Thermodynamics of the Eu(III)-Mg-SO-HO and Eu(III)-Na-SO-HO systems. Part II: spectroscopy experiments, complexation and Pitzer/SIT models.

A time-resolved laser fluorescence spectroscopy (TRLFS) study was carried out to investigate the Eu(III)-SO complexation at room temperature over a wide range of NaSO concentrations (0-2 mol kg). Spectroscopic observations confirm the step-wise formation of the aqueous complexes Eu(SO), Eu(SO) and Eu(SO) over the investigated NaSO concentrations. Combining TRLFS data obtained in this study and solubility data reported in Part I of this work for the Eu(SO)-NaSO-HO and Eu(SO)-MgSO-HO systems, thermodynamic and activity models were derived based on the SIT and Pitzer formalisms.

Thermodynamics of the Eu(III)-Mg-SO-HO and Eu(III)-Na-SO-HO systems. Part I: solubility experiments and the full dissociation Pitzer model.

The solubility of Eu(III) was investigated under undersaturated conditions in acidic, dilute to concentrated MgSO and NaSO solutions at = (22 ± 2) °C. After attaining equilibrium conditions, solid phases were characterized by a multi-method approach, including X-ray diffraction (XRD), Raman and infrared (IR) spectroscopy, quantitative chemical analysis (ICP-OES) and thermogravimetric analysis (TG-DTA). A total of 45 solubility samples were investigated for the systems Eu(SO)-MgSO-HO (19 samples) and Eu(SO)-NaSO-HO (26 samples).

Mass diffusion and Soret coefficient measurements of triethylene glycol/water binary mixtures by dynamic shadowgraphy.

The investigation of the transport properties of binary fluid mixtures remains a topic of interest in relation to the more challenging studies of ternary mixtures. In fact, the study of the phase boundary limits of the Gibbs composition triangle can be the initial step for a more complete analysis of ternary mixtures. In this paper, we apply the dynamic shadowgraphy optical technique to study non-equilibrium fluctuations induced by the presence of a gradient of temperature and/or concentration in the triethylene glycol (TEG)/water system.

Thermodynamic evidence of giant salt deposit formation by serpentinization: an alternative mechanism to solar evaporation.

The evaporation of seawater in arid climates is currently the main accepted driving mechanism for the formation of ancient and recent salt deposits in shallow basins. However, the deposition of huge amounts of marine salts, including the formation of tens of metres of highly soluble types (tachyhydrite and bischofite) during the Aptian in the South Atlantic and during the Messinian Salinity Crisis, are inconsistent with the wet and warm palaeoclimate conditions reconstructed for these periods. Recently, a debate has been developed that opposes the classic model of evaporite deposition and argues for the generation of salt by serpentinization.

A double layer model of the gas bubble/water interface.

Zeta potential is a physico-chemical parameter of particular importance to describe sorption of contaminants at the surface of gas bubbles. Nevertheless, the interpretation of electrophoretic mobilities of gas bubbles is complex. This is due to the specific behavior of the gas at interface and to the excess of electrical charge at interface, which is responsible for surface conductivity.

Salt precipitation and trapped liquid cavitation in micrometric capillary tubes.

Laboratory evidence shows that the occurrence of solid salt in soil pores causes drastic changes in the topology of the porous spaces and possibly also in the properties of the occluded liquid. Observations were made on NaCl precipitation in micrometric cylindrical capillary tubes, filled with a 5.5 M NaCl aqueous solution and submitted to drying conditions.

In-pore tensile stress by drying-induced capillary bridges inside porous materials.

We present here some evidences that capillary liquid bridges are able to deform micrometric cylindrical pores by tensile stress. Brine-soaked filter membranes are submitted to drying conditions leading to NaCl precipitation inside the 5-10 μm pores. A close examination demonstrated that two forms of NaCl crystallites are successively generated.

Environmental impacts of unmanaged solid waste at a former base metal mining and ore processing site (Kirki, Greece).

The Kirki project aimed to identify, among the mining waste abandoned at a mine and processing plant, the most critical potential pollution sources, the exposed milieus and the main pathways for contamination of a littoral area. This was accompanied by the definition of a monitoring network and remedial options. For this purpose, field analytical methods were extensively used to allow a more precise identification of the source, to draw relevant conceptual models and outline a monitoring network.

Reactivity of waste generated during lead recycling: an integrated study.

Lead consumption in Europe is 2.054 M tonnes/year, more than 70% of which is produced by recycling and, more specifically, the recycling of car batteries. This industry is jeopardised by the method employed so far, recycling by alkaline fusion, because the treatment produces 200,000 tonnes of toxic and unstable slag.