Papers by Keyword: Cu²⁺

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: Calcium silicate hydrate gel (CSH) was synthesized by calcium acetate and sodium silicate. The structure and morphology of CSH were characterized by X-ray diffraction analysis, Fourier transform infrared spectroscopy and Scanning electron microscopy. The adsorption performance of CSH was measured by static adsorption method. The results show that CSH has porous structure and large specific surface area, and the optimum reaction conditions is the reaction temperature of 25°C and calcium-silicon ratio of 1.2. It has the maximum adsorption capacity of more than 150 mg/g and the removal rate of more than 86% with Cu²⁺. And it shows the excellent adsorption performance, even when the concentration of Cu²⁺ is less than 200mg/L, the removal rate is above 90%. The research may provide a low-cost and high-efficiency adsorbent.

Abstract: The research of adsorption of Cu²⁺ metal ion on dithizone-immobilized natural bentonite (DNB) had been carried out. The experiment was begun by the activation of natural bentonite with HCl 4 M and dithizone-immobilized on activated bentonite surface. This study included synthesis and characterization of dithizone-immobilized bentonite and its application in adsorption of Cu²⁺ metal ions. The type of interaction occurred in the adsorption was tested by sequential desorption. The result showed that dithizone successfully immobilized on activated natural bentonite (ANB). The optimum conditions for Cu²⁺ metal ions adsorption using dithizone-immobilized natural bentonite are at pH 5; 0.1 g mass of adsorbent, with interaction time 60 min, and the initial concentration of ion at 80 ppm. Kinetics and adsorption isotherm studies suggest that the capacity, of the dithizone-immobilized natural bentonite in adsorbing Cu²⁺ metal ion is significantly improved compared to activated natural bentonite. The adsorption of Cu²⁺ metal ions by activated natural bentonite was through several interactions dominated by electrostatic interaction (82%). Otherwise, the interaction of dithizone-immobilized natural bentonite with Cu²⁺ metal ions in the sequence were dominated by the mechanism of complex formation of (75%). The result shows that the immobilization of dithizone changes the type of electrostatic interaction into complex formation.

Abstract: Several kinds of modified carbon molecular sieves (CMSs) were applied for air dynamic separation by pressure swing adsorption (PSA) at ambient temperature. The textural properties were characterized by N₂ adsorption/desorption isotherms at 77 K. Linear driving force (LDF) model was used to fit the experimental data for the mixed gas. Results had shown that the modified CMSs with Cu²⁺ had the highest separation factor for air separation comparing to other samples.

Abstract: This document studies test methods on modification of activated carbon by potassium permanganate to adsorb Cu²⁺. Ensure all factors’ effects on Cu²⁺ removal. Use potassium permanganate solution to modify activated carbon, investigate main factors’ effects on Cu²⁺ removal and analyze mechanism by changing potassium permanganate solution concentration, adsorption time, activated carbon’s additive amount and temperature. The results show that modification of activated carbon by 0.03mol/L potassium permanganate solution (0.03K-GAC) can adsorb Cu²⁺ best. 0.03K-GAC’s removal rate on Cu²⁺ is 98% when the initial concentration of Cu²⁺ is 50mg/L, the additive amount of 0.03K-GAC is 2.0g, the pH value is 5.5, the temperature is 25°C and the adsorption time is 4h. Modification of activated carbon by potassium permanganate has good adsorbability on Cu²⁺. Potassium permanganate solution concentration, adsorption time and additive amount can influence the adsorption of Cu²⁺ by activated carbon. However, temperature’s influence on the effect of adsorption is non-significant.

Abstract: In this study, using solidified landfilled sludge (SLS) and its pyrolyzed produce (PSLS) as adsorbents, adsorption characteristics of Cu²⁺ and Zn²⁺ onto SLS and PSLS was investigated. These results revealed that PSLS had more irregular pores and its surface roughness increased, and the surface area of PSLS was twice than that of SLS. Adsorption studies showed that adsorption capacity of Cu²⁺ and Zn²⁺ increased with the increasing dosage of adsorbents, and the adsorption process of Cu²⁺ and Zn²⁺ onto SLS or PSLS could be divided into the first rapid step and the second slower step. Based on Langmuir equation, the maximum limiting adsorption capacities of Cu²⁺ and Zn²⁺ onto PSLS was much higher that onto SLS. Moreover, FTIR analysis showed that the adsorption of Cu²⁺ and Zn²⁺ on SLS depended on active functional group such as hydroxy aldehydes while that relied on the groups such as C=C bond of aromatic rings, Si-O-Si or Si-O-C structures for PSLS.

Abstract: In order to investigate the biosorption of Cu²⁺ by anaerobic granular sludge, the effect of equilibrium time, pH, sludge dosage, biosorption kinetics, biosorption thermodynamics and biosorption isotherms had been studied. Results showed that pseudo second-order kinetic model was useful to describe the biosorption process of Cu²⁺. Both Langmuir and Freundlich isotherm equations could well describe the desorption process at 15-55 °C. Thermodynamic studies showed that the biosorption process was spontaneous and endothermic in nature. When the solution temperature maintained at 35 °C, pH of 6~7, a good biosorption process could be obtained.

Abstract: Applications of PBTCA modified nanoscale zero valent iron (P-Fe⁰) prepared by borohydride reduction for removal of Cu²⁺ ions from aqueous solution are investigated under a variety of experimental conditions. According to X-ray photoelectron spectroscopy (XPS) results, Cu²⁺ ions were removed primarily via a redox mechanism that resulted in the formation of Cu⁰ and Cu₂O. The contact of P-Fe⁰ with aqueous media caused extensive formation of iron oxide.

Abstract: A 1,8-naphthyridine modified rhodamine B derivative, one Cu²⁺-selective chemosensors was designed, synthesized and characterized, which display a high selectivity for Cu²⁺ among environmentally and biologically relevant metal ions. It can detect Cu²⁺ in aqueous solution selectively with a dramatic colour change from colorless to magenta. The detection mechanism involves a ring-opening process as a consequence of metal complex formation. Jobs plots study indicated that the chemosensor chelated Cu²⁺ with 2:1 stoichiometry.

Abstract: The spin Hamiltonian parameters (g factors g||, g and the hyperfine structure constants A||, A) for the Cu²⁺ centers in alkali barium borate glasses were theoretically studied based on the high-order perturbation formulas of these parameters for a 3d⁹ ion in a tetragonally elongated octahedron. From the calculations, the ligand octahedra around Cu²⁺ are suggested to suffer about 9.4%, 10.7%, and 11.1% relative elongation along C4 axis for the alkali barium borate glasses (Li-Ba-B, Na-Ba-B and K-Ba-B, respectively), the results are in good agreement with the observed values. In addition, the negative signs for A|| and A of the studied Cu²⁺ centers were also suggested in the discussion.