Mesoporous MCM-41 Research Articles

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.

4-Dimethylaminopyridine grafted on MCM-41 as an efficient and highly stable catalyst for the production of α-tocopherol acetate

N,N′-dimethyl-N-(4-pyridyl)-1,2-ethanediamine (DMPE) as a special N-alkylation precursor of 4-dimethylaminopyridine (DMAP) was grafted on the surface of γ-chloropropylated functionalized mesoporous silica MCM-41 to prepare immobilized DMAP. Characterization results of small angle X-ray diffraction, thermogravimetry and derivative thermogravimetry, Fourier transform infrared, scanning electron microscopy, energy-dispersive X-ray and transmission electron microscopy indicated that DMAP was successfully covalently bound to the surface of MCM-41. The highest loading of DMAP reached 0.9 mmol/g, which was 2.5 times higher than that of DMAP immobilized on the normal silica gel. The prepared immobilized DMAP as nucleophilic heterogeneous catalysts was successfully used for the acetylation reaction to produce α-tocopherol acetate. The highest yield reached 90.1% under the optimal condition which was summarized as follows: immobilized DMAP 100 mg, substrates mole ratio (acetic anhydride/α-tocopherol) 3:1, reaction temperature 50 ℃, stirring intensity 500 rpm, reaction in toluene for 12 h. The recyclability and stability of the DMAP grafted MCM-41 were excellent, as demonstrated by its use 20 times during batch operation without any loss of productivity.

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.

Light olefin production using the mixture of HZSM-5/MCM-41 and γ-Al2O3 as catalysts for catalytic pyrolysis of waste tires

In this paper, micro-mesoporous HZSM-5/MCM-41 zeolites were prepared by a two-step hydrothermal method using commercial HZSM-5 with two different silica/alumina ratios (38 and 50) as starting materials. The structures, morphologies and acidity of as-prepared zeolites were analyzed using XRD, FT-IR, SEM, N2-adsorption/desorption and NH3-TPD. The HZSM-5/MCM-41 zeolites combined the acidity of microporous HZSM-5 with the pore advantages of mesoporous MCM-41. Mesopores and microspores of 3.34 and 0.95 nm in diameter were found to be present in HZSM-5/MCM-41 zeolites. When they were used to catalyze the pyrolysis of waste tires, the selectivity of light olefins for HZSM-5/MCM-41 prepared using HZSM-5 with the silica/alumina ratio of 50 as starting materials was 21.42%, higher than 18.43% of HZSM-5/MCM-41 synthesized using HZSM-5 with the silica/alumina ratio of 38. In order to further overcome the pore size constraints and mass transfer limitations of HZSM- -5/MCM-41 zeolites for catalyzing pyrolysis of waste tires, macroporous ?-Al2O3 were mixed with HZSM-5/MCM-41 and used as catalysts. The selectivity to light olefins for the mixture of ?-Al2O3 and HZSM-5/MCM-41 prepared using HZSM-5 with the silica/alumina ratio of 50 as starting materials was 33.65%, which was obviously enhanced by the introduction of ?-Al2O3.

CO2 from waste to resource by developing novel mixed matrix membranes.

Mixed matrix membranes (MMMs) were fabricated by the hydrothermal synthesis of ordered mesoporous KIT-6 type silica and incorporating in polyimide (P84). KIT-6 and MMMs were characterized to evaluate morphology, thermal stability, surface area, pore volume, and other characteristics. SEM images of synthesized MMMs and permeation data of CO2 suggested homogenous dispersion of mesoporous fillers and their adherence to the polymer matrix. The addition of KIT-6 to polymer matrix improved the permeability of CO2 due to the increase in diffusivity through porous particles. The permeability was 3.2 times higher at 30% loading of filler. However, selectivity showed a slight decrease with the increase in filler loadings. The comparison of gas permeation results of KIT-6 with the well-known MCM-41 revealed that KIT-6 based MMMs showed 14% higher permeability than that of MMMs composed of mesoporous MCM-41. The practical commercial viability of synthesized membranes was examined under different operating temperatures and mixed gas feeds. Mesoporous KIT-6 silica is an attractive additive for gas permeability enhancement without compromising the selectivity of MMMs. Graphical abstract.

Hydrothermal Synthesis of a Novel Mesoporous Silica Fluorescence Carbon Dots and Application in Cr(VI) and Folic Acid Detection

Highly blue fluorescence carbon dots (CDs-MCM) were successfully prepared via a simple hydrothermal method with citric acid and ethylene diamine tetraacetic acid doped mesoporous silica MCM-41. The CDs-MCM exhibited uniform particle size and possessed good excitation-dependent characteristic. It showed highly selectivity and sensitivity in detection of Cr(VI), folic acid and good linear ranges of 0–37.5[Formula: see text][Formula: see text]M ([Formula: see text]) and 0–50[Formula: see text][Formula: see text]M ([Formula: see text]). The low detection limits were 79.31[Formula: see text]nM and 118.73[Formula: see text]nM for Cr(VI) and folic acid, respectively. It revealed that inner filter effect dominated in Cr(VI) quenching of the CDs-MCM fluorescent, while that of folic acid belonged to static quenching. The CDs-MCM were successfully used to detect the Cr(Vl) and folic acid in water and vegetable samples with satisfactory results. It provided new insight into environmental Cr(VI) and folic acid detection.

Mesoporous Zeolitic Materials (MZMs) Derived From Zeolite Y Using a Microwave Method for Catalysis.

Mesostructured zeolitic materials (MZMs) with relatively high acidity in comparison with the mesoporous siliceous MCM-41 were prepared via an efficient, mild, and simple post-synthetic treatment of Y zeolite facilitated by microwave irradiation, i.e., microwave-assisted chelation (MWAC). The disordered mesoporous aluminosilicates materials (DMASs) of MZM were created from Y zeolite in the absence of using mesoscale templates. The prepared DMASs showed the good mesoporous features with the mesopore area and volume of ~260 m2 g−1 and ~0.37 cm3 g−1, respectively, and with the mesopore sizes distributed in a range of 2–10 nm. MZMs possess a total acidity of about 0.6 mmol g−1 and exhibited comparatively superior catalytic activity to the parent Y zeolite and MCM-41 in the vapor phase catalytic dealkylation of 1,3,5-triisopropylbenzene (TiPBz) and liquid phase catalytic aldol condensation of benzaldehyde with 1-heptanal. Although the yield loss was inevitable for preparing MZMs using the MWAC method, the preliminary economic analysis of the preparation cost of MZMs showed the promise. Additionally, a comprehensive comparison of the state-of-the-art mesoporous materials concerning their sustainable aspects was made, showing that MZMs are promising mesoporous materials for further development and functionalization for catalysis.

Sulfonic Acid Derivative-Modified SBA-15, PHTS and MCM-41 Mesoporous Silicas as Carriers for a New Antiplatelet Drug: Ticagrelor Adsorption and Release Studies.

Three mesoporous, siliceous materials, i.e., SBA-15 (Santa Barbara Amorphous), PHTS (Plugged Hexagonal Templated Silica) and MCM-41 (Mobil Composition of Matter), functionalized with a sulfonic acid derivative, were successfully prepared and applied as the carriers for the poorly water-soluble drug, ticagrelor. The siliceous carriers were characterized using nitrogen sorption analysis, X-ray diffraction (XRD), transmission electron microscopy (TEM) and elemental analysis. The adsorption studies were conducted in acetonitrile. At the highest equilibrium concentrations, the amount of ticagrelor Qe that adsorbed onto the examined silicas was in the range of 83 to 220 mg/g, increasing in the following order: PHTS-(CH2)3-SO3H < SBA-15-(CH2)3-SO3H < MCM-41-(CH2)3-SO3H. The equilibrium adsorption data were analyzed using the Freundlich, Jovanovich, Langmuir, Temkin, Dubinin-Radushkevich, Dubinin-Astakhov and Redlich-Peterson models. In order to find the best-fit isotherm for each model, a nonlinear fitting analysis was carried out. Based on the minimized values of the ARE function, the fit of the isotherms to the experimental points for ticagrelor adsorption onto the modified silicas can be ordered as follows: SBA-15-(CH2)3-SO3H (Redlich-Peterson > Dubinin-Astakhov > Temkin), PHTS-(CH2)3-SO3H (Redlich-Peterson > Temkin > Dubinin-Astakhov), MCM-41-(CH2)3-SO3H (Redlich-Peterson > Dubinin-Astakhov > Langmuir). The values of adsorption energy (above 8 kJ/mol) indicate the chemical nature of ticagrelor adsorption onto propyl-sulfonic acid-modified silicas. The results of release studies indicated that at pH 4.5, modified SBA-15 and MCM-41 carriers accelerate the drug dissolution process, compared to the dissolution rate of free crystalline ticagrelor. Intriguingly, modified PHTS silica provides prolonged drug release kinetics compared to other siliceous adsorbents and to the dissolution rate of crystalline ticagrelor. A Weibull release model was employed to describe the release profiles of ticagrelor from the prepared carriers. The time necessary to dissolve 50% and 90% of ticagrelor from mesoporous adsorbents at pH 4.5 increased in the following order: SBA-15-(CH2)3-SO3H < MCM-41-(CH2)3-SO3H < PHTS-(CH2)3-SO3H.

A novel method for synthesis of mesoporous ZSM-5 from iron ore tailings

Mesoporous ZSM-5 was prepared from iron ore tailings (IOT) using a two-step process. Mesoporous MCM-41 was first synthesized using cetyltrimethylammonium bromide (CTAB) as mesoporous template and IOT as silica source. The CTAB in the as-synthesized MCM-41 was used as the mesoporogen to produce the mesoporous ZSM-5, by recrystallizing the amorphous walls of MCM-41 with tetrapropylammonium bromide (TPABr) as the structure-directing agent via solid-phase conversion. To evaluate the textural properties of mesoporous ZSM-5, the as-synthesized samples were characterized using x-ray diffraction, scanning electron microscopy, transmission electron microscopy, 29Si, 27Al magic angle spinning nuclear magnetic resonance spectroscopy, and nitrogen adsorption. The results show that phase separation between the surfactant and zeolite crystals was avoided in the solid-phase conversion process, which transforms the as-synthesized MCM-41 to mesoporous zeolite. Therefore, the synthetic route presented herein provides a novel method for the synthesis of mesoporous ZSM-5 from IOT.

An amine functionalized ZnCr LDH/MCM-41 nanocomposite as efficient visible light induced photocatalyst for Cr(VI) reduction

Achieving photocatalytic carcinogenic hexavalent chromium (Cr(VI)) reduction by utilising a visible light promoted semiconductor based nanocomposite is challenging as a eco-friendly and sustainable approach. Mesoporous MCM-41 modified ZnCr Layered double hydroxide (LDH) nanocomposite was prepared by in-situ co precipitation method having great porosity, large surface area, high chemical stability and plentiful surface –OH grafting sites. These sites can be easily tailored with APTES group as amine source using a facile reflux process to design amine functionlisation ZnCr LDH/MCM-41 nanohybrid material. The structural identity, textural properties, optical response and functional groups of the as-prepared materials were systematically analysed by powder X-ray diffraction (PXRD), N2 adsorption–desorption technique, ultraviolet–visible diffuse reflectance (UV–vis DRS) and fourier-transform infrared (FTIR). It is revealed that the amine functionlisation ZnCr LDH/MCM-41 possesses enhanced visible-light absorption property in compared to ZnCr/MCM-41 nanocomposite, which was attributed to the chromophoric amino group of the organic linker. Under optimum conditions, amine functionlisation ZnCr LDH/MCM-41 exhibited 95% Cr(VI) reduction in 2 h from aqueous solution under visible-light irradiation, which was 1.2 times higher than that of unmodified ZnCr LDH/MCM-41 nanocomposite and 1.5 times superior than pure ZnCr LDH. The lowest PL intensity of amine functionlisation ZnCr LDH/MCM-41 supported the optimum photocatalytic activity. Under the explore of visible light, the presence of LMCT spectra (O2p → Cr-3dt2g and Zn 4 s) an d–d transition (Cr-3d-t2g → Cr-3 deg) in the ZnCr LDH are the key reason for excited of photoelectrons and transportation from amine functionlisation ZnCr LDH/MCM-41 to Cr(VI), accelerating the reduction process of Cr(VI). In summary, amine functionalized MCM-41 modified ZnCr LDH could be prospective photocatalyst candidate for the treatment of Cr(VI)-contained wastewater under visible light irradiation.

Underlying Processes Driving the Evolution of Nanoporous Silica in Water and Electrolyte Solutions

In this study, we related the alteration of mesoporous materials in aqueous solutions to the properties of confined water in the presence of ions, that is, its structure and its dynamics. To reach this goal, we have determined and quantified the evolution of the morphology of hexagonal mesoporous silica-based materials, that is, MCM-41 (mean pore size of 2.9 nm and dense pore wall) and SBA-15 (mean pore size of 6.8 nm and microporous pore wall), during their alteration in water and electrolyte solutions with ions presenting various kosmotropic properties ([XCl2] = 1 M and X = Ba, Ca, Mg) at 50 °C by in situ small and wide angle X-ray scattering. The experimental results and the calculated small-angle X-ray scattering spectra have demonstrated that the alteration behavior is strongly dependent on the type of silica and the water properties (water dynamics at a picosecond time scale and water structure) related to the confinement size, the nature of the cations, and their surface ion excesses. For MCM-41 silica, having reduced water dynamics, the alteration behavior is mainly driven by silica hydrolysis—recondensation/precipitation processes leading to a pore deformation and a possible precipitation of XCl2 metastable phases partially clogging the pores. In case of SBA-15, its alteration behavior in aqueous solutions starts with an initial increase of the pore size and the formation of an alteration layer within its microporosity which grows following a diffusive process of the solution. Inside the microporosity, similar alteration processes to MCM-41 silica occur. These recondensation/precipitation processes may continue until a thermodynamically stable silica phase is formed. The results obtained within the scope of this work revealed the importance of the influence of the dynamics and the structure of water in chemical reactions taking place in confined media filled with water and ions.

Long effective tea tree oil/mesoporous silica sustained release system decorated by polyethyleneimine with high antibacterial performance

Mesoporous silica MCM-41 was prepared and decorated by polyethyleneimine (PEI) with different molecule weight before loading tea tree oil (TTO) to construct an environment-friendly antimicrobial sustained release system. The characterization results proved that the PEI was successfully introduced to pores of the mesoporous silica without destruction of the structure integrity. The strength of electrostatic interaction between PEI and MCM-41 was measured by the value of zeta potential which indicated that PEI with low molecule weigh was easier to be adsorbed by MCM-41 pores due to its low viscosity. The interaction of MCM-41 with TTO was strengthened after PEI modification. As a result, TTO/PEI600-MCM-41 performed the lowest cumulative release rate of 46.88% in 12 h due to the strongest interaction with TTO among all the samples. Kinetics study indicated that PEI constructed a new barrier for drug diffusion and volatilization through winding and swelling. The kinetic model for TTO/MCM-41 sustained release changed from first-order to Weibull model after PEI modification. What’s more, the service life of TTO in antimicrobial was also obviously prolonged after supported on mesoporous silica modified by PEI.

Comparison in thermal stability and catalytic performance of H4PMo11VO40 heteropolyacid supported on mesoporous and macroporous silica materials

Ordered mesoporous silica, SBA-15 and MCM-41, and three-dimensionally ordered macroporous SiO2 were used as the supports of H4PMo11VO40 heteropolyacid for methacrolein oxidation. The dispersion and structural evolutions of the heteropolyacid along with thermal treatment were investigated. It was found that the heteropolyacid entered the one-dimensional mesoporous channels of SBA-15 and MCM-41, and the crystallization and growth were limited, leading to high dispersion of the heteropolyacid. However, the thermal stability was decreased under high dispersion. The migration of the heteropolyacid was observed to the end of the one-dimensional channels of SBA-15 and the outer surface of MCM-41 with calcination, accompanied by the decomposition of the heteropolyacid and the formation of MoO3. In comparison, the crystallization and growth of heteropolyacid were not limited in the open macropores of three-dimensionally ordered macroporous SiO2. Dispersed particles on the surface of the macropores with size of about 5 nm exhibited a higher thermal stability. The decomposition of the heteropolyacid in the SBA-15 and MCM-41 supported catalysts resulted in the loss of strong acid sites, causing low selectivity to methacrylic acid in methacrolein oxidation. High thermal stability with high exposure of the active sites in the three-dimensionally ordered macroporous SiO2 supported catalyst contributed to the enhancement in the catalytic performance.

Synthesis and Study on Thermal Stability of PMMA Microspheres by Emulsion Polymerization

Polymethyl methacrylate (PMMA) was prepared by emulsion polymerization using methyl methacrylate (MMA) as monomer, potassium per sulfate as initiator. Polymethyl methacrylate/mesoporous molecular sieve composite (PMMA/MCM-48) was synthesized via the addition of mesoporous molecular sieve MCM-48 silica nanomaterial. The synthesized samples were systematically characterized using XRD, SEM, TEM, FT-IR, and TG. The results showed that PMMA microspheres with a diameter of 80-110 nm were prepared by emulsion polymerization. Compared with pure PMMA, PMMA/mesopores molecular sieve MCM-48 composites have good thermal stability. Pure PMMA microspheres can be completely decomposed at a lower temperature (400°C), and the thermal stability of PMMA/MCM-48 composites were improved by the addition of mesoporous molecular sieves.

Ruthenium Catalysts Templated on Mesoporous MCM-41 Type Silica and Natural Clay Nanotubes for Hydrogenation of Benzene to Cyclohexane

Mesoporous ruthenium catalysts (0.74–3.06 wt%) based on ordered Mobil Composition of Matter No. 41 (MCM-41) silica arrays on aluminosilicate halloysite nanotubes (HNTs), as well as HNT-based counterparts, were synthesized and tested in benzene hydrogenation. The structure of HNT core-shell silica composite-supported Ru catalysts were investigated by transmission electron microscopy (TEM), X-ray fluorescence (XRF) and temperature-programmed reduction (TPR-H2). The textural characteristics were specified by low-temperature nitrogen adsorption/desorption. The catalytic evaluation of Ru nanoparticles supported on both the pristine HNTs and MCM-41/HNT composite in benzene hydrogenation was carried out in a Parr multiple reactor system with batch stirred reactors (autoclaves) at 80 °C, a hydrogen pressure of 3.0 MPa and a hydrogen/benzene molar ratio of 3.3. Due to its hierarchical structure and high specific surface area, the MCM-41/HNT composite provided the uniform distribution and stabilization of Ru nanoparticles (NPs) resulted in the higher specific activity and stability as compared with the HNT-based counterpart. The highest specific activity (5594 h−1) along with deep benzene hydrogenation to cyclohexane was achieved for the Ru/MCM-41/HNT catalyst with a low metal content.

One-pot synthesis of bio-fuel additives from glycerol and benzyl alcohol: Mesoporous MCM-41 supported iron (III) chloride as a highly efficient tandem catalyst

The demand for renewable resources, surplus availability, low cost and lower environmental impact has led to the utilization of bio-glycerol into high-value derivatives and functional chemicals for sustainability of the bio-diesel industry. The production of bio-fuel additives is of great interest as there is a gradual shift from petro-based chemicals to green chemicals. This work involves the direct synthesis of oxygenated fuel additives, 1,3-dioxalane and 1,3-dioxane from glycerol and benzyl alcohol over FeCl3/MCM-41 catalyst. The reaction progresses successfully to produce 1,3-dioxalane primarily by in-situ oxidation of benzyl alcohol to benzaldehyde and subsequent condensation reaction of benzaldehyde with glycerol. Glycerol primarily acted as green solvent to facilitate the oxidation of benzyl alcohol to benzaldehyde and as a fuel additive precursor to produce 1,3-dioxalane in the preceding reaction. FeCl3/MCM-41 catalyst presented high performance achieving 92% glycerol conversion with 75% selectivity to 1,3-dioxalane in a reaction performed at 100 °C for 60 min.

Microwave Synthesis of MCM-41 and Its Application in CO2 Absorption by Nanofluids

Microwave synthesis method is a green chemical process with mild reaction conditions, fast reaction, and low energy consumption. In this work, an order mesoporous silica material MCM-41 was synthesized by microwave technology. Functionalized MCM-41 was prepared by wet impregnation with polyethyleneimine (PEI). XRD, SEM, TEM, DLS, N2 adsorption-desorption, FTIR, and TG were used to characterize the physicochemical properties of samples. Furthermore, CO2 absorption performance in water in the presence of uncalcined MCM-41 and PEI-MCM-41 nanoparticles was evaluated. In addition, the mechanisms of enhanced absorption were also elaborated. The experimental results indicated that the optimum conditions for preparation of MCM-41 were the microwave time of 15 min, microwave temperature of 100°C, and microwave power of 200 W. Under this condition, MCM-41 with narrow particle size distribution, average diameter of 50 nm, and SBET of 1210.3 m2g-1 was obtained. The enhancement effect of PEI-MCM-41 nanoparticles was more obvious than that of uncalcined MCM-41. PEI-MCM-41 as a promoter not only increased the CO2 diffusion rate but also enhanced the adsorption capacity due to the fact that it owns more active sites that may react with CO2. The CO2 absorption improvement of PEI-MCM-41 (0.1 wt%)/H2O was 25.35% higher than that of water.

Use of nanometer mesoporous MCM-41 for the removal of Pb(II) from aqueous solution

Mobil Composition of Matter (MCM)-41 molecular sieve was successfully synthesized. Power X-ray diffraction, scanning electron microscopy and transmission electron microscopy (TEM) were used to characterize the sample. The sample showed spherical particles, and the morphology was regular. Its average particle diameter was 110 nm. TEM images showed that the sample structure presented a honeycomb pore structure and the average pore diameter was 3.5 nm. Pb2+ was adsorbed from water body by the MCM-41. The effects of acidity, contact time, temperature, adsorbent material amount and initial Pb2+ concentration on the adsorption rate were studied, and the optimum conditions of adsorption were obtained. The results show that when acidity pH value was 4.5, temperature was 25 °C, contact time was 40 min and the adsorbent material MCM-41/Pb2+ = 7.5, the adsorptive effect was the best, the adsorption rate reached 98.78% and the adsorptive capacity was 131.71 mg/g. Kinetic and thermodynamic properties of the adsorptive process were studied. Experimental results show that the adsorption of Pb2+ by MCM-41 belongs to the pseudo-second-order adsorption. According to thermodynamic equation, ΔG = ΔH − TΔS, ΔH = − 24.86 kJ/mol and ΔS = − 72.34 J/(mol K) were obtained by calculation, indicating that the adsorption was exothermic and an entropy reduction process. At the temperature of 298, 308 and 318 K, the free energy change was, respectively, ΔG1 = − 3.286 kJ/mol, ΔG2 = − 2.586 kJ/mol and ΔG3 = − 1.86 kJ/mol, illustrating that at the above temperature the reaction can be carried on spontaneously. Nitric acid, hydrochloric acid and acetic acid were, respectively, used to investigate their effect on desorption. The results show that the desorption effect using nitric acid as a desorption agent was better than those of hydrochloric acid and acetic acid. When desorption was 5 h and the nitric acid concentration was 0.5 mol/l, the desorption rate was the highest that was reached 70.01%.

Preparation of new nanocomposite poly(GDMA)/mesoporous silica and its adsorption behavior towards cationic dye

In this work, a new nanocomposite based on crosslinked Glycerol Dimethacrylate (GDMA) and the mesoporous silica MCM-41 was prepared. The GDMA is first synthesized by the ring opening of glycidyl methacrylate (GMA) using methacrylic anhydride (MA) and promoted by a new solvent-free green catalysis process at room temperature. The nanocomposites are further obtained by in-situ polymerization of the GDMA in the channels of the mesoporous silica and then tested for the removal of methylene blue (MB) dye. Effect of polymer content, adsorbent mass, contact time and initial dye concentration were studied and discussed in terms of affinity and adsorption efficiency. The results showed that the poly(GDMA) was well immobilized in the internal and external surface of the mesoporous silica MCM-41. The adsorption efficiency of MB dye increased with increasing poly(GDMA) content in which the nanocomposite (NC-3) exhibited the best adsorption capacity of MB dye. The adsorption of MB dye by nanocomposite NC-3 followed Langmuir adsorption isotherm models and pseudo-second-order kinetics. The maximum adsorbed amount of MB dye on nanocomposite NC-3 is 111.11 mg/g.

Properties of Salvia officinalis L. and Thymus serpyllum L. Extracts Free and Embedded into Mesopores of Silica and Titania Nanomaterials.

This study evidenced the nanoconfinement effect on polyphenolic extracts prepared from Salvia officinalis L. and Thymus serpyllum L. into the mesopores of silica and titania nanomaterials on their radical scavenging capacity and antimicrobial potential. The ethanolic and hydroalcoholic extracts obtained either by conventional or microwave-assisted extraction were characterized in terms of total polyphenols, total flavonoids, and chlorophyll content, as well as radical scavenging activity by consecrated spectrometric determinations. The phytochemical fingerprint of extracts was analyzed by high-performance liquid chromatography-photodiode array detector. Salvia officinalis extracts exhibited better radical scavenging capacity and antimicrobial potential than Thymus serpyllum extracts. The mesoporous MCM-41 silica and titania nanomaterials, prepared by the sol–gel method, were characterized by small- and wide-angle powder diffraction, FTIR spectroscopy, nitrogen adsorption–desorption isotherms, scanning electron microscopy and transmission electron microscopy, while the materials containing embedded extracts were analyzed through Fourier-transform infrared spectroscopy, N2 sorption measurements, and thermal analysis. All extracts free and embedded in mesoporous matrix exhibited high radical scavenger properties and good bactericidal activity against several reference strains. It was proved that by embedding the polyphenolic extracts into mesopores of silica or titania nanoparticles, the phytochemicals stability was enhanced as the materials containing extract exhibited higher radical scavenger activity after 3–6 months storage than that of the free extracts. Additionally, the extract-loaded material showed mild improved antimicrobial activity in comparison with the corresponding free extract.