سال:1392 | دوره: | شماره: |تعداد مقالات:3

The focus of this work is to study the effect of sodium montmorillonite (MMT-Na) clay content on the rate and extent of enzymatic hydrolysis polyvinyl alcohol (PVA) /starch (S) /carboxymethyl cellulose (CMC) blends using enzyme cellulase. The rate of glucose production from each nanocomposite substrates was most rapid for the substrate without MMT-Na and decreased with the addition of MMT-Na for PVA/S/CMC blend (51.5 mg/ml h), PVA/ S/CMC/1% MMT (45.4 mg/ml h), PVA/S/CMC/3% MMT (42.8 mg/ml h), and PVA/S/CMC/5% MMT (39.2 mg/ml h). The results of this study have revealed that films with MMT-Na content at 5 wt.% exhibited a significantly reduced rate and extent of hydrolysis. Enzymatic degradation behavior of MMT-Na containing nanocomposites of PVA/S/CMC was based on the determinations of weight loss and the reducing sugars. The degraded residues have been characterized by various analytical techniques, such as Fourier transform infrared spectroscopy, scanning electronic microscopy, and UV-vis spectroscopy.

Polypyrrole-multiwall carbon nanotube (PPy-MWCNT) nanocomposites were chemically synthesized via in situ oxidative polymerization of pyrrole. Ammonium peroxydisulfate and p-toluenesulfonic acid were used as an initiator and surfactant dopant, respectively. The molar ratio of monomer unit to initiator and dopant was 1: 1: 1, and the percentage of MWCNT in PPy varied from 1 to 10 wt.%. PPy-MWCNT nanocomposites were characterized to study chemical structure, morphology, thermal, electrical, and surface properties. To accomplish this, the samples have been characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, four probe resistivity method, and atomic force microscopy. The results showed that PPy-MWCNT nanocomposites were successfully synthesized via in situ oxidative polymerization method, and also, electrical conductivity of nanocomposites was increased when the content of MWCNT increase.

The leaf extract of Acacia nilotica (Babool) is rich in different types of plant secondary metabolites such as flavanoids, tannins, triterpenoids, saponines, etc. We have demonstrated the use of the leaf extract for the synthesis of gold nanoparticles in water at room temperature under very mild conditions. The synthesis of the gold nanoparticles was complete in several minutes, and no extra stabilizing or capping agents were necessary. The size of the nanoparticles could be controlled by varying the concentration of the leaf extract. The gold nanoparticles were characterized by HRTEM, surface plasmon resonance spectroscopy, and X-ray diffraction studies. The synthesized gold nanoparticles have been used as an efficient catalyst for the reduction of 4-nitrophenol to 4-aminophenol in water at room temperature.