And 3-aminopropyltrimethoxysilane Research Articles

Improved Raman and photoluminescence sensitivity achieved using bifunctional Ag@SiO₂ nanocubes.

SiO2 coated silver nanocubes Ag@SiO2 with enhanced surface-enhanced Raman scattering (SERS) and metal enhanced photoluminescence (MEPL) sensitivity were synthesized and characterized. The silver nanocubes (NCs) were synthesized by the polyol method and modified, first with different coupling agents, such as 3-mercaptopropyltrimethoxysilane (MPTMS) and 3-aminopropyltrimethoxysilane (APS), and secondly with tetraethylorthosilicate (TEOS) to improve their SERS and photoluminescence (PL) performances. The SERS and PL intensity of rhodamine 6G (R6G) can be manipulated by tuning the Ag nanocube's SiO2 shell thickness. Modified Ag NCs (with a 2 nm silica layer) were prepared using 1 mM APS and 1 mM TEOS and found to have a SERS intensity 3 fold higher than bare Ag NCs. Additionally, it was found that APS modified Ag@SiO2 NCs possessed both enhanced SERS and PL intensities.

Immobilized V-MIL-101 on modified Fe3O4 nanoparticles as heterogeneous catalyst for epoxidation of allyl alcohols and alkenes

As a new heterogeneous catalyst, Fe3O4 nanoparticles were prepared and modified with sodium silicate and (3-aminopropyl) trimethoxysilane (APTMS) followed by complexation with V-MIL-101 and designated as Fe3O4@SiO2@APTMS@VMIL-101. It was characterized using FTIR, TEM, and VSM techniques. The Fe3O4@SiO2@APTMS@VMIL-101 was found to successfully catalyze the epoxidation of allyl alcohols and alkenes with tert-butylhydroperoxide (TBHP) in moderate to high yields. The epoxidation of trans-stilbene, norbornen, cyclooctene, geraniol, trans-2-hexene-1ol and 1-octene-3-ol with 100% selectivity is promising. Investigation of the stability and reusability of Fe3O4@SiO2@APTMS@V-MIL-101 revealed the heterogeneity character of the catalyst with no desorption during the course of epoxidation reactions. High yields, clean reactions, ease of catalyst separation and recyclability of the solid catalyst are some advantages of this method.

Shaping amine-based solid CO2 adsorbents: Effects of pelletization pressure on the physical and chemical properties

Amine-based solid adsorbents are promising candidates for the separation of CO2 from dilute gas streams. Here we report the effect of pelletization pressure on the physical and chemical properties of an array of supported amine adsorbents, based on mesoporous silica and γ-alumina supports. The virgin powders based on poly(ethyleneimine) (PEI) and 3-aminopropyltrimethoxysilane (APS) functionalized oxides are pressed at 1000 and 5000psig pressure to form self-supporting pellets and their physical and chemical properties are compared. No change in chemical structure of the adsorbents is observed after pelletization, though the porosity of each material changes to some degree. Of the three mesoporous supports examined in this study, the commercial porous silica is the most stable support for both class 1 and class 2 adsorbents, whereas lab synthesized mesoporous SBA-15 silica and lab synthesized mesoporous γ-alumina are found to be the least stable supports for class 1 and class 2 adsorbents, respectively. The CO2 uptake results show a significant drop in equilibrium capacity for the pellets pressed at 5000psig, regardless of the support used, while the 1000psig pellets retain their capacity and show comparable performance to their powder counterparts. CO2 breakthrough experiments suggest an increase in mass transfer resistance for the pellet samples as compared with virgin powders, resulting in the dispersion of the concentration fronts during CO2 breakthrough using a fixed bed. These findings suggest that shaping solid supported amine adsorbents into binderless pellets requires pressing the powders at low to moderate pressures to ensure that these materials retain their performance in processes that require pelletized samples.

Mesochanneled hierarchically porous aluminosiloxane aerogel microspheres as a stable support for pH-responsive controlled drug release.

The molecular-scale self-assembly of a 3D aluminosiloxane (Al-O-Si) hybrid gel network was successfully performed via the cocondensation of hydrolyzed alumina (AlOOH) and (3-aminopropyl)trimethoxysilane (APS). It was transformed into a microspherical aerogel framework of Al-O-Si containing mesochannels with tunable hierarchically bimodal meso/macroporosities by a subcritical drying technique. Good homogeneity of AlOOH and APS brought during the synthesis guaranteed a uniform distribution of two metal oxides in a single body. A systematic characterization of the aerogel support was carried out using FTIR, SEM, TEM, nitrogen adsorption/desorption analysis, WAXS, SAXS, and ξ-potential measurement in order to explore the material for drug uptake and release. The drug loading and release capacity and chemical stability of an aluminosiloxane aerogel were studied using two nonsteroidal antiinflammatory drugs, ibuprofen and aspirin. A comprehensive evaluation of the aluminosiloxane aerogel with ordered mesoporous MCM-41 was also performed. Aerogel supports showed a high drug loading capacity and a pH-responsive controlled-release property compared to MCM-41. Meanwhile, kinetic modeling studies indicate that the drug releases with a zero-order profile following the Korsmeyer-Peppas model. The biocompatibility of aluminosiloxane aerogels was established via ex vivo and in vivo studies. We also outline the use of aluminosiloxane aerogel as a support for a possible 3D matrix for an osteoconductive structure for bone tissue engineering.

Optical fiber temperature sensor utilizing alloyed Zn(x)Cd(1-x)S quantum dots.

In this paper, optical fiber temperature sensors have been prepared by using alloyed Zn(x)Cd(1-x)S quantum dots as sensing media. The surface of the optical fiber was silanized to enhance covalent bond between quantum dots and optical fiber. The quantum dots were bonded to the surface of optical fiber and further encapsulated via sol-gel coating using 3-glycidoxypropyl trimethoxysilane (GPTMS) and 3-aminopropyl trimethoxysilane (APTMS) in ethyl alcohol in acidic condition. Quantum dots with green, yellow, and red fluorescence were used. The dependence of photoluminescence (PL) intensity from quantum dots on ambient temperature has been studied. Linear relation between the fluorescent intensity and temperature was obtained from alloyed quantum dots immobilized on the surface of optical fiber. The PL intensity, sensitivity, and thermal stability were increased by the silica encapsulation.

Preparation and evaluation of bovine serum albumin immobilized chiral monolithic column for affinity capillary electrochromatography

A system of capillary silica monolith with bovine serum albumin (BSA) functionalized through two approaches for affinity monolithic capillary electrochromatography (AMCEC) was developed. Covalent immobilization conditions for two different Schiff base methods, which employed 3-glycidopropyl trimethoxysilane (GPTS) and 3-aminopropyl trimethoxysilane (APTS) as starting materials, respectively, were investigated to obtain good and stable chiral separation. The BSA immobilized silica monoliths were evaluated in terms of morphology, electroosmotic flow, retention time, column efficiency and resolution of model compound (±)-tryptophan. The columns exhibited satisfactory run-to-run, column-to-column repeatability and maintained their enantioselectivity for more than 3months. Both developed methods can baseline separate tryptophan enantiomers, whereas shorter retention time, better column efficiency, and enantiomeric recognition between two pairs of drug enantiomers (pantoprazole and atenolol) were obtained by the GPTS method.

Versatile synthesis of thiol- and amine-bifunctionalized silica nanoparticles based on the ouzo effect.

In this article, we report a novel, nanoprecipitation-based method for preparing silica nanoparticles with thiol and amine cofunctionalization. (3-Mercaptopropyl)trimethoxysilane (MPTMS) and 3-aminopropyltrimethoxysilane (APTMS) were used as the organosilane precursors, which were subjected to acid-catalyzed polycondensation in an organic phase containing a water-miscible solvent (e.g., dimethyl sulfoxide). A pale colloidal solution could be immediately formed when the preincubated organic phase was directly injected into water. The initial composition ratio between MPTMS and APTMS is an important factor governing the formation of nanoparticles. Specifically, large, unstable micrometer-sized particles were formed for preparation using MPTMS as the sole silane source. In contrast, when APTMS was used alone, no particles could be formed. By reducing the fraction of APTMS (or increasing that of MPTMS) in the initial mixture of organosilanes, the formation of nanometer-sized particles occurred at a critical fraction of APTMS (i.e., 25%). Remarkably, a tiny fraction (e.g., 1%) of APTMS was sufficient to produce stable nanoparticles with a hydrodynamic diameter of about 200 nm. Other factors that would also affect particle formation were determined. Moreover, an interesting temperature effect on particle formation was observed. The TEM micrographs show spherical nanospheres with mean sizes of 130-150 nm in diameter. The solid-state (29)Si NMR spectra demonstrate that the hybrid silica materials contain fully and partially condensed silicon structures. The bifunctionalized silica nanoparticles have positive zeta potentials whose magnitudes are positively correlated with the amount of APTMS. The total thiol content, however, is negatively correlated with the amount of APTMS. The cationic nanoparticles can bind an antisense oligonucleotide in a composition-dependent manner.

Fluorescent silica nanoparticles functionalized on multi-walled carbon nanotubes: Fabrication and fluorescent properties

We report the fabrication and fluorescent properties of hybrid material composed of fluorescent silica nanoparticles (FSNs) functionalized multi-walled carbon nanotubes(MWCNTs). Stober method derived FSNs were successfully conjugated with MWCNTS chemically activated concentrated acids, poly(acrylic acid) (PAA) and 3-aminopropyl-trimethoxysilane (APTES) to obtain the nanocomposite FSNs/MWCNTs. Electron microscopic investigations revealed the spherical shape and smooth surface of FSNs with the diameter ~150±50 nm. Activated functional groups of MWCNTs provided the necessary support for functionalization of FSNs. FT-IR spectral analysis shows the structural integrity of FSNs, MWCNTs, and the hybrid FSNs/MWCNTs. Fluorescent emission property of FSNs/MWCNTs are observed to be significant than pristine dye fluorescein isothiocyanate and FSNs. Enhanced fluorescent emission and photostability of FSNs/MWCNTs provides promising feasibility for further exploration in biomedical applications.

Self assembled monolayer based liquid crystal biosensor for free cholesterol detection

A unique cholesterol oxidase (ChOx) liquid crystal (LC) biosensor, based on the disruption of orientation in LCs, is developed for cholesterol detection. A self-assembled monolayer (SAM) of Dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP) and (3-Aminopropyl)trimethoxy-silane (APTMS) is prepared on a glass plate by adsorption. The enzyme (ChOx) is immobilized on SAM surface for 12 h before utilizing the film for biosensing purpose. LC based biosensing study is conducted on SAM/ChOx/LC (5CB) cells for cholesterol concentrations ranging from 10 mg/dl to 250 mg/dl. The sensing mechanism has been verified through polarizing optical microscopy, scanning electron microscopy, and spectrometric techniques.

Preparation of a Novel Composite Membrane and PtRu/Hollow Carbon Sphere (HCS) Anode Catalyst for Alkaline Direct Methanol Fuel Cell (ADMFC)

This work demonstrated the synthesis process of the anion-exchange nanocomposite membrane based on Poly(vinyl alcohol (PVA) and Quaternary ammonium silica precursor (QASP), which was synthesized by using Glycidytrimethyl ammonium chloride (GTMAC) and 3-Aminopropyl trimethoxysilane (AMPTS). The suitable amount of functional SiO2 fillers was added into the PVA composite polymer membrane to reduce the methanol permeability and also improve the thermal and mechanical properties. A novel and high activity PtRu/Hollow carbon sphere (HCS) was synthesized to use as a catalyst in the anode for methanol oxidation. It was found that this as-prepared PtRu/HCS shows excellent electrochemical activity, as compared with PtRu black. The characteristic properties were examined by thermal gravimetric analysis (TGA), X-ray diffraction (XRD), micro-Raman and FTIR spectroscopies, scanning electron microscopy (SEM), and AC impedance method. It was observed that the maximum ionic conductivity of anion-exchange composite polymer membrane is around 5.12×10-2 S cm-1 at room temperature. It was observed that the highest peak power density of alkaline direct methanol fuel cell (ADMFC) with a 4M KOH + 2M CH3OH fuel was around 70 mW cm-2 at 70oC. The methanol permeability is around 10-6∼10-7 cm2 s-1. The results demonstrate that the PVA/QASP/SiO2 composite membranes exhibit a good candidate for application to ADMFC.

Mechanical Properties and Fracture Behavior of Dual-Curable Epoxyacrylate Composites Filled with Different Functionalized Silica Particles

To investigate the interfacial effect on properties of epoxyacrylate-silica composites, sub-micron silica particles were synthesized by sol-gel reaction in an ammonia/ethanol solution and their surfaces were endowed with different functional groups by reaction with several silanes including 3-methacryloxypropyl trimethoxysilane (MPTMS), vinyl trimethoxysilane (VTMS), 3-glycidoxypropyl trimethoxysilane (GPTMS) and 3-aminopropyl trimethoxysilane (APTMS). Except the APTMS-modified silica particles due to its severe aggregation, the modified silica particles with size ranging from 150∼250 nm were then added to the pre-synthesized difunctional epoxyacrylate resin at a concentration of 15 phr, in addition to the photo- and thermo-curing agents. Tensile mechanical properties and the fracture toughness were all increased by adding the silica particles into the epoxyacrylate. Particularly, the composite filled with the MPTMS-modified silica particles (EA-MPS15) had the best performance. The reason is that the vinyl double bond of the MPTMS on the surface of the silica particles could took part in the curing reaction of the epoxyacrylate, thus providing strong interfacial chemical bonding between the silica particles and the polymer matrix and also improving the dispersion of the silica particles. The increase of fracture toughness was due to the crack deflection and particle-matrix debonding as evidenced by SEM pictures on the fracture surface.

Synthesis of Mesoporous Silica from Tetraethylorthosilicate by Using Sodium Ricinoleic as a Template and 3-Aminopropyltrimethoxysilane as Co-Structure Directing Agent with Volume Variation of Hydrochloric Acid 0.1 M

Synthesis of mesoporous silica from tetraethylorthosilicate (TEOS) by using sodium ricinoleic as a template and 3-aminopropyltrimethoxysilane (APMS) as a co-structure directing agents (CDSA) in a volume variation of acid addition has been carried out. Preparation of mesoporous silica was conducted in HCl 0.1 M at volume variations of 2 ml, 35 ml, 40 ml and 50 ml. In acid conditions, the amine groups of APMS will protonate, which will then interact electrostatically with the carboxylate groups from ricinoleic acid, while the methoxy groups from APMS will condense with the silanol groups from TEOS to form an end product of mesoporous silica. The reaction products were characterized by using X-ray diffractometer (XRD), Fourier transform infra-red spectrometer (FTIR), surface area analyzer (BET), scanning electron microscope (SEM), and transmission electron microscope (TEM). X-ray diffractograms of the products from all of the acid volume variation additions show broadening peaks indicating amorphous materials as a characteristic of mesoporous materials. Infrared spectra show that all of the products have Si-OH and Si-O-Si groups that are characteristics for mesoporous silica. Imaging results from SEM and TEM show morphology and particle size differences in accordance with the differences in volume variation of acid addition. Adsorption/desorption isotherm by using nitrogen at 77 K of the products from the addition of 2 ml of HCl show an isotherm Type II (adsorption on the surface layer) with irregular pore size distribution, whereas from the addition of 30 ml, 35 ml, 40 ml and 50 ml HCl show an isotherm Type IV with a hysteresis loop that is characteristic for mesoporous materials with a regular pore size distribution.

Synthesis of Mesoporous Silica from Tetraethylorthosilicate by Using Sodium Ricinoleic as a Template and 3-Aminopropyltrimethoxysilane as Co-Structure Directing Agent with Volume Variation of Hydrochloric Acid 0.1 M

Synthesis of mesoporous silica from tetraethylorthosilicate (TEOS) by using sodium ricinoleic as a template and 3-aminopropyltrimethoxysilane (APMS) as a co-structure directing agents (CDSA) in a volume variation of acid addition has been carried out. Preparation of mesoporous silica was conducted in HCl 0.1 M at volume variations of 2 ml, 35 ml, 40 ml and 50 ml. In acid conditions, the amine groups of APMS will protonate, which will then interact electrostatically with the carboxylate groups from ricinoleic acid, while the methoxy groups from APMS will condense with the silanol groups from TEOS to form an end product of mesoporous silica. The reaction products were characterized by using X-ray diffractometer (XRD), Fourier transform infra-red spectrometer (FTIR), surface area analyzer (BET), scanning electron microscope (SEM), and transmission electron microscope (TEM). X-ray diffractograms of the products from all of the acid volume variation additions show broadening peaks indicating amorphous materials as a characteristic of mesoporous materials. Infrared spectra show that all of the products have Si-OH and Si-O-Si groups that are characteristics for mesoporous silica. Imaging results from SEM and TEM show morphology and particle size differences in accordance with the differences in volume variation of acid addition. Adsorption/desorption isotherm by using nitrogen at 77 K of the products from the addition of 2 ml of HCl show an isotherm Type II (adsorption on the surface layer) with irregular pore size distribution, whereas from the addition of 30 ml, 35 ml, 40 ml and 50 ml HCl show an isotherm Type IV with a hysteresis loop that is characteristic for mesoporous materials with a regular pore size distribution.

Preparation of Poly(N-isopropylacrylamide) Grafted Polydimethylsiloxane by Using Electron Beam Irradiation

A poly(N-isopropylacrylamide) (PIPAAm) grafted poly(dimethylsiloxane) (PDMS) surface was prepared as a temperature-responsive cell culture surface by using electron beam (EB) irradiation. Different chemical treatments to modify the bare PDMS surface were investigated for subsequent grafting of PIPAAm, and treatment conditions were optimized to prepare the temperature-responsive cell culture surface. The PDMS surface was initially activated to form silanol groups with conventional O2 plasma or hydrochloric acid (HCl) treatment. Activated PDMS surfaces were individually immobilized with three different conventional silane compounds, i.e., 3-mercaptopropyltrimethoxysilane (MerTMS), 3-methacryloxypropyltrimethoxysilane (MetTMS), and 3-aminopropyltrimethoxysilane (AmiTMS). O2 plasma treatment made PDMS more hydrophilic. In contrast, PDMS surfaces activated with HCl treatment were relatively hydrophobic. Observation of the activated PDMS surface modified with MerTMS, MetTMS, and AmiTMS indicated that these silane compounds had been favorably immobilized on plasma-treated PDMS surfaces. FT-IR/ATR analysis demonstrated that immobilized silane compounds enabled PIPAAm grafting on the PDMS surface. Cell attachment and detachment analysis also suggested that the PDMS surface sequentially treated with O2 plasma and AmiTMS compound was a substrate appropriate for preparing a temperature-responsive cell culture surface by EB irradiation-induced PIPAAm grafting method. The intelligent surface may further be applied to mechanically stretchable temperature-responsive cell culture surfaces.

Insulator surface modification of field-effect transistor using isolated poly(3-hexylthiophene) nanofiber

The surface modification of insulators and electrodes of field-effect transistor (FET) devices using a poly(3-hexylthiophene) (P3HT) nanofiber was investigated. The mobility of the P3HT nanofiber using an insulator surface modified by perfluorodecyltrimethoxysilane (FAS) was much larger than that modified by other reagents, i.e. octadecyltrimethylsilane (OTS) and 3-aminopropyltrimethoxysilane (APS). In addition, the threshold increased with the use of FAS and was in a normally-on state. In particular, an FET of isolated nanofibers upon insulator surface modification by FAS showed a high mobility of 6.8×10−1cm2V−1s−1.

Synthesis and characterization of APTMS/melamine cured hyperbranched polyester-epoxy hybrid coatings

An epoxy-terminated hyperbranched polyester (EPHBP) was prepared by the reaction of hyperbranched polyester (HBP) and epichlorohydrin (EPH). Herein, we have synthesized a new kind of highly epoxy ended branched polyester to enhance the chemical bonding at the interfaces and to reduce the melt viscosity. The structural investigation of the hyperbranched polyesters was carried by spectroscopic techniques such as nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR) while molar masses were determined using gel permeation chromatography (GPC). The effect of the content of hexamethoxy methyl melamine (HMMA) and 3-amino propyltrimethoxysilane (APTMS) mixture on the thermal, mechanical and interfacial properties of EPHBP resins were also studied. The thermal, dynamic mechanical and mechanical properties of the heat cured coating films were also investigated. The combined analysis of the results indicate that the introduction of APTMS results in the enhancement of the thermal stability, glass-transition temperature (Tg), storage modulus, tensile strength and contact angle of the cured films. The improvement in properties depends on the APTMS content of the cured films. The cured films have also shown higher elongation at break due to the use of HMMA and presence of unmodified epoxide groups which indicates good flexibility and toughness of the coating films.

Selective adsorption of CO2 on amino-functionalized silica spheres with centrosymmetric radial mesopores and high amino loading

Amino-functionalized silica spheres with centrosymmetric radial mesopores and high amino loading were synthesized using the anionic surfactant N-lauroylsarcosine sodium (Sar-Na) as template and 3-aminopropyltrimethoxysilane (APTMS) as co-structure directing agent (CSDA) by an orthogonal experiment optimization. The synthesized amino-functionalized mesoporous silica (AFMS) was used as adsorbent to the selective adsorption of CO2. The effects of water vapor in the adsorptive stream on the adsorption properties of CO2 were investigated in detail. The results show that the synthesized adsorbent possesses a high adsorption selectivity for CO2 over CH4 and N2 due to the specific interactions between CO2 and amino groups. The presence of water vapor in the adsorptive stream can dramatically enhance the adsorbed amount of CO2 because of the partial formation of bicarbonate in the presence of moisture. Furthermore, the adsorbent shows a good stability, confirmed by adsorption-regeneration cycles. Based on these excellent properties, the application of the developed AFMS adsorbent in the selective adsorption of CO2 is anticipated.

Properties of polyimide hybrids with mixed metal oxide

AbstractPolyimide/silica–titania (PI/SiO2–TiO2) hybrid films were prepared via an in situ sol–gel process. The PI precursor, poly(amic acid) (PAA), which contains 2,2'‐bis[4‐(4‐aminophenoxy)‐phenyl]propane (p‐BAPPP), 3,3',4,4'‐ benzophenetetracarboxylic anhydride (BTDA) and 3‐aminopropyltrimethoxysilane (APrTMOS), was first synthesized; this was followed by the addition of phenyltrimethoxysilane (PTMS) and/or tetraethyl orthotitanate (Ti(OEt)4) to fabricate PI/SiO2–TiO2 films. The relative content of SiO2 to TiO2 has remarkable effects on the crosslink structure and resultant properties of the hybrids. XPS results confirm that the amount of Si on the surface of the hybrids is higher than that in the bulk. The distribution of Ti in the hybrid films is contrary to the above trend because of the formation of three‐dimensional SiOSi, SiOTi, and TiOTi networks. The SiO2 content of the hybrids containing only silica significantly affects their refractive index, contact angle, and dielectric constant. The films with added PTMS show higher contact angles than pure PI because nonpolar segments, C2H6 or benzene groups, tend to distribute on the surface. Upon the addition of (Ti(OEt)4), some hydrophilic segments on the surface of the hybrids are induced because of the formation of a crosslinked structure. The denser crosslinked molecular structure, and consequently lower CTE and higher Tg are obtained from hybrids containing more TiO2. By comparing the above properties and flexibility, the best composition of metal oxides (SiO2/TiO2) in hybrids is 20/80. That is, an optimum ratio of metal oxides in PI hybrids induces superior properties for advanced practical applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Adsorption of Pb2+ and Cu2+ on anionic surfactant-templated amino-functionalized mesoporous silicas

Amino-functionalized mesoporous silicas (AFMS) were synthesized using the anionic surfactant N-lauroylsarcosine sodium (Sar-Na) as template and 3-aminopropyltrimethoxysilane (APTMS) as co-structure directing agent (CSDA). Orthogonal experiments were applied to optimize the synthesis of AFMS with high amino loading, high surface area, and large pore size. The synthesized AFMS were characterized by FT-IR, TG-DTA, XRD, N2 adsorption–desorption, and TEM techniques. The removal of Cu2+ or Pb2+ from aqueous solutions by the synthesized AFMS was investigated in detail. The pH value of an aqueous solution containing Cu2+ or Pb2+, adsorption temperature, and the dosage of the used AFMS affect the removal efficiency of Cu2+ or Pb2+ greatly. The unary adsorption isotherms of Cu2+ and Pb2+ on the optimized AFMS adsorbent are well described by the Sips isotherm model, in which the adsorption capacities are 2.18 and 4.74mmol/g for Cu2+ and Pb2+, respectively, under the optimized conditions, much higher than the literature data. Furthermore, the AFMS adsorbent shows a good stability, confirmed by adsorption–regeneration cycles. Based on these excellent properties, the application in the removal of Cu2+ and Pb2+ from wastewater is anticipated.

Organosilanes affecting the structure and formation of mesoporous cellular foams

Purely siliceous and niobium-containing mesoporous molecular foams (MCFs) were synthesized by modifying a standard synthesis route. This was accomplished by decreasing considerably the content of chloride ions in the gel. The samples prepared under such conditions contained the MCF and SBA-15 phases. Mesostructured cellular foams were modified with (3-mercaptopropyl)trimethoxysilane (MPTMS) and (3-aminopropyl)trimethoxysilane (APTMS) via the direct synthesis, with increased efficiency of formation of the spherical MCF phases. All the materials obtained were characterized by XRD, sorption of nitrogen, FT-IR, UV–Vis, thermogravimetric analysis, 29Si MAS NMR, 13C CP/MAS NMR, and electron microscopy. We demonstrated that organosilanes added at the end of the synthesis procedure play a double role; as a source of the anchored catalytic active species (propylamines and propylsulfonic chains) and a source of methanol released during the interaction between MPTMS (APTMS) and hydrolyzed tetraethyl orthosilicate (TEOS). The methanol obtained in this way acts as a co-surfactant increasing the activity of ethanol released during hydrolysis of TEOS and enhancing the transformation of cylindrical SBA-15 towards the spherical MCF phase. Finally, it was shown that niobium species enhanced the oxidation of thiol groups in MPTMS towards sulfonic species and also affected slightly the morphology of the samples. The presence of niobium moieties did not influence, however, the formation of the pure MCFs mesostructured materials and their structural parameters.