123 resultados para Cr3
Resumo:
1 -91012132425--5H15H23H-[bq][17101319416]-616 (7H17H)-2.210-10 M54.5 mV/dec.1.010-9-1.010-5 MI-Br-Cl- 2124- 124-35-(-2-)-1-(-2H-)-1H-124-2.610-7 M Hg2+29.30.3 mV/dec.1.010-6-3.010-4 M2pH 2.6-5.2EDTA 3 (E)-N'-(-2-)-2-((E)--2-)7.410-7M Zn2+25.9 mV/dec.1.010-6-1.010-3 M3pH 3.4-5.8EDTA 4 ICP-MS 5BCr3+ B2--8--(III)1:18.010-7-8.010-5 M1.910-7 M(III)
Resumo:
Cr3+,,pHCr3+;,Cr3+,U=β0(/β1×C+1),;ED10ED5050.59865.7 mg.kg-1;VmaxkCr3+,,,,;
Resumo:
GGAGGA+UU Sr2FeMoO6Sr2CoMoO6Sr2FeMoO6Sr2CoMoO6Ba2YIrO6Ba2LaIrO6 Fm-3m, R-3 P21/nBa2YIrO6Ba2LaIrO6 P21/nR-3 Mn-O-MnYBaMn2O5Mn-O-Mn 157.8oG-A-170170AGYBaMn2O5GAYBaMn2O5 CaCu3M4O12 M3dTi, V, Cr, Mn, Fe, CoMMCaCu3Ti4O12Ti4+d0Cu-CuCaCu3M4O12 (M= V4+d1, Cr4+d2, Mn4+d3, Fe4+d4dn0<n<5)Cu-M Cu-CuM-MCaCu3Co4O12Co4+d5Cu-Cu, Cu-CoCo-CoMCaCu3Ti4O12Ti4+t2g0CaCu3V4O12V4+t2g1CaCu3Cr4O12Cr4+t2g2CaCu3Mn4O12Mn4+t2g3CaCu3Fe4O12Fe4+t2g3eg1CaCu3Co4O12Co4+t2g5 CaCu3Cr2Sb2O12CaCu3Cr4O12 Sb5+ Cr-CrCr3+3dCaCu3Cr2Sb2O12CaCu3Cr4O12 MSb5+MCaCu3Fe4O12CaCu3Co4O12CaCu3Fe2Sb2O12 CaCu3Ru4O12Ru4+4d4CaCu3Ru4O12Ru-O dpRu-O-RuRu 4dCu 3dO 2pCu 3dRu 4dCaCu3Ru4O12CaRuO3CaRuO3Ru-O-Ru
Resumo:
ABBLaSr2Mn2O7CrTiNiFeMnBCr3Mn4Cr3crNi2Fe3MnLaS2Mn2O7MnMnMnFex0.2MR28OK74LasrZMn2O7Bi3+Sr2+x0.2Bi3Bi3TcoGdn=3Laca4kMn3O10La3-3xCa13xMn3O100.5x1.0La3x0.50.7x=0.8-1.0La3Mn3Mn3+Mn4+LaxCa4-xMn3O10x0-0.9Mn4x0.2x0.2xG-AFMx0.9C-AFM
Resumo:
CNO13% X-() (Thiobacillus Beijerinek)(Thiobacillu ferrooxidans, TF), (Thiobacillus thiooxidans, TT)TT (15-20)20g/L60% 48.5h91.2281.6hPH (1) Arrhenius(2) PHPHPH (3) 30g/L(4) TT10g/L25-36 100% Fe2+Fe3+Fe3+ Cr3+Cr6+,Cr6+CrO3This paper has studied bioleaching and recovery of Chronium(Cr)from electroplating sludge by two consortum of bacteria and their combination, with sludge produced by microbiological process treating electroplating wastewater containing Cr as material. The share of Cr is 13% and its state is Cr (OH)3 in the sludge. One of the bacteria in the paper was isolated from acid sewage sludge and the other was from acid mineral water. The former was tested and determined as Thiobacillus ferroxidans(TF) and the latter was Thiobacillus thiooxidans(TT). Different microorganisms, responsible for the metal leaching activity, have great influence on the efficiency of leaching. The results showed that TT has biggest power. Experiments were conducted to examined effects of three different ways of leaching(Shaking, Down-leaching, Static-leaching). When temperature was in-door's (15-20)and concentration of the sludge was 20g/L, the bioleaching time required to reach 60% of Cr solubilization with the above three ways were 91.2, 48.5, 81.6h respectively. Down-leaching was proved to be the most efficient. The influence of different temperature, initial PH, concentration of the sludge and non-mature inoculum had been studied. The results obtained reveal that: (1) The variation of temperature is important during the time from initial to middle of leaching. The reaction of bioleaching belongs to first-order. The relation between the bioleaching rate constant(In k)and temerature can be expressed by Arrhenius function. (2) The fittest initial PH is the nature PH of mature inoculum. Any alteration with it could cause clearly negative effection. (3) The concentration of the sludge can make strong influence on the bioleaching efficiency. But when the concentration is above 30g/L, the increasing of Cr in the solution is little. (4) If non-mature inoculum acts as the bioleachin microorganism, little quantity of Cr would be gained from the sludge. But the micormass in the solution is very active. The results from electron microscope showed that microorganisms adhered to the surface of the sludge and the adherence was the first stage of the bioleaching. Some salts of Cr can be obtained afer the water of the bioleaching solution being evaporated. By analysing the results of experiment with X-Ray spectroscopy, the salt was identified as CrO3. The recovery rate of Cr is 78.4%.
Resumo:
A plasticized Cr3+ ion sensor by incorporating 2,3,8,9-tetraphenyl-1,4,7,10-tetraazacyclododeca-1,3,7,9-tetraene (TTCT) ionophore exhibits a good potentiometric response for Cr3+ over a wide concentration range (1.010-6-1.010-1 M) with a slope of 19.5 mV per decade. The sensor response is stable for at least three months. Good selectivity for Cr3+ in comparison with alkali, alkaline earth, transition and heavy metal ions, and minimal interference are caused by Li+, Na+, K+, Co2+, Hg2+, Ca2+, Pb2+ and Zn2+ ions, which are known to interfere with other chromium membrane sensors. The TTCT-based electrode shows a fast response time (15 s), and can be used in aqueous solutions of pH 3 - 5.5. The proposed sensor was used for the potentiometric titration of Cr3+ with EDTA and for a direct potentiometric determination of Cr3+ content in environmental samples.
Resumo:
The electronic and magnetic properties of CaCu3Cr4O12 and CaCu3Cr2Sb2O12 are investigated by the use of the full-potential linearized augumented plane wave (FPLAPW) method. The calculated results indicate that CaCu3- Cr4O12 is a ferrimagnetic and half-metallic compound, in good agreement with previous theoretical studies. CaCu3- Cr2Sb2O12 is a ferrimagnetic semiconductor with a small gap of 0.136 eV. In both compounds, because Cr4+ 3d (d(2)) and Cr3+ 3d (d(3)) orbitals are less than half filled, the coupling between Cr-Cu is antiferromagnetic, whereas that between Cu-Cu and Cr-Cr is ferromagnetic. The total net spin moment is 5.0 and 3.0 mu(B) for CaCu3Cr4O12 and CaCu3Cr2Sb2O12, respectively. In CaCu3Cr4O12, the 3d electrons of Cr4+ are delocalized, which strengthens the Cr-Cr ferromagnetic coupling. For CaCu3Cr2Sb2O12, the doping of nonmagnetic ion Sb5+ reduces the Cr-Cr ferromagnetic coupling, and the half-filled Cr3+ t(2g) (t(2g)(3)) makes the chromium 3d electrons localized. In addition, the ordering arrangement of the octahedral chromium and antimony ions also prevents the delocalization of electrons. Hence, CaCu3Cr2Sb2O12 shows insulating behavior, in agreement with the experimental observation.
Resumo:
The high-resolution emission spectra of KMgF3 : Eu and KMgF3 : Eu-X(X = Ce, Cr, Gd, Cu) single crystals were measured at 300 and 77 K. The vibronic side bands of Eu2+ were characterized and an assignment of the normal mode frequencies to particular vibrations has been made. The correlation between the vibronic frequencies of Eu2+ and the site substitution of other co-dopcd ions was first found. The relationship between vibronic intensity of Eu2+ and other doped ions concentration showed that Cr3+, Gd3+ ions competed K+ sites with Eu2+ ions. Ce3+ and Eu3+ occurred the electron transference. The introduction of Cu+ made for Eu2+ substuting for K+ sites.
Resumo:
Energy transfer processes between Eu2+ and Gd3+, Cr3+, Ce3+ ions in KMgF3, which are difficult to study spectroscopically, have been investigated by using the proposed four-level decay model of the P-6(7/2) excited state of the Eu2+ ion. Gd3+ and Ce3+ transfer its energy to the vibronic transition of the P-6(7/2) --> S-8(7/2) transition of Eu2+, whereas Cr3+ receive energy from Eu2+ via the d-d interaction. The energy transfer from the Eu2+ 4f(6)5d level to the Ce3+ 4f5d state is observed spectroscopically, and the energy transfer mechanism is discussed. (C) 2001 Elsevier Science B.V. All rights reserved.
Resumo:
Two new compounds with the formula of CdYMWO7 (M = Cr, Mn) were prepared by solid state reaction. They crystallized with orthorhombic structure with the cell parameters of a = 11.7200 Angstrom, b = 7.1779 Angstrom, c = 6.9805 Angstrom (CdYCrWO7), and a = 11.7960 Angstrom, b = 6.1737 Angstrom, c = 7.6530 Angstrom (CdYMnWO7). These compounds are insulators with high resistivities at room temperature. The temperature dependence of the magnetic susceptibility of CdYMWO7 (M = Cr and Mn) show Curie-Weiss Law's behaviors from 80 to 300 K. The magnetic moments at room temperature fit very well with those corresponding to Cr3+ and Mn3+ ions. This suggests that both Cr and Mn ions exist in + 3 oxidation state in CdYMWO7 compounds. (C) 1998 Elsevier Science Ltd. All rights reserved.
Resumo:
Hydrotalcite-like compounds (HTLcs): CoMAlCO3-HTLcs (M=Cu2+, Ni2+, Mn2+, Cr3+, Fe3+), were synthesized by coprecipitation and characterized with XRD and IR. The catalysis of these HTLcs and their calcined products were studied in the p-cresol oxidation, and the effects of the temperature of HTLcs calcination, the ratio of Co/Cu, different promoters, reaction temperatures and reaction times on reaction activities were investigated. It has been found that calcined HTLcs have higher activity than uncalcined samples and mechanical mixed oxides in this reaction. The best yield was obtained from the CoCuAlCO3-HTLc (Co/Cu/Al=3:1:1) calcined at 450 degrees C. A tentative reaction mechanism was also proposed. (C) 1998 Elsevier Science B.V.
Resumo:
The synthesis temperature of YGa3B4O12 and the effect of the synthesis temperature and chromium doping on the luminescence properties were studied. YGa3-xCrxB4O12 were synthesized and their magnetic properties were described. Results show that the fluorescence intensity increases with the increasing of synthesis temperature. The structure of compounds was stabilized, and their emission spectra were changed when small quantity of chromium was doped in. The magnetic susceptibilities increase with the increasing of Cr3+ concentration.
Resumo:
The heteropolyanions of the Keggin structure ZW(11)O(39)M(H2O)(n-)(Z = Si, Ge, P; M = Ni2+, Cu2+, Cr3+, Co2+, n = 4 similar to 6) and Dawson structure P(2)W(17)O(61)M(H2O)(n-)(M = Ni2+, Cu2+, Cr3+, Co2+, n = 7, 8) have been transferred into the non-polar
Resumo:
X-ray and electrochemical studies of spinel-related manganese chromium oxides, LiCrxMn2-xO4 (0 less-than-or-equal-to x less-than-or-equal-to 1) were carried out in a lithium nonaqueous cell. X-ray diffraction spectra indicated that the substitution of manganese in LiMn2O4 by trivalent transition metals (Cr3+) cause the linear decrease of lattice parameter with the x in the LiCrMn2-xO4. Some discharge-capacity loss was obtained due to the lattice contraction of LiCrMn2-xO4, but it has a better rechargeability than LiMn2O4. Cyclic voltammetry and electrochemical impedance experiments have shown that the excellent rechargeability of LiCrxMn2-xO4 may be attributed to the good reversibility of the change in its crystal structure for the insertion and extraction of lithium ions.
Resumo:
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+
