One-Pot Synthesis and Surfactant Removal from MCM-41 Using Microwave Irradiation.

This research pioneers the application of microwave irradiation as an innovative strategy for one-pot synthesis and surfactant elimination (cetyltrimethylammonium bromide-CTAB) from MCM-41, introducing a rapid and efficient methodology. MCM-41 silica is widely utilized in various applications due to its unique textural and structural properties. Nonetheless, the presence of residual surfactants after synthesis poses a challenge to its effective application. MCM-41 synthesis, conducted in a microwave reactor at 60 °C, provided a result within 0.5 to 1 h. Comprehensive analyses of structural, chemical, morphological, and surface characteristics were undertaken, with a focus on the impact of synthesis time on these properties. Surfactant extraction involved the use of ethanol as a solvent at 120 °C for 6 min within the microwave reactor. The acquired particles, coupled with the properties of textural and structural features, affirmed the efficacy of the synthesis process, resulting in the synthesis of MCM-41 within 36 min. This study presents the first instance of one-pot synthesis and surfactant removal from MCM-41 using a microwave reactor. The proposed method not only addresses the surfactant removal challenge, but also substantially accelerates the synthesis process, thereby enhancing the potential for MCM-41's application in diverse fields.

Influence of Pore Size and Surface Functionalization of Mesoporous Silica Nanoparticles on the Solubility and Antioxidant Activity of Confined Coenzyme Q10.

Coenzyme Q10 is a potent antioxidant that plays an important role in the maintenance of various biochemical pathways of the body and has a wide range of therapeutic applications. However, it has low aqueous solubility and oral bioavailability. Mesoporous silica nanoparticles (MCM-41 and SBA-15 types) exhibiting varying pore sizes and modified with phosphonate and amino groups were used to study the influence of pore structure and surface chemistry on the solubility, in vitro release profile, and intracellular ROS inhibition activity of coenzyme Q10. The particles were thoroughly characterized to confirm the morphology, size, pore profile, functionalization, and drug loading. Surface modification with phosphonate functional groups was found to have the strongest impact on the solubility enhancement of coenzyme Q10 when compared to that of pristine and amino-modified particles. Phosphonate-modified MCM-41 nanoparticles (i.e., MCM-41-PO3) induced significantly higher coenzyme Q10 solubility than the other particles studied. Furthermore, MCM-41-PO3 led to a twofold decrease in ROS generation in human chondrocyte cells (C28/I2), compared to the free drug in a DMSO/DMEM mixture. The results confirmed the significant contribution of small pore size and negative surface charge of MSNs that enable coenzyme Q10 confinement to allow enhanced drug solubility and antioxidant activity.

Highly Dispersed FeAg-MCM41 Catalyst for Medium-Temperature Hydrogen Sulfide Oxidation in Coke Oven Gas.

The traditional hydrolysis-cooling-adsorption process for coke oven gas (COG) desulfurization urgently needs to be improved because of its complex nature and high energy consumption. One promising alternative for replacing the last two steps is selective catalytic oxidation. However, most catalysts used in selective catalytic oxidation require a high temperature to achieve effective desulfurization. Herein, a robust 30Fe-MCM41 catalyst is developed for direct desulfurization at medium temperatures after hydrolysis. This catalyst exhibits excellent stability for over 300 h and a high breakthrough sulfur capacity (2327.6 mgS gcat-1). Introducing Ag into the 30Fe-MCM41 (30Fe5Ag-MCM41) catalyst further enhances the H2S removal efficiency and sulfur selectivity at 120 °C. Its outstanding performance can be attributed to the synergistic effect of Fe-Ag clusters. During H2S selective oxidation, Fe serves as the active site for H2S adsorption and dissociation, while Ag functions as the catalyst promoter, increasing Fe dispersion, reducing the oxidation capacity of the catalyst, improving the desorption capacity of sulfur, and facilitating the reaction between active oxygen species and [HS]. This process provides a potential route for enhancing COG desulfurization.

Development of dispersive liquid-liquid microextraction with solid-phase evaporation as a novel hyphenated method prior to ion mobility spectrometry and its application for trace analysis of fluoxetine.

For the hyphenating of dispersive liquid-liquid microextraction (DLLME) with nano mesoporous solid-phase evaporation (SPEV) as a novel method, MCM-41@SiO2 was synthesized and used as a nano mesoporous adsorbent for coating on the solid-phase fiber, preconcentration of fluoxetine antidepressant drug (as a model compound), and total evaporation of the extraction solvents obtained by the DLLME method. To detect the analyte molecules, a corona discharge ionization-ion mobility spectrometer (CD-IMS) was applied. In order to increase the extraction efficiency and the IMS signal of the fluoxetine drug, some variables including extraction solvent and its volume, disperser solvents and its volume, sample solution pH, desorption temperature, and evaporation time of the solvent from the solid-phase fiber were chosen and optimized. Some analytical parameters including limit of detection (LOD), limit of quantification (LOQ), linear dynamic range (LDR) with determination coefficient, and relative standard deviations (RSDs) were calculated under the optimized conditions. LOD (S/N = 3), 3 ng mL-1; LOQ (S/N = 10), 10 ng mL-1; LDR, 10-200 ng mL-1; and intra- and inter-day RSDs (n = 3), 2.5% and 9.6% for 10 ng mL-1, and 1.8% and 7.7% for 150 ng mL-1, respectively. To investigate the ability of the hyphenated method to determine fluoxetine in real samples, fluoxetine tablets, and some biological samples such as human urine and blood plasma were selected and the relative recovery values were calculated to be 85-110%. The accuracy of the proposed method was compared with that of the HPLC standard method.

Mesoporous-Layered Double Oxide/MCM-41 Composite with Enhanced Catalytic Performance for Cyclopentanone Aldol Condensation.

Layered double oxides are widely employed in catalyzing the aldol condensation for producing biofuels, but its selectivity and stability need to be further improved. Herein, a novel MCM-41-supported Mg-Al-layered double oxide (LDO/MCM-41) was prepared via the in situ integration of a sol-gel process and coprecipitation, followed by calcination. This composite was first employed to catalyze the self-condensation of cyclopentanone for producing high-density cycloalkane precursors. LDO/MCM-41 possessed large specific surface area, uniform pore size distribution, abundant medium basic sites and Bronsted acid sites. Compared with the bulk LDO, LDO/MCM-41 exhibited a higher selectivity for C10 and C15 oxygenates at 150 °C (93.4% vs. 84.6%). The selectivity for C15 was especially enhanced on LDO/MCM-41, which was three times greater than that on LDO. The stability test showed that naked LDO with stronger basic strength had a rapid initial activity, while it suffered an obvious deactivation due to its poor carbon balance. LDO/MCM-41 with lower basic strength had an enhanced stability even with a lower initial activity. Under the optimum conditions (50% LDO loading, 170 °C, 7 h), the cyclopentanone conversion on LDO/MCM-41 reached 77.8%, with a 60% yield of C10 and 15.2% yield of C15.

Architectural MCM 41 was anchored to the Schiff base Co(II) complex to enhance methylene blue dye degradation and mimic activity.

A sequence of Schiff base Cobalt (II) Mobile Composite Matter 41 heterojunction (SBCo(II)-MCM 41) was prepared by post-synthetic protocols. Various characterization techniques were used to characterize the above samples and MCM 41: Morphology, functional groups, optical properties, crystalline nature, pore diameter, and binding energy by scanning electron microscope (SEM), High-resolution transition electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FTIR), Ultra Violet-Visible Spectroscopy (UV), X-ray powder diffraction (XRD), Brunauer-Emmett-Teller (BET) and X-ray Photoelectron Spectroscopy (XPS). After the encapsulation of SBCo(II) on the MCM 41, the intensity in the 100-plane in powder x-ray diffraction (XRD) decreased significantly; moreover, the light absorption behavior in UV analysis was improved. The change in the surface area and the decrease in the pore diameter of the sample were also demonstrated by the BET study. The XPS results confirmed the presence of Si, O, C, N, and Co in the SBCo(II)-MCM 41 complex. The photocatalytic performance of MCM 41 and SBCo(II)-MCM 41 materials tested by the degradation of methylene blue dye (MBD) shows that MCM 41 immobilization with SBCo(II)complex is rapidly degraded under natural sunlight irradiation. The optimized 10 mg SBCo(II)-MCM 41 catalyst concentrations showed effective enhancement with the highest efficiency of 98% achieved within 2 h compared to the other two SBCo(II)-MCM 41 concentrations. Moreover, the catalytic efficiency of SBCo(II)-MCM 41 showed a biomimetic reaction without using an oxidant, which exposed it as an effective catalyst for amine to imine conversion; it was useful in the medical field for enzymes with structural assembly.

Self-Diffusion in Confined Water: A Comparison between the Dynamics of Supercooled Water in Hydrophobic Carbon Nanotubes and Hydrophilic Porous Silica.

Confined liquids are model systems for the study of the metastable supercooled state, especially for bulk water, in which the onset of crystallization below 230 K hinders the application of experimental techniques. Nevertheless, in addition to suppressing crystallization, confinement at the nanoscale drastically alters the properties of water. Evidently, the behavior of confined water depends critically on the nature of the confining environment and the interactions of confined water molecules with the confining matrix. A comparative study of the dynamics of water under hydrophobic and hydrophilic confinement could therefore help to clarify the underlying interactions. As we demonstrate in this work using a few representative results from the relevant literature, the accurate assessment of the translational mobility of water molecules, especially in the supercooled state, can unmistakably distinguish between the hydrophilic and hydrophobic nature of the confining environments. Among the numerous experimental methods currently available, we selected nuclear magnetic resonance (NMR) in a field gradient, which directly measures the macroscopic translational self-diffusion coefficient, and quasi-elastic neutron scattering (QENS), which can determine the microscopic translational dynamics of the water molecules. Dielectric relaxation, which probes the re-orientational degrees of freedom, are also discussed.

Three Different Interaction Patterns between MCM-41 and Proteins.

As one of the most studied mesoporous silica nanoparticles (MSNs) in drug delivery systems, Mobil Composition of Matter No. 41 (MCM-41) possesses unique properties including perfect channel architecture, excellent load capacity, and good biocompatibility. However, the applications of MCM-41 nanoparticles in drug delivery have not yet been industrialized, due to the interaction between MCM-41 and biomolecules (especially proteins) that affect their in vivo behaviors after dosing. To investigate the interactions between MCM-41 and proteins, this study selected bovine serum albumin (BSA), lysozyme (Lyso), and bovine hemoglobin (BHb) as model proteins and characterized the ultraviolet-visible, fluorescence, circular dichroism spectra and the protein adsorption of MCM-41-protein complex. The UV-Vis spectra exhibited the different absorption increment degrees of three proteins. The fluorescence spectra showed that the fluorescence intensity of proteins changed by different trends. The CD spectra indicated that the secondary structure changes were ranked as BSA > Lyso > BHb, which is consistent with the protein's adsorption capability on MCM-41. It was shown that there were three different patterns of MCM-41-proteins interactions. The hydrophilic and low-charged BSA followed the strong interaction pattern, the hydrophilic but heavily charged Lyso followed the moderate interaction pattern, and the hydrophobic BHb followed the weak interaction pattern. Different interaction patterns would lead to different effects on the structural properties of proteins, the surface chemistry of MCM-41, and the absorption capability of proteins on MCM-41. We believe our study will provide a better insight into the application of MCM-41 nanoparticles in drug delivery systems.

Can We Form Mesoporous Zeolites by Steam Assisted Crystallization of MCM-41?

The possibility of crystallizing silicalite-1 (MFI) from the pore walls of as-synthesized MCM-41 via steam-assisted crystallization (SAC) was thoroughly investigated. A kinetic study was conducted through the impregnation of as-synthesized MCM-41 with the structure-directing agent tetrapropyl-ammonium hydroxide (TPAOH). Materials obtained after different SAC treatment times (1−288 h) were characterized by XRD, nitrogen physisorption at 77 K, TGA/DTA, and SEM. The achieved results allowed us to conclude that during SAC treatment, rapid destruction of the hexagonal mesophase occurs with the enlargement of mesopores, probably by their coalescence, until achieving non-porous amorphous silica. Only thereafter is the crystallization of the MFI phase evidenced through the development of micron-sized (>10 µm) MFI structured crystals. This study suggests the probable practical impossibility of even partial crystallization of the pore walls of mesoporous materials by SAC.

Reactive Adsorption Performance and Behavior of Gaseous Cumene on MCM-41 Supported Sulfuric Acid.

Efficient removal of cumene from gaseous streams and recovery of its derivatives was accomplished using a MCM-41-supported sulfuric acid (SSA/MCM-41) adsorbent. The results indicated that the removal performance of the SSA/MCM-41 for cumene was significantly influenced by the process conditions such as bed temperature, inlet concentration, bed height, and flow rate. The dose-response model could perfectly describe the collected breakthrough adsorption data. The SSA/MCM-41 adsorbent exhibited a reactive temperature region of 120-170 °C, in which the cumene removal ratios (Xc) were greater than 97%. Rising the bed height or reducing the flow rate enhanced the theoretical adsorption performance metrics, such as theoretical breakthrough time (tB,th) and theoretical breakthrough adsorption capacity (QB,th), whereas increasing the inlet concentration resulted in tB,th shortening and QB,th rising. As demonstrated in this paper, the highest tB,th and QB,th were 69.60 min and 324.50 mg g-1, respectively. Meanwhile, the spent SSA/MCM-41 could be desorbed and regenerated for cyclic reuse. Moreover, two recoverable adsorbed products, 4-isopropylbenzenesulfonic acid and 4, 4'-sulfonyl bis(isopropyl-benzene), were successfully separated and identified using FTIR and 1H/13C NMR characterization. Accordingly, the relevance of a reactive adsorption mechanism was confirmed. This study suggests that the SSA/MCM-41 has remarkable potential for application as an adsorbent for the resource treatment of cumene pollutants.

Study of rice husk ash derived MCM-41-type materials on pore expansion, Al incorporation, PEI impregnation, and CO2 adsorption.

Conventional MCM-41 (M41), silica-pure pore-expanded MCM-41 (PM41), and Al-containing pore-expanded MCM-41 (PM41Ax) were synthesized from rice husk ash and tested as polyethyleneimine (PEI) supports for CO2 capture. Samples were characterized by small-angle X-ray diffraction, X-ray fluorescence spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, granulometric analysis, and nitrogen adsorption techniques. The PEI loading rate and CO2 adsorption-desorption performance were determined via thermogravimetric analysis. The effects of pore expansion, heteroatom Al incorporation, PEI loading rate, and Si/Al ratio on CO2 adsorption performance were examined. For the first time, the amount of PEI impregnated in PM41 was increased beyond 55 wt%, and the low-Si/Al-ratio PM41Ax support was used to load PEI in a novel procedure. Results show that at the same PEI loading rate, PM41 is always superior to M41 regarding adsorption capacity and adsorption rate. For a PEI loading rate >50 wt%, the superiority is amplified, reaching 15.9% and 21.3%, respectively. The use of the high-Al-containing PM41Ax support further increases adsorption capacity and adsorption rate by 13.4% and 9.6%, respectively. The presented reaction has a hybrid adsorption characteristic that includes both chemisorption and physisorption. Avrami's fractional-order kinetic model describes the adsorption best. Over the entire time scale, the adsorption rate is determined by several kinetic diffusion-controlled processes. The intraparticle diffusion and equilibrium adsorption are two predominant rate-limiting steps, and their control ranges change with temperature. After five cycles of adsorption and desorption, the desorption ratio was as high as 99%, and the working capacity still retained 96.5% of the original capacity. In addition, the presence of water vapor increased the adsorption capacity of the adsorbents presented in this study. These advantages make them successful iin capturing CO2 in the post-combustion scenario.

Niclosamide encapsulated in mesoporous silica and geopolymer: A potential oral formulation for COVID-19.

COVID-19 is a rapidly evolving emergency, for which there have been no specific medication found yet. Therefore, it is necessary to find a solution for this ongoing pandemic with the aid of advanced pharmaceutics. What is proposed as a solution is the repurposing of FDA approved drug such as niclosamide (NIC) having multiple pathways to inactivate the SARS-CoV-2, the specific virion that induces COVID-19. However, NIC is hardly soluble in an aqueous solution, thereby poor bioavailability, resulting in low drug efficacy. To overcome such a disadvantage, we propose here an oral formulation based on Tween 60 coated drug delivery system comprised of three different mesoporous silica biomaterials like MCM-41, SBA-15, and geopolymer encapsulated with NIC molecules. According to the release studies under a gastro/intestinal solution, the cumulative NIC release out of NIC-silica nanohybrids was found to be greatly enhanced to ~97% compared to the solubility of intact NIC (~40%) under the same condition. We also confirmed the therapeutically relevant bioavailability for NIC by performing pharmacokinetic (PK) study in rats with NIC-silica oral formulations. In addition, we discussed in detail how the PK parameters could be altered not only by the engineered porous structure and property, but also by interfacial interactions between ion-NIC dipole, NIC-NIC dipoles and/or pore wall-NIC van der Waals in the intra-pores of silica nanoparticles.

In vitro toxicity evaluation of lomefloxacin-loaded MCM-41 mesoporous silica nanoparticles.

Lomefloxacin (LF) is interesting as a model molecule from a safety point of view because of its high potential for serious adverse drug effects (i.e. phototoxic reactions). In this study, MCM-41 mesoporous silica nanoparticles (MCM-41) were loaded with lomefloxacin, aiming to overcome the drug's intrinsic cytotoxicity. The good biocompatibility of the empty drug carrier (0.1-1.0 mg/ml) was established by the absence of red blood cell lysis (hemolysis assay). The cytotoxicity of empty MCM-41 and lomefloxacin-loaded MCM-41 (LF-MCM-41) was evaluated by using a battery of in vitro cytotoxicity assays: Alamar blue, lactate dehydrogenase release and reactive oxygen species formation by dichlorofluorescein assay. Three cell cultures models: hepatoma HepG2, fibroblasts L929 and endothelial EA.hy926 cells were used to compare the cytotoxicity and reactive oxygen species formation by free drug, empty MCM-41, and LF-MCM-41. The findings from the study indicated that empty MCM-41 (0.1-1.0 mg/ml) showed a low cytotoxic potential in HepG2, followed by L929 and EA.hy926 cells. Lomefloxacin loading in MCM-41 mesoporous silica nanocarrier reduced the cytotoxicity of the free lomefloxacin, especially in the high concentration (1.0 mg/ml MCM-41, containing 120 µg/ml LF). L929 and EA.hy926 cells were more sensitive to the protective effects of LF-MCM-41, compared to HepG2 cells. The results indicate that an improvement in lomefloxacin safety might be expected after incorporation in an appropriate drug delivery system.

Efficient Activation of Coal Fly Ash for Silica and Alumina Leaches and the Dependence of Pb(II) Removal Capacity on the Crystallization Conditions of Al-MCM-41.

In this study, four different coal fly ashes (CFAs) were used as raw materials of silica and alumina for the preparation of the alumina-containing Mobil Composition of Matter No. 41 (Al-MCM-41) and the exploration of an activation strategy that is efficient and universal for various CFAs. Alkaline hydrothermal and alkaline fusion activations proceeded at different temperatures to determine the best treatment parameters. We controlled the pore structure and surface hydroxyl density of the CFA-derived Al-MCM-41 by changing the crystallization temperature and aging time. The products were characterized by small-angle X-ray diffraction, nitrogen isotherms, Fourier-transform infrared spectroscopy, 29Si silica magic-angle spinning nuclear magnetic resonance, and transmission electron microscopy, and they were then grafted with thiol groups to remove Pb(II) from aqueous solutions. This paper innovatively evaluates the CFA activation strategies using energy consumption analysis and determines the optimal activation methodology and parameters. This paper also unveils the effect of the crystallization condition of Al-MCM-41 on its subsequent Pb(II) removal capacity. The results show that the appropriate selection of crystallization parameters can considerably increase the removal capacity over Pb(II), providing a new path to tackle the ever-increasing concern of aquic heavy-metal pollution.

A new anti-fouling polysulphone nanofiltration membrane blended by amine-functionalized MCM-41 for post treating waste stabilization pond's effluent.

Developing an effective and stable separation membrane for water treatment is of much interest while challenging because of the restrictions of membrane fouling and water flux reduction. To minimize this problem, in this work, highly porous and hydrophilic nanostructure of NH2-modified MCM-41 (NH2-MCM-41) was embedded successfully into the nanofiltration (NF) membrane body via commonly used phase inversion method. The unmodified and modified nanofiller was analyzed by Fourier Transform Infrared (FTIR) spectroscopy, X-Ray powder diffractometry (XRD), field emission scanning electron microscopy (FE-SEM), thermogravimetric analysis (TGA), and nitrogen adsorption-desorption. Furthermore, the modified membranes were characterized through surface and cross section FE-SEM images, the membrane surface roughness, hydrophilicity, antifouling properties and dye rejection. Benefiting from porous networks and enhanced hydrophilicity, the mixed matrix membranes (MMMs) revealed more prominent hydrophilic property as well as higher pure water flux (PWF) compared with naked membrane. The polysulphone (PSf) membrane modified with NH2-MCM-41-1.0 exhibited the highest pure water flux (PWF) of 65.43 kg/m2.h and superior antifouling characteristics with a flux recovery ratio (FRR) of around 97.0% and an irreversible fouling resistance (Rir) of 3.2%. Furthermore, the optimal membrane possessed high dye rejection (100%) and antifouling capacity (FRR of 97%) while filtering a field sample, effluent from a local stabilization pond treating municipal wastewater. The fabricated membrane in this study is believed to pave pathways for constructing NF membranes with superior effectiveness for other municipal and industrial wastewaters treatment.

Spherical Al-MCM-41 Doped with Copper by Modified TIE Method as Effective Catalyst for Low-Temperature NH3-SCR.

Aluminum containing silica spherical MCM-41 was synthesized and modified with copper by the template ion-exchange method (TIE) and its modified version, including treatment of the samples with ammonia solution directly after template ion-exchange (TIE-NH3). The obtained samples were characterized with respect to their chemical composition (ICP-OES), structure (XRD), texture (low temperature N2 sorption), morphology (SEM-EDS), form and aggregation of deposited copper species (UV-vis DRS), reducibility of copper species (H2-TPR), and surface acidity (NH3-TPD). The deposition of copper by the TIE-NH3 method resulted in much better dispersion of this metal on the MCM-41 surface comparing to copper introduced by TIE method. It was shown that such highly dispersed copper species, mainly monomeric Cu2+ cations, deposited on aluminum containing silica spheres of MCM-41, are significantly more catalytically effective in the NH3-SCR process than analogous catalysts containing aggregated copper oxide species. The catalysts obtained by the TIE-NH3 method effectively operated in much broader temperature and were less active in the side process of direct ammonia oxidation by oxygen.

Bringing Homogeneous Iron Catalysts on the Heterogeneous Side: Solutions for Immobilization.

Noble metal catalysts currently dominate the landscape of chemical synthesis, but cheaper and less toxic derivatives are recently emerging as more sustainable solutions. Iron is among the possible alternative metals due to its biocompatibility and exceptional versatility. Nowadays, iron catalysts work essentially in homogeneous conditions, while heterogeneous catalysts would be better performing and more desirable systems for a broad industrial application. In this review, approaches for heterogenization of iron catalysts reported in the literature within the last two decades are summarized, and utility and critical points are discussed. The immobilization on silica of bis(arylimine)pyridyl iron complexes, good catalysts in the polymerization of olefins, is the first useful heterogeneous strategy described. Microporous molecular sieves also proved to be good iron catalyst carriers, able to provide confined geometries where olefin polymerization can occur. Same immobilizing supports (e.g., MCM-41 and MCM-48) are suitable for anchoring iron-based catalysts for styrene, cyclohexene and cyclohexane oxidation. Another excellent example is the anchoring to a Merrifield resin of an FeII-anthranilic acid complex, active in the catalytic reaction of urea with alcohols and amines for the synthesis of carbamates and N-substituted ureas, respectively. A SILP (Supported Ionic Liquid Phase) catalytic system has been successfully employed for the heterogenization of a chemoselective iron catalyst active in aldehyde hydrogenation. Finally, FeIII ions supported on polyvinylpyridine grafted chitosan made a useful heterogeneous catalytic system for C-H bond activation.

Selective sorptive removal of Methyl Red from individual and binary component solutions by mesoporous organosilicas of MCM-41 type.

Organosilicas with chemically immobilized 3-aminopropyl and Methyl Red-containing surface groups were prepared by sol-gel condensation of tetraethyl orthosilicate and (3-aminopropyl)triethoxysilane in the presence of dye as part of the mixed micelles or dye-containing silane as silica source. The hexagonally arranged mesoporous structure of synthesized materials was confirmed by low-temperature nitrogen adsorption-desorption, x-ray diffraction, and TEM studies. Chemical composition of MCM-41-type organosilicas was established by FT-IR spectroscopy and chemical analysis of surface layer. Sorption of Methyl Red by organosilicas was studied from diluted phosphate buffer solutions in dependence of medium pH, duration of contact, and equilibrium concentration of dye. It was found that effective removal of Methyl Red takes place at pH values within a range of 2.5-5. Kinetic curves of Methyl Red sorption on organosilicas were analyzed by the Lagergren, Ho-McKey, and Weber-Morris kinetic models. It was found that the pseudo-second-order model fits the kinetics of Methyl Red sorption on all synthesized materials and the intraparticle diffusion is not the only one mechanism controlling the rate of Methyl Red sorptive removal. The parameters of equilibrium sorption of Methyl Red on organosilicas of MCM-41 type were calculated using Langmuir, Freundlich, Redlich-Peterson, and Brunauer-Emmett-Teller models. Sorption of acid dyes with geometry similar or substantially different from Methyl Red on mesoporous silicas was studied from single and binary component mixtures in aqueous solutions with pH 4.8 and 5.5. It was found that selective sorption process is highly dependent on the structural characteristics and protolytic state of silica surface as well as acid dye.

Determination of personal care products in water using UHPLC-MS after solid phase extraction with mesoporous silica-based MCM-41 functionalized with cyanopropyl groups.

A silica-based MCM-41 mesoporous material functionalized with cyanopropyl groups has been synthesized by cocondensation, characterized and applied to preconcentrate six parabens and three UV filters in river and swimming-pool waters. The analytes were quantified by ultra-high performance liquid chromatography-tandem mass spectrometry, according to the Directive 96/23/EC. Even though matrix effect was negligible, quantification in river water samples with the standard addition approach improved the recoveries obtained using solvent-based and even with matrix-matched calibration. The method quantification limits in river water samples were 0.05 ng/mL for 2,4-dihydroxybenzophenone and 0.01 ng/mL for the rest. Recoveries, evaluated for a concentration level of 0.5 ng/L, were in the range 93.5-107.6% for parabens and in the range 64.2-85.8% for UV filters, with relative standard deviations intraday ≤10.2 and 10.8%, respectively. This parameter, evaluated for a concentration level of 0.1 ng/L, ranged between 98.3 and 110.4% for parabens and between 61.9 and 89.9% for UV filters, with relative standard deviation intraday ≤15.3 and 15.5%, respectively. The two UV filters with lower recoveries were the most affected by the addition of sodium chloride. River and swimming pool waters were analyzed and all the personal care products were found in the swimming pool water, whereas only methylparaben was detected in the river water.

Production of MCM-41 Nanoparticles with Control of Particle Size and Structural Properties: Optimizing Operational Conditions during Scale-Up.

The synthesis of Mobil Composition of Matter 41 (MCM-41) mesoporous silica nanoparticles (MSNs) of controlled sizes and porous structure has been performed at laboratory and pilot plant scales. Firstly, the effects of the main operating conditions (TEOS -Tetraethyl ortosilicate- addition rate, nanoparticle maturation time, temperature, and CTAB -Cetrimonium bromide- concentration) on the synthesis at laboratory scale (1 L round-bottom flask) were studied via a Taguchi experimental design. Subsequently, a profound one-by-one study of operating conditions was permitted to upscale the process without significant particle enlargement and pore deformation. To achieve this, the temperature was set to 60 °C and the CTAB to TEOS molar ratio to 8. The final runs were performed at pilot plant scale (5 L cylindrical reactor with temperature and stirring speed control) to analyze stirring speed, type of impeller, TEOS addition rate, and nanoparticle maturation time effects, confirming results at laboratory scale. Despite slight variations on the morphology of the nanoparticles, this methodology provided MSNs with adequate sizes and porosities for biomedical applications, regardless of the reactor/scale. The process was shown to be robust and reproducible using mild synthesis conditions (2 mL⋅min-1 TEOS addition rate, 400 rpm stirred by a Rushton turbine, 60 min maturation time, 60 °C, 2 g⋅L-1 CTAB, molar ratio TEOS/CTAB = 8), providing ca. 13 g of prismatic short mesoporous 100-200 nm nanorods with non-connected 3 nm parallel mesopores.