Solvent Extraction of Copper from Sulfate–Chloride Solutions Using LIX 84-IC and LIX 860-IC

ABSTRACT

The effect of chloride ions on the copper extraction equilibria, the rate of extraction, copper/iron selectivity, and chloride extraction was studied for organic phases containing pure ketoxime (LIX 84-IC) and pure nonylaldoxime (LIX 860N-IC). In these systems, the used aqueous phase contained total chloride concentrations from 0 to 110 g/l. It was determined that the chloride ions in the aqueous solution had a large negative effect on the extraction equilibria for LIX 84-IC and a small effect for LIX 860N-IC. This deleterious effect is attributed to an increase in the hydrogen ion activity coefficient in the presence of chloride ions. The chloride accelerated the rate of copper extraction even though the reaction was fast in all the tested conditions. An increase in the temperature from 25°C to 35°C affected positively the extraction equilibria for LIX 84-IC.     

An extension of ASM2d including pH calculation

This paper presents an extension of the Activated Sludge Model No. 2d (ASM2d) including a chemical model able to calculate the pH value in biological processes. The developed chemical model incorporates the complete set of chemical species affecting the pH value to ASM2d describing non-equilibrium biochemical processes. It considers the system formed by one aqueous phase, in which biochemical processes take place, and one gaseous phase, and is based on the assumptions of instantaneous chemical equilibrium under liquid phase and kinetically governed mass transport between the liquid and gas phase. The ASM2d enlargement comprises the addition of every component affecting the pH value and an ion-balance for the calculation of the pH value and the dissociation species. The significant pH variations observed in a sequencing batch reactor operated for enhanced biological phosphorus removal were used to verify the capability of the extended model for predicting the dynamics of pH jointly with concentrations of acetic acid and phosphate. A pH inhibition function for polyphosphate accumulating bacteria has also been included in the model to simulate the behaviour observed. Experimental data obtained in four different experiments (with different sludge retention time and influent phosphorus concentrations) were accurately reproduced.     

Spatial and temporal trends of petroleum hydrocarbons in wild mussels from the Galician coast (NW Spain) affected by the Prestige oil spill

Polycyclic aromatic hydrocarbons (PAHs) were determined in tissues of wild mussels (Mytilus galloprovincialis) from the Galicia coast (NW Spain) in order to assess the extent of the environmental impact caused by the Prestige oil spill (November 13, 2002). Three sampling campaigns were carried out in February, June and November 2003 at 24 stations along the Galicia coast, from La Guardia (Pontevedra) to Ribadeo (Lugo). The spatial distribution of PAHs found in the first sampling period, clearly revealed the central area (Costa da Morte) as the most affected by the oil spill. In these stations, concentrations up to 7780 microg/kg dw of the sum of 13 parent PAHs were found 2-3 months after the spill. Molecular parameters within the aliphatic and aromatic fractions confirmed the presence of the Prestige oil in these samples. The levels markedly decreased at most of the stations in the second sampling and recovered to levels found before the spill in November 2003, 1 year after the accident (29-279 microg/kg dw, av. 133+/-83 microg/kg dw). However, a certain increase was observed in some sites which could be related to the remobilization of oil residues from still unclean intertidal spots or sediments due to the winter marine weather conditions.     

Radon concentration in houses over a closed Hungarian uranium mine

High radon concentration (average 410 kBq m-3) has been measured in a tunnel of a uranium mine, located 15-55 m below the village of Kovágószolos, Hungary. The mine was closed in 1997; the artificial ventilation of the tunnel was then terminated and recultivation works begun. In this paper, a study has been made as to whether the tunnel has an influence on the radon concentration of surface dwellings over the mining tunnel. At different distances from the surface projection of the mining tunnel, radon concentration, the gamma dose, radon exhalation and radon concentration of soil gas were measured. The average radon concentration in the dwellings was 483 Bq m-3. Significantly higher radon concentrations (average 667 Bq m-3) were measured in houses within +/-150 m from the surface projection of the mining tunnel +50 m, compared with the houses further than the 300-m belt (average 291 Bq m-3). The average radon concentration of the soil gas was 88.8 kBq m-3, the average radon exhalation was 71.4 Bq m-2 s-1 and higher values were measured over the passage as well. Frequent fissures crossing the passage and running up to the surface and the high radon concentration generated in the passage (average 410 kBq m-3) may influence the radon concentration of the houses over the mining tunnel.     

Paleonutritional analysis of the pre-Hispanic population from Fuerteventura (Canary Islands)

In this study, from histological and chemical perspectives, we analyse the human remains belonging to the pre-Hispanic inhabitants from Fuerteventura (one of the Canary Islands) and compare the results with those obtained on a sample of pre-Hispanic inhabitants from Gran Canaria (Canary Islands). We observe that trabecular bone mass was normal in the samples from Fuerteventura except for an elderly woman; this result is in sharp contrast with the decreased bone mass observed in the population from Gran Canaria. The pre-Hispanic population from Fuerteventura showed lower bone strontium, Sr/Ca ratio, and bone barium, but slightly higher bone copper, than that from Gran Canaria. All these data indicate a greater consumption of marine products by the population of Fuerteventura. The high prevalence of osteoporosis observed in the population from Gran Canaria may be interpreted as a consequence of protein-calorie malnutrition, a condition which seemed to be not so prevalent in the population of Fuerteventura.     

Sorption of phosphorous to Filtralite-P--the effect of different scales

Sorption of P to the filter material Filtralite-P was examined at a small, medium and large scale. In the small- and meso-scale laboratory models, the sorbed amount of total phosphorus (P) was heterogeneously distributed with more P sorbed in the inlet zone and the bottom layers. The full-scale system had, on the other hand, the highest sorbed concentration in the outlet region. The overall P sorption capacity of the material was 8030, 4990 and 521 mg P kg(-1) Filtralite-P for Box 1, Box 2 and meso scale, respectively. This equals 4.4, 2.8 and 0.29 kg P m(-3) material, respectively. However, the maximum sorption capacities found were 2500, 3887 and 4500 mg P kg(-1) Filtralite-P for the two small-scale box systems and the meso-scale container, respectively. In the full-scale system the overall P sorption capacity of the material was 52 mg P kg(-1) Filtralite-P (0.029 kg P m(-3) Filtralite-P with a maximum sorbed amount of P of 249 mg P kg(-1). Results from both the small- and meso-scale system show that when a constructed wetland (CW) is saturated, i.e. when the outlet concentration has reached its maximum allowed concentration of 1.0 mg P l(-1), only parts of the filter material will have reached the sorption capacity. Sequential extractions of Filtralite-P showed that the loosely bound P, Ca-P and Al-P were the primary P sorption pools both in the small-scale models and in the full-scale CW. However, the proportion of these three fractions varied with time and change in pH. A white product precipitated in the outlet zone of both the small-scale box models as well as the onsite CW. The surface of these precipitation particles was identified by X-ray diffraction and SEM method as CaCO3 and precipitated Ca- and Mg-phosphates.     

Urban policies and gentrification trends in Madrid's inner city

This article was written as part of a wider research project on Madrid's social geography supported by the Spanish Ministry of Education and Science (Project PB88/0181). It was initially presented as a paper at the International Research ConferenceEuropean Cities: Growth and Decline The Hague, The Netherlands, 13–16 April 1992.     

Homogeneous iron-catalyzed photochemical degradation of muconic acid in water

Iron photochemical oxidation has been used to remove muconic acid from water. Two different light systems were used: black lamps and solar irradiation. The effect of iron concentration, intensity of incident radiation, pH and presence of oxalic acid was investigated. The first two variables yield positive effects on the removal rate of muconic acid while higher efficiency was achieved at pH 3. Oxalic acid enhances the oxidation rate because of the formation of photoactive ferrioxalate ion. Stoichiometric results indicated formation of two hydroxyl radicals to degrade 1 mol of muconic acid. At similar experimental conditions, initial oxidation rates of muconic acid were higher when solar light was used to irradiate the aqueous solutions, although in this case, the oxidation process is stopped because of the consumption of photoactive species.     

Spatial variation in nitrogen dioxide in three European areas

In order to estimate the spatial variation within well-defined study areas, nitrogen dioxide was measured with diffusion samplers (Palmes tube) in 40-42 sites each in Germany (Munich), the Netherlands and Sweden (Stockholm County). Each site was measured over four 2-week periods during 1 year (spring 1999 to summer 2000). In each country, one reference site was measured during all periods and the results were used to adjust for seasonal variability, to improve the estimates of the annual average. Comparisons between the chemiluminescence method (European reference method) and Palmes tube measurement indicated a good agreement in Germany (with a ratio of 1.0 for Palmes tube/chemiluminescence) but underestimation for Palmes tube measurement in the Netherlands and Sweden (0.8 for both countries). The r2 values were between 0.86 and 0.90 for all three countries. The annual average values for NO2 for different sampling sites were between 15.9 and 50.6 (mean 28.8 microg/m3) in Germany, between 12.1 and 50.8 (mean 28.9 microg/m3) in the Netherlands and between 6.1 and 44.7 (mean 18.5 microg/m3) in Sweden. Comparing spatial variation between similar sites in the three countries, we did not find any significant differences between annual average levels for urban traffic sites. In Sweden, annual average levels in urban background and suburban backgrounds sites were about 8 microg/m3 lower than comparable sites in Germany and the Netherlands. Comparing site types within each country only urban traffic sites and suburban background sites differed in Germany. In the Netherlands and Sweden, the urban traffic sites differed from all other sites and in Sweden also the urban background sites differed from the other background sites. The observed contribution from local traffic was similar in the Netherlands and Sweden (10 and 8 microg/m3, corresponding to 26-27% of the NO2 concentration found in the urban traffic sites). In Germany, the contribution from local traffic was only 3 microg/m3, corresponding to 9% of the NO2 concentration found in the urban traffic sites. The spatial variation was substantially larger for NO2 than the variation for PM2.5 and similar to PM2.5 absorbance, measured in the same locations.