Comparative Antibacterial Effects of a Novel Copper and Silver- Based Core/Shell Nanostructure by Sonochemical Method

In this study, the antibacterial effect of novel copper (Cu) and silver (Ag) metal-based core-shell nanostructures against Escherichia coli (E. coli-Gram negative) was investigated. The novel copper- and silver-based nanostructures were prepared separately by using nontoxic, biodegradable, and biocompatible biopolymers chitosan and guar gum-polyvinyl alcohol (GG-PVA), which were modified by inorganic phases SiO2 and sepiolite. On the other hand, guar gum-PVA (GG-PVA) was modified by sepiolite, and this nanostructure was prepared only for silver. Besides, Cu was dispersed in a different biopolymer chitosan by sonochemical method in the presence and absence of SiO2. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and X-ray diffraction (XRD) techniques were used to characterize the surface chemistry and morphology of the core/shell nanostructure. Nanoscale zero-valent Cu (NZVCu) was found under thin CuO film according to the XPS results. SEM images showed that spherical Cu/CuO@SiO2 nanostructures (∼100 nm) were homogenously dispersed in the chitosan by using sonochemical method. Antibacterial property of the core-shell nanostructures was analyzed by well-diffusion method against Escherichia coli (E. coli-Gram negative). Cu/CuO@SiO2 nanostructures were found very effective against the E. coli due to high ratio of NZVCu in the nanostructure

The Viscosity Behaviour of PEGylated Locust Bean Gum/Rosin Ester Polymeric Nanoparticles

In this study, PEGylated locust bean gum–rosin glycerol ester polymeric nanoparticles (PEG-LBG/RE PNPs) were synthesized by using simple ultrasonic irradiation method. The nanoparticles were characterized by using Fourier-transform infrared spectroscopy (FTIR) and scanning transmission electron microscopy (STEM). The viscosity behaviors of nanoparticles were studied in different conditions (pH, sonication time, and salt). The experimental results were calculated by Huggins, Kraemer, Tanglertpaibul-Rao, and Higiro models to understand the colloidal stability, the miscibility mechanism, and coefficients of nanoparticles. The results confirmed that the homogenous distribution of nanostructure was related to sonication time (30 min) and the presence of NaOH salt. With the addition of NaOH, the nanosystem based on ionotropic gelation technique was made more homogeneous. The results made us think that nanoparticles can be a good candidate for drug delivery systems in biomedical and pharmaceutical applications

Preparation, Characterization, and Swelling Behavior of PEGylated Guar Gum @ Ag Nanoparticles

In this study, polyethylene glycol/guar gum @ silver nanoparticles (PEG/GG@AgNPs) were synthesized by using simple sonication method. The nanoparticles were characterized using Fourier-transform infrared spectroscopy (FTIR) and scanning transmission electron microscopy (STEM). The swelling behaviors of nanoparticles were studied in different pHs (5.5 and 7.4). The experimental results were calculated by Fickian diffusion and Schott kinetic models to understand the swelling mechanism and coefficients of the nanoparticles. The results showed that the linear equation of the Fickian diffusion kinetic model was best fit to explain the water diffusion mechanism of the nanoparticle with high correlation coefficient (R2 = 0.982–0.987). The results confirmed that the swelling degree of nanoparticles were 9.71 g/g at pH 5.5. Also, the results confirmed that PEG/GG@AgNPs can be a good candidate for drug delivery systems in pharmaceutical applications

The effect of various cations and pH on the adsorption of U(VI) on Amberlite IR-118H resin

The effects of various metal cations and pH on the adsorption of uranium(VI) on strongly acidic cation exchanger Amberlite IR-118H (AIR-118H) were studied. The metal cations suppress U(VI) adsorption differently depending on their ionic radii. Adsorption of U(VI) on AIR-118H peaks at pH 3.4, which was attributed to the occurrence of different forms of U(VI) at different pH values. The adsorption data were then processed using the Frumkin-Fowler-Guggenheim equation, and the standard free energy of adsorption was calculated. (C) 2003 Elsevier Science Ltd. All rights reserved

Adsorption of uranium from aqueous solution on heat and acid treated sepiolites

In this work adsorption of uranium on natural, heat and acid treated sepiolite was studied. For acid treatment HCl and H(2)SO(4) were used separately. Heat and acid treatment caused some, changes in sepiolite such as surface area, micropore volume (cm(3)/g) and average pore diameter (A). Different amounts of Mg ions were extracted from the lattice depending on the type of acid. After acid treatment with MCl, the amount of Mg left in the sepiolite changed a little. During H(2)SO(4) treatment the sepiolite structure was progressively transformed into amorphous silica. These heat and acid treatments changed adsorption capacity and mechanism of uranium on sepiolite. Data obtained from the adsorption experiments were applied to Langmuir and Dubinin-Radushkevich (D-R) adsorption isotherms. Using these isotherms different adsorption capacities were found for natural and treated sepiolite samples. The capacity values were 3.58 x 10(-3), 3.14 x 10(-3), 2.78 x 10(-3) and 1.55 x 10(-3) mol/g for HCl treated, heat treated, natural and H(2)SO(4) treated sepiolite samples, respectively. In order to evaluate the adsorption mechanism adsorption energies were calculated by the D-R isotherm. According to the adsorption energy values uranium fixed to the natural and heat treated sepiolite surface with ion exchange (12.75 and 12.12 kJ/mol, respectively). Simple physical attractions were the driving force for adsorption on HCl and H(2)SO(4) treated ones (6.62 and 6.87 kJ/mol, respectively). (C) 2010 Elsevier Ltd. All rights reserved

Thermodynamic and kinetic investigations of uranium adsorption on amberlite IR-118H resin

The adsorption behavior of uranium(VI) on a strongly acidic cation exchanger amberlite IR-118H has been studied as a function of the solution concentration and temperature. Results have been analyzed by Langmuir and Dubinin-Radushkevich (D-R) adsorption isotherms. The mean energy of adsorption 7.14 kJ mol(-1) was calculated from the D-R adsorption isotherm. In order to understand the significance of the diffusion mechanisms and to accurately estimate the diffusivities inside the adsorbent particles, a model for uranium(VI) adsorption on amberlite IR-118H was used. The rate constants have been calculated for 293, 313 and 333 K using Lagergren equation and the activation energy (Ea) was derived using the Arhenius equation. The thermodynamic quantities for the process of adsorption have been estimated by plotting Ln K-D versus 1/T. The DeltaHdegrees and DeltaGdegrees values of uranium(VI) adsorption on amberlite IR-118H show endothermic heat of adsorption; higher temperatures favor the process. (C) 2003 Elsevier Science Ltd. All rights reserved

The adsorption behavior of natural sand in contact with uranium contaminated seawater

This study was undertaken to investigate the interaction between uranium contaminated seawater and the sand in contact with this seawater. Adsorption data have been evaluated from column experiments of seawater from Marmara, Black Sea and Mediterranean contaminated with 10(-7) M uranium. The uranium uptake on the fractionated and non-fractionated sand of these sea have been measured as a function of time. The adsorption proceeds via a rather fast stage followed by a slower one. Results could be correlated with particle size and porosity of the sand. Adsorption isotherms are also derived from amount of adsorbed uranium vs. time plots and the results have been analyzed by the Langmuir, Freundlich and Dubinin-Radushckevich (D-R) isotherm equations over the entire range of uranium concentrations. By fitting the data to D-R isotherm, we have calculated the adsorption energy and decided to type of the adsorption