International Journal Of Nanoscience and Nanotechnology
Volume:20 Issue: 1, Winter 2024

The kinetics of catalytic degradation of methyl violet using biosynthesized silver   nanoparticles was studied spectrophotometrically. The biosynthesis process synthesized the silver nanoparticles using Azadirachta indica leaves extract and characterized by spectral techniques. Uv spectra showed the reduction of silver nitrate into silver nanoparticles. Atomic force microscopy analysis showed the configuration, morphology, and size of silver nanoparticles. It was observed silver nanoparticles are spherical and produced in high percentages. The kinetics of degradation of methyl violet with silver nanoparticles was analyzed by observing the change in absorbance with respect to time at 583nm as a function of pH, concentration of nanoparticle, catalyst, and temperature. The reaction follows pseudo-first-order kinetics depends on the concentration of nanoparticles and is independent of the concentration of methyl violet. The degradation process was found to be more favorable at low temperatures and in the basic medium at pH 11 The activation parameters are also evaluated.

The simple and free solvent green synthesis approach is promising for the preparation of nanoparticles due to its eco-friendly and straightforward, which replaced the use of toxic chemicals. This work reports the synthesis of iron nanoparticles using the eucalyptus leaf extracts and it has been studied their structural, functional groups, morphological, and elemental properties. Initially, X-ray diffraction (XRD) pattern showed the presence of organic materials and iron (α-Fe phase). Next, Fourier transform infrared (FTIR) and Raman spectroscopy (RS) were confirmed the presence of iron oxide (Fe-O) stretching vibrations at 550 cm-1 and 575 cm-1, respectively. The UV-visible absorbance spectrum endorsed the existence of the plasma enhancement in between 250 to 370 nm, and scanning electron microscopy (SEM) micrographs shown the formation of irregular spherical grains. The energy-dispersive X-ray spectroscopy (EDX) investigation was evidenced the presence of iron (Fe) nanoparticles. Finally, the successful preparation of iron nanoparticles used as the catalyst for the photo degradation (~98% for 150 min.) study of Rhodamine B dye and results discussed.

Hydrogen has been considered as one of the worthy fuels for the high potential energy and nonpolluting combustion. With increasing the concerns about fossil fuels pollution for the environment, attempts have been concentrated on the improving of new green fuels such as hydrogen. Particularly, the safe and cost-effective production of hydrogen has been widely studied, in which the catalysts deserved remarkable progresses. Herein, photocatalytic activity of cobalt-phthalocyanine/graphene quantum dots/TiO2 was investigated in the formic acid degradation under visible irradiation toward hydrogen generation. TiO2 as a semiconductor trapped photons to generate electron/hole pairs and graphene quantum dots made delay in their recombination to provide long time for promoting the hydrogen and carbon dioxide evolution reactions by electrons/holes. Cobalt (II)-phthalocyanine as a catalyst utilized the electrons in the transformation of protons to H2, while in the positive region carbon dioxide was producing. The reaction was progressed efficiently affording H2 with the rate of 3.60 mmol.h-1 and activation energy was calculated to be 16 KJ.mol-1. This three-component catalyst showed satisfying stability to run the reaction for long time. Notable catalytic activity, and employing light power for the reaction done are two significant characteristics of this hybrid.

In this paper we propose a method to study the impact of the CNT parameter variations on performance of CNTFET digital circuits. In particular we consider CNT parameters that fully identify the geometrical properties of a regular CNT, which are the length and structural indices (n, m) of CNT. We analyse in particular the effects on NAND gate using a N and P type CNTFET, polarizing at a fixed voltage and varying the CNT parameters.  As regards the indices, we limit the analysis to zig-zag CNT, highlighting that the proposed procedure can be applied to other types of CNT.

Viola odorata L. (Sweet violet) has been known with various biologic activities due to its secondary metabolites including flavonoids, glycosides, alkaloids, tannins and saponins. Nanoencapsulation of its extract can be an effective approach to improve the pharmaceutical application of Sweet violet phytochemicals. This study aimed to prepare encapsulated violet extract by two encapsulation methods and compare the antioxidant activity, and evaluate the encapsulation efficiency and physicochemical properties. The extract was encapsulated by double nanoemulsion (gum Arabic-gelatin complex) and nanoemulsion (Lepidium perfoliatum seed gum) methods and using the spray and freeze-drying processes. As a result, the highest encapsulation efficiency (85.82%) and more than antioxidant activity (136.67%) was in double nanoemulsion with freeze-drying. Nanoemulsions showed a higher stability index (97.75%) and greater emulsifying ability (99.84%) than double nanoemulsion due to higher zeta potential. . Due to Dynamic light scattering analysis, the nanoemulsion particle size (306.5 nm) was smaller than that of double nanoemulsion (798.3 nm). Density and moisture content of the double emulsion with freeze-drying were higher than those of nanoemulsions. The results implied elected methods effectiveness to prepare encapsulated Sweet violet extract, and obtained encapsulated extracts have the potential to be used in further pharmaceutical and food studies.

The current research work focuses on the synergistic effect of tin doped Zinc oxide(Sn- ZnO) nanorods in combination with ozonation for the degradation of dyes in the water released from textile industries. Well crystalline mono dispersed Sn doped ZnO (Sn-ZnO) nanorods have been synthesized by simple hydrothermal method.  The XRD results show the hexagonal wurtzite structure of the prepared catalyst. The result of EDAX and XPS revealed that Sn was doped in to ZnO lattices. FESEM image show that the sample possesses hexagonal rod morphology with an average of 1µm in length and 50 to 100nm in diameter.  Optical transmittance of the sample was recorded in the wavelength range of 300–800 nm, and the band gap was determined. The prepared nanocatalyst in combination with ozone is used for the photocatalytic ozonation (nano PCO) of the azo dyes taken for the present study. Nano PCO is carried out in a laboratory scale photocatalytic ozonation reactor.  The experiments were conducted under different ozone dosages (0.12-0.57 g/h), pH (3-9), catalyst dosage (0-2 g/L) and dye concentration (5-50 mg/L) to arrive at optimized reaction conditions for degradation of dyes by Sn-ZnO assisted PCO.  Three experimental sets (Sn-ZnO/UV, UV/O3 and Sn-ZnO/UV/O3) were carried out under optimized reaction conditions to prove the synergistic effect of ozone on Sn-ZnO.  Use of ozone with Sn-ZnO leads to 95% decolourisation of the dyes in 30 min and 79.4% mineralization in 180 min.   The reusability of the photocatalyst was checked six times and the results revealed that the efficiency of the sample slightly decreased at the end of sixth cycle.  Based on the above results, the current route is promising for the application of Sn-ZnO based nanocatalyst in combination with ozonation for wastewater treatment.