RESUMEN
Phytosynthesis of gold nanoparticles (AuNPs) has achieved an indispensable significance due to the diverse roles played by biomolecules in directing the physiochemical characteristics of biosynthesized nanoparticles. Therefore, the precise identification of key bioactive compounds involved in producing AuNPs is vital to control their tunable characteristics for potential applications. Herein, qualitative and quantitative determination of key biocompounds contributing to the formation of AuNPs using aqueous Elaeis guineensis leaves extract is reported. Moreover, roles of phenolic compounds and flavonoids in reduction of Au3+ and stabilization of AuNPs have been elucidated by establishing a reaction mechanism. Fourier-transform infrared spectroscopy (FTIR) showed shifting of OâH stretching vibrations toward longer wavenumbers and CâO toward shorter wavenumbers due to involvement of polyphenolic compounds in biosynthesis and oxidation of polyphenolic into carboxylic compounds, respectively, which cape nanoparticles to inhibit the aggregation. Congruently, pyrolysis-gas chromatography-mass spectrometry revealed the major contribution of polyphenolic compounds in the synthesis of AuNPs, which was further endorsed by reduction of total phenolic and total flavonoids contents from 48.08 ± 1.98 to 9.59 ± 0.92 mg GAE/g and 32.02 ± 1.31 to 13.8 ± 0.97 mg CE/g within 60 Min, respectively. Based on experimental results, reaction mechanism explained the roles of phenolic compounds and flavonoids in producing spherical-shaped AuNPs.
Asunto(s)
Flavonoides/química , Oro/metabolismo , Tecnología Química Verde , Nanopartículas del Metal/química , Fenoles/química , Extractos Vegetales/química , Hojas de la Planta/química , Arecaceae/química , Flavonoides/aislamiento & purificación , Oro/química , Estructura Molecular , Tamaño de la Partícula , Fenoles/aislamiento & purificación , Procesos Fotoquímicos , Extractos Vegetales/aislamiento & purificación , Estrés Mecánico , Propiedades de Superficie , Agua/química , Agua/metabolismoRESUMEN
PURPOSE: The present work was intended to evaluate the radioprotective effect of quercetin against gamma radiation-induced oxidative stress on red blood cells (RBC). MATERIALS AND METHODS: Swiss albino male mice were treated with quercetin (100 mg/kg body wt) for three consecutive days prior to 5 Gy (60)Co-gamma irradiation. RBC was isolated to estimate the level of intracellular reactive oxygen species (ROS), membrane lipid peroxidation (LPO), intracellular reduced glutathione (GSH), mean corpuscular hemoglobin concentration (MCHC), osmotic fragility and morphological alterations by atomic force microscope (AFM). RESULTS: Irradiation increased intracellular ROS and membrane LPO whereas it decreased the intracellular GSH. Quercetin pretreatment ameliorated these alterations. The MCHC value decreased after irradiation whereas quercetin pretreatment restored it. The average osmotic fragility (H50) and the maximum rate of hemolysis (dH/dC)max increased after irradiation. Quercetin pretreatment decreased the H50 and (dH/dC)max. The AFM study showed that irradiation transformed RBC from biconcave to echinocytes, increased their surface roughness and decreased the vertical distance whereas pretreatment of quercetin significantly prevented both the alterations. CONCLUSIONS: Gamma radiation produced ROS and LPO which rendered oxidative stress and ultimately damaged RBC whereas quercetin ameliorated these changes and protected RBC from radiation-mediated damage.
Asunto(s)
Eritrocitos/fisiología , Estrés Oxidativo/fisiología , Quercetina/administración & dosificación , Especies Reactivas de Oxígeno/metabolismo , Irradiación Corporal Total , Animales , Antioxidantes/administración & dosificación , Supervivencia Celular/efectos de los fármacos , Supervivencia Celular/fisiología , Supervivencia Celular/efectos de la radiación , Células Cultivadas , Eritrocitos/efectos de los fármacos , Eritrocitos/efectos de la radiación , Rayos gamma , Masculino , Ratones , Estrés Oxidativo/efectos de los fármacos , Estrés Oxidativo/efectos de la radiación , Dosis de Radiación , Protectores contra Radiación/administración & dosificaciónRESUMEN
Hexavalent chromium, emanating primarily from the tannery and electroplating industries, can be reduced to the less toxic trivalent variety by several methods, including reduction with metallic iron. In the present work, electrolytic-grade iron dust was used to reduce chromium(VI) in the form of potassium dichromate. Loading of iron dust was varied from 0.5 to 1.0 g in 50 mL of solution; the pH of the medium was varied from 1.5 to 3.5; and the initial concentration of the dichromate solution was varied from 50 to 125 mg/L. Under the specified experimental conditions, maximum removal of the hexavalent chromium achieved was approximately 90% of its original value. The time-concentration data followed a pseudo-first-order kinetic model. The conversion and rate of reduction increased with an increase in iron loading and acidity of the medium, whereas an increase in the initial concentration of chromium(VI) caused a decrease in the reduction.
Asunto(s)
Cromo/química , Hierro/química , Contaminantes Químicos del Agua/química , Purificación del Agua/métodos , Cromo/análisis , Concentración de Iones de Hidrógeno , Residuos Industriales , Cinética , Solubilidad , Propiedades de Superficie , Contaminantes Químicos del Agua/análisisRESUMEN
Tamarind seed kernel powder (TSKP) is a cheap starchy biodegradable material that has not been tested before for its flocculating properties. Sedimentation of clay slurry has been studied using this material. We have also done experiments with chemical grade starch and its blends with TSKP and compared their performance with that of potash alum for sedimentation of the clay slurry. The sedimentation phenomenon showed constant and falling rate zones. Sedimentation velocity, mass flux and concentration have been calculated at different time intervals for all the flocculants. Among the three types of natural flocculants, starch showed the highest rate constant in the constant rate zone and TSKP offers faster sedimentation in the falling rate zone. Thus TSKP, starch and their blends are potentially attractive environmentally benign flocculants. A qualitative explanation of the flocculating property of TSKP has been given.
Asunto(s)
Silicatos de Aluminio , Semillas/química , Compuestos de Alumbre , Materiales Biocompatibles , Carbohidratos/análisis , Arcilla , Indicadores y Reactivos , Cinética , Ensayo de Materiales , Polvos , TamarindusRESUMEN
White or plastic pollution has become a serious concern to the environmentalists for the last few years. Degradation of waste plastics in conventional incinerators leads to emission of carcinogenic dioxins to the atmosphere. In this work, an attempt has been made for the photocatalytic degradation of polyvinyl chloride (PVC) using ZnO as semi-conductor catalyst in the form of PVC-ZnO composite film. The surface morphology as well as the FTIR spectroscopy of the irradiated film has been critically examined. The degradation was measured by weight loss data and was found to follow a pseudo-first order rate equation. The various parameters studied were loading of the semi-conductor, intensity of UV radiation and presence of Eosin Y as a sensitizing dye. It was observed that dye-sensitization enhanced degradation of PVC to a large extent. A possible mechanism has been suggested and the corresponding rate equation has been modeled for the dye-sensitized rate of degradation. The model has been validated by the experimental data.
Asunto(s)
Contaminantes Ambientales , Eosina Amarillenta-(YS)/química , Colorantes Fluorescentes/química , Cloruro de Polivinilo , Rayos Ultravioleta , Óxido de Zinc/química , Catálisis , Contaminantes Ambientales/química , Contaminantes Ambientales/efectos de la radiación , Cinética , Fotoquímica , Cloruro de Polivinilo/química , Cloruro de Polivinilo/efectos de la radiación , Espectroscopía Infrarroja por Transformada de FourierRESUMEN
A detailed investigation on the kinetics of the oxidative degradation of a reactive dye, C. I. Reactive Red 2 by hydroxyl radicals generated by H202 and Fe2+ has been carried out in aqueous acidic media. Effects of different parameters like initial concentration of dye, H2O2, Fe2+, pH of the solution, reaction temperature and added electrolytes on the oxidation process have been studied. The results indicate that 1.63 x 10(-4) mol dm(-3) dye can be most effectively degraded at a dye: Fe2+: H2O2 molar ratio of 1:0.22: 8.13 at pH approximately 2.7 and at 299 K. The addition of excess 2-propanol or t-butyl alcohol, well known scavengers of hydroxyl radicals, almost stopped the degradation of the dye indicating the absence of any possible reductive pathways in the degradation. The results may be useful for designing the treatment systems of wastewater containing various reactive dyes.