Abstract
Amines can be applied in the synthesis of various important compounds such as dyes, drugs, polymers, pharmaceutical products, and biologically active materials. The significant subject in ...the preparation of amines is the selection of the most effective heterogeneous catalyst to get the best catalytic efficiency, stability, recoverability, and reusability. For this target, we prepared new alginate magnetically recoverable nanocatalyst by stabilization of Ag nanoparticles on the surface of the halloysite (HS) HS-Alginate-Ag/Fe
3
O
4
. Several detection methods confirmed the production of HS-Alginate-Ag/Fe
3
O
4
nanocatalyst and the results obtained were well explained in the context. HS-Alginate-Ag/Fe
3
O
4
presented good catalytic performance for the hydrogenation of nitro compounds using NaBH
4
as the reducing agent and hydrogen donor. The good activity and durability of this catalyst can be attributed to the good dispersion and nano-sized particle of silver nanoparticles.
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Using natural materials, i.e. halloysite nanoclay that is a biocompatible naturally occurring clay and Heracleum persicum extract that can serve as a green reducing agent, a novel magnetic catalyst, ...Fe
O
/Hal-Mel-TEA(IL)-Pd, has been designed and fabricated. To prepare the catalyst, halloysite was first magnetized (magnetic particles with mean diameter of 13.06 ± 3.1 nm) and then surface functionalized with melamine, 1,4 dibromobutane and triethanolamine to provide ionic liquid on the halloysite surface (5 wt%). The latter was then used as a support to immobilize Pd nanoparticles that were reduced by Heracleum persicum extract. The characterization of the catalyst established that the loading of Pd in Fe
O
/Hal-Mel-TEA(IL)-Pd was very low (0.93 wt%) and its specific surface area was 63 m
g
. Moreover, the catalyst showed magnetic property (Ms = 19.75 emu g
) and could be magnetically separated from the reaction. The catalytic performance of the magnetic catalyst for reductive degradation of methyl orange and rhodamine B in the presence of NaBH
in aqueous media was investigated. The activation energy, enthalpy, and entropy for the reduction of methyl orange were estimated as 42.02 kJ mol
, 39.40 kJ mol
, and -139.06 J mol
K
, respectively. These values for rhodamine B were calculated as 39.97 kJ mol
, 34.33 kJ mol
, and -155.18 Jmol
K
, respectively. Notably, Fe
O
/Hal-Mel-TEA(IL)-Pd could be reused for eight reaction runs with negligible loss of the catalytic activity (~3%) and Pd leaching (0.01 wt% of the initial loading).
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Abstract
Silver nanoparticles were immobilized on magnetic polyallylamine (PAA) decorated g-C
3
N
4
by using
Heracleum persicum
extract as a biological reducing and stabilizing agent. The resulting ...nanocomposite, Fe
3
O
4
-g-C
3
N
4
-TCT-PAA-Ag, was then characterized using BET, VSM, XRD, TGA, FTIR, TEM, EDS and ICP. The catalytic performance of the synthesized nanocatalyst was considered in the reduction of rhodamine B, and methyl orange in the presence of sodium borohydride in the aqueous medium at room temperature. The results showed that Fe
3
O
4
-g-C
3
N
4
-TCT-PAA-Ag nanocomposite could promote both reduction reactions efficiently in very short reaction times (70–100 s). In addition, Fe
3
O
4
-g-C
3
N
4
-TCT-PAA-Ag could be magnetically recovered and recycled for several cycles with no significant decrease in its catalytic performance. Using the experimental results, the rate constant, enthalpy, and entropy of the reduction reactions of both dyes were estimated.
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This current study involves the novel synthesis of Au nanoparticles (Au NPs) decorated biguanidine modified mesoporous silica KIT-5 following post-functionalization approach. The tiny Au NPs were ...being stabilized over the in situ prepared biguanidine ligand. The high surface area material was characterized using analytical techniques like Fourier Transformed infrared (FT-IR) spectroscopy, N
-adsorption-desorption isotherm, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectroscopy (EDS), and X-ray Diffraction study (XRD). Our material was found to be an efficient catalyst in the reductive degradation of harmful water contaminating organic dyes like Methylene blue (MB), Methyl Orange (MO) and Rhodamin B (RhB) in presence of NaBH
at room temperature. The whole procedure was followed up with the help of time dependant UV-Vis spectroscopy. All the reactions followed pseudo-unimolecular kinetics and corresponding rate constant were determined. The reduction rate becomes high in presence of higher load of catalysts.
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Layered double hydroxides (LDHs) are recognized as two-dimensional (2D) clay materials, which comprise the interlayer anions and host layers with a positive charge (brucite-like M(OH)
6
octahedral). ...They have been used as effective and eco-friendly heterogeneous catalytic systems in cross-coupling reactions. In this review, we try to underscore the applications of (LDHs) as an efficient and green catalyst in some important name reactions, namely Suzuki, Heck, Sonogashira, and Ullmann cross-coupling reactions leading to carbon–carbon bond formations.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
This study reports the preparation of a novel type of support based on magnetically recyclable bentonite functionalized with divinylbenzene-polyvinyl pyridine (PVP-DVB) for Pd (II) nanocatalyst by a ...simple cost-effective method. Firstly, the conventional co-precipitation method synthesized Fe
O
nanoparticles (NPs) onto bentonite sheets. Then the prepared magnetic support surface was functionalized by divinylbenzene-polyvinyl pyridine (PVP-DVB) to create a cross-linked polymer with a high coordination ability with palladium. Repeated nitrogen units in the PVP-DVB polymer chain increase the number of Pd bonds and thus lead to higher performance of the nanocatalyst. Finally, the palladium NPs were simultaneously synthesized and immobilized under mild conditions. The synthesized nanocatalyst was characterized by several methods such as scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, vibrating sample magnetometer, inductively coupled plasma mass spectrometry and thermogravimetric analysis. The efficiency of synthesized heterogeneous nanocatalyst was investigated in Suzuki-Miyaura cross-coupling reactions between a range of aryl halides (X = Cl, Br, I) with phenylboronic acid and in the reduction of 4-nitrophenol (4-NP). Moreover, the synthesized nanocatalyst could be easily recovered and reused several times with an efficiency greater than 90%.
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This article displays synthesis of gold nanoparticles (Au NPs) decorated on sodium alginate (Alg) covered magnetite (Fe3O4@Alg-AuNPs) nanocomposite. Sodium alginate shell as a natural anionic ...polysaccharide on Fe3O4 microparticles core acted as a stabilizing agent for immobilization of Au NPs. Its catalytic performance was tested in the reduction of 4-nitrophenol to 4-aminophenol. The structural features of the synthesized nanocatalyst were investigated by Fourier-transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Transmission electron microscopy (TEM), Energy Dispersive X-Ray Analysis (EDX), and Vibrating-sample magnetometer (VSM) studies. The catalytic activity of the material in the reduction process was quantitatively monitored using Ultraviolet–visible (UV–Vis) spectroscopy and it resulted excellent yields (99%) at short reaction time (1.5–4 min) in aqueous media at room temperature using very low catalyst load (1–3 mg). The kinetics study was also performed which afforded a good rate constant. Additionally, the catalyst showed high reproducibility as was easily retrievable and recoverable without noticeable loss in its catalytic activity.
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•Gold nanoparticles decorated on sodium alginate functionalized magnetic nanoparticles (Fe3O4@Alg-Au NPs).•The novel catalyst applied for 4-nitrophenol at ambient temperature.•Low metal loading was used in the reaction.•The catalyst can be reused several consecutive cycles.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
Fe
3
O
4
/
g
-C
3
N
4
/Alginate-Ag nanocomposite as a novel and effective nanocatalyst was successfully prepared. This nanocomposite was fully characterized using several techniques such as ...X‐ray diffraction (XRD), field emission scanning electron microscopy with energy dispersive spectroscopy (FESEM-EDS), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR). In addition, the catalytic activity of this novel and characterized nanocatalyst was investigated in the regioselective synthesis of 1,4-disubstituted 1,2,3-triazoles via click reaction and A
3
and KA
2
coupling reaction in aqueous media. The prepared nanocatalyst was simply recovered by using an external magnet and reused for several times with a slight loss of catalytic activity.
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Abstract
Catalysts are essential materials in biotechnology, medicine, industry, and chemistry. On the other hand, recycling and using waste materials is important in economic efficiency and green ...chemistry. Thus, biochar was prepared from the stem and roots of the
Spear Thistle
to recover waste. After magnetizing the biochar, its surface was modified with polyvinyl imidazole. Finally, this modified biochar was decorated with Pd nanoparticles and used as a selective and recyclable nanocatalyst in the hydrogenation of nitroarenes and the Sonogashira reaction. The structure of this organic–inorganic nanocatalyst has been characterized by FESEM-EDS, XRD, FT-IR, TEM, and VSM techniques. In the hydrogenation reaction with the amount of 30 mg of nanocatalyst, the temperature of 50 °C in the water solvent, the reaction efficiency reached 99% for 30 min. In addition, under optimal conditions for the Sonogashira reaction: 1.0 mmol iodobenzene, 1.2 mmol phenylacetylene, 20 mg MBC-PVIm/Pd, 2 mmol K
2
CO
3
in H
2
O at 50 C for 15 min, the reaction efficiency reached 95%. The recyclability of magnetic nanocatalysts was investigated and recognized this nanocatalyst can be used several times without notable loss of its activity.
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Abstract
Green synthesis of a noble metal such as Ag nanoparticles is an enormously developed research area. In this study, a biochar/Fe
3
O
4
–Ag magnetic nanocatalyst was produced via a green path ...by using Celery stalk as a carbon-based substrate and
Celery
leaf extract as reducing and stabilizing agents to construct Ag nanoparticles. The synthesized nanocatalyst was determined using various techniques, such as UV–Vis spectroscopy, FT-IR spectroscopy, XRD (X-ray diffraction), SEM/EDX spectroscopy (scanning electron microscopy/energy-dispersive X-ray), TEM (transmission electron microscopy), and VSM (vibrating sample magnetometer). To survey the catalytic action of the biochar/Fe
3
O
4
–Ag nanocatalyst, it was used in the reduction reaction of disparate nitroaromatics, aldehydes, and ketones. This catalyst has demonstrated good characteristics in terms of the amount, reusability, recoverability, activity, and structural integrity of the catalyst during the reaction. In addition, biochar/Fe
3
O
4
–Ag could be detached magnetically and recycled multiple times without significantly reducing its catalytic performance.
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