Existence Of Cu2 Research Articles

Single and simultaneous sorption of copper ions and p-cresol into surfactant-modified hydrotalcite-like compound with chelating ligand

In this study, the simultaneous sorption of Cu2+ and p-cresol, which are frequently encountered together in waste waters, into Mg–Al hydrotalcite-like compound (HTlc) modified with dodecylsulfate and ethylenediaminetetraacetate ions (SDS–EDTA-HTlc) was described and compared to a single adsorbate situation. Modification can decrease the specific surface area of the Mg–Al HTlc but promote the sorption for Cu2+ and p-cresol, respectively. Pseudo-second order equations were fitted to the kinetic data, and the rate constants were evaluated. The effect of pH on the simultaneous sorption efficiency was also studied. Freundlich isotherm model was used to analyze the equilibrium data for each adsorbate in both single and binary systems. In binary mixtures, competition for binding sites was identified. The equilibrium Cu2+ uptake decreased with an increased initial p-cresol concentration, whereas the existence of Cu2+ in the solution enhanced the p-cresol removal.

Hydrolysis and Hydrolysis Pathways of Composite of Copper (II) and Cypermethrin

The composite of copper ion and cypermethrin (CPM) may affect the hydrolysis of CPM. The experiments considered different factors which may affect the hydrolysis of pesticides, using buffer solutions with different pH to study the hydrolysis of CPM. The results showed that the existence of Cu2+ significantly promoted the hydrolysis of CPM, which might be related to the complexes that Cu2+ and CPM had produced. The hydrolysis kinetics of CPM followed the first-order kinetics. We used GC/MS to detect the hydrolysis of CPM intermediates and proposed the possible hydrolysis pathways.

“Turn-On” Fluorescent Sensor for Hg2+ via Displacement Approach

A new Cu2+ compound Cu- NB, (where H2 NB is bis(2-hydroxyl-naphthalene-carboxaldehyde) benzil dihydrazone) was synthesized as a highly selective fluorescence chemosensor for the detection of Hg2+ in aqueous media through a displacement "turn-on" signaling strategy. Whereas the coordination of Cu2+ resulted in a considerable quenching of the typical luminescence of the naphthol rings in Cu-NB, the addition of Hg2+ ion led to a dramatic increase in the emission intensity of Cu-NB at about 530 nm (excitation at 430 nm). The competitive fluorescent experiments showed that alkali, alkaline earth metal ions, the group 12 metals Zn2+, Cd2+, the first-row transition-metal ions such as Mn2+, Fe2+, Co2+, and Ni2+, as well as Pb2+ could not inhibit the Hg2+-binding fluorescent enhancement. It is postulated that the existence of Cu2+ in the luminescent probe Cu-NB could turn away the interferences of other metal cations from Hg2+ detection. The optical responses of the free ligand upon addition of Cu2+ ion, and of the Hg-H2NB compound upon the addition of Cu2+ were also investigated for comparisons.

A spectroscopic study of the nature and accessibility of protonic and cationic sites in H- and partially exchanged Cu- and Co-MFI zeolites

A study of the nature and accessibility of internal and external protonic and cationic sites has been carried out on protonic and partially Co- or Cu-exchanged ZSM5zeolite samples through UV-Vis and FT-IR spectroscopies. The samples were prepared by ionic exchange. o-toluonitrile has been chosen as a probe for the external surface of the zeolites. The existence of Cu2+ and Co2+ sites at positions different from those exchanging the active protons of the zeolites is emphasized.

Effect of Cu doping on the magnetoresistive behavior of double perovskite Sr2FeMoO6 polycrystals

The electrical, magnetic, and transport properties of Cu-doped polycrystalline samples Sr2Fe1−xCuxMoO6 with ordered double perovskite structure have been investigated systematically. Analysis of the x-ray powder diffraction pattern based on the Rietveld analysis indicates that the substitution of Fe3+ ions by Cu2+ ions enhances the site location order of Fe, Cu, and Mo on the B site for the high-doping-level samples (x=0.20, 0.25, 0.30). With increasing doping level, a transition from semiconductor to metal behavior was also found to occur. Furthermore, the transition temperature was found to decrease either by the application of a magnetic field or by increasing the doping level. It can be concluded that the existence of Cu2+ ions induces the occurrence of Fe3+δ ions and the double exchange interaction in Fe3+–O–Mo–O–Fe3+δ. The transport mechanism in these samples can be attributed to the competition between the metal phase and the semiconductor phase arising from the doping of Cu2+ ions. Both the semiconductor-to-metal transition and the magnetoresistive behavior can be explained by the percolation threshold model.

Adsorption of Copper at Aqueous Illite Surfaces

In this paper, we conducted potentiometric titrations, batch adsorption experiments and FT-IR analysis to study the uptake of copper in illite/water suspensions and then applied the constant capacitance surface complexation model to interpret the reaction mechanism at the aqueous illite surfaces. Our research shows that the copper adsorption at these surfaces is strongly dependent on pH and that the adsorption causes a deprotonation of surface groups. We propose that the uptake of copper in the carbonate-free illite suspensions can be explained by the formation of mononuclear surface complexes, ≡SOCu+and ≡SOCuOH, and a multinuclear surface complex, ≡SOCu2(OH)2+, followed by the formation of a bulk precipitate, Cu(OH)2(s), or a surface precipitate, ≡SOCu2(OH)3(sp). For the illite suspensions containing carbonates, we propose that the copper–illite interaction can be depicted by the formation of mononuclear surface complexes, ≡SOCu+and ≡SOCuOH, followed by the formation of a copper hydroxylcarbonate precipitate, Cu2(OH)2CO3(s), rather than a copper hydroxide precipitate. The existence of Cu2(OH)2CO3(s) in the carbonate-containing illite suspensions was identified by FT-IR analysis.

Studies on Bi-Sr-Ca-Cu-O glasses and superconducting glass ceramics

Bi-Sr-Ca-Cu-O glasses and glass ceramics of various compositions were synthesised. The glass transition temperature varies from 396 to 422°C depending on the glass composition. The bulk glass ceramics of 4334, 4336, 2223 and 4246 compositions show superconductivity when the corresponding glass samples were heat-treated in air at 820°C for 3, 9, 12 and 24 h respectively. X-ray diffraction studies show that the superconducting phase present in all these compositions is Bi2Sr2Ca1Cu2O x . The 4334 glass ceramic is almost a single-phase material with a preferred orientation such that thec axis is normal to the sample surface. The 2223 glass ceramic has a higherT c (onset) than the other three compositions indicating the presence of highT c phase (110K) also. ESR studies on the glass samples indicate the existence of Cu2+. The effect of heat treatment on ESR shows that the intensity of resonance decreases with increase in heat-treatment duration. This effect is more pronounced for the 4334 and 2223 compositions. The advantages of synthesizing superconducting materials by glass route are discussed in view of practical applications.