Synthesis Of MCM-41 Research Articles

Industrially compatible synthesis of MCM-41 with spatial organization at the macro-mesoscale

Nowadays industrial requirements point to high-performance processes but cost-effective materials to maximize their benefit/cost balance. This paper describes the properties of a macro-mesoporous MCM-41 silica with very high surface area obtained from inexpensive reagents —industrial sodium silicate as a source of silicon and industrial CTAC as template— with potential use in an environmental application such as CO2 capture. The MCM-41 silica exhibits an aperiodic 3D hierarchical spatial organization at the macro-mesoscale, formed by well-ordered MCM-41 particles with bowl-like mesopores. These particles are interconnected in three dimensions, creating a web-like structure that imparts macroporosity. This organization can be rationalized in terms of the nature and interaction of the reactants. Thus, the conjunction of poly (N-silicate) and features in CTAC, such as the weakly bonding counterion (Cl−), ethanol and unreacted amine, gave rise to different morphologies and variable channel lengths, porosity at different length scales producing meso/macro arrangements, and a spongy structure as a disordered minority phase. The hierarchical organization enhances the potential of the material for uniform APTS loading, thereby improving CO2 capture. Then the use of industrial reactants offers two important advantages: (i) The presence of macro-mesocavities, enabling applications requiring greater porosity than that intrinsic to MCM-41; (ii) A reduction in production costs by at least 80 % compared to traditional synthesis methods using alkoxysilanes and CTAB, and negligible costs compared to synthesis with analytical grade CTAC.In summary, this study demonstrates the synthesis of a hierarchically structured MCM-41 silica using cost-effective industrial reagents, offering a promising and economical solution for different applications.

Microwave synthesis of amino-functionalized MCM-41 from coal gasification fine slag for efficient bidirectional adsorption of anionic and cationic dyes

Coal based solid waste has been recognized as a sustainable raw material for the preparation of high added value materials for wastewater treatment. In this paper, a preparation route was designed for the rapid, efficient, and low-cost preparation of MCM-41 zeolite using coal gasification fine slag as raw material. Functionalization modification of MCM-41 was carried out by grafting amino groups on its surface to improve its application performance. Moreover, the prepared functionalized material is used for bidirectional adsorption of anionic and cationic dyes. The experimental results indicate that MCM-41 zeolite with highly ordered pore structure was rapidly prepared using the advantages of fast heating and strong permeability of microwave synthesis method, with a specific surface area of up to 862.03 m2/g. Amine functionalized MCM-41 exhibits strong adsorption capacity for both cationic and anionic dyes, with maximum adsorption capacities for methylene blue and Congo red being 292.40 mg/g and 354.61 mg/g, respectively. The study of adsorption kinetics and adsorption mechanism indicate that the adsorption process is mainly controlled through chemical adsorption, including electrostatic attraction, hydrogen bonding, and π-π interactions. The results of this study will provide useful references for the use of coal based solid waste to prepare functional materials for the treatment of organic wastewater.

Alternative Synthesis of MCM-41 Using Inexpensive Precursors for CO2 Capture

We explore the use of industrial sources of silicon and surfactant for obtaining low-cost MCM-41 materials and evaluate their performances as CO2 adsorbents. All of them presented a high specific surface area with different structural characteristics and textural properties. Interestingly, the MCM-41 manufactured with the most economical reagents presented a SBET of 1602 m2·g−1. The template was removed by using thermal treatments in an air atmosphere or a washing process. Preservation of silanol groups proved to be more effective under washing or mild thermal treatment conditions with the advantage of their lower cost and environmental benefit. Surface reactivity against CO2 was enhanced by anchoring APTS to silanol groups through wet grafting. All amino-functionalized materials showed a performance as CO2 adsorbents comparable to those reported in the literature, reaching values close to 30 cm3·g−1 at 25 °C and 760 mmHg. Samples with a higher concentration of silanol groups showed better performance. Our studies indicate that adsorbed CO2 is retained at least up to 50 °C, and the CO2 is chemisorbed on the silica modified with amine groups. The chemisorbed gas at very low pressures points to the potential use of these materials for CO2 storage.

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.

Impregnation of Fe<sup>3+</sup> into MCM-41 Pores: Effect of Fe<sup>3+</sup> Concentration on the Weight Percent of Fe-Frameworks and Fe-Non-Frameworks

Silica from rice husks (RH) has been used as a starting ingredient in the sonication synthesis of MCM-41 (RH-MCM-41). The impregnation of Fe3+ into RH-MCM-41 pores to produce RH-MCM-41 containing Fe2O3 and Fe (denoted as Fe2O3-Fe-RH-MCM-41) was carried out by examining the effect of various Fe3+ concentrations on the weight percent of Fe-frameworks (Fe3+ that replaces Si4+ in silicate frameworks) and Fe-non-frameworks, i.e., the iron oxide formed outside the silicate frameworks. Fe2O3-Fe-RH-MCM-41 was washed with a 0.01 M HCl solution to remove Fe-non-frameworks from the materials and give Fe-RH-MCM-41 containing Fe-frameworks. The Fe content in Fe2O3-Fe-RH-MCM-41 (Fe-total) and Fe-RH-MCM-41 (Fe-frameworks) for each sample was determined by an AAS (atomic absorption spectrometer), whereas the content of Fe-non-frameworks was calculated from the difference between Fe-total and Fe-frameworks. The XRD (X-ray diffraction) pattern, N2 adsorption-desorption isotherm profile, as well as the TEM (transmission electron microscope) image clearly demonstrate that the RH-MCM-41 exhibits an ordered p6mm hexagonal mesostructure with a large specific surface area and uniform pore size. Based on the weight percents of Fe-frameworks found in each sample, it is clear that the content of Fe-non-frameworks is significantly enhanced compared to that of Fe-frameworks when the more concentrated Fe3+ is used.

Synergistic Antimicrobial Activity of Magnetite and Vancomycin-Loaded Mesoporous Silica Embedded in Alginate Films

The aim of the present study was to obtain a hydrogel-based film as a carrier for the sustained and controlled release of vancomycin, an antibiotic commonly used in various types of infections. Considering the high-water solubility of vancomycin (>50 mg/mL) and the aqueous medium underlying the exudates, a prolonged release of vancomycin from an MCM-41 carrier was sought. The present work focused on the synthesis of malic acid coated magnetite (Fe3O4/malic) by co-precipitation, synthesis of MCM-41 by a sol-gel method and loading of MCM-41 with vancomycin, and their use in alginate films for wound dressing. The nanoparticles obtained were physically mixed and embedded in the alginate gel. Prior to incorporation, the nanoparticles were characterized by XRD, FT-IR and FT-Raman spectroscopy, TGA-DSC and DLS. The films were prepared by a simple casting method and were further cross-linked and examined for possible heterogeneities by means of FT-IR microscopy and SEM. The degree of swelling and the water vapor transmission rate were determined, considering their potential use as wound dressings. The obtained films show morpho-structural homogeneity, sustained release over 48 h and a strong synergistic enhancement of the antimicrobial activity as a consequence of the hybrid nature of these films. The antimicrobial efficacy was tested against S. aureus, two strains of E. faecalis (including vancomycin-resistant Enterococcus, VRE) and C. albicans. The incorporation of magnetite was also considered as an external triggering component in case the films were used as a magneto-responsive smart dressing to stimulate vancomycin diffusion.

Drug delivery with solvent-free synthesized polyimide-COF/amino-functionalized MCM-41 nanohybrid

The present study focuses on a covalent organic framework-based (COF) nanohybrid as a new drug delivery system for erythromycin (E) antibiotic with a desirable loading capacity and controlled release rate. Solvent-free synthesis of PI-COF (polyimide-COF) plus pre-synthesized amino-functionalized MCM-41 resulted in a nanohybrid structure of improved textural properties as a drug delivery system (DDS) with considerable biocompatibility. The environmentally friendly, economical, and ease-execution melting method was employed for erythromycin incorporation in DDS. Results represent an increased loading efficiency of the pure covalent organic framework (86.86%) and the nanohybrid mode (56.2%) DDSs compared to other parallel structures reported. The release studies of erythromycin were performed in a simulated body environment (phosphate buffer solution (PBS) medium, pH = 7.4) at 37 ± 1 °C. Furthermore, the antibiotic-loaded DDSs were investigated for antibacterial activity against Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa), and Staphylococcus aureus (S. aureus) strains. The [email protected] attained a prolonged and sustained drug release (a maximum release of 69.7% for 50 h) and displayed potent antibacterial activity against Staphylococcus aureus. Zero and First-order, Higuchi, Hixson-Crowell, and Korsmeyer-Peppas kinetic models were applied to describe the release profile of erythromycin. Fitting mathematical models to the experimental data indicated Fickian and non-Fickian diffusion kinetics for nanohybrid sample and individual monomers, respectively.

Rapid synthesis of MCM-41 and SBA-15 by microwave irradiation: promising adsorbents for CO2 adsorption

It is known that the world scenario is one of constant search for sustainable technologies that can reduce the emission of carbon dioxide (CO2) in the atmosphere. This is because CO2 is seen as the main responsible for the increase in the generation of greenhouse gases, which leads to global warming and climate change. The development of efficient adsorbents for CO2 capture is a current challenge. MCM-41 and SBA-15 were synthesized in a microwave reactor and used as adsorbents in this work. Microwave irradiation presents itself as an easy synthesis strategy with less preparation time and energy requirement. The silica synthesis period was extremely reduced (1 h) at a temperature of 60 and 80 °C in the microwave reactor, obtaining silica with good textural and chemical properties. The CO2 adsorption isotherms were performed at 0, 25, and 40 °C at 1 bar. The MCM-41 and SBA-15 present favorable results for CO2 capture processes, showing that pure silica synthesized by microwave already obtains promising results, reaching a maximum adsorption capacity of 2.16 mmol g−1 (1 bar—0 °C) and a good fit for the Langmuir, DsL and Toth models. Furthermore, to increase CO2 adsorption, the mesoporous silica was also modified via impregnation with branched polyethylene diamine (PEI) or tetraethylenepentamine (TEPA). It is worth mentioning that microwave irradiation reduced the synthesis steps and improved the properties and adsorption capacity of the silica. This work opens new opportunities in the efficient preparation of materials that require optimizing the adsorbent synthesis process.Graphical CO2 adsorption capacity of MCM-41 and SBA-15 prepared by rapid synthesis using microwave irradiation and amino functionalized.

Synthesis of MCM-48 contains NaCl and Surfactant as Catalyst in the Esterification of Nyamplung Oil (Calophyllum inophyllum L.) to Biodiesel

Synthesis of MCM-48 contains NaCl and Surfactant as Catalyst in the Esterification of Nyamplung Oil (Calophyllum inophyllum L.) to Biodiesel

Selectivity of the New Catalyst ZnO-MCM-48-CaO in Esterification of Calophyllum inophyllum Oil

The synthesis of MCM-48 containing surfactants (CTAB and Triton X-100), ZnO, and CaO aimed to find a potential heterogeneous catalyst in the esterification of Calophyllum inophyllum oil to biodiesel. This research is important in the production of biodiesel from vegetable oils with more than 2% free fatty acids (FFA), such as Calophyllum inophyllum oil using heterogeneous catalysts. Synthesis of heterogeneous catalysts, MCM-48 and ZnO-MCM-48-CaO (ZMC), using the hydrothermal method at various calcination temperatures was conducted to find the optimum calcination temperature for the reaction. The activity of the catalyst in the reaction was determined using acid-base titration methods and GC-MS. The MCM-48 catalyst calcined at 650 °C (MCM-48/650) had a catalytic activity of 35.74% and was selective for converting linoleic acid in Calophyllum inophyllum oil to biodiesel. In addition, this catalyst was also capable of cracking the compounds contained in Calophyllum inophyllum oil into suitable hydrocarbons for biodiesel. In the esterification of vegetable oils, four heterogeneous catalysts (MCM-48/550, ZMC/550, ZMC/650, and ZMC/750) had the potential to replace conventional catalysts (H2SO4), particularly in the generation of biodiesel from Calophyllum inophyllum oil.

Synthesis of Rice Husk-Based MCM-41 for Removal of Aflatoxin B1 from Peanut Oil.

Edible oils, especially peanut oil, usually contain aflatoxin B1 (AFB1) at extremely high concentrations. This study focused on the synthesis of rice husk-based mesoporous silica (MCM-41) for the removal of AFB1 from peanut oil. MCM-41 was characterized by X-ray diffraction, N2 physisorption, and transmission electron microscope. MCM-41 was shown to have ordered channels with high specific surface area (1246 m2/g), pore volume (1.75 cm3/g), and pore diameter (3.11 nm). Under the optimal concentration of 1.0 mg/mL of the adsorbent dose, the adsorption behavior of MCM-41, natural montmorillonite (MONT), and commercial activated carbon (CA) for AFB1 were compared. The adsorption of AFB1 in peanut oil onto the three adsorbents was slower compared to that of AFB1 in an aqueous solution. In addition, the pseudo-second-order kinetic model better fit the adsorption kinetics of AFB1, while the adsorption mechanism followed the Langmuir adsorption isotherm on the three adsorbents. The calculated maximum adsorbed amounts of AFB1 on MONT, MCM-41, and CA were 199.41, 215.93, and 248.93 ng/mg, respectively. These results suggested that MCM-41 without modification could meet market demand and could be considered a good candidate for the removal of AFB1 from peanut oil. This study provides insights that could prove to be of economic and practical value.

Externally Silylated RH-MCM-48 from Rice Husk Silica with Superparamagnetic Iron Oxide for Multifunctional Applications

Rice husk silica has been used as a raw material for the sonochemical synthesis of MCM-48 (RH-MCM-48). Silylation on the outer surface of RH-MCM-48 using trimethylchlorosilane before removal of the template to prevent the formation of iron oxide in the outer of RH-MCM-48. The impregnation of Fe3+ into the externally silylated-RH-MCM-48 porous system was done by optimizing the concentration of Fe3+, contact time and temperature. The XRD pattern, N2 adsorption/desorption isotherms and TEM images showed that RH-MCM-48 has an ordered Ia3d cubic mesostructure with high specific surface area and narrow porous size distribution. FTIR spectra confirmed the successful implementation of external silylation. Moreover, DR-UV-vis spectra, EPR spectra and magnetization curve show that the impregnation of Fe3+ into the externally silylated-RH-MCM-48 pores produce a superparamagnetic iron oxide nanoparticles formed inside the pores and induces partial isomorphic substitution of Si4+ by Fe3+ on the wall pores.

Green Synthesis for MCM-41 and SBA-15 Silica Using the Waste Mother Liquor

In an attempt to synthesize silicas with respect to green chemistry, the synthesis of MCM-41 and SBA-15 silicas by a low-cost approach through the recycling of waste mother liquors was investigated. The addition of the mother liquor in consecutive syntheses was carried out in order to evaluate the different effects on the physical and chemical properties of the silicas. MCM-41 silicas were characterized by X-ray diffraction, which confirmed the formation of the hexagonal phase in the mother liquor used. According to the results of XRD, BET and SEM, SBA-15 silica has a structure that includes mesopores of various levels, crystallites and grains within the original particles. From the analysis of the textural characteristics of the various samples obtained through nitrogen adsorption/desorption studies carried out at -196 °C, the following conclusions can be highlighted: (i) For the synthesis of MCM-41, there was a trend of increase in specific surface areas, reduction in pore diameter and increase in wall thickness; (ii) For the synthesis of SBA-15 there was an increase in the specific surface area, an increase in the pore diameter and a reduction in the wall thickness. It was found that, under the synthesis conditions, the mother liquor user had an influence on the final characteristics of these materials.

Green synthesis of MCM-41 derived from renewable biomass and construction of VOx-Modified nickel phyllosilicate catalyst for CO2 methanation

In order to achieve green synthesis of MCM-41 and address the sintering problem of Ni-based catalyst supported on silica material, MCM-41 with regular spherical morphology was prepared using sodium silicate extracted from renewable equisetum fluviatile as silicon source, and then a group of nickel phyllosilicates were synthesized via the reaction of MCM-41 sphere and nickel nitrate under hydrothermal condition. Much denser nanosheets corresponding to lamellar nickel phyllosilicate were formed on the surface of MCM-41 sphere with the raise of hydrothermal temperature in the range of 180–220 °C, resulting in the nickel content varying from 17.2 to 41.8 wt%. Fine Ni particles with size smaller than 6 nm could be obtained on the 750oC-reduced catalyst owing to the strong nickel-silica interaction derived from Ni-phyllosilicate. After the addition of V2O5 promoter, Ni particle size was further reduced to around 4.5 nm at high Ni loading above 30 wt%. Vanadium species was in the mixed valence state of V(III), V(IV) and V(V) after reduction, which increased the electron cloud density of Ni0, resulting in high catalytic activity of the VOx-modified Ni-phyllosilicate catalyst for CO2 methanation. In a 100 h-400oC-lifetime test and 600 °C-steam hydrothermal treatment, the VOx-modified Ni-phyllosilicate catalyst also showed high long-term stability, excellent sintering resistance of metallic nickel particles and high hydrothermal stability due to the strong surface confinement effect of nickel phyllosilicate and promotion of VOx species. In all, this work provided a green synthesis of MCM-41 as well as an efficient Ni/SiO2 catalyst derived from nickel phyllosilicate for CO2 methanation.

Effects of acid ionization on the formation mechanism of bimodal mesoporous Al-MCM-41s from coal gasification fine residue and evaluation of adsorption capabilities

The development of synthetic methods to obtain high value-added mesoporous Al-MCM-41 from a low-cost silicon-aluminum source with low toxicity is an active research topic in solid waste resource utilization. In particular, the controlled synthesis of MCM-41 with a two-level pore distribution is a challenging task. In this work, the synthesis of unimodal and bimodal mesoporous Al-MCM-41s was achieved using acids with different degrees of ionization from coal gasification fine residue (CGFR) as bulk solid waste generated by the coal gasification process. We determined that the degree of acid ionization affected the self-assembly of inorganic/organic species as well as condensation processes, resulting in some changes of the hexagonal mesoscopic structure. The unimodal mesoporous Al-MCM-41 with acetic acid HAc and bimodal mesoporous Al-MCM-41s with an inorganic acid environment (HCl, HNO3 or H2SO4) could be effectively prepared in a controllable manner by the silicon and aluminum source obtained at alkali dissolution time 6 h and crystallization conditions at pH 10.5 and 383 K in 72 h. Moreover, the synthesis of Al-MCM-41-HAc with different SiO2/Al2O3 molar ratios (18–89) could also be realized by different alkali dissolution times. And alkali dissolution time (2–24 h) and the crystallization conditions (pH 4.5–11.5, temperatures 373–393 K, and time 48–96 h) also affected the formation of unimodal and bimodal mesoporous Al-MCM-41-HAc. In addition, the maximum adsorption amount onto bimodal mesoporous Al-MCM-41-H2SO4 (476.19 mg g−1 at 308 K) was larger than that onto unimodal mesoporous Al-MCM-41-HAc (243.90 mg g−1 at 303 K). The mesoporous Al-MCM-41s showed good stability.

Synthesis, Characterization and Performance Evaluation of Pure Silica MCM-41 for Effective Removal of Dibenzothiophene from Petroleum Distillate

The presence of sulfur-containing compound (e.g. Dibenzothiophene, DBT) in petroleum distillates such as diesel is of great concern due to the environmental problems it poses on the environment. In this study, synthesis and performance evaluation of MCM-41 adsorbent for enhanced removal of DBT from petroleum distillates in batch adsorption mode is reported. MCM-41, employed in this study for adsorptive desulphurization, was successfully synthesized with Cetyltrimethylammonium bromide (C19H42BrN) and fumed silica (SiO2). The gel was stirred for 30 min at room temperature and allowed to age at varied durations ( 24 h, 48 h & 72 h) before hydrothermal synthesis and then calcined at 550 C. Different analytical techniques were used to characterize the synthesized adsorbents, such as; Fourier transform infrared (FTIR) to check the surface nature, N2 physi-sorption at 77 K to examine the textural property; Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) equipped with Energy Dispersive X-ray (EDX) to check the surface morphology/elemental composition; and X-ray diffraction (XRD) to check the crystallinity of the adsorbent. The adsorptive desulphurization experiments were carried out using a model diesel prepared by dissolving 0.1 g of dibenzothiophene in 100 mL of hexane. The desulfurized model diesel was analyzed using Gas Chromatography/Mass Spectrometer (GC/MS). The adsorption performance of each adsorbent was evaluated in a batch mode. The results showed that, aging time has significant impact on the crystallinity and textural properties of MCM-41. The results show that crystallinity increased with decreasing aging period with smaller surface area as compared to adsorbent whose gel was aged for more hours. Furthermore, the textural properties seem to improve as the aging time increased. MCM-41, whose gel was aged for 72 h showed the highest adsorption capacity of 36.2 mg/g with highest DBT removal of 96.5 %. The information and results presented in this study could therefore provide a platform for further studies in this field.

Synthesis of MCM-41 supported cobalt (II) complex for the formation of polyhydroquinoline derivatives

A new and green heterogeneous MCM-41@PDCA-Co catalyst has been prepared via immobilization of cobalt (II) complex onto the surface of MCM-41. This was characterized by different techniques such as FT-IR, TEM, TGA, low angle Powder XRD, MP-AES and nitrogen sorption. The MCM-41@PDCA-Co has been applied in the synthesis of polyhydroquinoline (PHQs) and its derivatives in 98% yield which is four component reaction under solvent free condition at 100 °C. The synthesized catalyst can be easily recovered from the reaction mixture by simple filtration method. This can be reused several times without any significant loss in stability and activity.

Study on the Effect of Different Template Agents on the Synthesis of MCM-48 Molecular Sieves

At present, most of molecular sieves (MCM-48) are prepared by using dual template agents. In this paper, the effect of different template agents on the synthesis of MCM-48 under the same conditions is studied. MCM-48 was synthesized by different combinations of templates (CTAB + TEAOH, CTAB + TBAB, CTAB + P123). The specific surface areas of them were compared under different crystallization temperature and different crystallization time. The results show that the specific surface area of MCM-48 prepared by CTAB + TEAOH is higher than that of other dual template agnets at the same crystallization time and temperature when the molar ratio of CTAB to another template is 9.

Efficient removal of chromate ions from aqueous solution using a highly cost-effective ferric coordinated [3-(2-aminoethylamino)propyl]trimethoxysilane-MCM-41 adsorbent.

The present investigation involves synthesis and characterization of MCM-41–AEAPTMS–Fe(iii)Cl using coordinated Fe(iii) on MCM-41–AEAPTMS for efficient removal of hazardous Cr(vi) ions from aqueous solution. The adsorbent MCM-41–AEAPTMS–Fe(iii)Cl was characterized using small-angle X-ray diffraction (SAX), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier-transform infrared (FT-IR) and Brunauer–Emmett–Teller (BET) surface analyzer techniques. The BET surface area was found to be 87.598 m2 g−1. The MCM-41–AEAPTMS–Fe(iii)Cl effectively adsorbs Cr(vi) with an adsorption capacity acquiring the maximum value of 84.9 mg g−1 at pH 3 at 298 K. The data followed pseudo-second-order kinetics and obeyed the Langmuir isotherm model. The thermodynamic data proved the exothermic and spontaneous nature of Cr(vi) ion adsorption on MCM-41–AEAPTMS–Fe(iii). Further, the higher value of ΔH° (−64.339 kJ mol−1) indicated that the adsorption was chemisorption in nature.

Aminopropyltriethoxysilane functionalized MCM-41 and SBA-15 nanostructured materials for carbon dioxide adsorption

The design of effective CO2 capture materials is a current challenge. Here, we report the synthesis of aminosilanes-functionalized MCM-41 and SBA-15 materials with high efficiency toward carbon dioxide adsorption. The functionalization of the mesoporous silicas involves a post-synthesis method by impregnation with 3-aminopropyltriethoxysilane. The carbon dioxide adsorption capacities for the samples were carried out under ambient pressures. The results evidenced that aminosilanes with a terminal amine were functionalized through covalent coupling of this group onto the channels' surface in the ordered mesoporous silica. It means that the amine is anchored on the surface of the largest pores of the MCM-41 and SBA-15 supports. The Lagergren kinetic model evidenced the enhanced carbon dioxide adsorption capacity and stability of the functionalized ordered mesoporous molecular sieves.