Papers by Keyword: Ag⁺

Abstract: In this work, the optical and structural properties of the modified crystalline structures of the nanostructured cadmium sulphide (CdS) semiconductor caused by doping with (Cu²⁺, Ag⁺, Au⁺) transition metal ions are studied. Using the chemical bath deposition technique, thin CdS films of good crystalline quality were deposited, which were doped in synthesis without the need for additional steps, obtaining thicknesses of around 100 nm. The chemical binding energies and their interactions of the CdS semiconductor compound with the different transition metal ions were determined by X-ray photoelectron spectroscopy. The crystalline and quality phase of the CBD-CdS thin films were determined by X-ray diffraction that were confirmed by Raman scattering, obtaining that the dominant crystalline phase is zinc blende in the (1 1 1) crystalline direction. A change in crystalline quality from monocrystalline to polycrystalline was observed by XRD in the CdS thin films doped with transition metal ions, keeping the crystalline direction (1 1 1) of the zinc blende phase of CdS as the dominant one; this crystalline behaviour was confirmed by HRTEM micrographs, in addition to the different levels of quantum confinement favoured by each transition metal incorporated into the CdS. By Raman scattering measurements, the crystalline zinc blende phase of CdS was confirmed and also allowed the analysis of the phononic interactions of the binary compound, where Raman shifts provided information on the structural quality and also confirm the effects of quantum confinement. UV-visible optical spectroscopy describes the effects of the crystalline structural modifications with blue shifts on the optical band gap energies of the evaluated CdS samples, related with the different levels of quantum confinement given by the (Cu²⁺, Ag⁺, Au⁺) transition metal dopants.

Abstract: Effects of parameters including pH value, temperature, absorbent dosage, initial ion concentration, and absorbed time, on the removal efficiency of Ag⁺ from aqueous solution were investigated through single factor experiment. Vinasse before and after adsorption were characterized by IR. The maximum removal efficiency of Ag⁺ on vinasse is 97%. The equilibrium sorption is well demonstrated by Freundlich isotherm model.

Abstract: A highly selective chemosensor for Ag⁺ based on heterocyclic compound Diethyl 6-anilino-5H-2,3-dithia-5,7-diazacyclopenta (cd) indene-1,4-dicarboxylate (D1) was investigated. The deprotonation of N-H was observed easily in spectra of D1 (2.5×10^-5 M) in 50% H₂O/THF solution after NaOH addition, and the deprotonated D1 could interact with Ag⁺, resulted in the sharp decrease of deprotonated absorption. The addition of other metal ions would not produce an obvious change, which means quite extreme selectivity for Ag+ compared with other metal ions. The LOD of the method to detect Ag⁺ was 8.07×10^-8 M. It is indicated that a novel high selective chemosensor for Ag⁺ was build up.

Abstract: Aptamer was modified the gold nanoparticle (AuNP) to form stable aptamer-AuNP probe that was not gathered in the pH 7.2 2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid (HEPES) buffer solution and in the presence of NaCl. The Ag+ react with the aptamer-AuNP probe to fold a hairpin structure complex of Ag+-aptamer and release AuNPs that were aggregated to large particles, which lead to resonance Rayleigh scattering (RRS) peak at 596 nm enhancement. The enhanced value ΔI596nm is linear to Ag + concentration in the range of 6.7×10-8-1.33×10-6 mol/L. Thus, a new RRS methods were proposed for detection of Ag+, with high sensitivity, good selectivity and simplicity.

Abstract: This paper reports the feasibility of using rice husk to remove Ag+ from synthetic wastewater. Effect of various adsorption parameters, namely, pH, adsorbent dose, initial silver concentration and contact time has been studied in batch systems. The results indicated that rice husk offered high removal efficiency, fast adsorption rate and high uptake capacity for Ag+ ions. The equilibrium was attained within 20 min and the maximum removal efficiency at 11g/L rice husk and at pH 2 was found to be 99.76%. The kinetic data was fitted well to pseudo-second order model. The isotherm adsorption data was well described by the Langmuir isotherm model and the maximum uptake capacity of Ag+ ions onto rice husk was found to be 42.43 mg/g.