Effect Of Cu Loading Research Articles

Copper behaviour in a Podosol. 1. pH-dependent sorption - desorption, sorption isotherm analysis, and aqueous speciation modelling

The effects of pH and Cu loading on the solid/solution partitioning of Cu in a Podosol from south-east Queensland, Australia was examined. Sorption–desorption of Cu exhibited maximum linear distribution coefficients (KD) at approximately pH 5. Observed decrease in KD values at pH >5 was attributed to increased solubility of native dissolved organic carbon (DOC) at higher pH and subsequent formation of non-sorbing Cu–DOC complexes. Speciation modelling with the MINTEQA2 code indicated that >90% of aqueous Cu was present as Cu–DOC complexes at pH >5.5. The effect of Cu loading was examined with sorption isotherm analysis at pH 5 using solid : solution ratio approaches that were both constant (1 : 2 and 1 : 10) and variable. As the solid : solution ratio increased, the proportion of Cu sorbed decreased due to the formation of Cu-DOC complexes. However, this effect was negligible once these Cu–DOC complexes were accounted for via free Cu2+ sorption isotherms. This indicated that Cu2+ sorption at concentrations <0.08 mg/L was described by a KD value of approximately 3000 L/kg. Despite this relatively high KD value for Cu2+ sorption, the results indicate that Cu–DOC complexes significantly enhance Cu solubility in soils high in DOC.

Effect of method of preparation of copper – magnesium oxide catalyst on the dehydrogenation of cyclohexanol

Abstract The superior catalytic activity in the dehydrogenation of cyclohexanol to cyclohexanone of Cu/MgO coprecipitated catalyst over corresponding impregnated and solid–solid wetting catalysts is ascribed to the higher Cu metal area and interaction between the microcrystals of CuO and MgO associated with coprecipitated catalyst. Further, the effect of Cu loading on the activity of Cu/MgO coprecipitated catalysts indicates that the catalyst comprising of ∼16 wt.% Cu exhibits higher activity. The catalysts have been characterized by different techniques, viz. X-ray diffraction (XRD), atomic absorption spectroscopy (AAS), temperature programmed reduction (TPR), BET-surface area measurements and N2O decomposition for measuring Cu metal surface areas and the results have been correlated with the activities of catalysts where ever possible.

Effect of Cu loading and addition of modifiers on the stability of Cu/ZSM-5 in lean NO x reduction catalysis

The stability of Cu/ZSM-5 catalysts of different Cu loadings or modified by addition of Na, La, or Ce was studied in lean NO x reduction. Samples were characterized by H 2-TPR, EPR and XRD before and after deactivation. Increasing the Cu loading above 68% of the exchange capacity improved the stability, as did La addition, presumably because these decreased the concentration of protons which were instrumental in the dealumination of the ZSM-5 framework. Addition of Ce had little effect, because CeO 2 was formed and thus did not compete with protons for exchange sites. Addition of Na decreased the stability, because it promoted the formation of inactive CuO particles; in addition, migration of Cu 2+ to a different coordination environment also seemed to contribute to the catalyst deactivation.

Transport and distribution of copper injected into an albumin-deficient (analbuminemic) rat

1. Copper (Cu) concentrations in blood, liver, kidney, spleen and pancreas of an albumindeficient (Nagase analbuminemic) rat (NAR) were compared with those of a control (Sprague-Dawley) rat (SDR). 2. Cu concentrations were significantly higher in the blood and significantly lower in the liver of the NAR strain than those of the SDR strain in female control (saline-injected) groups at 8 weeks old. 3. Female NAR and SDR 8-week-old rats were injected i.p. with Cu at a single dose of 2.0 mg/kg body wt and killed 18hr later. Concentrations of Cu and other essential elements in the blood, liver, kidney, spleen and pancreas were determined simultaneously by inductively coupled plasma-atomic emission spectrometry. 4. Cu concentration in the liver was significantly lower in the NAR than in the SDR strain suggesting a role for albumin as a carrier protein of free Cu ions in the blood. 5. The effects of Cu loading on other essential elements (Zn, Fe, Ca, Mg, P) were also compared between the NAR and SDR strains.