193 resultados para Cd2
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This article presents the investigation of the coordination behavior of a newly synthesized tricarboxylate ligand, obtained by joining imidazole dicarboxylic acid and 4-carboxybenzyl moieties cbimdaH(3), 1-(4-carboxybenzyl)-1H-imidazole-4,5-dicarboxylic acid]. Two novel coordination polymers were obtained through solvothermal reactions under similar conditions namely Sr(cbimdaH)(H2O)](n) (1) and Cd-2(cbimdaH)(2)(H2O)(6)](n)center dot(DMF)(3n)(H2O)(3n) (2), with the ligand behaving as a dianionic tricarboxylate linker. The single crystal X-ray structures show that while 1 forms a 3D coordination polymer, 2 forms a 1D polymer which is further assembled in three dimensions through supramolecular interactions (H-bonding). Complex 1 consists of Sr2+ ions in a distorted dodecahedral coordination geometry, while 2 consists of Cd2+ ions in distorted pentagonal bipyramidal geometries. A topology study reveals that 1 has a new topology based on the 5,6-coordinated 3D net architecture. The luminescence properties of the complexes in the solid state and their thermal stabilities were studied.
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TTRBCEE(CO_(2))E2 CD_(2), CD58(LFA-3)T11TS, S42, S14S110-220, TRBC,TRBCE , , T TRBC,TRBC 416
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The effects of single Cd2+ and Pb2+, and combined Cd2+ and Pb2+ on dehydrogenase activity and polysaccharide content of the substrate biofilms in the integrated vertical-flow constructed wetland (IVCW) were studied. Dehydrogenase activities decreased linearly with the increasing concentrations of Cd2+ and Pb2+ at different times (6, 24, 72, and 120 h). The activities at both 6 and 24 h were significantly higher than that at 72 and 120 h in the case of single and combined treatments. The single Cd2+ and Pb2+ treatments significantly inhibited dehydrogenase activities at concentrations in excess of 20 mu mol/L Cd2+ and 80 mu mol/L Pb2+, respectively. The inhibitory effect of Cd2+ was much greater than that of Pb2+. At the same time, the combined treatment of Cd2+ and Pb2+ Significantly inhibited dehydrogenase activities at all five concentrations studied and the lowest combined concentration was 1.25 mu mol/L Cd2+ and 5 mu mol/L Pb2+. A synergistic effect of Cd2+ and Pb2+ was observed. On the other hand, polysaccharide contents varied unpredictably with the increasing concentrations of Cd2+ and Pb2+ and extended experimental time. There were no significant statistical differences within the range of concentration and time studied, whether singly or in combination. These results implied that the effects of heavy metals on biofilms should be a concern for the operation and maintenance of constructed wetlands.
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In this paper, marine brown algae Laminaria japonica was chemically modified by crosslinking with epichlorohydrin (EC1 and EC2), or oxidizing by potassium permanganate (PC), or crosslinking with glutaraldehyde (GA), or only washed by distilled water (DW). They were used for equilibrium sorption uptake studies with Cd2+, Cu2+, Ni2+ and Zn2+.
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In this paper, marine brown algae Laminaria japonica was chemically modified by crosslinking with epichlorohydrin (EC1 and EC2), or oxidizing by potassium permanganate (PC), or crosslinking with glutaraldehyde (GA), or only washed by distilled water (DW). They were used for equilibrium sorption uptake studies with Cd2+, Cu2+, Ni2+ and Zn2+. The experimental data have been analyzed using Langmuir, Freundlich and Redlich-Peterson isotherms. The results showed that the biosorption equilibrium was well described by both the Langmuir and Redlich-Peterson isotherms.
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Carbon modified by the reduction of aromatic diazonium derivatives was first used as electrode for the electrochemical stripping analysis of heavy metals. As a model, the glassy carbon electrode was modified with benzoic acid by electrochemical reduction of diazobenzoic acid, and the resulting modified electrodes were used for determination of Cd2+ and Pb2+. The anodic peak currents of cadmium and lead at the benzoic acid-modified glassy carbon electrode are 7.2 and 6 times of that at the bare glassy carbon electrode. A linear response was observed for Pb2+ and Cd2+ in the range of 0.5-50 mu g/l.
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A family of supramolecular polymers was prepared via Cd2+-directed self-assembly polymerization of his (2,2':6',2 ''-terpyridine)-based ligand monomers, using oligofluorenes and triphenylamine as bridges under mild conditions. The polymers were fully characterized using thermogravimetric analysis, inherent viscosity, electrochemical measurements, UV-visible spectroscopy, photoluminescence (PL) and electroluminescence (EL). Polymers with oligofluorenes as spacers exhibited blue emission (434-442 nm) in dimethyl acetamide (DMAc) solution, while polymers with triphenylamine as spacer presented an emission peak at 494 nn in DMAc solution. Complexation polymerization of bis(2,2':6',2 ''-terpyridine)-based ligand monomers with cadmium(II) improved fluorescence quantum yields dramatically, and the film PL quantum yields of these polymers were about 0.38-0.54. Single-layer light-emitting diodes were fabricated with the configuration indium tin oxide (ITO)/polymer/Ca/Al; the EL showed green emission and the onset voltages of the devices were 8-11 V.
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Plussian blue(PB)/Pt modified electrode Tvas studied in the CdCl2 electrolyte solution by cyclic voltammetry and in situ FTIR spectroelectrochemistry. It was found that Cadmium ion was capable of substituting the high-spin iron of PB in an electrochemically induced substitution reaction and hexacyanoferrate cadmium (CdHCF) can be formed in the PB film. But PB and CdHCF in mixture film showed their own electrochemistry properties without serious effect on each other. The mechanism of substitution reaction has been given in detail.
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NP>>3 g/L35NP Cu2+Pb2+Cd2+pH5.0Na+K+Ca2+Mg2+Cl-NO3-SO42-C2O42-EDTALangmuirFreundlichCu2+Pb2+Cd2+25Cu2+Pb2+Cd2+1.61 mmol/g0.96 mmol/g0.98 mmol/gCu2+Pb2+Cd2+pseudo-30minEDTACu2+Pb2+Cd2+ Cr6+Cr6+Cr6+pH23pHCr6+pH5.0CrCr6+Cr3+Cr3+Cr6+Cr6+ Cu2+Pb2+Cd2+Cr6+LangmuirFreundlich25pH5.0LangmuirCu2+Pb2+Cd2+4.20 mmol/g3.13 mmol/g2.97 mmol/gCr6+
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The adsorption and desorption of algae Cladophora fascicularis and their relation with initial Cd2+ concentration, initial pH, and co-existing ions were studied. Adsorption equilibrium and biosorption kinetics were established from batch experiments. The adsorption equilibrium was adequately described by the Langmuir isotherm, and biosorption kinetics was in pseudo-second order model. The experiment on co-existing ions showed that the biosorption capacity of biomass decreased with an increasing concentration of competing ions. Desorption experiments indicated that EDTA was efficient desorbent for recovery from Cd2+. With high capacities of metal biosorption and desorption, the biomass of Cladophora fascicularis is promising as a cost-effective biosorbent for the removal of Cd2+ from wastewater.
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<p>A number of ectomycorrhizal (ECM) fungi, from sites uncontaminated by toxic metals, were investigated to determine their sensitivity to Cd<sup>2-</sup>, Pb<sup>2+</sup>, Zn<sup>2+</sup> and Sb<sup>3-</sup>, measured as an inhibition of fungal biomass production. Isolates were grown in liquid media amended with the metals, individually (over a range of concentrations) and in combination (at single concentrations) to determine any significant interactions between the metals. Significant interspecific variation in sensitivity to Cd<sup>2+</sup> and Zn<sup>2+</sup> was recorded, while Pb<sup>2+</sup> and Sb<sup>3-</sup> individually had little effect. The presence of Pb<sup>2+</sup> and Sb<sup>3-</sup> in the media did however, ameliorate Cd<sup>2+</sup> and Zn<sup>2+</sup> toxicity in some circumstances. Interactions between Cd<sup>2+</sup> and Zn<sup>2+</sup> were investigated further over a range of concentrations. Zn<sup>2+</sup> was found to significantly ameliorate the toxicity of Cd<sup>2+</sup> to three of the four isolates tested. The influence of Zn<sup>2+</sup> varied between ECM species and with the concentrations of metals tested.</p>
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As solues aquosas obtidas aps o tratamento final de efluentes de processos de eletrodeposio de Cd contm baixas concentraes de ons Cd2+. Neste trabalho determinaram-se as melhores condies para a utilizao de eletrodos de carbono vtreo reticulado (CVR) no polimento destas solues. A eletrodeposio do on Cd2+ sobre eletrodo de carbono vtreo reticulado de porosidades distintas, 30, 60 e 100 ppi, com e sem recobrimento com polipirrol, foi investigada em solues aquosas aeradas de cido sulfrico e sulfato de potssio em pH 4,8. Sob condies potenciostticas, uma elevada eficincia de remoo foi obtida para solues contendo 5 e 10 mg L-1 de on Cd2+, na faixa de potenciais entre 0,9 e 1,1 V para CVR e em 3,0 V para CVR recoberto com polipirrol (CVR-PPy0). Aps cada experimento de eletrodeposio, a diminuio da concentrao do on Cd2+ no eletrlito foi monitorada por voltametria de redissoluo andica. Neste experimenteo, empregando um eletrodo de gota pendente de mercrio sendo estes resultados comparados com medidas por espectrometria de emisso atmica (ICP). Para o eletrodo de CVR, neste intervalo de potenciais, -0,9 e 1,1 V, a eletrodeposio do on cdmio controlada por transporte de massa e a concentrao de ons cdmio varia exponencialmente com o tempo, seguindo uma cintica de pseudo primeira ordem. Para a concentrao 10 mg L-1 e usando eletrodo de CVR 30 ppi, as eficincias de corrente e de remoo determinadas a -1,1 V aps 30 minutos de eletrlise foram, 38 % e 97% , respectivamente. Para eletrodo de CVR 60 ppi foram encontrados 30 % e 99 %, respectivamente. Para o eletrodo de CVR-PPy0 a maior eficincia de remoo encontrada foi de 84% aps 90 minutos de eletrlise em 3,0 V, sendo a eficincia de corrente menor do que 2%. A presena de Cd metlico depositado na superfcie do eletrodo de CVR e CVR-PPy0 depois da reduo em 1,1 V e 3,0 V, respectivamente, foi confirmada por anlise de Microscopia Eeletrnica de Varredura (MEV) e espectrometria de energia dispersiva (EDS).
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Among the waste generated in the petrochemical industry water associated with oil production is the most important. It is considered one of the great challenges due to the presence of considered toxic chemicals present in this composition. The presence of these substances difficult to reuse the water associated with the enhanced recovery processes, so that prior to their reuse or disposal, treatment is necessary. This paper aimed to study the removal efficiency of chemical species: Ba2+, Ni2+, Cd2+, Cu2+, Cr3+, Sr2+ and Zn2+, present in the composition of the water associated with oil production by electrocoagulation. The evaluation of removal of these chemical species was performed by laboratory tests using electrochemical batch reactors and continuous flow. Initial tests were performed with electrocoagulation of synthetic wastewater in batch reactor using iron electrode. Results of removal of Zn2+ and Ni2+ were 78 % and 59 % respectively. While the percentage of removed Ba2+ was 19 % by 30 minutes of treatment and by applying current of 1.10 A. The tests were performed on effluent batch reactor applying the electrochemical technique with stainless steel electrodes 304, the objective was to remove part of the dispersed oil and also of organic compounds in the effluent. Under the experimental conditions used, the maximum result was obtained TOG was 60 % and TOC was approximately 50 % compared to the initial concentration. In the experiments carried out in continuous reactor, with effluent semisynthetic, have been used electrodes of iron and aluminum and the results were 100 % removal of Cd2+, Cu2+, Cr3+ and Zn2+ and 77 % of Sr2+. These percentages were only attainable through the use of the iron electrode. However, when the electrode was replaced by aluminum, there was a reduction in the percentage of removal to 65 %, using the same flow rate and current. Therefore according to the results obtained using the iron electrode was more effective in removing these metals and the conditions of lower current and lower flow rate was satisfactory, as observed in the experimental design adopted
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An intracellular protein termed CD2 binding protein 2 (CD2BP2), which binds to a site containing two PPPGHR segments within the cytoplasmic region of CD2, was identified. Mutagenesis and NMR analysis demonstrated that the CD2 binding region of CD2BP2 includes a 17-aa motif (GPY[orF]xxxxM[orV]xxWxxx GYF), also found in several yeast and Caenorhabditis elegans proteins of unknown function. In Jurkat T cells, over-expression of the isolated CD2BP2 domain binding to CD2 enhances the production of interleukin 2 on crosslinking of CD2 but not the T cell receptor. Hence, a proline-binding module distinct from SH3 and WW domains regulates proteinprotein interactions.