scholarly journals Synthesis, characterization and fabrication of copper nanoparticles in N-isopropylacrylamide based co-polymer microgels for degradation of p-nitrophenol

2015 ◽  
Vol 33 (1) ◽  
pp. 185-192 ◽  
Author(s):  
Zahoor H. Farooqi ◽  
Tanzila Sakhawat ◽  
Shanza Rauf Khan ◽  
Farah Kanwal ◽  
Muhammad Usman ◽  
...  
Keyword(s):  
Acrylic Acid ◽  
Aqueous Medium ◽  
Copper Nanoparticles ◽  
Catalytic Reduction ◽  
Copper Ions ◽  
Effect Of Temperature ◽  
Ft Ir ◽  
Catalyst Dosage ◽  
Hybrid Microgels

AbstractPoly(N-isopropylacrylamide-co-acrylic acid) [P(NIPAM-co-AAc)] microgels were synthesized by precipitation polymerization. Copper nanoparticles were successfully fabricated inside the microgels by in-situ reduction of copper ions in an aqueous medium. The microgels were characterized by Fourier Transform Infrared Spectroscopy (FT-IR) and Dynamic Light Scattering (DLS). Hydrodynamic radius of P(NIPAM-co-AAc) microgel particles increased with an increase in pH in aqueous medium at 25 °C. Copper-poly(N-isopropylacrylamide-co-acrylic acid) [Cu-P(NIPAM-co-AAc)] hybrid microgels were used as a catalyst for the reduction of 4-nitrophenol (4-NP). Effect of temperature, concentration of sodium borohydride (NaBH4) and catalyst dosage on the value of apparent rate constant (kapp) for catalytic reduction of 4-NP in the presence of Cu-P(NIPAM-co-AAc) hybrid microgels were investigated by UV-Vis spectrophotometry. It was found that the value of kapp for catalytic reduction of 4-NP in the presence of Cu-P(NIPAM-co-AAc) hybrid microgel catalyst increased with an increase in catalyst dosage, temperature and concentration of NaBH4 in aqueous medium. The results were discussed in terms of diffusion of reactants towards catalyst surface and swelling-deswelling of hybrid microgels.

Engineering of silver nanoparticle fabricated poly (N-isopropylacrylamide-co-acrylic acid) microgels for rapid catalytic reduction of nitrobenzene

2016 ◽  
Vol 36 (1) ◽  
pp. 87-96 ◽  
Author(s):  
Zahoor H. Farooqi ◽  
Khalida Naseem ◽  
Aysha Ijaz ◽  
Robina Begum
Keyword(s):  
Acrylic Acid ◽  
Rate Constant ◽  
Apparent Rate Constant ◽  
Reduction Method ◽  
Catalytic Reduction ◽  
Visible Spectroscopy ◽  
Uv Visible ◽  
Polymerization Method ◽  
Hybrid Microgels

Abstract Three different poly(N-isopropylacrylamide-co-acrylic acid) [p(NIPAM-AA)] microgel samples were prepared using a precipitation polymerization method by varying the concentration of NIPAM and AA in aqueous medium. The microgels were used as microreactors to fabricate Ag nanoparticles (NPs) by in situ a reduction method. Fourier transform infrared (FTIR) and UV-visible spectroscopy were used to characterize the pure and hybrid microgels. The hybrid microgels with different AA content were used as catalysts for reduction of nitrobenzene (NB) into aniline. The progress of the reaction was monitored by a UV-visible spectrophotometer. The results show that the value of the apparent rate constant for catalytic reduction of NB decreases from 0.431 min-1 to 0.227 min-1 by increasing AA content from 3 mol% to 7 mol%, respectively. Decrease in apparent rate constant with increase of AA content can be attributed to an increase in hydrophilicity with increase of AA contents of the microgels. The increase in induction period with increase of AA contents indicates that diffusion of NB towards the catalytic surface becomes difficult due to an increase of hydrophilicity.

scholarly journals Poly(N-isopropylacrylamide-co-methacrylic acid) microgel stabilized copper nanoparticles for catalytic reduction of nitrobenzene

2015 ◽  
Vol 33 (3) ◽  
pp. 627-634 ◽  
Author(s):  
Zahoor H. Farooqi ◽  
Zonarah Butt ◽  
Robina Begum ◽  
Shanza Rhauf Khan ◽  
Ahsan Sharif ◽  
...  
Keyword(s):  
Copper Nanoparticles ◽  
Methacrylic Acid ◽  
Catalytic Reduction ◽  
Aqueous Media ◽  
Activation Parameters ◽  
Reducing Agent ◽  
Different Temperatures ◽  
Entropy Of Activation ◽  
Micro Reactors

Abstract Poly(N-isopropylacrylamide-co-methacrylic acid) microgels [p(NIPAM-co-MAAc)] were synthesized by precipitation polymerization of N-isopropylacrylamide and methacrylic acid in aqueous medium. These microgels were characterized by dynamic light scattering and Fourier transform infrared spectroscopy. These microgels were used as micro-reactors for in situ synthesis of copper nanoparticles using sodium borohydride (NaBH4) as reducing agent. The hybrid microgels were used as catalysts for the reduction of nitrobenzene in aqueous media. The reaction was performed with different concentrations of cat­alyst and reducing agent. A linear relationship was found between apparent rate constant (kapp) and amount of catalyst. When the amount of catalyst was increased from 0.13 to 0.76 mg/mL then kapp was increased from 0.03 to 0.14 min-1. Activation parameters were also determined by performing reaction at two different temperatures. The catalytic process has been discussed in terms of energy of activation, enthalpy of activation and entropy of activation. The synthesized particles were found to be stable even after 14 weeks and showed catalytic activity for the reduction of nitrobenzene.

scholarly journals Hydrogenative Cyclization of Levulinic Acid to γ-Valerolactone with Methanol and Ni-Fe Bimetallic Catalysts

Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1096
Author(s):  
Ligang Luo ◽  
Xiao Han ◽  
Qin Zeng
Keyword(s):  
Photoelectron Spectroscopy ◽  
Levulinic Acid ◽  
Hydrogen Donor ◽  
Effect Of Temperature ◽  
X Ray ◽  
Transmission Electron ◽  
Ft Ir ◽  
Temperature Programmed

A series of Ni-Fe/SBA-15 catalysts was prepared and tested for the catalytic hydrogenation of levulinic acid to γ-valerolactone, adopting methanol as the only hydrogen donor, and investigating the synergism between Fe and Ni, both supported on SBA-15, towards this reaction. The characterization of the synthesized catalysts was carried out by XRD (X-ray powder diffraction), TEM (transmission electron microscopy), H2-TPD (hydrogen temperature-programmed desorption), XPS (X-ray photoelectron spectroscopy), and in situ FT-IR (Fourier transform–infrared spectroscopy) techniques. H2-TPD and XPS results have shown that electron transfer occurs from Fe to Ni, which is helpful both for the activation of the C=O bond and for the dissociative activation of H2 molecules, also in agreement with the results of the in situ FT-IR spectroscopy. The effect of temperature and reaction time on γ-valerolactone production was also investigated, identifying the best reaction conditions at 200 °C and 180 min, allowing for the complete conversion of levulinic acid and the complete selectivity to γ-valerolactone. Moreover, methanol was identified as an efficient hydrogen donor, if used in combination with the Ni-Fe/SBA-15 catalyst. The obtained results are promising, especially if compared with those obtained with the traditional and more expensive molecular hydrogen and noble-based catalysts.

Synthesis and characterization of composite polysulfone membranes for desalination in nanofiltration technique

2010 ◽  
Vol 62 (11) ◽  
pp. 2655-2663 ◽  
Author(s):  
A. Akbari ◽  
M. Homayonfal ◽  
V. Jabbari
Keyword(s):  
Acrylic Acid ◽  
Polyacrylic Acid ◽  
Graft Polymerization ◽  
Irradiation Time ◽  
Polymerization Process ◽  
Synthesis And Characterization ◽  
Porous Support ◽  
Ft Ir

Composite nanofiltration (NF) membrane was developed polyacrylic acid (PAA) in situ UV graft polymerization process using ultrafiltration (UF) polysulfone (PSF) membrane as porous support. FT-IR spectra indicated that grafting was performed and it show peaks at 1,732 cm−1 and 3,396 cm−1 region for CO and OH starching bond of acrylic acid (AA) monomer, respectively. AFM microscopy showed the roughness of surface was reduced by increase of UV irradiation times. Effect of irradiation time on the grafting of acrylic acid (AA) in the same concentration was discussed. The salts rejection increase was accompanied with grafting of polysulfone (PSF) ultrafiltration (UF) membrane. The rejection of Na2SO4, MgSO4, NaCl and CaCl2 salts by PSF-grafted-PAA nanofiltration (NF) membrane was in 98, 60, 52 and 30% respectively, under 0.3 MPa.

Preparation and Properties of Nanocomposites Based on Poly(Vinyl acetate) and Montmorillonite Organized with Acrylic Acid

2011 ◽  
Vol 335-336 ◽  
pp. 3-11
Author(s):  
Jun Wang
Keyword(s):  
Acrylic Acid ◽  
Vinyl Acetate ◽  
Differential Scanning Calorimetric ◽  
X Ray Diffraction ◽  
Covalent Bonds ◽  
Emulsion Copolymerization ◽  
Fourier Transformation Infrared Spectroscopy ◽  
Ft Ir ◽  
Vinyl Group

The nanocomposites of poly(vinyl acetate)/montmorillonite (PVAc/MMT) were prepared using vinyl acetate and organically modified alkaline calcium base montmorillonite (MMT) by in situ emulsion copolymerization. The organic modification was acrylic acid including terminal reactive vinylic group. The samples were characterized using fourier transformation infrared spectroscopy (FT-IR), X-ray diffraction (XRD). Thermal properties of the PVAc/MMT films were studied by thermogravimetric (TG) and differential scanning calorimetric (DSC). The FT-IR results indicated that the vinyl group on the surface of the vinyl MMT nanoparticles had been successfully copolymerized with vinyl acetate. The XRD results demonstrated that the MMT was exfoliated during polymerization. The exfoliated PVAc/MMT nanocomposites showed a lower glass transition temperature (Tg) and a worse thermal stability compared with the pure PVAc. However, bonding power of the nanocomposite latex of PVAc/MMT was improved due to the strong interaction between silica nanoparticles and polymer matrix via covalent bonds.

scholarly journals Methane-to-methanol conversion over zeolite Cu-SSZ-13, and its comparison with the selective catalytic reduction of NOx with NH3

2018 ◽  
Vol 8 (4) ◽  
pp. 1028-1038 ◽  
Author(s):  
Ramon Oord ◽  
Joel E. Schmidt ◽  
Bert M. Weckhuysen
Keyword(s):  
Selective Catalytic Reduction ◽  
Active Site ◽  
Catalytic Reduction ◽  
Methanol Conversion ◽  
Nuclear Site ◽  
Ft Ir ◽  
Reduction Of Nox

Using in situ FT-IR and operando UV-vis-NIR DRS, performed on a series of different Cu–ion-exchanged SSZ-13 zeolites, both a mono-nuclear site or a dimeric copper active site are consistent for methane-to-methanol activation.

scholarly journals Thermal effects on the surface plasmon resonance of Cu nanoparticles in phosphate glass: impact on Cu+ luminescence

2019 ◽  
Vol 1 (5) ◽  
pp. 1826-1832 ◽  
Author(s):  
José A. Jiménez
Keyword(s):  
Surface Plasmon Resonance ◽  
Surface Plasmon ◽  
Copper Nanoparticles ◽  
Phosphate Glass ◽  
Plasmon Resonance ◽  
Thermal Effects ◽  
Effect Of Temperature ◽  
Spectroscopy Study ◽  
Cu Nanoparticles

A joint in situ absorption and photoluminescence spectroscopy study exposes the effect of temperature on copper nanoparticles in phosphate glass and their influence on Cu+ luminescence.

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