Mesoporous Silica MCM-41 Research Articles

Antitumoral action of carvedilol–a repositioning study of the drug incorporated into mesoporous silica MCM-41

We have studied repositioning of carvedilol (an antihypertensive drug) incorporated into MCM-41 mesoporous silica. The repositioning proposes a reduction in the slow pace of discovery of new drugs, as well as toxicological safety and a significant reduction in high research costs, making it an attractive strategy for researchers and large pharmaceutical companies. We obtained MCM-41 bytemplatesynthesis and functionalized it by post-synthesis grafting with aminopropyltriethoxysilane (APTES) only or with folic acid (FA), which gave MCM-41-APTES and MCM-41-APTES-FA, respectively. We characterized the materials by scanning and transmission electron microscopy, zeta potential (ZP) measurements, Fourier transform infrared absorption spectroscopy, x-ray diffractometry, nitrogen gas adsorption, and CHNS elemental analysis. We quantified the percentage of drug that was incorporated into the MCM-41 materials by thermogravimetric analysis and evaluated their cytotoxic activity in non-tumor human lung fibroblasts and the tumor human melanoma and human cervical adenocarcinoma cell lines by XTT salt reduction (2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-arboxanilide). The x-ray diffractograms of the MCM-41 materials displayed low-angle peaks in the 2θrange between 2° and 3°, and the materials presented type IV nitrogen adsorption isotherms and H2 hysteresis typical of the MCM-41hexagonal network. The infrared spectra, the charge changes revealed by ZP measurements, and the CHN ratios obtained from elemental analysis showed that MCM-41 was amino-functionalized, and that carvedilol was incorporated into it. MCM-41-APTES incorporated 23.80% carvedilol, whereas MCM-41 and MCM-41-APTES-FA incorporated 18.69% and 12.71% carvedilol, respectively. Incorporated carvedilol was less cytotoxic to tumor and non-tumor cells than the pure drug. Carvedilol repositioning proved favorable and encourages further studies aimed at reducing its cytotoxicity to non-tumor cells. Such studies may allow for larger carvedilol incorporation into drug carriers or motivate the search for a new drug nanocarrier to optimize the carvedilol antitumoral activity.

A Novel Drug Delivery Platform Against Bacterial Resistance: Synthesis and Characterization of Ciprofloxacin-loaded MCM-41 Mesoporous Silica Nanoparticle

A Novel Drug Delivery Platform Against Bacterial Resistance: Synthesis and Characterization of Ciprofloxacin-loaded MCM-41 Mesoporous Silica Nanoparticle

Beyond the boundaries of organics biosorption: Reusable and cost-effective millet-straw-based carboxylate-functionalized mesoporous MCM-41

In this study, we prepared highly porous citric acid-functionalized mesoporous MCM-41 (C-MCM-41) molecular sieve adsorbent from millet straw agricultural residue, which was used for the effective remediation of wastewater contaminated with methylene blue (MB) and ciprofloxacin (CIP). The two-step synthesis process involved extracting highly pure silica from millet straw as a precursor for the ordered mesoporous silica MCM-41. The MCM-41 was synthesized via surfactant-mediated pore design before calcination, followed by citric acid grafting to improve surface functionality and enhance adsorption efficiency. Characterization techniques including XRD, SEM, HRTEM, FTIR, and zeta potential analysis confirmed the mesophase structure, honeycomb pore architecture, functional groups incorporation, and a more electronegative surface, respectively, due to the incorporated carboxyl moieties. Nitrogen adsorption-desorption studies showed a high surface area, which reduced slightly after functionalization. Adsorption of MB and CIP on the C-MCM-41 was superior to the unmodified MCM-41, and the Langmuir isotherm and pseudo-second-order models fitted the equilibrium and kinetic data, respectively. Reuse and cost analysis revealed that C-MCM-41 maintained over 90 % efficiency after four adsorption-desorption cycles and offers a sustainable and cost-effective alternative to conventional adsorbents, demonstrating higher efficiency in treating real wastewater. SynopsisSustainable and cost-effective silica was sourced from biomass and employed for the synthesis of reusable citric acid-functionalized ordered mesoporous silica which was used for the effective treatment of antibiotics contaminated wastewater

Cobalt-catalyzed carbonization from polyacrylonitrile for preparing nitrogen-containing ordered mesoporous carbon CMK-1 electrode with high electric double-layer capacitance

Ordered mesoporous carbon CMK-1 was prepared via carbonization at a relatively low temperature (the first step) followed by partial graphitization (the second step of carbonization at higher temperature) inside the ordered mesopores of cobalt-loaded mesoporous silica MCM-48 using polyacrylonitrile (PAN) as a carbon/nitrogen source. This first step of the carbonization is called “infusibilization”, and the resultant material is denoted as PANinf. In an advanced temperature-programmed desorption analysis of the PANinf/MCM-48 composite, the temperature of the observed HCN signal indicated that carbonization was reduced from 550 to 450 °C by a Co catalyst. The amount of typical N2 formation associated with the selective removal of pyridinic N species, resulting in the graphitic surface formation, also increased at a relatively high temperature (approximately 1000 °C) with the aid of the Co catalyst. The CMK-1 prepared through cobalt-catalyzed carbonization exhibited a higher electric double-layer capacitance with an Et4N+BF4–/propylene carbonate electrolyte, and higher electrical conductivity than CMK-1 prepared without a catalyst. This also implied the progress of graphitization within the carbonaceous wall. These results suggest that the edge planes of the graphitic domains in CMK-1 are predominantly exposed on the surfaces of the carbonaceous walls, resulting in an increase in the number of adsorptive sites for the electrolyte during capacitance measurements.

Evolution of the Pd0/PdO phase change on Pd-MCM-41 catalyst for efficient production of furfural from the fast pyrolysis of cellulose

Furfural (C5H4O2) is a high-value platform chemical that is traditionally derived from the solvolysis of hemicellulose. However, its production from pyrolysis is far from satisfactory. In particular, the abundant cellulose within lignocellulosic biomass has yet to be successfully upgraded into furfural. Consequently, the overall yield of furfural from a lignocellulosic biomass is extremely low. Herein, we report a facile heterogeneous catalyst prepared from a simple impregnation of palladium (Pd) onto MCM-41 mesoporous silica. The catalyst demonstrated a remarkably high selectivity of ∼58.5% and yield of ∼32.5 wt% for furfural from the fast pyrolysis of wet cellulose. It was also confirmed to reach a selectivity of 65.4% and yield of 44.5 wt% for furfural from wet xylan, as well as a furfural yield of 23.9 wt% from wet sugarcane bagasse. All these values are superior to the literature reports. Through advanced characterisation including in-situ synchrotron high-temperature XRD and DRIFTS measurement, the loading of Pd in a tiny quantity of 1 mol% was confirmed to be sufficient in enhancing the surface hydrophilicity of the MCM-41 support, promoting the adsorption of reactants especially the formaldehyde group (HCHO), as well as the desorption of the target product furfural. In addition, Pd oxide (i.e., Pd2+O) was confirmed to be the catalytic active site. However, it was partly reduced into metallic Pd0 during the cellulose pyrolysis, due to the preferred reduction by adsorbed formaldehyde group and other reductants including H2 and CO in the vicinity of the PdO sites on the Pd-O-Si interface. Nevertheless, the catalyst was proven to retain the memory of its initial state after combustive regeneration in air, having oxidation state of Pd, particle size, and dispersion degree being reversed to its original construction. Accordingly, its activity remained stable upon cyclic testing. All these results demonstrate a high practical viability of this heterogenous catalyst for the valorisation of cellulose-rich biomass, an otherwise abundant crop waste across the world.

Formulation of zeolite-mesoporous silica composite catalysts for light olefin production from catalytic cracking

Framework materials such as zeolites and mesoporous silicas are commonly used for many applications, especially catalysis and separation. Here zeolite-mesoporous silica composite catalysts (employing zeolite Y, ZSM-5, KIT-6, SBA-15 and MCM-41 mesoporous silica) were prepared (with different weight percent of zeolite Y and ZSM-5) and assessed for catalytic cracking (using n-heptane, as the model compound at 550 °C) with the aim to improve the selectivity/yield of light olefins of ethylene and propylene from n-heptane. Physicochemical properties of the parent zeolites and the prepared composites were characterized comprehensively using several techniques including X-ray diffraction, nitrogen physisorption, scanning electron microscopy, fourier transform infrared spectroscopy, pulsed-field gradient nuclear magnetic resonance and thermogravimetric analysis. Catalytic cracking results showed that the ZY/ZSM-5/KIT-6 composite (20:20:60 wt %) achieved a high n-heptane conversion of 85% with approximately 6% selectivity to ethylene/propylene. In contrast, the ZY/ZSM-5/SBA-15 composite achieved a higher conversion of 95% and an ethylene/propylene ratio of 8%, indicating a more efficient process in terms of both conversion and selectivity. Magnetic resonance relaxation analysis of the ZY/ZSM-5/KIT-6 (20:20:60) catalyst confirmed a micro-mesoporous environment that influences n-heptane diffusion and mass transfer. As zeolite Y and ZSM-5 have micropores, n-heptane can move and undergo hydrogen transfer reactions, whereas KIT-6 has mesopores that facilitate n-heptane’s accessibility to the active sites of zeolite Y and ZSM-5.

A unified description of ion exchange and complete adsorption isotherms, including cluster growth and cavity filling

In the context of micro- and mesoporous materials, the interpretation of ion exchange and gas adsorption isotherms rarely covers the full information content of the experimental data. Based on our earlier work regarding the role of entropy in multiple equilibria, we have revisited cation exchange data of zeolite A in more detail and addressed the analysis of Ar and N2 adsorption isotherms of nonporous, microporous and mesoporous silicates. The previously reported analysis is thereby extended and improved. The theory is presented in a unified and compact manner through rigorous application of the concept of fractional amount, including particle distribution, cluster growth, and cavity filling. A result is that the structure of mesoporous silica MCM-41 can be described as consisting of the main channel and two types of cavities, which can be interpreted as surface roughness. In a further step, the information delivered by the inflection points in type I, II and IV gas adsorption isotherms is considered. The adsorption of simple gases begins with the formation of a monolayer on the pristine surface. The inflection point thereby represents the start of a new process, indicating that the adsorption isotherms must be understood as the signature of several sequential chemical equilibrium steps. Information can be extracted by inspecting this signature more closely. The results demonstrate the ability of the reported procedure to elicit additional insight including structural features from experimental equilibrium isotherm data.

Green synthesis, characterization, and adsorption of Co(II) and Cu(II) ions from aqueous solution by mesoporous silica MCM-41

Green synthesis, characterization, and adsorption of Co(II) and Cu(II) ions from aqueous solution by mesoporous silica MCM-41

Synthesis of Composite Sorbents with Chitosan and Varied Silica Phases for the Adsorption of Anionic Dyes.

In this work, various types of silica materials were used for the synthesis of chitosan-silica composites. The composites were obtained using the chitosan (Ch) immobilization process from an aqueous solution on various silica phases, i.e., amorphous diatomite (ChAD), crystalline diatomite (ChCD), mesoporous silica MCM-41 (ChMCM), and mesoporous silica SBA-15 (ChSBA). Textural, structural, morphological, and surface properties of the materials were determined by using various measurement techniques, i.e., low-temperature adsorption/desorption isotherms of nitrogen, X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), potentiometric titration, high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The adsorption properties towards various anionic dyes, i.e., acid red 88 (AR88), acid orange 8 (AO8), and orange G (OG), were evaluated based on kinetic and equilibrium measurements. The ChSBA, ChAD, and ChMCM composites were characterized by relatively high adsorption capacities (am) for AR88, with values equal to 0.78, 0.71, and 0.69 mmol/g, respectively. These composites were also distinguished by the rapid AR88 adsorption rate, with the values of half-time parameter t0.5 equal to 0.35, 2.84, and 1.53 min, respectively. The adsorption equilibrium and kinetic data were analyzed by applying the generalized Langmuir isotherm and the multi-exponential equation (m-exp), respectively. An interaction mechanism between the dyes and the obtained materials was proposed.

Influence of Baccharis salicifolia Extract on Iron Oxide Nanoparticles in MCM-41@IONP and Its Application in Room-Temperature-Fabricated Metal–Insulator–Semiconductor Diodes

This work presents the green synthesis of iron oxide nanoparticles (IONPs) using Baccharis salicifolia extract and their incorporation in mesoporous silica MCM-41, obtaining an MCM-41@IONP composite. The MCM-41@IONP composite was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), nitrogen adsorption and desorption, scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The use of the natural reducing agent Baccharis salicifolia resulted in nanoparticles with an average size of 31 nm. Furthermore, we showcase the application of the MCM-41@IONP nanocomposite in a metal–insulator–semiconductor (MIS) diode, which was fabricated at room temperature. The current–voltage and capacitance–voltage curves of the MIS diode were carefully measured and subjected to detailed analysis. The results demonstrate the potential utility of MCM-41@IONP nanocomposite-based MIS diodes, suggesting their applicability in the design of biosensors or as discrete components in electronic devices.

Separation and purification of polyprenols from Ginkgo biloba leaves by silver ion anchored on imidazole-based ionic liquid functionalized mesoporous MCM-41 sorbent.

Polyprenols (PPs) are compounds with excellent biological activities and are applied in food, pharmaceutical, and cosmetic industries. However, its strong non-polar nature makes it difficult to separate with many saturated impurities (such as saturated fatty acids) extracted together. Complexation extraction is an effective method for separating saturated and polyunsaturated compounds. In this study, mesoporous silica MCM-41 was modified by imidazole-based ionic liquids (IL) followed by coating these MCM-41-supported IL compounds with silver salt to construct π-complexing adsorbent (AgBF4/IL•MCM-41) to enrich PPs from Ginkgo biloba leaves (GBL) extract. The mesoporous π-complexing sorbent was characterized by small-angle X-ray scattering (SAXS), FTIR, and nitrogen adsorption-desorption. The effect of the ratio of silver salt to IL•MCM-41 on the adsorption capacity of polyprenols from GBL was compared, and the dosage of AgBF4 was determined to be 1.5 mmol/g IL•MCM-41. Adsorption isotherms and kinetics indicate that the π-complexing adsorbent has excellent PPs adsorption performance (153 mg/g at 30 °C) and a fast adsorption rate (the time to reach adsorption equilibrium is 210 s). The PPs were separated using the fixed bed after treatment for only one cycle with AgBF4/IL•MCM-41, and the content of PPs in the product was increased from 38.54% to 70.2%, with a recovery rate of 86.6%. The π-complexing adsorbent showed excellent reusability for ≥3 adsorption-desorption cycles.

Temperature-Driven Structural Evolution during Preparation of MCM-41 Mesoporous Silica.

This study explores the influence of micelles on the evolution of MCM-41's pore structure via 24 h hydrothermal treatments in a range of temperatures from 100 °C to 200 °C. MCM-41 was characterized using BET, SAXD, FTIR, TEM, and TG-DSC. The findings demonstrate that with temperature elevation from 100 °C to 160 °C, the micelles undergo expansion, leading to an enhanced lattice constant from 4.50 nm to 4.96 nm and an increase in pore diameter from 3.17 nm to 3.45 nm, while maintaining the structural orderliness of the pore channels. Upon cooling, the reversible contraction of micelles and the strategic addition of water glass contribute to a reduction in pore size. However, at a threshold of 180 °C, the SAXD (100) peak's half-peak width surges by approximately 40% relative to that at 160 °C, illustrating a progressive disruption of the hexagonal configuration of MCM-41. Coupled with elevated silica dissolution at higher temperatures in an alkaline solution, a total disintegration of the ordered pore structure at 200 °C results in a drastic reduction in the specific surface area to 307 m2/g. These results are beneficial to developing structural transformation mechanisms of MCM-41 materials and designing mesoporous materials via temperature modulation innovatively.

Synthesis of N,N′-alkylidene bisamides and Suzuki–Miyaura coupling reaction derivatives with Pd organometallic catalyst anchored to channels of mesoporous silica MCM-41

At first, an organometallic catalyst namely, Pd-DPyE@MCM-41@MNP was prepared through magnetic (Fe3O4) nanoparticles-doped into channels of mesoporous silica MCM-41 and then, anchoring a novel complex composed of di(4-pyridyl)ethylene and palladium on the inner surface of the support. This immobilized catalyst was successfully identified via VSM, ICP-OES, TEM, FTIR, TGA, SEM, BET, XRD, EDX and elemental mapping analyses. After that, it was used as a versatile, heterogeneous, and magnetically reproducible catalyst in the generation of N,N′-alkylidene bisamides (1a-13a, 8–20 min, 90–98%, 50 °C, solvent-free) and Suzuki–Miyaura coupling (SMC) reaction derivatives (1b-26b, 10–140 min, 86–98%, 60 °C, PEG-400). The VSM plot of Pd-DPyE@MCM-41@MNP displays that this nanocatalyst can be easily recycled by applying an external magnetic field. In both synthetic paths, this nanocatalyst was reused at least seven times without palladium leaching and significantly reducing its catalytic performance. Also, stability and heterogeneous nature of catalyst were approved via ICP-OES technique and hot filtration test.

Functionalization of Ordered Mesoporous Silica (MCM-48) with Task-Specific Ionic Liquid for Enhanced Carbon Capture.

This work presents new composites of AAILs@MCM-48 obtained by functionalizing ordered mesoporous silica MCM-48 with two amino acid-based ionic liquids (AAILs) ([Emim][Gly] and [Emim][Ala]) to improve carbon capture and the selectivity of CO2 over nitrogen. Thermogravimetric and XRD analyses of the composites showed that the MCM-48 support's thermal and structural integrity was preserved after the AAILs were encapsulated. An N2 adsorption-desorption study at 77 K confirmed AAIL encapsulation in the porous support. Under post-combustion flue gas conditions, both [Emim][Gly]@MCM-48 and [Emim][Ala]@MCM-48 demonstrated improved CO2 adsorption in comparison to the unmodified MCM-48, with a CO2 partial pressure of around 0.15 bar. Regarding the maximal CO2 uptake, the 40 wt.%-[Emim][Gly] composite outperformed the others at 303 K, with values of 0.74 and 0.82 mmol g-1, respectively, at 0.1 and 0.2 bar. These numbers show a 10× and 5× increase, respectively, compared to the pure MCM-48 under identical conditions. In addition, the selectivity of the composites was improved significantly at 0.1 bar: the selectivity of composites containing 40 wt.% [Emim][Ala] increased to 17, compared to 2 for pristine MCM-48. These composites outperform other silica-based studies reported in the literature, even those using amines as solvents. The presented composites offer therefore promising prospects for advancing carbon capture technology.

Comparison of adsorption of U(VI) by magnetic MCM-41, MCM-48 and SBA-15 mesoporous silicas

Comparison of adsorption of U(VI) by magnetic MCM-41, MCM-48 and SBA-15 mesoporous silicas

Mesoporous Silica MCM-41 from Fly Ash as a Support of Bimetallic Cu/Mn Catalysts for Toluene Combustion.

The main outcome of this research was to demonstrate the opportunity to obtain a stable and well-ordered structure of MCM-41 synthesized from fly ash. A series of bimetallic (Cu/Mn) catalysts supported at MCM-41 were prepared via grinding method and investigated in catalytic toluene combustion reaction to show the material's potential application. It was proved, that the Cu/Mn ratio had a crucial effect on the catalytic activity of prepared materials. The best catalytic performance was achieved with sample Cu/Mn(2.5/2.5), for which the temperature of 50% toluene conversion was found to be 300 °C. This value remains in line with the literature reports, for which comparable catalytic activity was attained for 3-fold higher metal loadings. Time-on-stream experiment proved the thermal stability of the investigated catalyst Cu/Mn(2.5/2.5). The obtained results bring a valuable background in the field of fly ash utilization, where fly ash-derived MCM-41 can be considered as efficient and stable support for dispersion of active phase for catalyst preparation.

Improvement of Thermal Protection in Recycled Polyolefins through Hybrid Mesoporous Silica–Antioxidant Particles

The deficient management of plastic waste has caused a serious worldwide environmental problem. Thus, one of the main challenges for the industry in the plastics sector in contributing to sustainability and a circular economy consists of providing a subsequent service life to this waste. For that purpose, the appropriate incorporation of antioxidants will play a key role in preventing or postponing the degradation of plastic waste, where the formation of radicals is initiated during its previous lifetime by the action of degrading agents. Functionalized particles, based on mesoporous MCM-41 silica with Irganox 1076, were prepared with two different protocols and were further incorporated into a material containing virgin PP and 30 wt.% of recycled PP, with the purpose of guaranteeing thermal stability during its next service life. A very significant increase in the thermal stability of the resulting composites was found, attributable to the synergistic action between the Irganox 1076 antioxidant and the MCM-41 particles. In addition, the presence of hybrid particles leads to an important nucleating effect for the crystallization of PP. Moreover, a reinforcing role was also played by these modified mesoporous silicas in the resultant systems. The presented methodology constitutes, therefore, a promising strategy for contributing to the circular economy—since the synergy between the Irganox 1076 antioxidant and MCM-41 particles was found to play an important role in the ultimate performance of recycled polyolefins.

Synthesis of sustainable rice husk ash-derived nickel-decorated MCM-41 and SBA-15 mesoporous silica materials for hydrogen storage

To promote sustainability, it is essential to make use of biomass waste to create resources that can be transformed into mesoporous materials like silicates. These materials can be used as effective adsorbents for solid-state H2 storage systems. To meet the requirements of these systems, materials must be inexpensive, possess high specific surface areas, have proper pore arrangements, and exhibit reasonable H2 uptake. In this study, sustainable rice husk ash-derived MCM-41-RHA and SBA-15-RHA mesoporous silica materials were developed. These materials were engineered with different levels of Ni loading (2.5–10 wt%) and are used for H2 storage. The prepared MCM-41-RHA and SBA-15-RHA materials have a high BET-specific surface area of 1092.6 m2/g and 539.2 m2/g, respectively, with a mesopore distribution. The best results were observed for samples with a Ni loading of 5 wt%, such as MCM-41-RHA-Ni5 and SBA-15-RHA-Ni5, which demonstrated the highest H2 uptake of 3.64 wt% and 2.48 wt%, respectively, at 77 K and 1 bar. This was due to the strong interaction between the adsorbent and split over hydrogen despite the decrease in the BET-specific surface area after the incorporation of Ni. The enhanced interaction was evidenced by the increased isosteric heat of adsorption observed for MCM-41-RHA-Ni5 and SBA-15-RHA-Ni5, ranging from 21.1 to 8.1 kJ/mol, in contrast to the range of 6.9 to 4.1 kJ/mol for the pristine MCM-41-RHA and SBA-15-RHA. After five successive H2 uptake/release cycles, more than 92 % of the initial capacity was retained. This study presents a sustainable and cost-effective RHA-derived mesoporous silica material decorated with Ni- nanoparticles for solid-state H2 storage.

Two Mesoporous Domains Are Better Than One for Catalytic Deconstruction of Polyolefins.

Catalytic hydrogenolysis of polyolefins into valuable liquid, oil, or wax-like hydrocarbon chains for second-life applications is typically accompanied by the hydrogen-wasting co-formation of low value volatiles, notably methane, that increase greenhouse gas emissions. Catalytic sites confined at the bottom of mesoporous wells, under conditions in which the pore exerts the greatest influence over the mechanism, are capable of producing less gases than unconfined sites. A new architecture was designed to emphasize this pore effect, with the active platinum nanoparticles embedded between linear, hexagonal mesoporous silica and gyroidal cubic MCM-48 silica (mSiO2/Pt/MCM-48). This catalyst deconstructs polyolefins selectively into ∼C20-C40 paraffins and cleaves C-C bonds at a rate (TOF = 4.2 ± 0.3 s-1) exceeding that of materials lacking these combined features while generating negligible volatile side products including methane. The time-independent product distribution is consistent with a processive mechanism for polymer deconstruction. In contrast to time- and polymer length-dependent products obtained from non-porous catalysts, mSiO2/Pt/MCM-48 yields a C28-centered Gaussian distribution of waxy hydrocarbons from polyolefins of varying molecular weight, composition, and physical properties, including low-density polyethylene, isotactic polypropylene, ultrahigh-molecular-weight polyethylene, and mixtures of multiple, post-industrial polyolefins. Coarse-grained simulation reveals that the porous-core architecture enables the paraffins to diffuse away from the active platinum site, preventing secondary reactions that produce gases.

Atomic insights into the heterogeneity and the interface interactions of nanoconfined aqueous electrolyte solution

The structure and properties of nanoconfined electrolyte (nano electrolyte) solutions are important subjects in biochemistry, electrochemistry, separation science, etc. In the present work, neutron scattering and data driven reverse Monte Carlo were employed to quantitatively reveal the microstructure of aqueous CaCl2 solution in mesoporous silica MCM-41 at the atomic level. The electrolyte solution distributes in-homogeneously in the pores of mesoporous silica along the radial direction, which can be divided into the core, the transition, and the interface regions. The hydrogen bond structure of water in nano electrolytes is strengthened in the core region, analogous to that of nano water confined in nanochannels, and the ion association was enhanced in the transition region. The structure of the solution in the interface region was analogous to the bulk electrolyte solution under high pressure because of the confinement and interface effects. When the package ratio of nano electrolyte solution is insufficient, small amount of solution quasi-monolayer adsorb on the internal surface of mesoporous silica, the majority solution preferentially forms clusters with different sizes to adhere to the wetted interface. The anomalous hydrogen-bonding structure and ion association found in the present work improve our understanding of nanoconfined electrolyte solutions.