Amine-functionalized MCM-41 Research Articles

Design of Nanostraws in Amine-Functionalized MCM-41 for Improved Adsorption Capacity in Carbon Capture.

Polymeric amine encapsulation in high surface area MCM-41 particles for CO2 capture is well established but has the drawback of leaching out the water-soluble polymer upon exposure to aqueous environments. Alternatively, chemical (covalent) grafting amine functional groups from an alkoxysilane such as 3-aminopropyltriethoxysilane (APTES) on MCM-41 offer better stability against this drawback. However, the diffusional restriction exhibited by the narrow uniform MCM-41 pores (2-4 nm) may impede amine functionalization of the available silanol groups within the inner mesoporous core. This leads to incomplete amine functionalization and could reduce the CO2 adsorption capacity in such materials. Our concept to improve access to the MCM-41 interior is based on the incorporation of nanostraws with larger inner diameter (15-30 nm) to create a hierarchical porosity and enhance the molecular transport of APTES. Halloysite nanotubes (HNT) are used as tubular straws that are integrated into the MCM-41 matrix using an aerosol-assisted synthesis method. Characterization results show that the intrinsic structure of MCM-41 remains unaltered after the incorporation of the nanostraws and amine functionalization. At an optimal APTES loading of 0.5 g (X = 2.0), the amine-functionalized composite of MCM-41 with straws (APTES/M40H) has a 20% higher adsorption capacity than the amine-modified MCM-41 (APTES/MCM-41) adsorbent. Furthermore, the CO2 adsorption capacity APTES/M40H doubles that of APTES/MCM-41 when normalized based on the composition of MCM-41 in the composite particle with straws. The facile integration of nanostraws in MCM-41 leading to hierarchical porosities could be effective toward the mitigation of diffusional restriction in porous materials with potential for other catalytic and adsorption technologies.

High-density amine-functionalized MCM-41 derived from pumice: facile synthesis and antibiotic adsorption

High-density amine-functionalized MCM-41 derived from pumice: facile synthesis and antibiotic adsorption

Sterically hindered amine-functionalized MCM-41 composite for efficient carbon dioxide capture

Sterically hindered amine-functionalized MCM-41 composite for efficient carbon dioxide capture

Amine-functionalized MCM-41 as an efficient catalyst for the synthesis of sulfur/dinitrogen-fused heterocycles via [3+3] cycloaddition in water

The sulfur/dinitrogen-containing heterocycle is an important chemical motif and is found widely in natural products, drug molecules, catalysts and functional materials.

Performance of CO2 adsorption by hybrid amine-functionalized MCM-41

Performance of CO2 adsorption by hybrid amine-functionalized MCM-41

Influence of surfactant on CO2 adsorption of amine-functionalized MCM-41

ABSTRACT Concerning the increasing greenhouse effect, the development of efficient CO2 adsorbents is very important. In this study, the influence of surfactant on the adsorption performance of amine-functionalized MCM-41 was analysed. The results showed that the residual amount of surfactant in MCM-41 was gradually decreased with the increase of calcination temperature which improved the pore structure. The maximum adsorption capacity (5.495 mmol/g) appeared at PEI-MCM-41-100°C indicated that the adsorption capacity could be improved under the function of surfactant. By calculating the diffusion coefficient of CO2 adsorption process in PEI-MCM-41-100/200/300/400/550°C, the diffusion resistance of CO2 was the lowest in PEI-MCM-41-100°C, which directly proved that the synergism of surfactant and organic amine could reduce the diffusion resistance of CO2 in the pore.

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.

Hydroxylation of benzene to phenol over heteropoly acid H5PMo10V2O40 supported on amine-functionalized MCM-41.

Supported catalysts with Keggin type heteropoly acids (H5PMo10V2O40) loaded onto amine-functionalized MCM-41 for the catalytic hydroxylation of benzene to phenol with H2O2 were prepared by a wet impregnation method. The effects of the preparation conditions on the properties and activity of the supported catalysts were fully investigated. The results showed that the catalyst retained the mesoporous structure of MCM-41 and H5PMo10V2O40 was dispersed uniformly on the surface of the amine-functionalized MCM-41. Meanwhile, the reusability and catalytic performance of the catalyst were affected by two key factors, i.e., the interaction between the heteropoly acid and the surface of MCM-41, and the hydrophobicity of the catalyst since they decide the leaching of H5PMo10V2O40 and the adsorption of benzene. The catalyst with H5PMo10V2O40 loaded onto amine-functionalized MCM-41, which was prepared using ethanol as the solvent, exhibited the highest phenol yield (20.4%), a turnover frequency value of 20.3 h−1 and good reusability. We believe this work offers an effective and facile strategy for the preparation of a new catalyst for hydroxylation of benzene to phenol.

Preparation and Characterization of Novel Hybrid Nanomaterial Catalyst MCM-41@AzaCrown-SB-cu and its Application in Synthesis of Hexahydroquinoline Derivatives under Solvent-Free Conditions

Synthesis of efficient and reusable catalyst was carried out by immobilizing azacrown ether onto the covalently linked amine-functionalized mesoporous MCM-41 via a simple method. Application of this linked azacrown ether functionalized MCM-41 catalyst was also investigated as an effective, heterogeneous in the synthesis of hexahydroquinoline derivatives under solvent-free conditions at environment temperature. The heterogeneous catalyst is characterized by TGA, XRD, TEM, 1HNMR, 13CNMR, and FT-IR techniques. The results of theses analysis showed that, MCM-41@azacrown-SB-Cu catalyst with a 22.99% mol loading of copper has given excellent catalytic activity and high efficiency in a short time. It is noted that one of the most valuable factors in this work is the recyclability of the catalyst.

Preparation and characterization of novel hybrid nanomaterial catalyst MCM-41@AzaCrown-SB-Cu and its application in synthesis of 1, 2, 3-triazole derivatives in click chemistry

Synthesis of efficient and reusable catalyst was carried out by immobilization of azacrown ether onto the covalently linked amine-functionalized mesoporous MCM-41 via a simple method. Application of this linked azacrown ether functionalized MCM-41 catalyst was also investigated as an effective, heterogeneous and host material in the regioselective ring opening and triazole cyclization of epoxides by phenylacetylene and sodiumazide in click reaction. The heterogeneous catalyst was characterized by TGA,XRD,TEM, 1HNMR, 13CNMR and FT-IR techniques. The results of theses analysis showed that, MCM-41@azacrown-Cu with a 22.99% mol loading of copper has given excellent catalytic activity and high efficiency in short time. It is noted that one of the most valuable factors in this work is the recyclability of the catalyst.

A high-permeance organic solvent nanofiltration membrane via covalently bonding mesoporous MCM-41 with polyimide

A high permeance is corresponding to a low membrane area and a reduced capital investment in the organic solvent nanofiltration (OSN) process. Currently, to increase the permeance, only a few microporous fillers were utilized to prepare the mixed matrix membranes (MMMs). In this study, MCM-41, a typical mesoporous filler, was selected and doped into a polyimide (PI) matrix, aiming to increase the solvent permeance of the MMMs. To break the trade-off between permeance and rejection, a covalent bridge between amine-functionalized MCM-41 (NH2-MCM-41) and PI was constructed so as to avoid forming the non-selective interfacial voids in the filler-polymer interface. As a result, the water, ethanol and isopropanol permeances of 5 wt% NH2-MCM-41/PI MMM were increased by 102%, 78% and 131% compared with pure PI membrane, without obvious reductions of rejections. Overall, the NH2-MCM-41/PI MMM shows its great potential in high-efficiency organic solvent nanofiltration in practical applications.

Synthesis and characterization of copper (II)-poly(acrylic acid)/M-MCM-41 nanocomposite as a novel mesoporous solid acid catalyst for the one-pot synthesis of polyhydroquinoline derivatives

In this study, a novel mesoporous silica nanocomposite (MSNC) based on poly(acrylic acid) and amine-functionalized MCM-41 mesoporous silica as amplification agents was constructed via an ultrasonic-assisted method as a straightforward, fast, eco-friendly and it is denoted as M-MCM-41. Then Cu (II) was immobilized on PAA/M-MCM-41 surface and the novel heterogeneous reusable catalyst was fully characterized using appropriate techniques such as Fourier transform infrared (FT-IR), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), field emission scanning electron microscopy (FE-SEM), thermogravimetry analysis (TGA) and N2 adsorption–desorption. The resulting catalyst was successfully used for the condensation of various aromatic aldehydes, dimedone, ß-ketoester and ammonium acetate under solvent-free and mild conditions to yield polyhydroquinoline derivatives in good to excellent yields. Also, the experimental evidence was demonstrated that Cu (II)-PAA/M-MCM-41 nanocomposite could act as a recoverable and reusable nanocatalyst without a meaningful drop in the yield and the reaction time at least four times.

CO2 capture over amine-functionalized MCM-41 and SBA-15: Exploratory analysis and decision tree classification of past data

This study aims to extract knowledge for CO2 capture by amine-functionalized mesoporous silica (MCM-41 and SBA-15) through exploratory analysis and decision tree classification of the data reported in over 100 papers published between the years 2002 and 2017. A database containing 1039 data points showing the effects of 15 input variables (grouped in four as support properties, preparation method, amine properties and operational variables) over two performance variables as CO2 adsorption capacity and amine efficiency (CO2 captured/amino groups involved) was constructed. Box and whisker plots were applied (as a part of exploratory data analysis) to determine how various input variables influence the performance variables. Moreover, decision tree classification was used to determine the relative significance of the input variables and the possible combinations of these variables leading to high performance (to deduce heuristics for high CO2 uptake). It was found from the exploratory data analysis that amine density was the most significant variable affecting the adsorption capacity whereas remaining pore volume and adsorption temperature were the most influential variables in case of amine efficiency. Furthermore, various combinations of input variables leading to high CO2 capture performance were revealed through the decision tree analysis, all of which may be used as guidelines for future studies in this area.

Fast and Sensitive Detection of Salmonella in Milk Samples Using Aptamer-Functionalized Magnetic Silica Solid Phase and MCM-41-Aptamer Gate System.

General detection methods for S. enterica include PCR analysis, immunologic methods, solid culturing techniques, and various microscopic studies. Milk and other food samples demonstrate an especially difficult challenge for direct detection, resulting from high biological contents. In this report, we aimed for fast detection of pathogen cells through an efficient magnetic capture and subsequent quick detection based on aptamer affinity. The Fe3O4@SiO2@pGMA and MCM-41 particles were prepared separately and used for preconcentration and detection, respectively. Aptamer oligonucleotide sequences against S. enterica were fixed on both amine-functionalized MCM-41 and Fe3O4@SiO2@pGMA particles via glutaraldehyde coupling. The captured Salmonella cells were determined by a fluorescent homogeneous assay in the samples by aptamer-gated MCM-41 silica particles. Our method achieved a sensitive assay to detect Salmonella cells in milk samples as low as 103 CFU/ml without any culturing. Hence, the proposed sensing strategy might be an efficient platform for pathogen detection in a food matrix.

CO2 Adsorption by Amine-Functionalized MCM-41: A Comparison between Impregnation and Grafting Modification Methods

Modifications by impregnation and grafting are commonly used for the preparation of amine-functionalized MCM-41. A comprehensive evaluation of the advantages and disadvantages of the two methods was performed in this work. MCM-41 was synthesized by the hydrothermal method, setting the amine-loading mass fraction at 40, 50, and 60 wt %. Three amine-modified adsorbents were prepared by impregnating polyethylenimine (PEI), and the three other adsorbents were prepared by grafting 3-aminopropyltriethoxysilane (APTS) onto MCM-41. The as-prepared adsorbents were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and N2 adsorption–desorption techniques. CO2 adsorption capacities were measured, and the experimental data were fitted with adsorption kinetic models. The cyclic stability of the adsorbents prepared by the two kinds of amine-modified methods was compared using the cyclic adsorption–desorption experiments. The characteriz...

Study on thermal, mechanical and adsorption properties of amine-functionalized MCM-41/PMMA and MCM-41/PS nanocomposites prepared by ultrasonic irradiation

In this study, two common industrial polymers, poly(methyl methacrylate) (PMMA) and polystyrene (PS), were incorporated into amine-functionalized MCM-41 mesoporous silica as reinforcement agents via an ultrasonic assisted method as a facile, fast, eco-friendly, and versatile synthetic tool. Amino functionalization of MCM-41 were performed by 3-aminopropyl triethoxysilane as a coupling agent and it is denoted as APTS-MCM-41. The obtained nanocomposites (NCs), APTS-MCM-41/PMMA and APTS-MCM-41/PS, were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning and transmission electron microscopies (SEM and TEM), and thermogravimetric analysis (TGA). Their mechanical properties were also probed via stress–strain curves and improved tensile properties were observed in the NCs relative to the neat polymers. Additionally, APTS-MCM-41/PMMA exhibited better mechanical properties than APTS-MCM-41/PS. Sorption studies were carried out on the two NCs and the effect of different process parameters, namely, pH, contact time, and initial Cd(II) concentration investigated in batch mode. Pseudo-second order and intraparticle diffusion models explain the Cd(II) kinetics more effectively for APTS-MCM-41/PMMA and APTS-MCM-41/PS, respectively. The adsorption isotherm data fitted well to Langmuir isotherm for both NCs and the maximum monolayer adsorption capacities were found to be 24.75mg/g and 10.42mg/g for APTS-MCM-41/PMMA and APTS-MCM-41/PS, respectively. The results demonstrate that the NCs show potential for use in adsorption of heavy metal ion such as Cd(II) from aqueous media.

Application of amine-functionalized MCM-41 as pH-sensitive nano container for controlled release of 2-mercaptobenzoxazole corrosion inhibitor

In the present study, a pH-responsive corrosion inhibitor system is designed based on aminopropylated MCM-41 as nanocontainer and 2-mercaptobenzoxazole (MBOH) as anti-corrosion agent. This hybrid material shows long-term inhibition capability in 3.5wt% NaCl solution for Cu and stainless steel. The pH-sensitive composite was prepared via grafting the aminopropyl groups to the surface of mesoporous MCM-41 followed by loading of anti-corrosion agent. The XRD, FT-IR, BET, TGA, TEM, and SEM techniques were used to study the morphological and structural properties of the nanocontainer. The loading and releasing properties of nanocontainer were studied using UV–Visible spectroscopy. The results demonstrate that the minimum release rate of MBOH occurs in neutral condition and that with increase of acidity or basicity of the media, the release rate of the corrosion inhibitor from mesoporous silica increases. The self-healing property of nanocontainer was evaluated by electrochemical impedance spectroscopy (EIS). The results of the approach in this paper can be used in many applications where active corrosion protection of materials is required.

Synthesis of amine-functionalized MCM-41 and its highly efficient sorption of U(VI)

Herein, the amine-functionalized MCM-41 mesoporous silica (denoted as MCM-41-NH2) was synthesized and applied to adsorption and recovery U(VI) ions from aqueous solutions. The results showed that the sorption of U(VI) on MCM-41-NH2 was strongly dependent on pH and ionic strength. The sorption was mainly dominated by outer-sphere surface complexation and the sorption equilibrium can be reached within 60 min. The maximum sorption capacity of MCM-41-NH2 for U(VI) was calculated to be 386.98 mg g−1 at pH 5.60, much higher than that of the other reported materials.

Heteropolyacids anchored on amino-functionalized MCM-41 and SBA-15 and its application to the ethanol conversion reaction

A series of heteropolyacids (HPA)–silica composites were prepared from H3PMo12O40 (HPM) and H4PVMo11O40 (HPVM) by chemically anchoring to the amine-functionalized mesoporous MCM-41 and SBA-15. These composites were characterized by FT-IR, XRD, N2 adsorption, SEM, and TEM for their structural integrity and physicochemical properties. The effect of the support on thermal stability was investigated by TG–DTG and DTA. The evolved gases during the thermal analysis of prepared composites were identified by online mass spectrometry coupled with TG technique. It was evidenced that HPAs species were finely dispersed on amine-functionalized molecular sieves via chemical immobilization and the structure of the HPAs is preserved over mesoporous materials. From thermal analysis of HPA–silica composites was observed an important mass loss above 553 K which is due to the decomposition of amino propyl functional group. For this reason prepared composites can be utilized as dispersed catalysts for the reactions performed below 553 K. Catalytic properties of these composites were studied by using ethanol conversion at different temperatures. The HPA supported on molecular sieves exhibited an enhanced oxidation catalytic activity (formation of acetaldehyde) and a lower acid catalytic activity (formation of ethylene and diethyl ether) compared to the parent catalysts. The favorable effect of HPAs deposition on silica supports for oxidehydrogenation pathway to acetaldehyde results from the examination of and reaction rate values. For all reaction temperatures, the reaction rates of acetaldehyde formation are higher for supported samples than unsupported ones.

Optimization of Nitrate Removal from Aqueous Solution by Amine-functionalized MCM-41 Using Response Surface Methodology

In this study, response surface methodology (RSM) was used to optimize the experimental conditions in nitrate removal processes using 20% AEPTMS amine-functionalized MCM-41 as the adsorbent. The adsorbent was synthesized via co-condensation method and then characterized by using scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). Subsequently, total 19 adsorption experiments with different experimental conditions generated by the Design of Experiments (DoE) software have been conducted. The experimental results were fitted well with the quadratic model suggested by the software and the R2 value obtained was 0.9935. It was found that the highest percentage removal of nitrate was 70% obtained at initial nitrate concentration of 0.25 mM, adsorbent dosage of 0.50 g and contact time of 1 h. On the other hand, the optimum nitrate removal of 56% was obtained at the optimum conditions suggested by the software, with the initial nitrate concentration of 0.25 mM, adsorbent dosage of 0.124 g, and contact time of 1 h.