 U/mg (immobilization efficiency 85.03%). Compared with free HRP, the Km value of the immobilized enzyme was decreased by 42%, the activity retention rate was increased by 35–50% at 80 °C and pH 4–9, and the activity was maintained by 65% after five repeated uses. In this study, MAF-7 was combined with MnO₂/SiO₂ for HRP immobilization for the first time, and the triple effect of rigid support-catalytic synergy-confined protection synergistically improved the stability of the enzyme, providing a new strategy for the industrial application of oxidoreductases. Full article

Continuous excessive CO₂ emissions have a negative impact on the environment. In order to address the issue of CO₂ emission control, its conversion to some valuable commodities is the way forward in dealing with this issue. Additionally, the conversion of CO₂ to some valuable product such as methanol fuel will not only tackle the issue but also result in producing energy. Here, the co-precipitation method was used to synthesize Cu-ZnO bimetallic catalysts based on TiO₂ support to be applied for CO₂ conversion to methanol fuel. To elucidate the role of potassium (K) as a promoter, varied concentrations of K were added to parent Cu-ZnO/TiO₂ catalysts. A number of analytical techniques were used to scrutinize the physico-chemical properties of calcined Cu-ZnO/TiO₂ catalysts. The crystalline nature of TiO₂ catalyst support with high metal oxide dispersion were the major findings disclosed based on X-ray diffraction examinations. The combination of the mesoporous and microporous character of the K-promoted Cu-ZnO/TiO₂ catalysts was discovered using the N₂ adsorption–desorption technique. Similarly, N₂ adsorption–desorption studies also revealed surface defects by K-promotion. The creation of surface defects was also endorsed by X-ray photoelectron spectroscopy (XPS) by showing additional XPS peaks for O1s in higher binding energy (BE) regions. XPS also showed the oxidation states of K-promoted Cu-ZnO/TiO₂ catalysts as well as metal–support interactions. Activity results demonstrated the active profile of K-promoted Cu-ZnO/TiO₂ catalysts for methanol synthesis via CO₂ reduction in a liquid phase slurry reactor. The methanol synthesis rate was accelerated from 35 to 53 g.MeOH/kg.cat.h by incorporating of K to parent Cu-ZnO/TiO₂ catalysts at reaction temperature and pressure of 210 °C and 30 bar, respectively. Structure–activity investigations revealed a promoting role of K by facilitating Cu reduction as well metal–support interaction. The comparative study further revealed the importance of K promotion for the title reaction. Full article

This study presents a systematic approach for converting low-grade carbon derived from mining waste into functional carbon–zeolite composites with enhanced adsorption performance. To promote carbon deposition within and around zeolite frameworks, four industrially relevant zeolites, including zeolite socony mobil-5 (ZSM-5), Faujasite-type zeolite (Zeolite-Y), beta zeolite (Zeolite-β), and mordenite (MOR), were mechanically mixed with low-grade carbon under controlled stirring conditions (24 h at 250 rpm) and subsequently pyrolyzed at 800 °C. These treatments enabled a detailed assessment of structural stability and carbon–zeolite interactions. Scanning electron microscopy revealed pronounced modifications in surface morphology and carbon distribution after carbon treatment, while X-ray diffraction confirmed that the crystalline zeolite frameworks remained structurally intact despite the deposition of amorphous carbon. The adsorption performance of the resulting composites was evaluated through CO₂ adsorption measurements under controlled temperature and pressure conditions, demonstrating a clear enhancement relative to the pristine zeolites. Overall, this work highlights an effective strategy for valorizing low-grade carbon waste into high-performance carbon–zeolite hybrid adsorbents and provides new mechanistic insights into framework stability, selective atom removal, and carbon–zeolite interactions in high-temperature and acidic environments. Full article

Revealing the evolution of micropore structure in industrial by-product solidified sludge is essential for elucidating strength development mechanisms and promoting the engineering utilization of industrial wastes. In this study, a series of tests, including unconfined compressive strength (UCS), low-field nuclear magnetic resonance, direct shear, and scanning electron microscopy coupled with energy-dispersive spectroscopy, were conducted on granulated blast furnace slag–carbide slag–titanium gypsum (GCT)-solidified sludge (GSDS) and cement-solidified sludge (CSDS). The results demonstrate that GSDS exhibits significantly superior compressive strength, deformation resistance, and pore-filling capacity compared with CSDS. With increasing curing age, both materials show logarithmic increases in UCS and mesopore volume fraction, accompanied by power-law decreases in total pore volume and the most probable pore size. On this basis, quantitative relationships between micropore characteristics and macroscopic mechanical properties are established for both solidified sludges. Microscopic analyses reveal that strength development in GSDS is primarily attributed to the formation of abundant C-(A)-S-H gels and expansive ettringite crystals, which effectively cement soil particles and refine interparticle pores. The synergistic solidification mechanism of GCT, involving ion exchange, cementitious bonding, and pore filling, promotes particle aggregation, enhances interparticle bonding, and refines pore structure, thereby markedly improving structural integrity and macroscopic strength in GSDS. Full article

In situ preparation routes have become central to advancing lead sulfide (PbS) quantum dots (QDs) for solar-energy conversion, owing to their ability to create strongly coupled QD/oxide interfaces that are difficult to achieve with ex situ colloidal methods, along with their simplicity and potential for low-cost, scalable processing. This review systematically examines the fundamental mechanisms, processing levers, and device implications of the dominant in situ approaches successive ionic layer adsorption and reaction (SILAR), voltage-assisted SILAR (V-SILAR), and chemical bath deposition (CBD). These methods enable conformal QD nucleation within mesoporous scaffolds, improved electronic coupling, and scalable low-temperature fabrication, forming the materials foundation for high-performance PbS-based architectures. We further discuss how these in situ strategies translate into enhanced solar-energy applications, including quantum-dot-sensitized solar cells (QDSSCs) and photoelectrochemical (PEC) hydrogen production, highlighting recent advances in interfacial passivation, scaffold optimization, and bias-assisted growth that collectively suppress recombination and boost photocurrent utilization. Representative device metrics reported in recent studies indicate that in-situ-grown PbS quantum dots can deliver photocurrent densities on the order of ~5 mA cm⁻² at applied potentials around 1.23 V versus RHE in photoelectrochemical systems, while PbS-based quantum-dot-sensitized solar cells typically achieve power conversion efficiencies in the range of ~4–10%, depending on interface engineering and device architecture. These performances are commonly associated with conformal PbS loading within mesoporous scaffolds and quantum-dot sizes in the few-nanometer regime, underscoring the critical role of morphology and interfacial control in charge transport and recombination. Recent studies indicate that performance improvements in PbS-based solar-energy devices are primarily governed by interfacial charge-transfer kinetics and recombination suppression rather than QD loading alone, with hybrid heterostructures and inorganic passivation layers playing a key role in modifying band offsets and surface trap densities at the PbS/oxide interface. Remaining challenges are associated with defect-mediated recombination, transport limitations in densely loaded porous scaffolds, and long-term chemical stability, which must be addressed to enable scalable and durable PbS-based photovoltaic and photoelectrochemical technologies. Full article