Degradation Of Cu Research Articles

Simultaneous adsorption and degradation of Zn2+ and Cu2+ from wastewaters using nanoscale zero-valent iron impregnated with clays

Clays such as kaolin, bentonite and zeolite were evaluated as support material for nanoscale zero-valent iron (nZVI) to simultaneously remove Cu(2+) and Zn(2+) from aqueous solution. Of the three supported nZVIs, bentonite-supported nZVI (B-nZVI) was most effective in the simultaneous removal of Cu(2+) and Zn(2+) from a aqueous solution containing a 100 mg/l of Cu(2+) and Zn(2+), where 92.9 % Cu(2+) and 58.3 % Zn(2+) were removed. Scanning electronic microscope (SEM) revealed that the aggregation of nZVI decreased as the proportion of bentonite increased due to the good dispersion of nZVI, while energy dispersive spectroscopy (EDS) demonstrated the deposition of copper and zinc on B-nZVI after B-nZVI reacted with Cu(2+) and Zn(2+). A kinetics study indicated that removing Cu(2+) and Zn(2+) with B-nZVI accorded with the pseudo first-order model. These suggest that simultaneous adsorption of Cu(2+)and Zn(2+) on bentonite and the degradation of Cu(2+)and Zn(2+) by nZVI on the bentonite. However, Cu(2+) removal by B-nZVI was reduced rather than adsorption, while Zn(2+) removal was main adsorption. Finally, Cu(2+), Zn(2+), Ni(2+), Pb(2+) and total Cr from various wastewaters were removed by B-nZVI, and reusability of B-nZVI with different treatment was tested, which demonstrates that B-nZVI is a potential material for the removal of heavy metals from wastewaters.

Low temperature-synthesis of BiVO4 nanorods using polyethylene glycol as a soft template and the visible-light-activity for copper acetylacetonate decomposition

Monoclinic sheelite BiVO4 nanorods (ms-BiVO4 NRs) have been synthesized from an aqueous solution of Bi(NO3)3 and NH4VO3 at 370K containing polyethylene glycol (PEG), while micron-sized BiVO4 crystals (ms-BiVO4 MCs) are formed without PEG. The UV–vis absorption spectra of the PEG solutions of NH4VO3 suggested the formation of a complex consisting of VO3− ion and PEG. In this synthetic route, PEG can suppress the reactivity of VO3− ions by the stabilization to further act as a soft template for the formation of ms-BiVO4 NRs. The as-grown ms-BiVO4 NRs exhibit a high level of photocatalytic activity for the degradation of Cu(acac)2 without sacrificial agents under illumination of visible-light (λ>430nm). The local symmetry of VO4 tetrahedron affecting the light absorption intensity in addition to the large surface area and high crystallinity have been suggested to be a crucial factor to achieve the high visible-light-activity of ms-BiVO4.

Application of Ferrate(VI) on the Decomplexation of Cu(II)-EDTA

In this study, Fe(VI) was employed as a multi-functional agent to treat the simulated industrial wastewater contaminated with Cu(II)-EDTA through oxidation of EDTA, decomplexation of Cu(II)-EDTA and subsequent removal of free copper through precipitation. The decomplexation of 10 -4 M Cu(II)-EDTA species was performed as a function of pH at excess concentration of Fe(VI). It was noted that the acidic conditions favor the decomplexation of Cu(II)-EDTA as the decomplxation was almost 100% up to pH 6.5, while it was only 35% at pH 9.9. The enhanced degradation of Cu(II)-EDTA with decreasing the pH could be explained by the different speciation of Fe(VI). HFeO4 - and H2FeO4, which are relatively more reactive than the unprotonated species FeO4 2- , are predominant species below neutral pH. It was noted that the decomplexation reaction is extremely fast and within 5 to10 min of contact, 100% of Cu(II)-EDTA was decomplexed at pH 4.0. However, at higher pH (i.e., pH 10.0) the decomplexation process was relatively slow and it was observed that even after 180 min of contact, maximum ca 37% of Cu(II)-EDTA was decomplexed. In order to discuss the kinetics of the decomplexation of Cu(II)-EDTA, the data was slightly fitted better for the second order rate reaction than the first order rate reaction in the excess of Fe(VI) concentration. On the other hand, the removal efficiency of free Cu(II) ions was also obtained at pH 4.0 and 10.0. It was probably removed through adsorption/coagulation with the reduced iron i.e., Fe(III). The removal of total Cu(II) was rapid at pH 4.0 whereas, it was slow at pH 10.0. Although the decomplexation was 100% at lower pH, the removal of free Cu(II) was relatively slow. This result may be explicable due to the reason that at lower pH values the adsorption/coagulation capacity of Fe(III) is greatly retarded. On the other hand, at higher pH values the decomplexation of Cu(II)-EDTA was partial, hence, slower Cu(II) removal was occurred.

Control of reactive plasmas for low-k/Cu integration

We proposed models for controlling surface reactions during etching of SiOCH and organic material. The etch rate of each material can be determined by the balance between the total atom fluxes of O, C, F, N, and H that were supplied from both the plasma and the etched material to the reactive layer. Low-k films (SiOCH, porous SiOCH, and organic material) have narrow process windows for obtaining good etching properties, such as selectivity, because the polymer and reactive layers on these films can be changed by only slight changes in the plasma parameters. Therefore, the partial pressure and dissociation of parent gas molecules in fluorocarbon or N–H plasma as well as plasma–wall interaction must be controlled. To create highly reliable interconnects, the interfaces between the metal and low-k must be optimized during the etching of stopper material and ashing. The surface of Cu is very reactive, the remaining F induces degradation of Cu. SiOCH can easily be oxidized during ashing processes, and the adsorption of H2O on damaged SiOCH causes interconnect failure during electrical tests. To suppress problems in the etching and ashing processes, the balance of the total atom fluxes should be quantitatively and instantaneously controlled to the optimum point for each material.

Cu(In,Ga)Se-based thin-film photovoltaic modules optimized for long-term performance

Abstract In this contribution we give an overview of the mechanisms behind degradation of Cu(In,Ga)Se 2 -based modules. Based on the results from a detailed analysis of power losses in modules, prior to and after extended damp heat exposure, we discuss to what extent modules can be designed to achieve enhanced long-term performance. For conventional modules, we show that the stability can be improved by optimizing the interconnect and the front contact. Furthermore, we argue that gridded modules are better from a long-term performance point of view. A novel interconnect structure, specifically designed for long-term durability, is briefly discussed.

Dielectric Degradation of Cu/ SiO2/Si Structure during Thermal Annealing

The impact of Cu on the dielectric layer was studied using a Cu//Si metal oxide semiconductor capacitor and rapid thermal annealing (RTA) treatment. With the RTA treatment, no chemical reaction was observed up to 900°C; however, dielectric degradation occurred following RTA at 300°C for 60 s and became worse with the increase of annealing temperature. The interface‐trap density at the /Si interface also increased from 5 × 1010 to after 800°C RTA treatment. The RTA anneal introduced a large number of positive Cu ions into the dielectric layer. Under bias‐temperature stress, Cu ions drift quickly in the layer and may drift across the /Si interface and enter the Si substrate. With the use of 1200 Å thick TiN and TiW barrier layers, respectively, the dielectric strength of the Cu/(barrier)//Si structures was able to remain stable up to 500 and 600°C.

Degradation of Cu(II)-partly alkylated wool keratin complex by hygrogen peroxide.

In order to obtain some information regarding the degradation or morphological components of wool keratin fiber brought about by hydrogen peroxide under conditions in which the Cu (II) ion is bound to wool keratin the degradation of partly alkylated wool keratin fiber prepared by alkylating the generated sulfhydyl groups with 2-vinylpyridine was studied for the Cu (II)-partly alkylated wool keratin complex/hydrogen peroxide system. At the early stage of the degradation, peptide fragments in the treat. ment solution were found to contain a large amount of s-β-(2-pyridylethyl) cysteine residue and the tyrosine content in the wool fiber residue, which belongs in quantity to high-glycine-tyrosine proteins of an amorphous matrix, increased as the initial degradation proceeded. These results suggest that the high-sulfur proteins were easily degraded in the peptide bond cleavage of these proteins, which are contained especially in the cuticle.

Biodegradation of metal-nitrilotriacetate complexes by a Pseudomonas species: mechanism of reaction.

A nitrilotriacetate (NTA)-degrading Pseudomonas species was shown to degrade Ca, Mn, Mg, Cu, Zn, Cd, Fe, and Na chelates of NTA at nearly equal rates when the appropriate metal concentrations are low enough to avoid toxicity from the freed metal. Ni-NTA, however, was not degraded. When higher concentrations of metal-NTA substrates were used, soil stimulated degradation of Cu, Zn, and Cd complexes, probably as a result of binding toxic freed metals. The metal associated with the NTA substrate does not appear to be transported into the cell, since metals do not accumulate in the cells and the presence of NTA reduces metal toxicity. The data are consistent with the hypothesis that an envelope-associated component, probably a transport protein involved in binding, is responsible for the disassociation of the metal from the NTA. Both soil and this NTA-degrading organism destabilize the metal-NTA complex, which suggests that in the natural environment both would act to limit mobilization of metals as soluble NTA chelates. Crude soluble enzyme preparations degrade Fe-, Mn-, and Na-NTA complexes but not Cu-NTA.

Biodegradation of Metal-Nitrilotriacetate Complexes by a Pseudomonas Species: Mechanism of Reaction1

A nitrilotriacetate (NTA)-degrading Pseudomonas species was shown to degrade Ca, Mn, Mg, Cu, Zn, Cd, Fe, and Na chelates of NTA at nearly equal rates when the appropriate metal concentrations are low enough to avoid toxicity from the freed metal. Ni-NTA, however, was not degraded. When higher concentrations of metal-NTA substrates were used, soil stimulated degradation of Cu, Zn, and Cd complexes, probably as a result of binding toxic freed metals. The metal associated with the NTA substrate does not appear to be transported into the cell, since metals do not accumulate in the cells and the presence of NTA reduces metal toxicity. The data are consistent with the hypothesis that an envelope-associated component, probably a transport protein involved in binding, is responsible for the disassociation of the metal from the NTA. Both soil and this NTA-degrading organism destabilize the metal-NTA complex, which suggests that in the natural environment both would act to limit mobilization of metals as soluble NTA chelates. Crude soluble enzyme preparations degrade Fe-, Mn-, and Na-NTA complexes but not Cu-NTA.