A dielectric measurement for the aqueous solutions at lower frequencies (20Hz to 2MHz) has been carried out in frequency domain using Agilient Precision LCR meter (E4980A). The dielectric permittivity spectra of over entire concentrations with aqueous solutions are measured at 25 ̊C. From observed spectra, static dielectric constants (ε0) have been determined. Dielectric Spectroscopy is especial...

introduction: arsenic is known as a carcinogenic compound in drinking water . it can cause acute and chronic effects on human health. in this study, the effect of polyamidoamine dendrimer generation 3(pamam g3) as adsorbents for removal of arsenic (v) from aqueous solutions was evaluated.     methods: adsorption experiment was studied in batch system and the effect of different variables like p...

hydroxyapatite nanocrystals were synthesized by sol-gel combustion method for the sorption ofhg(ii) ions from aqueous solutions. the effects of varying parameters such as ph, temperature, initialmetal concentration, and contact time on the adsorption process were examined. adsorptionequilibrium was established in 360 minutes and the maximum adsorption of hg(ii) on thehydroxyapatite was observed...

The need to elimination heavy metal from aqueous solutions cannot be over emphasized.Very studies have investigated the removal heavy metal from water. In this study a new magnetic nanocomposite of PEI on magnetized Sawdust (SD/MNP/PEI) was prepared. Investigations were conducted to study the adsorption behavior of heavy metal Zn (II) on the SD/MNP/PEI nanocomposite in aqueous medium by varying...

Matract-Polyphenok condens with 2-methylbut-3cne-2-d or y,ydimethylallyl alcohol in 5% aqueous citric acid solution to yield phenolic 2Jdimethylchromans These facik condensation provide chemical support for the biogenetic theory of C-isopentenylation of phenols by 7,7dimcthylallyl pyrophosphate. Iso-psoralidin (20) has been synthesized from 7-hydroxy-2Jdimethylchroman (12) by a novel and conven...

Hydrogen bond dynamics of water in NaBr solutions are studied by using ultrafast 2D IR vibrational echo spectroscopy and polarization-selective IR pump-probe experiments. The hydrogen bond structural dynamics are observed by measuring spectral diffusion of the OD stretching mode of dilute HOD in H(2)O in a series of high concentration aqueous NaBr solutions with 2D IR vibrational echo spectrosc...

The composition of aqueous fluoroberyllate solutions has been studied by 9Be and l9F NMR spectroscopy for various ratios of the beryllium and fluorine concentrations, and at different pH values. The equilibrium constants have been determined for the ligand exchange processes, which involve the species [Be(OH2)4]2+, [BeF(OH2)3]+, [BeF2(OH2)2], [BeF3(OH2)]_ , and [BeFzi]2 . These equilibria are s...

published in Advance ACS Abstracts, December 1, 1994. 0022-3654/95/2099-0454$09.00/0 we present here the results of experimental and theoretical studies of a ternary solution constituted of the proteins yma (designated as protein A), a “high-Tc” protein, and yw (designated as protein B), a “low-Tc” protein, in aqueous solution. The solution pH was kept constant at 7.1 by a 100 mM phosphate buff...

Between 100 kHz and 2 GHz ultrasonic attenuation spectra of disaccharides in water have been measured at 25 degrees C. Some additional measurements have been performed at different temperatures between 10 and 35 degrees C and as a function of saccharide concentration c (0.5 mol/l</=c</=1.8 mol/l). The analytical description of the spectra in terms of relaxation spectral functions revealed four ...

(2)H-nuclear magnetic resonance (NMR) and neutron scattering (NS) on isotopically labelled samples have been combined to investigate the structure and dynamics of polyvinylpyrrolidone (PVP) aqueous solutions (4 water molecules/monomeric unit). Neutron diffraction evidences the nanosegregation of polymer main-chains and water molecules leading to the presence of water clusters. NMR reveals the s...