Description: Das Projekt "Study of sorption of the mobile forms of mercury by fly ash from thermal power plants with the aim of immobilising them in silts and soils" wird vom Umweltbundesamt gefördert und von GALAB durchgeführt. It is known that power station fly ash can act as a sorbent for mercury in aqueous solutions, and that it appears to bind strongly to mercury present in soil. Fly ash itself is a multi-component system, however, composed of a glass, amorphous, crystalline and carbon phases. In addition, mercury appears in many forms, varying significantly in their stability and the degree of threat posed to human health and the environment. The overall behaviour of the ash-mercury system is thus extremely complex, and may involve both physical and chemical bonding, precipitation and entrapment. For fly ash to be considered as a potential remediation material, detailed knowledge of the processes by which it removes mercury is needed. The project objectives are thus: - To determine kinetic characteristics of the sorption/desorption reactions, including those at high sorbate concentrations, of different mercury species with power station fly ash and its sub-components; - To add to the understanding of which components of power station fly ash are responsible for mercury immobilisation and the mechanisms through which this takes place; - To identify, characterise and quantify the different forms of mercury that result from its interaction with power station fly ash and its sub-components; - To assess the availability of mercury sorbed on power station fly ash to biological methylation; - To provide fundamental kinetic data for future use in the estimation of the suitability of power station fly ash for the stabilisation and remediation of mercury contaminated sites. The project will use two distinct ash types: the first with high alkalinity, the second type characteristic of coals with a low calcium content which form a lower alkalinity ash. As well as unmodified ash, the study will look at ash sorted to give fractions rich in the major constituents: glass cenospheres, isotropic and anisotropic coke, and intertinite. The sorption behaviour of the total ash and its fractions will be investigated with respect to the most important mercury species: inorganic (cationic, anionic in chloride complexes, oxidic), elementary (mercury vapour) and organic (CH3HgCl). Sorption and desorption characteristics and equilibrium constants will be established using isotherm techniques for mercury species in solution (and mercury vapour - at different partial pressures) exposed to ash and its components at their inherent pH which may range from 4 to 10.5. The rates of adsorption and desorption will be established, with time sequencing analysis of the sorbate solutions. The equilibrium and kinetic parameters of dissolution of elementary mercury and mercury oxides in weakly mineralised water (0.5 g/l) will be experimentally determined to establish the relationship with pH. Oxidation-reduction transformations of sorbed mercury will be carried out on ash samples containing various concentrations of inorganic or elementary mercury, with the help of weak redox reagents (oxygen from air, aldehy
Types:
SupportProgram
Origin: /Bund/UBA/UFORDAT
Tags: Quecksilbergehalt ? Eberesche ? Gesundheitsgefährdung ? Isotherme ? Kohlenstaub ? Quecksilberoxid ? Biopharmazeutikum ? Altlast ? Asche ? Kohlenstoff ? Koks ? Quecksilber ? Adsorption ? Flugasche ? Kohle ? Methylierung ? Umweltbelastung ? Verbrennung ? Wärmekraftwerk ? Schluff ? Oxidation ? Partialdruck ? pH-Wert ? Bodenlösung ? Chemikalien ? Redoxpotential ? Redoxreaktion ? Sauerstoffgehalt ? Schadstoffimmobilisierung ? Sorption ? Studie ? Daten ? Desorption ? Altlastensanierung ? Wasserprobe ? Kraftwerk ? Luftschadstoff ? Thermisches Verfahren ? Bodenschadstoff ? Basizität ? Auflösen ? Menschliche Gesundheit ? Kenngröße ? Reaktionskinetik ? Schadstoffminderung ? Niederschlag ? CO2-Abscheidung und -Speicherung ?
Region: Schleswig-Holstein
Bounding box: 9.75° .. 9.75° x 54.2° .. 54.2°
License: cc-by-nc-nd/4.0
Language: Deutsch
Time ranges: 2001-09-01 - 2003-08-31
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