And Functionalized With 3-aminopropyltriethoxysilane Research Articles

Novel copper desorption from a functionalized fly ash adsorbent using 1,1,1-trifluoro-2,4-pentanodione in ionic liquid [bmim][Tf2N]: Experimental and quantum chemistry calculations

In the context of the current environmental issues and the need to consolidate effective efforts according to the criteria of a circular economy, adsorption of copper from water with functionalized materials has shown high performance at low cost. However, desorption requires high amounts of acid and base to regenerate the functionalized material. In order to overcome this drawback, this work proposes an alternative desorbing phase based on a specific extractant for copper 1,1,1-trifluoro-2,4-pentanodione (TFA) dissolved in the ionic liquid (IL) 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. In this way, adsorption experiments were carried out using adsorbent fly ash, modified with a mesoporous siliceous material, and functionalized with 3-aminopropyl-triethoxysilane (APS). Under the operating conditions of this study, the best desorption performance was achieved using the lowest functionalization percentage of the absorbent material. The desorption percentage reached 45% after 200 min of contact with a stirred solution of TFA 0.2 [M] in IL. This percentage can be increased to around 70% through a second contact with fresh desorbing phase. Meanwhile, the conventional desorption technique with nitric acid showed faster kinetics and a slightly higher desorption percentage close to 50%. In turn, the final pH of the adsorbent slightly decreased when the proposed desorbing phase was used, representing an advantage over the use of acid. Additionally, it was possible to decrease the amount of desorbing phase allowing the concentration of copper. The COSMO-RS calculations indicate that a more hydrophobic IL could increase desorption percentage.

Nanodot zirconium trisulfide based highly efficient biosensor for early diagnosis of lung cancer

In present work, we report results of the studies related to the synthesis of nanodot metal chalcogenide (zirconium trisulfide, ∼5.7 nm in size) based biosensing platform for early detection of lung cancer serum biomarker (CKAP4). The nanodot zirconium trisulfide (nZrS3) was synthesized through low temperature hydrothermal method (200 °C for 72 h) and functionalized with 3-aminopropyl triethoxysilane (APTES) molecules via chemical process. To fabricate thin and uniform film onto the pre-hydrolyzed indium tin oxide (ITO) coated glass electrode of functionalized nanomaterials (APTES/nZrS3), an optimized electrophoretic condition (25 V for 60 s) was applied. Further, for covalent immobilization of anti-CKAP4 onto the APTES/nZrS3/ITO electrode, EDC-NHS chemistry was used and for blocking of non-specific binding sites, bovine serum albumin (BSA) was non-covalently immobilized via drop-cast method. The synthesized as well as functionalized nanomaterial and fabricated electrodes were characterized through X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. Further, the electrochemical response studies of developed biosensing platform i.e., BSA/anti-CKAP4/APTES/nZrS3/ITO were carried out through DPV technique. The biosensing platform has ability to detect CKAP4 biomarker in the range of 100 pg mL−1-800 pg mL−1 with ultra-sensitivity of 68.76 µA [log (pg mL−1)]−1cm−2, notable lower detection limit of 86 pg mL−1 and shelf life upto 36 days. Moreover, the electrochemical data obtained, exhibit a good correlation with the concentrations of the cancer biomarker CKAP4 found in lung cancer patients as determined by the enzyme-linked immunosorbent assay (ELISA) technique.

Rice husk derived Aminated Silica for the efficient adsorption of different gases

In this present work, we successfully prepared aminated silica (ASiO2) from rice husk ash (RHA) and functionalized with 3-aminopropyltriethoxysilane (APTES). Physical and chemical properties of the synthesized material were investigated by various techniques SEM–EDX, XPS, FTIR, TGA. The surface area of RHA was 223 m2/g, while for ASiO2 was 101 m2/g. Molecular level DFT calculations revealed that the functionalization of ASiO2 resulted in a significant decrease in the HOMO–LUMO energy gap, a reduction in hardness, and a consequent increase in charge transfer characteristics. The adsorption behavior at low pressure (1 atm.) of aminated silica on different gases CO2, CH4, H2, and N2 at temperatures 77, 273, 298 K was studied. The adsorption of hydrogen was reported for the first time on aminated silica with an excellent adsorption capacity of 1.2 mmol/g. The ASiO2 exhibited excellent performance in terms of gas separation in binary mixtures of CO2/CH4, CO2/N2 and CO2/H2 at 273, and 298 K, respectively. The catalyst further exhibits high stability during three cycles with less than 10% variation in the separation capacity.

CVD Synthesis, Functionalization and CO2 Adsorption Attributes of Multiwalled Carbon Nanotubes

Carbon dioxide is one of the major greenhouse gases and a leading source of global warming. Several adsorbent materials are being tested for removal of carbon dioxide (CO2) from the atmosphere. The use of multiwalled carbon nanotubes (MWCNTs) as a CO2 adsorbent material is a relatively new research avenue. In this study, Fe2O3/Al2O3 composite catalyst was used to synthesize MWCNTs by cracking ethylene gas molecules in a fluidized bed chemical vapor deposition (CVD) chamber. These nanotubes were treated with H2SO4/HNO3 solution and functionalized with 3-aminopropyl-triethoxysilane (APTS). Chemical modification of nanotubes removed the endcaps and introduced some functional groups along the sidewalls at defected sites. The functionalization of nanotubes with amine introduced carboxylic groups on the tube surface. These functional groups significantly enhance the surface wettability, hydrophilicity and CO2 adsorption capacity of MWCNTs. The CO2 adsorption capacity of as-grown and amine-functionalized CNTs was computed by generating their breakthrough curves. BELSORP-mini equipment was used to generate CO2 breakthrough curves. The oxidation and functionalization of MWCNTs revealed significant improvement in their adsorption capacity. The highest CO2 adsorption of 129 cm3/g was achieved with amine-functionalized MWCNTs among all the tested samples.

CO2/CH4 adsorption at high-pressure using silica-APTES aerogel as adsorbent and near infrared as a monitoring technique

The synthesis of adequate adsorbents and efficient methods to separate CO2 present in natural gas streams in petroleum industry has been receiving increased attention in academic and industrial centers. The presence of CO2 in those streams causes serious inconvenient in the transport and processing of natural gas. In this work, the synthesis of pure (SA) and functionalized with (3-aminopropyl) triethoxysilane (APSA) silicas aerogel was performed under microwave irradiation and subsequent drying with supercritical CO2 (SC-CO2). Materials were characterized in relation to their surface area (BET), pore volume (BJH), thermal decomposition (TGA), carbon, hydrogen and nitrogen content (CHN), functional groups (FTIR) and morphology (SEM). The results indicated a modification of the surface of silica with APTES. In addition, the methodology for synthesis and drying of the silica aerogel was efficient and reduced the total time of synthesis. Materials were used as adsorbents in the separation of CO2/CH4 mixtures by using a high-pressure adsorption cell coupled to a near infrared spectroscopy (NIR) probe to monitor CO2 and CH4 concentrations. Adsorption experiments were conducted at 20°C, pressures from 90 to 120 bar and CO2 concentration in the mixture up to 10 mol%. Silica APSA presented adsorptive capacities of 3.30 mmol g−1 at 90 bar and 10.20 mmol g−1 at 120 bar, better than those obtained with the commercial 3-aminopropyl-functionalized silica gel (APSC) of 0.88 mmol g−1 at 90 bar and 9.43 mmol g−1 at 120 bar. NIR was able to quantify the adsorption of CO2 at high-pressure.

Investigating the anti-corrosion behaviors of the waterborne epoxy composite coatings with barrier and inhibition roles on mild steel

Herein, we employed the impermeability of hexagonal boron nitride (h-BN) nanosheets and the inhibition property of strontium zinc phosphate (SZP) corrosion inhibitor to prepare h-BN/SZP waterborne epoxy composite coatings and explored their corrosion protection performance while immersed in 3.5 wt% NaCl solution. On the basis of lip-lip interaction between hexagonal boron nitride, the h-BN nanosheets were exfoliated to a few layers and functionalized with 3-aminopropyltriethoxysilane (APTES). The anti-corrosion performance of the as-prepared waterborne epoxy composite coatings applied on mild steels was evaluated using potential and impedance measurements, fitted pore (pinhole) resistance and salt spray. The corrosion products and the localized electrochemical impedance spectroscopy (LEIS) analysis of the synthesized (Fh-BN, SZP)/EP coating suggested that the superior corrosion resistance of the coated mild steel was attributed to a synergetic effect between physical barrier role of h-BN and inhibition of SZP. Our strategy provides a new protection method in coatings for metallic substrates and will ameliorate the basic research and industrial applications of h-BN nanosheets.

Fabrication and characterization of a high-flux and antifouling polyethersulfone membrane for dye removal by embedding Fe3O4-MDA nanoparticles

Iron oxide (Fe3O4) magnetic nanoparticles were successfully synthesized and functionalized with (3-aminopropyl) triethoxysilane (APTES) and melamine-based dendrimer amine (MDA) groups. The resulted nanocomposites and unmodified Fe3O4 were characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM) and then, added to the polyethersulfone (PES) membrane casting solution, during the phase inversion technique in order to improve its hydrophilicity, permeability, and antifouling properties. Surface and cross-sectional morphology of the resulted bare and nanocomposite membranes were characterized by SEM images. The effect of blended nanoparticles on membrane hydrophilicity and performance were determined using water contact angle, pure water flux, BSA solution filtration, and Reactive Green 19 dye solution rejection. The water contact angle for the bare PES, PES-Fe3O4 (0.5 wt%), PES-Fe3O4-APTES (0.5 wt%), and PES-Fe3O4-MDA (0.5 wt%) were measured to be 60.31°, 51.08°, 44.86°, and 37.18°, respectively. The pure water flux of the blended PES membranes was enhanced significantly compared to the bare PES due to the higher hydrophilicity. The results of fouling resistance factors including reversible, irreversible, and total fouling showed PES-Fe3O4-MDA (0.5 wt%) as the best antifouling membrane. Compared to the all fabricated membranes, PES-Fe3O4-MDA (0.5 wt%) showed the highest hydrophilicity, permeability, rejection, and antifouling properties.

Polyurethane‐mesoporous silica gas separation membranes

The concept of mixed matrix membrane comprising dispersed inorganic fillers into a polymer media has revealed appealing to tune the gas separation performance. In this work, the membranes were prepared by incorporation of mesoporous silica into polyurethane (PU). Mesoporous silica particles with different pore size and structures, MCM‐41, cubic MCM‐48 and SBA‐16, were synthesized by templating method and functionalized with 3‐aminopropyltriethoxysilane (APTES). High porosity and aminated surface of the mesoporous silica enhance the adhesion of the particles to the PU matrix. The SEM and FTIR results showed strong interactions between the particles and the PU chains. Moreover, the thermal stability of the hybrid PUs improved compared to the pure polymer. Gas transport properties of the membranes were measured for pure CO2, CH4, O2, and N2 gases at 10 bar and 25°C. The results showed that the gas permeabilities enhanced with increasing in the loading of modified mesoporous silica particles. High porosity and amine‐functionalized particles render opportunities to enhance the gas diffusivity and solubility through the membranes. The enhanced gas transport properties of the mixed matrix membranes reveal the advantages of mesoporous silica to improve the gas permeability (CO2 permeability up to ~70) without scarifying the gas selectivity (α(CO2/N2)~ 30 for 5 wt% SBA‐16 content).

Design of a lipase-nano particle biocatalysts and its use in the kinetic resolution of medicament precursors

Superparamagnetic iron oxide nanoparticles (Fe3O4) were prepared by the co-precipitation method and functionalized with 3-amino-propyltriethoxysilane (APTES) or branched-polyethylenimine (PEI). After that, two parallels methods to immobilize the lipase from Thermomyces lanuginosus (TLL) were performed: the first one by ionic exchange and the second one by covalent attachment after the functionalization of the support with glutaraldehyde (GA). X-ray powder diffraction, magnetometry and infrared spectroscopy analysis were used to characterize the TLL preparations. These analyses showed that all samples presented superparamagnetic properties even after the immobilization procedure. The SPMN (superparamagnetic nanoparticle) @APTES covalent preparation had around 450min of half-life time at pH 7.0 and 70°C while that of the free enzyme was 46min. These biocatalysts were evaluated in the kinetic resolution of rac-1-methyl-2-(2,6-dimethylphenoxy)ethyl acetate in different co-solvents (acetonitrile, isopropanol, ethyl ether and tetrahydrofuran). The best results were for the enzyme/substrate ratio of 2:1, in the presence of the ethyl ether or THF (20% v/v both) at 30°C during 24h with the SPMN@PEI-TLL biocatalyst. The conversion attained was 50% and the enantiomeric excess of the product was 99%. The new SPMN support are an excellent strategy to easy recovery of the biocatalyst by applying a magnetic field.

Mesoporous MCM-48 Immobilized with Aminopropyltriethoxysilane: A Potential Catalyst for Transesterification of Triacetin

The ordered mesoporous silicas MCM-48, MCM-41, and SBA-15 were synthesized and functionalized with 3-aminopropyltriethoxysilane (APTES). The X-ray diffraction patterns before and after functionalization revealed no structural degradation during the process. FT-IR spectra of the materials clearly indicated the anchoring of the aminopropyl moiety with silanol groups. The amine concentrations were calculated using TG-DTA and CHN analysis. The amine-loaded materials were assessed as catalysts for the transesterification of triacetin with methanol. MCM-48-NH2, in which the pores are interconnected in a three-dimensional manner, exhibited superior catalytic activity to one- dimensional MCM41-NH2 and SBA-15-NH2, even with lower concentrations of the amine group.

Amino- and thiol-modified microporous silicalite-1 and mesoporous MCM-48 materials as potential effective adsorbents for Pb(II) in polluted aquatic systems

Aluminum-free zeolite silicalite-1 and the ordered mesoporous silicates Mobile Crystalline Material No. 48 (MCM-48) were prepared and functionalized with 3-aminopropyltriethoxysilane (APTES) and 3-mercaptopropyltrimethoxysilane (MPTMS) for the enhancement of adsorption capacity. Functionalization via post synthesis grafting method was adopted and the functionalized silicate systems were denoted as silicalite-1-NH2, silcalite-1-SH, MCM-48-NH2and MCM-48-SH. Functionalization, that was confirmed by XRD, FT-IR and surface area measurements, indicated no structural changes on the silicate materials. The adsorption of Pb(II) ions into these modified silicates was investigated in aqueous solutions with optimized pH at 5.5 where adsorption influencing factors including contact time, adsorbent dose and metal ion initial concentration were studied. Adsorption experimental data for silicalite-1-NH2, MCM-48-NH2and MCM-48-SH showed satisfactory correlation with Langmuir and Freundlich models. According to Langmuir isotherm, the maximum capacities for the above three modified silicate systems, for 100 ppm Pb(II) dose, are 43.5, 75.2 and 31.2 mg/g and with Kfconstant values of 16.9, 44.4 and 12.0 L/mg from Freundlich isotherm, respectively. The three modified silicate systems exhibited complete sequestration of Pb(II) ion concentrations in the range 0.48–1.7 ppm from samples collected from Zarqa River in four seasons of the year 2013.

Controlled chemical modification of the internal surface of photonic crystal fibers for application as biosensitive elements

Photonic crystal fibers (PCF) are one of the most promising materials for creation of constructive elements for bio-, drug and contaminant sensing based on unique optical properties of the PCF as effective nanosized optical signal collectors. In order to provide efficient and controllable binding of biomolecules, the internal surface of glass hollow core photonic crystal fibers (HC-PCF) has been chemically modified with silanol groups and functionalized with (3-aminopropyl) triethoxysilane (APTES). The shift of local maxima in the HC-PCF transmission spectrum has been selected as a signal for estimating the amount of silanol groups on the HC-PCF inner surface. The relationship between amount of silanol groups on the HC-PCF inner surface and efficiency of following APTES functionalization has been evaluated. Covalent binding of horseradish peroxidase (chosen as a model protein) on functionalized PCF inner surface has been performed successively, thus verifying the possibility of creating a biosensitive element.

Immobilization of metalloporphyrin on functionalized SBA-15 nanoporous silica

SBA-15 nanoporous silica was prepared by cooperation assembly of tetraethylorthosilicate precursor in the presence of poly (ethylene glycol)–block- poly (propylene glycol)–block- poly (ethylene glycol) copolymer surfactant and functionalized with (3-aminopropyl) triethoxysilane (APTES) via sol-gel reaction to obtain APTES-SBA-15. Tetra-(p-chlorophenyl) porphyrin (TClPP) was synthesized using modified Alder- Longo method. Zinc was inserted into the TClPP using zinc acetate as a metal source The existance of zinc in porphyrin was confirmed by the appearance of Soret band and Q band in UV- vis spectra. ZnTClPP was also characterized using FTIR and NMR spectroscopy SBA-15 was modified with APTES to immobilize the metalloporphyrin on SBA-15 surface. The product (NH-SBA-15 ZnP) can be used as a heterogenous catalyst in various reactions. The formation of this material was confirmed by FTIR spectroscopy, XRD and BET adsorption.

SAXS, FESEM AND BET STUDIES OF MESOPOROUS CATALYST SBA-15CONTAINING ZINC PORPHYRIN FOR EPOXIDATION OF LIMONENE

SBA-15 nanoporous silica was prepared by cooperative self-assembly of tetraethylorthosilicate precursor in the presence of poly(ethylene glycol)–block–poly(propylene glycol)–block–poly(ethylene glycol) copolymer surfactant and functionalized with (3-aminopropyl) triethoxysilane (APTES) via sol-gel reaction to obtain NH2-SBA-15. The metalloporphyrin, [meso-tetrakis-(p-chlorophenyl)porphyrinato]Zn(II) (ZnTClPP) was synthesized from the reaction of meso-tetrakis-(p-chlorophenyl) porphyrin (H2TClPP) using zinc acetate dihydrate as a metal source and then immobilized on SBA-15 surface. The material, NH2-SBA-15-ZnP was characterized by SAXS, FESEM and BET studies and showed a similar pattern as SBA-15 indicating that the mesoporous hexagonal structure of SBA-15 was still retained. Then, the material was applied to catalyze the epoxidation of limonene, using H2O2 / ammonium acetate at various temperatures and conditions. All the products formed from the epoxidation reaction were analyzed using GC-FID and GC-MS.

Direct electron transfer of glucose oxidase-boron doped diamond interface: a new solution for a classical problem.

A planar boron-doped diamond (BDD) electrode was treated with KOH and functionalized with 3-aminopropyltriethoxysilane (APTES) to serve as a biosensing platform for biomolecule immobilization with glucose oxidase (GOx) as a test model. The free amino groups of GOx and APTES were cross-linked by glutaraldehyde (X), a bifunctional chemical to form a stable enzyme layer (GOx-X-APTES) on BDD. Micrographs obtained by scanning electron microscopy revealed that a mesoporous structure uniformly covered the BDD surface. Cyclic voltammetry of GOx immobilized showed a pair of well-defined redox peaks in neutral phosphate buffer solution, corresponding to the direct electron transfer of GOx. The apparent heterogeneous electron transfer rate constant of the immobilized GOx was estimated to be 8.85 ± 0.47 s(-1), considerably higher than the literature reported values. The determination of glucose was carried out by amperometry at -0.40 V, and the developed biosensor showed good reproducibility and stability with a detection limit of 20 μM. Both ascorbic and uric acids at normal physiological conditions did not provoke any signals. The dynamic range of glucose detection was further extended by covering the enzyme electrode with a thin Nafion layer. The Nafion/GOx-X-APTES/BDD biosensor showed excellent stability, a detection limit of 30 μM, a linear range between 35 μM and 8 mM, and a dynamic range up to 14 mM. Such analytical performances were compared favorably with other complicated sensing schemes using nanomaterials, redox polymers, and nanowires. The APTES-functionalized BDD could be easily extended to immobilize other redox enzymes or proteins of interests.

Porcine pancreatic Lipase Immobilized in Amino-Functionalized Short Rod-Shaped Mesoporous Silica Prepared Using Poly(ethylene glycol) and Triblock Copolymer as Templates

Mesoporous materials have large ratio surface areas, an average pore diameter, and ordered pore arrangement, showing promising application in the fields of catalysis, adsorption, separation, and functional materials. In this study, short rod-shaped mesoporous silica (SRSMS) were prepared using poly(ethylene glycol) (PEG) and P123 as dual templates and functionalized with (3-aminopropyl)triethoxysilane (APTES) by a postsynthesis-grafting method. The synthesis conditions, including PEG chain length and PEG concentration, when the dual templates were added to the reaction system are discussed. The results show that the d100 increased continuously with the increase of PEG concentration and molecular weights (MW). When PEG with different MW was added, the pore size of SRSMS changed a little, while it increased with increasing PEG content. Pore volumes and surface areas of SRSMS decreased, while the two-dimensional hexagonal p6mm mesoscopic structure remained after functionalization. Porcine pancreatic lipase (PPL) was used as a model enzyme for studying the effect of amino-functionalization on loading amount and enzymatic activity. As a result, functionalized SRSMS immobilized PPL showed the better reusability, higher catalytic activity, and thermal stability.

Monoamine-grafted MCM-48: An efficient material for CO 2 removal at low partial pressures

Mesoporous cubic MCM-48 material was synthesized and functionalized with 3-aminopropyltriethoxy-silane (APTES) under different conditions and used for CO 2 adsorption. Before and after functionalization the materials were characterized by different techniques: XRD, TEM, TGA, fluorescence analysis of amino and adsorption–desorption isotherms of N 2 and CO 2. The results confirmed that CO 2 adsorption in amino modified materials involves both chemisorption and physisorption. The former is the primary mechanism at low partial pressures, and includes the formation of carbamates. This material demonstrated a high efficiency for CO 2 removal at low CO 2 partial pressures, with loadings of 0.5 mmolCO 2/molN at 5 kPa. The maximum adsorption capacity at 1 atm of CO 2 was 1.68 mmol/g.

A Hexagonally Ordered Nanoporous Silica-Based Fiber Coating for SPME of Polycyclic Aromatic Hydrocarbons from Water Followed by GC–MS

A highly porous fiber coating material was prepared and functionalized with 3-amino propyl triethoxysilane (APTES) on hexagonally ordered nanoporous silica (SBA-15). Applicability of this coating was assessed employing a laboratory made solid-phase microextraction (SPME) device and gas chromatography–mass spectrometry for the simultaneous sampling and determination of trace polycyclic aromatic hydrocarbons (PAHs) from aqueous sample solutions. A one at the time optimization strategy was applied to investigate and optimize important extraction parameters such as extraction temperature, extraction time, ionic strength and sonication time. In the optimum conditions, the relative standard deviations for deionized water, spiked with selected PAHs were between 3.3 and 7.7% (n = 3), and detection limits for the studied compounds were 4.2 and 26.1 pg mL−1. No significant change was observed in the extraction efficiency of the new SPME fiber, over 50 extractions. The proposed method was successfully applied to the extraction and determination of PAHs in the waste water samples.

Cu(II) complexes imobilized on functionalized mesoporous silica as catalysts for biomimetic oxidations

Mesoporous HMS silica was synthesized and functionalized with 3-aminopropyl-triethoxysilane (APTES) by a post-synthesis method. HMS and NH2-HMS supports were used for immobilization of two Cu(II) biomimetic complexes ([Cu(acac)(phen)(H2O)](ClO4), [Cu(acac)(Me2bipy)](ClO4)) or laccase enzyme. Mesoporous structure of the support; functionalization of silica surface, structure of ligands, and Cu complexes; and their immobilization were evidenced by XRD analysis, N2 adsorption–desorption, SEM microscopy, TGA-DTA, IR and UV–Vis spectroscopy, and elemental analysis. The results confirm the structural integrity of the mesoporous hosts and successful anchoring of the metal complexes over the supports. For comparison, copper-substituted mesoporous silica (Cu-HMS) by using dodecylamine as structure-directing agent was also synthesized. All the synthesized materials were tested for their catalytic activity on the oxidation of 4-aminoantipyridine, 2,2′-azinobis (3-ethyl-benzothiazoline)-sulfonic acid (ABTS) with air, as well as in liquid phase oxidation of anisole and phenol with hydrogen peroxide. In order to verify the complex biomimetic activity, the Trametes versicolor laccase was immobilized by adsorption in the same supports.