Search

Fe3O4-SiO2-NH2, Fe3O4-CTABSiO2-NH2 and Fe3O4-SiO2-CTABSiO2-NH2 magnetic adsorbents were successfully prepared and could be used effectively for the adsorption of Light Green from aqueous solutions. Unlike the first sample, mesoporous silica coatings were created using cetyltrimethylammoniumbromide micelles as molecular templates on superparamagnetic iron oxide in one sample, and on silica-coated iron oxide in the other sample to improve the adsorptive properties of the nanocomposites. The characterization by FT-IR, SEM/EDX, Zeta-potential, XRD, VSM, and N2-adsorption/desorption confirmed the production of mesoporous silica layer. Although coating processes with both silica and mesoporous silica layers led to a vaguely decrease in saturation magnetization of the Fe3O4-SiO2-CTABSiO2-NH2, the nanoparticles were protected with silica coatings for environment conditions and made more suitable for subsequent amino functionalization. The results determined from Batch adsorption experiments fitted to Langmuir isotherm model with maximum adsorption capacity (qmax) equal to 56.18, 196.08 and 227.27 mg g−1, for Fe3O4-SiO2-NH2, Fe3O4-CTABSiO2-NH2 and Fe3O4-SiO2-CTABSiO2-NH2, respectively, and it was seen from the kinetic results, the LG adsorption was identified by pseudo-second-order kinetics, revealing that LG adsorption process is homogeneous, monolayer and based on chemical interactions. According to the results, both silica and mesoporous silica coating strategy can play crucial role in improving the adsorptive properties of nanocomposites.

Multifunctional magnetic mesoporous nanocomposites are promising materials to remove the various pollutants from water due to the remarkable properties such as multiple binding sites, high surface area, and magnetic separation. Herein, we have developed a versatile nanocomposite, in which polydopamine (PDA) coated Fe3O4 nanoparticles are introduced during the synthesis of SBA-15 matrix for the first time to enhance adsorptive properties of hydrophilic magnetic mesoporous nanocomposite by combining the properties of high surface area, magnetization, and capability of interacting with more functional groups in one material. The resulting nanocomposite, Fe3O4@PDA@SBA-15, has been proved to be the effective sorbent for the removal of cationic dye, which can be ascribed to the functional groups of grafted PDA and the textural features of matrix SBA-15. On the other hand, after chemical modification via silanization of vinyltriethoxysilane (VTES), Fe3O4@PDA@SBA-15 nanocomposite turned to be a hydrophobic material, Fe3O4@PDA@SBA-15@VTES, which can adsorb oil with high adsorption capacity which could reach 8.83 times of its own weight. Moreover, both nanocomposites could be recycled by facile washing and drying processes. The materials provide a simple strategy for the preparation of multifunctional magnetic mesoporous nanocomposites satisfying various applications in water treatment.

Fe3O4@SiO2@NH2 nanocomposite was prepared for highly effective adsorption of two anionic dyes one of which is triarylmethane dye (light green, LG) and the other is azo dye (brilliant yellow, BY). T...

A multifunctional heterogeneous acid catalyst named as spFe3O4@SBA-15@HPW was prepared, which consists of versatile properties such as magnetic separability, high conversion efficiency and reusability. This catalyst was characterized by XRD, FT-IR, VSM, TEM and SEM/EDX techniques with respect to structural, morphological and magnetic properties. The catalyst showed higher catalytic activity than the commercial catalysts such as Amberlyst-15 and Dowex 50Wx4 and also heteropoly tungstic acid (HPW) alone in terms of conversion of oleic acid for biodiesel production by the esterification of oleic acid with methanol. The experimental data were correlated by pseudo-first-order homogeneous and Eley-Rideal heterogeneous models, and the results demonstrate the suitability of Eley-Rideal mechanism.

WOS: 000449033200003, In our approach for magnetic iron oxide nanoparticles surface modification, the fabrication of an inorganic shell, consisting of silica by the deposition of preformed colloids onto the nanoparticle surface and functionalization of these particles, was realized. The magnetic nanoparticles, non-coated and coated with silica layer by Stober method, are functionalized with chlorosulfonic acid. The magnetic nanoparticles (MNPs), in size of 10-13 nm, could be used as acid catalyst in biodiesel production and show superparamagnetic character. The prepared nanoparticles were characterized by different methods including XRD, EDX, FT-IR and VSM. The catalytic activity of the coated and non-coated solid acids was examined in palmitic acid-methanol esterification as an industrial reaction for biodiesel synthesis. Although thin silica layer results in only a minor obstacle with respect to magnetism, it can accelerate the mass transportation due to its relatively porous structure and magnetic core may be more stable in the acidic reaction medium by means of covering process. Accordingly, coating strategy can be efficient way for allowing applications of MNPs in acid catalyzed esterification., Commission of Scientific Research Projects of Uludag University [KUAP(F)-2014/33], This work was supported by The Commission of Scientific Research Projects of Uludag University, Project number: KUAP(F)-2014/33.

The magnetically separable mesoporous silica nanocomposites were successfully prepared through a one-pot method including the co-condensation of tetraethoxysilane (TEOS) as silica precursor and 3-mercaptopropyl trimethoxysilane (MPTMS) as functionalizing agent accompanied with hydrogen peroxide for oxidation of mercapto groups and triblock copolymers as structure directing agent in the presence of ferromagnetic and superparamagnetic Fe 3 O 4 nanoparticles. By incorporating the superparamagnetic (near zero coercivity) Fe 3 O 4 nanoparticles to the mesoporous silica (SBA-15) and functionalizing with sulfonic acid groups instead of ferromagnetic Fe 3 O 4 nanoparticles, we developed versatile nanocomposite having superior properties with respect to magnetism, catalysis and porosity. Reducing the particle size of Fe 3 O 4 from the ferromagnetic regime to the superparamagnetic regime, the pore closure could be eliminated because of the more open pore as well as saving magnetic properties.

3rd International Conference on Computational and Experimental Science and Engineering (ICCESEN) -- OCT 19-24, 2016 -- Antalya, TURKEY, WOS: 000412881200096, Organic functionality can be added to mesoporous silicates in two ways: either by covalent grafting (postsynthetic) of various functional groups onto the channel walls or by incorporating functionalities directly during the synthesis (one-pot). If the grafted catalytically active groups experience similar environments and are isolated from each other, catalysis process is greatly facilitated. For this purpose, boric acid, as boron source, was added into the initial reaction mixture and then acid functionalization was performed by post and direct method. The obtained acid catalysts were tested in the esterification of propionic acid with methanol and the activity of these new materials was compared to that of SBA-15-SO3H. Boron addition has facilitated the methyl propionate esterification for both postsynthetic and direct functionalized acid catalyst. Boron incorporated and postsynthetic functionalized mesoporous acid catalyst has highly enhanced the esterification reaction, compared to direct functionalized acid catalyst. The post functionalization method seems to be superior to one-pot functionalization method for preparation of mesoporous acid catalysts., Commission of Scientific Research Projects of Uludag University [OUAP(F)-2015/21], This work was supported by The Commission of Scientific Research Projects of Uludag University, Project number: OUAP(F)-2015/21.

Novel approach was developed towards the synthesis of heterogeneous mesoporous B-SBA-15-SO3H acid catalysts. That is: B-SBA-15 materials were hydrothermally synthesized by using three different boron sources (boric acid, trisiopropylborate and potassium borohydride) and then post-synthetically functionalized with sulfonic acid to test their catalytic activity for the esterification of propionic acid with methanol. Mesoporous and amorphous character of the materials as well as the incorporation of the boron into the framework were verified by XRD, N-2-adsorption/desorption, ICP-OES, SEM and FT-IR techniques. All of the boron incorporated acid catalysts showed better activity than pure SBA-15-SO3H for methyl propionate synthesis. Combining the advantageous of hydrothermal synthesis and post functionalization, the obtained B-SBA-15-SO3H catalysts should present versatile catalytic properties in terms of both catalytic activity and reusability. Boron incorporation and post functionalization encourage the structural configuration, since the grafted catalytically active groups may experience similar environments and be isolated from each other.

3rd International Conference on Computational and Experimental Science and Engineering (ICCESEN) -- OCT 19-24, 2016 -- Antalya, TURKEY, WOS: 000412881200098, Ordered mesoporous silicas can be utilized as support because of having large surface area, tunable porosity, uniform pore size distribution, high thermal stability and modifiable properties. However, these materials introduce separation problems in liquid-phase processes. We have prepared Fe3O4-SBA-15-SO3H solid acid catalyst by combining the properties of a magnetic material and the mesoporous character of silica. The sulfonic acid functionalized solid acid catalyst, containing both magnetic nanoparticles and mesoporous silica, is not only separable but also stable under hydrothermal conditions, which are usually employed for biodiesel production. Esterification of oleic acid with methanol for biodiesel production was carried out effectively and 75% conversion of ester was approximately reached within six hours in the presence of Fe3O4-SBA-15-SO3H magnetic solid acid catalyst. In addition, the catalyst could be separated from the reaction system by applying external magnetic field and reused without deactivation., Commission of Scientific Research Projects of Uludag University [OUAP(F)-2015/21, KUAP(F)-2014/33], This work was supported by The Commission of Scientific Research Projects of Uludag University, Project number: OUAP(F)-2015/21 and KUAP(F)-2014/33.

3rd International Conference on Computational and Experimental Science and Engineering (ICCESEN) -- OCT 19-24, 2016 -- Antalya, TURKEY, WOS: 000413982900062, SBA-15-SO3H supported tungstophosphoric acid (TPA, H3PW12O40) mesoporous materials were synthesized by impregnation of TPA into the hydrothermally synthesized SBA-15-SO3H and the catalytic performances were compared for the esterification reaction. The physical and chemical properties of the catalysts were characterized by XRD, SEM/EDX, FT-IR and N-2 adsorption/desorption techniques. The characterization results show that TPA/SBA-15-SO3H retained the typical mesoporous structure of SBA-15-SO3H. The experimental results indicated that TPA/SBA-15-SO3H is a more efficient catalyst than SBA-15-O3H for the esterification reaction. The higher activity of TPA/SBA-15-SO3H compared with that of SBA-15-SO3H was consistent with the material having the low pKa value, confirming that the esterification rate was mostly dependent on the acid strength of the additional functional groups of solid acid catalyst. Accordingly, the reason for the catalytic activity difference was simply explicated by the effect of TPA, having low pKa value, affecting the pore structure and the total acidity.

WOS: 000324103300007, The influence of poly(ethylene glycol) (PEG) and synthesis temperature in the synthesis of SBA-15-SO3H was investigated to evaluate the catalytic activity in the esterification of propionic acid with methanol. The catalysts were characterized by means of surface and structure analyses; X-ray diffraction, FT-IR, scanning electron microscopy, Thermo-gravimetric and N-2 adsorption/desorption techniques. It was found that, by the addition of PEG, the surface area and porosity of SBA-15-SO3H increased, while the structure and size of mesopores remained unchanged. Nitrogen sorption measurements indicate that PEG introduces additional pores into the pore walls of SBA-15-SO3H. Thus, a simple way of improving the porosity of mesoporous SBA-15-SO3H was presented that could enhance transport of substrates through the porous system and allow the generation of stable mesoporous replicas, important for catalytic applications and also beneficial for replication and nanocasting purposes., Commission of Scientific Research Projects of Uludag University [UAP(F)-2011/69], This work was supported by The Commission of Scientific Research Projects of Uludag University, Project number: UAP(F)-2011/69.

Magnetic vinylphenyl boronic acid microparticles, poly(ethylene glycol dimethacrylate-vinylphenyl boronic acid) [m-poly(EGDMA-VPBA)], produced by suspension polymerization, was found to be efficient solid acid catalyst for the esterification of methanol and propionic acid. Characterization techniques such as FT-IR, Elemental analyses, ICP-AES, ESR, SEM and N 2 sorption showed that both of Fe 3 O 4 and H 2 SO 4 are bonded to the polymer successfully. Esterification was studied for different molar percentages of H 2 SO 4 at temperature range of 50-70 o C. The apparent activation energy was found to be 27.7 kj.mol -1 for 10% H 2 SO 4 doped m-poly(EGDMA-VPBA). Combining of strong acid H 2 SO 4 with m-poly(EGDMA-VPBA), leads to materials with different functional properties. In addition, H 2 SO 4 species could be introduced into the structure as acid centers, therefore this micro-dimensional catalyst has potential candidate for applications in the catalytic esterifications such as propionic acid with methanol.

The magnetic-poly(divinylbenzene-4-vinylpyridine) [m-poly(DVB-4VP)] microbeads (average diameter: 180–212 μm) were synthesized by copolymerizing of divinylbenzene (DVB) with 4-vinylpyridine (4VP) and by mixing this copolymer with Fe 3 O 4 nanoparticles. The resultant material was characterized by N 2 adsorption/desorption, ESR, elemental analysis, scanning electron microscope (SEM) and swelling studies. After functionalized with sulfonic acid, m-poly(DVB-4VP-SO 3 H) was characterized by FT-IR and TGA analysis. The results showed that both of Fe 3 O 4 and –SO 3 H are bonded to the polymer successfully. N 2 adsorption/desorption isotherms of synthesized samples had the hysteresis behaviour associated with mesoporous materials (pore diameter: 3.73 nm). Sulfonic acid functionalized mesoporous m-poly(DVB-4VP-SO 3 H) has been demonstrated to have higher reactivity than commercially available solid acid catalysts for the conversion of propionic acid to methyl ester. The apparent activation energy was found to be 38.5 kJ mol −1 for m-poly(DVB-4VP-20%SO 3 H). The catalyst showed negligible loss of activity after four repetitive cycles.

Kinetics of heterogeneous catalysed esterification of propionic acid with n-amyl alcohol was studied with a microporous cation-exchange resin catalyst, Dowex 50Wx4, in a stirred batch reactor to synthesise amyl propionate. Effects of various parameters such as speed of agitation, catalyst loading, and reaction temperature on reaction rate were investigated. The equilibrium conversion of propionic acid increased with in catalyst loading and reaction temperature. Stirrer speed had virtually no effect on the reaction rate under the experimental conditions. The apparent activation energy was found to be 43.167 kJmol−1 for the formation of amyl propionate and the equilibrium constant, which is independent of temperature ranging from 318 to 348 K, was found to be 4.05. It was also observed that the initial reaction rate decreased with water concentrations and increased with that of acid and increased with that of alcohol linearly. The reaction was found to occur between an adsorbed acid molecule and a molecule of alcohol in the bulk and it was concluded that the reaction mechanism can be represented by Eley-Rideal model.

WOS: 000353876100015, The effect of calcination temperature on the structural and magnetic properties of Ni/SBA-15 nanocomposite prepared by reductant-impregnation method was studied using SBA-15 mesoporous silica as support. The structure, morphology and magnetic properties of the samples were characterized using X-ray diffraction, scanning electron microscopy with energy-dispersive X-ray spectrometry, N-2 adsorption/desorption (BET and BJH), vibrating sample magnetometer, and FT-IR. Characterization results showed the presence of crystalline phases characteristics of the Ni and/or NiO, and that the structural characteristics of the support were maintained after the impregnation of nickel ions followed by calcinations. Calcination process helps in crystallization and formation of the desired phase such as well crystalline NiO and Ni nano-particles. Moreover, this heat resulted in significant effects on different properties of the products such as the crystallite size, homogeneity, particle distribution, porosity, surface area and the sintering process. Magnetic measurements suggested that the magnetic properties in nanocomposites is probably the sum of two contributions: superparamagnetic and ferromagnetic one depending on the calcination temperature. Calcination at high temperatures affects both of the structural and magnetic properties of Ni/SBA-15. Because the location of the Ni particles depends on the pore size of the support, the uniformity of particle size was related to the interaction between the Ni particles and support., Commission of Scientific Research Projects of Uludag University [UAP(F)-2011/69], This work was supported by The Commission of Scientific Research Projects of Uludag University, Project number: UAP(F)-2011/69. The authors thank Sami Tekdemir and Ece Ozkan for assistance in VSM and XRD characterizations, respectively.

Esterifications of n-amyl alcohol with propionic acid catalyzed by macroporous (Amberlyst-15) and microporous (Dowex 50 W and Amberlite IR-120) polymeric ion-ex6hange resins were carried out between 333-348 K. When these catalysts were used as commercially available, Amberlyst-15 was observed to be the most effective catalyst with respect to rate constants, but after drying it became the less effective one. The reaction rate increased with increase in catalyst concentration and reaction temperature. Stirrer speed and different mesh sizes had virtually no effect on the rate under the experimental conditions. The effect of divinylbenzene content was examined for the micro porous resin Dowex 50 W, and the results showed that the propionic acid conversion decreased as the divinylbenzene content was increased. The rate data were correlated with a second-order homogeneous reaction model. The apparent activation energies, reaction enthalpies and entropy values were calculated for each catalyst. Reaction monitoring is simple and fast by volumetric method and the reproducibility of this method was the order of +/- %2.54.

Sulfonic acid functionalized poly(ethylene glycol dimethacrylate-1-vinyl-1,2,4-triazole), poly(EGDMA-VTAZ-SO 3 H), is evaluated in the esterification of lactic acid with methanol. From nitrogen physisorption data, high surface area (220 m 2 /g) and type IV isotherm are obtained. Conversion measurements indicate a stronger interaction of poly(EGDMA-VTAZ-20%SO 3 H) with water molecules than that occurring in poly(EGDMA-VTAZ-10%SO 3 H). Hence, the higher catalytic activity of poly(EGDMA-VTAZ-10%SO 3 H) is related to the more hydrophobic microenvironment of –SO 3 H sites, which reduces the acid site deactivation associated with adsorption of water generated during the reaction. Moreover, apparent activation energy is found to be 48.02 kJ mol −1 , which can be comparable with the literature values.

WOS: 000301320500021, PubMed ID: 22197058, Mesoporous silica SBA-15 has been synthesized and functionalized by one-step synthesis method to widen their various application possibilities. In this study, phenyltrimethoxysilane (PTMS), 3-mercapto-propyltrimethoxysilane (MPTMS) and trimethoxypropylsilane (TMPS) were used as silane precursors for the functionalization, and after treated with HCl solution, their catalytic activities were evaluated in the lactic acid-methanol esterification. The presence of anchoring of functional groups on SBA-15 was proved by XRD, FT-IR, BET surface area and pore size distributions. Good catalytic activity was observed especially for SBA-15-SO3H-MPTMS, and the catalytic activity order was determined as follows: SBA-15SO(3)H-MPTMS > SBA-15-TMPS > SBA-15-PTMS, which is directly associated with the surface area, pore size and pore volume. As compared with homogeneous catalyst, SBA-15-SO3H-MPTMS heterogeneous catalyst shows remarkable performance, such as separation, recovery and reusability

Sulfonic acid functionalized poly (ethylene glycol dimethacrylate-1-vinyl-1,2,4-triazole), poly (EGDMA–VTAZ–SO3H) (average diameter 1.0–1.5 mm), was found to be efficient solid acid catalyst for the esterification of methanol and propionic acid under heterogeneous reaction conditions. The pristine polymer, poly (EGDMA–VTAZ), was produced by suspension polymerization and then proton-conducting polymer was obtained by blending of poly (EGDMA–VTAZ) with different percentage of H2SO4 solutions. The protonation of aromatic heterocyclic rings was proved with Fourier-transform infrared spectroscopy (FT-IR). Thermo gravimetric (TG) analysis showed that the catalyst is thermally stable up to 573 K. The surface morphology of the catalyst was characterized by scanning electron microscopy (SEM). Poly (EGDMA–VTAZ–SO3H) beads can be regenerated and reused, so this provides a potential application. It has a rate constant which exceeds that of Amberlyst-15 by a factor of about four at 333 K. As for the reaction equilibrium constant (Ke), which is independent of temperature ranging from 318 to 343 K, was determined to be 3.16. The apparent activation energy was found to be 41.6 kJ mol−1 for poly (EGDMA–VTAZ–SO3H).

This paper describes the application of LFER in the form of Taft correlation to understand the mechanism of the esterification of propanoic acid with different alcohols over heterogeneous catalyst, Dowex 50Wx4. The rate constant (k1) in the rate equation decreases with change of alcohols in the order methanol, ethanol, n-propyl, n-butyl, n-pentyl, iso-butyl, iso-propyl and sec-butyl (2-buthanol). The reaction of propanoic acid with alcohols fits the Taft equation, log k1/kCH3= 1.0061 Es- 0.0012, which implies that the steric effect of the substituent governs that reaction and the mechanism is similar between the different alcohols. The experimental results were modelled according to a simple second-order model. It was found that the equilibrium constant of this reaction does not depend on the structure of the organic alcohols, and has for 333 K the value 4.04.

Summary Esterification of methyl alcohol with acetic acid catalysed by commercially available polymeric ion-exchange resins Amberlyst-15, Dowex 50W and Amberlite IR-120 was carried out in the temperature ranging between 323–338K. Mesh sizes and divinylbenzene contents had virtually no effect on the rate the data of which were correlated with a second-order homogeneous reaction. The samples were analysed with gas chromatography, refractometry and volumetry. The reproducibilities were the order of ±2.89%, ±5.07% and the order of ±6.58% respectively for the volumetric, chromatographic and refractometric methods.