•CoFe2O4-APTES-Pd (0) nanocomposite, as effective catalysts for reduction reactions.•It could be reused several times without significant loss in hydrogenation reaction.•So far, CoFe2O4-APTES-Pd (0) ...nanocomposite have not been synthesized.•CoFe2O4-APTES-Pd (0) nanocomposite was confirmed by XRD, FT-IR.•Pd containing nanoparticles embedded in organic surfactant observed by TEM.
A new magnetically recyclable catalyst, CoFe2O4-APTES-Pd(0) nanocomposite, as highly effective catalysts for reduction reactions in liquid phase was fabricated and characterized. The reduction of Pd2+ was accomplished with sodium borohydride (NaBH4). The chemical characterization of the product was done with X-ray diffractometry, infrared spectroscopy, transmission electron microscopy, UV–Vis spectroscopy and inductively coupled plasma. It was found that the combination of CoFe2O4 and 3-aminopropyltriethoxysilane (APTES) could give rise to structurally stable catalytic sites. Furthermore, the high magnetization CoFe2O4-APTES-Pd(0) catalyst can be recovered by magnet and reused for ten runs for hydrogenation reaction of 4-nitro aniline, 1,3 dinitro and cyclohexanone. The catalyst was easily isolated from the reaction mixture by a magnetic bar and reused at least 10 times without significant degradation in the activity which shows the indicative of a potential applications of these catalysts in industry.
A functionalized multiwall carbon nanotube (MWCNT)–COOH/Fe
3
O
4
hybrid was fabricated by co-precipitation method. Fe
3
O
4
nanoparticles were stably attached to the surface of carboxyl groups ...(COOH). The presence of Fe
3
O
4
nanoparticles and their surface conjugation to MWCNT have been confirmed by XRD, TEM and FT-IR techniques. Magnetic evaluation revealed a superparamagnetic character of the hybrid and therefore the attached Fe
3
O
4
nanoparticles. The crystallite size (9 ± 3 nm), particle size (9 ± 2 nm) and magnetic domain size estimated for Fe
3
O
4
are consistent with each other, which reveal the single crystalline character of the nanoparticles. Electrical conductivity and dielectric behavior have also been characterized by utilizing impedance spectroscopy up to 3 MHz for an isotherm line varying from 293 to 393 K by 10 K steps. Electrical characteristics and its complex dielectric approaches might be elucidated with the existence of a conventional tunneling conduction mechanism of temperature-independency. The AC conductivity of MWCNT–COOH/Fe
3
O
4
hybrid could also be a consequence of the estimations of the universal dynamic response.
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► Novel superparamagnetic Fe3O4–PPCA NPs were fabricated through one-pot reflux route. ► It could be reused several times without significant loss in catalytic activity for ...Knoevenagel rxn. ► No further modification of the Fe3O4–PPCA NPs is necessary for utilization as catalyst.
Piperidine-4-carboxylic acid (PPCA) functionalized Fe3O4 nanoparticles as a novel organic–inorganic hybrid heterogeneous catalyst was fabricated and characterized by XRD, FT-IR, TGA, TEM and VSM techniques. Composition was determined as Fe3O4, while particles were observed to have spherical morphology. Size estimations using X-ray line profile fitting (10nm), TEM (11nm) and magnetization fitting (9nm) agree well, revealing nearly single crystalline character of Fe3O4 nanoparticles. Magnetization measurements reveal that PPCA functionalized Fe3O4 NPs have superparamagnetic features, namely immeasurable coercivity and absence of saturation. Small coercivity is established at low temperatures. The catalytic activity of Fe3O4–PPCA was probed through one-pot synthesis of nitro alkenes through Knoevenagel reaction in CH2Cl2 at room temperature. The heterogeneous catalyst showed very high conversion rates (97%) and could be recovered easily and reused many times without significant loss of its catalytic activity.
Ag(0) NPs were prepared by chemical reduction method in which silver nitrate was taken as the metal precursor and cefditorene as a reducing/capping agent and NaOH as the catalyst for reaction ...enhancement. The formation of the Ag(0) NPs was monitored using UV–Vis absorption spectroscopy confirmed the formation of Ag(0) NPs by exciting the typical surface plasmon absorption maxima at 405 nm. Transmission electron microscopy (TEM) confirmed the spherical morphology of the (Ag(0) NPs). The crystallite (11 ± 3 nm) and particle size (14.1 ± 2.2 nm) obtained from TEM and XRD analysis were coinciding with each other. Prepared Ag(0) NPs were then used as catalyst against 2-nitroaniline, 3-nitroaniline and 4-nitroaniline, which all showed best catalytic activity.
Synthesis scheme of poly(1-vinyltriazole)-grafted SPION. Display omitted
► Superparamagnetic iron oxide nanoparticles (SPION) were fabricated by gel-to-crystalline conversion method. ► Telomerization ...of poly(1-vinyltriazole) on iron oxide nanoparticles was achieved via silanization process. ► Silica was coated on Fe3O4 nanoparticles to avoid the aggregation of the particles.
We reported on the synthesis and detailed physicochemical characterization of poly(1-vinyltriazole)-grafted iron oxide nanoparticles. Superparamagnetic iron oxide nanoparticles (SPION) were fabricated by gel-to-crystalline conversion method. Telomerization of poly(1-vinyltriazole) on iron oxide nanoparticles was achieved via silanization process. XRD analysis confirmed the crystalline phase as magnetite, and FT-IR analysis confirmed the presence of PVTri on nanoparticles. Particle morphology was observed to be polygonic, due to the synthesis process, while average size estimated from TEM micrographs is 7nm. Agreement between crystallite size estimated from XRD and particle size from TEM affirms single crystalline character of these nanoparticles. Dependence of conductivity on temperature showed a strong evidence for thermally activated polarization mechanism. Temperature and frequency dependence of dielectric permittivity revealed interfacial polarization and temperature-assisted-reorganization effects. Magnetic evaluation showed non-saturation and superparamagnetic characteristics of nanoparticles as well as magnetic particles being single domains.
Polyethylene glycol stabilized Cobalt oxide, (Co
3
O
4
), nanoparticles were prepared via simple, one-step, inexpensive hydrothermal method. In this process, polyethylene glycol was used as a solvent ...and surfactant; gaseous NH
3
was used as an alkalinity additive. Investigation of the structural, morphological, thermal, and magnetic properties were carried out using X-ray diffraction (XRD), infrared spectroscopy (FT-IR), transmission electron spectroscopy (TEM), thermal analysis (TGA), and vibrating sample magnetometer (VSM), respectively. The nanocrystalline nature of the sample was confirmed by XRD and TEM. FT-IR measurement revealed that the O from C–O coordinates with the surface of Co
3
O
4
NP’s. Room temperature VSM measurement showed the ferromagnetic behavior of the product.
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► Novel superparamagnetic NiFe2O4–Pd magnetically recyclable catalyst was fabricated through co-precipitation. ► It could be reused several times without significant loss in catalytic ...activity for hydrogenation reaction. ► No further modification of the NiFe2O4–Pd magnetically recyclable catalyst is necessary for utilization as catalyst.
Herein we report the fabrication and characterization magnetically recyclable catalysts of NiFe2O4–Pd nanocomposite as highly effective catalysts for reduction reactions in liquid phase. The reduction Pd2+ was accomplished with polyethylene glycol 400 (PEG-400) instead of sodium borohydride (NaBH4) and NiFe2O4 nanoparticles was prepared by sonochemically using FeCI3·6H2O and NiCl2. The chemical characterization of the product was done with X-ray diffractometry, Infrared spectroscopy, transmission electron microscopy, UV–Vis spectroscopy, thermal gravimetry and inductively coupled plasma. Thus formed NiFe2O4–Pd MRCs showed a very high activity in reduction reactions of 4-nitro aniline and 1,3-dinitrobenzene in liquid phase. It was found out that the catalytic activity of NiFe2O4–Pd MRCs on the reduction of 4-nitro aniline and 1,3-dinitrobenzene in liquid phase are between 99–93% and 98–93%, respectively. Magnetic character of this system allowed recovery and multiple use without significant loss of its catalytic activity. It is found that NiFe2O4–Pd MRCs showed very efficient catalytic activity and multiple usability.
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► This is the first report of synthesis of a poly(2-thiophen-3-yl-malonic acid)/Fe
3O
4 nanocomposite material. ► Conductivity measurements show that the material is semiconducting ...and also magnetization measurements indicates its super-paramagnetic character. ► A bidentate coordination between polymer and magnetite is evidenced by FT-IR analysis.
Poly(2-thiophen-3-yl-malonic acid)/Fe
3O
4 nanocomposite was synthesized by the precipitation of Fe
3O
4 in the presence of poly(2-thiophen-3-yl-malonic acid) (PT3MA). Characterizations of the nanocomposite were performed by XRD, FT-IR, TEM, TGA, AC/DC conductivity and dielectric measurements. The capping of PT3MA around Fe
3O
4 nanoparticles was confirmed by FTIR spectroscopy, the interaction being between bridging oxygen of the carboxylate and the nanoparticle surface through bidentate binding. The crystallite particle sizes of 6
±
3
nm and 7
±
3
nm were obtained from XRD line profile fitting and from TEM image analysis respectively, and they are in good agreement with each other. Magnetization measurements revealed that PT3MA coated magnetite particles do not saturate at higher fields. The material showed superparamagnetic character as revealed by the absence of coercivity and remnant magnetization. Magnetic particle size was calculated as 7.3
±
1.0
nm from the mean magnetization term in the Langevin function which is also in conformity with the values determined from TEM micrographs and XRD line profile fitting. The TEM particle size analysis of the nanoparticles revealed the presence of a slightly modified magnetically dead nanoparticle surface. AC and DC conductivity measurements were performed to elucidate the electrical conduction characteristics of the product.
