جستجوی مقالات مرتبط با کلیدواژه « نانوذرات zno » در نشریات گروه « پزشکی »

The investigation of the antibacterial activity of nanomaterials has regained importance due to increasing bacterial resistance to antibiotics. Inorganic antibacterial materials have several advantages over traditionally used organic agents; like chemical stability, thermal resistance, safety to the user, long lasting action period, etc. In this research, antibacterial properties of graphene - zinc oxide nanoparticles nanocomposite was evaluated for gram-positive (S. aureus) and gram-negative (E. coli and Pseudomonas aeruginosa) bacteria.
Material & The current study demonstrates homogenous decorating of zinc oxide nanoparticles (NPs) onto graphene oxide (GO) surface via simple chemical method.
Disk diffusion method and MIC were used to evaluate the antibacterial activity of ZnO nanoparticles on S. aureus, E. coli and Pseudomonas aeruginosa compared to standard commercial antibiotic disks.
XRD results revealed diffraction peaks for each of the two compounds in the nanocomposite. The XRD studies showed that the synthesized ZnO NPs have hexagonal wurtzite structure. It was found that GO addition induces a decrease in crystallite size. Average size of the ZnO NPs was estimated by transmission electron microscopy around 20 nm. ZnO nanoparticles showed bactericidal effects on Gram-positive and Gram-negative bacteria. The improved antibacterial activity of ZnO nanoparticles compared to its microparticles was related to the surface area enhancement in the nanoparticles.
The novel nanocomposite exhibits excellent antibacterial activity against gram-positive (S. aureus) and gram-negative (E. coli and Pseudomonas aeruginosa) bacteria.

As for the enhancement of the various industries such as loom industry, the reduction of the pollutants in the sewerage of these industries is focused by protection office of environment. Therefore, the main aim of this research is the elimination of the methyl orange from water using photocatalytic procedure and ZnO nanoparticles.
The kinetic of the photocatalytic oxidation reaction of methyl orange using ZnO nanoparticles and hybrids containing decorated Multi Wall Carbon Nanotubes (MWCNT) with ZnO nanoparticles is investigated. The influence of irradiation time (from 5 to 30 min) and the concentration of the photo catalysts (0.1, 0.2 and 0.5 %wt) on the kinetic reaction of methyl orange decomposition is studied.
The kinetic reaction of methyl orange decomposition using ZnO nanoparticles and synthesized hybrids is pseudo first order. The reaction rate constant using ZnO nanoparticles is lower than that of studied hybrids. This means that the reaction rate of methyl orange decomposition using ZnO nanoparticles is low. Meanwhile, according to the results it can observe that the attachment of the ZnO nanoparticleson the outer surface of MWCNTs leads to the enhancement of the reaction rate. Also, the reaction rate of pollutants decomposition increases with respect to the attached ZnO nanoparticles on the outer surface of MWCNTs.
Based on the observed results, the introducing and enhancement of the ZnO nanoparticles on the outer surface of MWCNTs leads to the augmentation of the methyl orange decomposition rate. Therefore, according to this technique the decomposition of the pollutants accelerates.

Owing to the extended usage in the safekeeping of environments, the photocatalytic materials have been widely applied. The purpose of the present study was to investigate the photocatalytic activity of ZnO and SnO2 nanoparticles in removal of methyl orange from aqueous media.
ZnO and SnO2 nanoparticles were synthesized through sol-gel and chemical precipitation respectively. Methyl orange was selected as model pollutant. The effect of weight fraction on the removal of pollutant was investigated in the range of 0.25, 0.5, and 1 weight percent. Meanwhile, for investigating the effect of radiation time, the suspension containing pollutant and nanoparticles was irradiated. The obtained results were analyzed by MSTATC, Ver 1.42 software and Duncan’s multiple range test.
The analysis of variance results of removal efficiency of methyl orange showed that in the suspension involving ZnO and SnO2, radiation time, weight fraction and the combined effect of them have a significant effect on the removal of methyl orange at 5% level of probability. Meanwhile, by increasing irradiation time from 5 to 25 min, the removal efficiency in suspensions containing ZnO and SnO2 reached 97.42 and 65.55% respectively. Investigation on the effect of concentration on the removal of methyl orange shows that the removal of methyl orange increases with respect to the weight fraction.
According to the obtained results, it was observed that the photocatalytic activity of ZnO is higher than that of SnO2. Therefore, the application of ZnO is more effective for removal of methyl orange from aqueous media.

Effluents containing synthetic dyes are hazardous to ecological systems and public health. Methylene blue is an important chemical aromatic dye which commonly used in textile industries. Due to being aromatic، it is often toxic، carcinogenic and mutagenic. The goal of this study was to investigate the efficiency of ZnO nano particles photocatalytic process for decolorization of methylene blue by UV irradiation from synthetic textile wastewater.

In this study methylene blue photocatalytic decomposition using Ultraviolet (UV) irradiation and zinc oxide nano particles having less than 50 nm in diameter was surveyed. A batch-through Plexiglass reactor having two compartment used to conduct the experiments. Wastewater was flowed to the compartment which contains of nano ZnO stabilized glasses. UV lamps were installed at another compartment. The variables of the study included: exposure time، color concentration، light intensity، and lamp distance to the catalyst surface.

ZnO nano particles characteristics were determined by Scanning Electron Microscope (SEM) and X-ray diffraction (XRD) analysis. Images showed that stabilizes nano particles on glass، their porosity remains in the optimal level. Optimium values for exposure time 120 minutes، color concentration 25 mg/l، light intensity 3950 μW/cm2، and distance to the catalyst surface 1 cm were achieved. At the optimal condition، methylene blue decolorization and COD removal was achieved 92. 2% and 75% respectively

Regarding the conducted experiments، the results of this studyshowed that ZnO/UV photocatalytic process has a significant efficiency in dye decolorization and COD removal. This method could be applied in the full scales.