Abstract: Synthesis of gold nanoparticles has attracted much
attention since the pioneering discovery of the high catalytic activity
of supported gold nanoparticles in the reaction of CO oxidation at
low temperature. In this research field, we used Na-montmorillonite
for gold nanoparticles stabilization; various gold loading percentage
1, 2 and 5% were used for gold nanoparticles preparation. The gold
nanoparticles were obtained using chemical reduction method using
NaBH4 as reductant agent. The obtained gold nanoparticles stabilized
in Na-montmorillonite were used as catalysts for the reduction of 4-
nitrophenol to aminophenol with sodium borohydride at room
temperature. The UV-Vis results confirmed directly the gold
nanoparticles formation. The XRD and N2 adsorption results showed
the formation of gold nanoparticles in the pores of montmorillonite
with an average size of 5 nm obtained on samples with 2% gold
loading percentage. The gold particles size increased with the
increase of gold loading percentage. The reduction reaction of 4-
nitrophenol into 4-aminophenol with NaBH4 catalyzed by Au-Namontmorillonite
catalyst exhibits remarkably a high activity; the
reaction was completed within 9 min for 1%Au-Na-montmorillonite
and within 3 min for 2%Au-Na-montmorillonite.
Abstract: Polyethylene (PE), Polypropylene (PP), Polyethylene
(vinyl acetate) (EVA) and PE-ionomer nanocomposite samples were
prepared by mixing of the polymer with organofilized
montmorillonite fillers Cloisite 93A and Dellite 67G. The amount of
each modified montmorillonite (MMT) was fixed to 5% (w/w). The
twin-screw kneader was used for the compounding of polymer matrix
and chosen nanofillers. The level of MMT exfoliation was studied by
the transmission electron microscopy (TEM) observations. The
mechanical properties of prepared materials were evaluated by
dynamical mechanical analysis at 30°C and by the measurement of
tensile properties (stress and strain at break).
Abstract: Montmorillonite (MMT) is a very abundant clay mineral and is versatile such that it can be chemically or physically altered by changing the ions between the sheets of its layered structure. This clay mineral can be prepared into functional nanoparticles that can be used as fillers in other nanomaterials such as nanofibers to achieve special properties. In this study, two types of iron-modified MMT, Iron-MMT (FeMMT) and Zero Valent Iron-MMT (ZVIMMT) were synthesized via ion exchange technique. The modified clay was incorporated in polymer nanofibers which were produced using a process called electrospinning. ICP analysis confirmed that clay modification was successful where there is an observed decrease in the concentration of Na and an increase in the concentration of Fe after ion exchange. XRD analysis also confirmed that modification took place because of the changes in the d-spacing of Na-MMT from 11.5 Å to 13.6 Å and 12.6 Å after synthesis of FeMMT and ZVIMMT, respectively. SEM images of the electrospun nanofibers revealed that the ZVIMMT-filled fibers have a smaller average diameter than the FeMMT-filled fibers because of the lower resistance of the suspensions of the former to the elongation force from the applied electric field. The resistance to the electric field was measured by getting the bulk voltage of the suspensions.
Abstract: This paper presents the results of an experimental characterization of a glass fibre-epoxy composite. The behavior of the traditional two-phase composite has been compared with the one of a new three-phase composite where the epoxy matrix was modified by addition of a 3% weight fraction of montmorillonite nano-particles. Two different types of nano-clays, Cloisite® 30B and RXG7000, produced by Southern Clay Products Inc., have been considered. Three-point bending tests, both monotonic and cyclic, were carried out. A strong reduction of the ultimate flexural strength upon nano-modification has been observed in quasi-static tests. Fatigue tests yielded a smaller strength loss. In both quasi-static and fatigue tests a more pronounced tendency to delamination has been noticed in three-phase composites, especially in the case of 30B nano-clay, with respect to the standard two-phase glass fiber composite.
Abstract: Contamination of aromatic compounds in water can
cause severe long-lasting effects not only for biotic organism but also
on human health. Several alternative technologies for remediation of
polluted water have been attempted. One of these is adsorption
process of aromatic compounds by using organic modified clay
mineral. Porous structure of clay is potential properties for molecular
adsorptivity and it can be increased by immobilizing hydrophobic
structure to attract organic compounds. In this work natural
montmorillonite were modified with cetyltrimethylammonium
(CTMA+) and was evaluated for use as adsorbents of aromatic
compounds: benzene, toluene, and 2-chloro phenol in its single and
multicomponent solution by ethanol:water solvent. Preparation of
CTMA-montmorillonite was conducted by simple ion exchange
procedure and characterization was conducted by using x-day
diffraction (XRD), Fourier-transform infra red (FTIR) and gas
sorption analysis. The influence of structural modification of
montmorillonite on its adsorption capacity and adsorption affinity of
organic compound were studied. It was shown that adsorptivity of
montmorillonite was increased by modification associated with
arrangements of CTMA+ in the structure even the specific surface
area of modified montmorillonite was lower than raw
montmorillonite. Adsorption rate indicated that material has affinity
to adsorb compound by following order: benzene> toluene > 2-chloro
phenol. The adsorption isotherms of benzene and toluene showed 1st
order adsorption kinetic indicating a partition phenomenon of
compounds between the aqueous and organophilic CTMAmontmorillonite.