Heavy Metal Chlorides Research Articles

Characteristics of Simultaneous Volatilization of Heavy Metal Chlorides from Molten Fly Ash under Reduced Pressure

本研究では, 減圧加熱下における溶融飛灰からの重金属塩化物の揮発特性を, 実溶融飛灰および模擬飛灰を用いて実験的に検討した。その結果, 減圧加熱下における単一重金属塩化物 (ZnCl2, PbCl2, CuCl) の揮発速度は, 減圧度の増大に伴って増加した。一方, ZnCl2-PbCl2-CuCl混合物からの各重金属塩化物の揮発速度は, 単一重金属塩化物のそれよりも小さくなり, 試料中重金属の含有量の減少に伴って減少した。このときの重金属塩化物の揮発速度は, 試料中の重金属濃度の1次式で表された。さらに減圧加熱下における重金属塩化物の揮発挙動に及ぼす灰組成の影響を調べた結果, ZnCl2揮発量は, Al2O3含有量の増加に伴って減少した。また, NaCl, KCl, CaCl2の共存によって, 溶融飛灰中重金属の揮発量は, NaCl, KClおよびCaCl2を含有しない模擬飛灰に対して0.27～0.65倍となることが認められた。

Thermodynamic Properties of l-Alanine in (RbCl or CsCl) + Water from 298.15 K to 313.15 K

The enthalpy of mixing for aqueous heavy rare alkali metal chloride (RbCl, CsCl) solutions with aqueous l-alanine solutions, as well as the dilution enthalpies of RbCl, CsCl, and l-alanine solution...

Enthalpic Pair Interaction of Rubidium Chloride with α‐Amino Acid in Water at 298.15 K

AbstractThe mixing enthalpies of aqueous heavy rare alkali metal chloride RbCl solutions with aqueous α‐amino acid (L‐glycine, L‐alanine and α‐aminobutyric acid) solutions, as well as the dilution enthalpies of RbCl and α‐amino acid solutions in pure water had been measured at 298.15 K. The transfer enthalpies of RbCl from pure water to aqueous α‐amino acid solutions could be obtained from these data. The enthalpic pair interaction parameters of RbCl with α‐amino acid in water have been evaluated according to the McMillan‐Mayer theory and discussed in terms of the electrostatic interaction, structure interaction and Savage‐wood group additivity mode.

Determination of heavy metal ions based on quenching of the rare earth luminescence

The determination of heavy metal ions based on quenching of the rare earth luminescence was investigated. A few heavy metal ions efficiently quenched the luminescence of Ce 3+ in polymerized cellulose films, which were obtained by Na-CMC (sodium carboxymethyl cellulose) solution and CeCl 3 solution or the mixed solution of CeCl 3 and a heavy metal chloride. Also, the decay time of Ce 3+ ions ( τ) in Ce 3+–Cu +, Ce 3+–Cu 2+, Ce 3+–Zn 2+ and Ce 3+–Pb 2+system was shorter than that of only Ce 3+ system ( τ 0). The linear relationship between the concentration of Cu 2+, Zn 2+ or Pb 2+ ions and τ 0/ τ reflected the dynamic quenching, as predicted by the Stern–Volmer equation.

Determination of transition metal irons based on quenching of the rare earth luminescence

The determination of heavy metal ions was investigated by the use of rare earth ions (Eu 3+) as spectroscopic probes. A few heavy metal ions efficiently quenched the luminescence of Eu 3+ in polymerized cellulose films which were obtained by sodium carboxymethyl cellulose (Na-CMC) solution and EuCl 3 solution or the mixed solution of EuCl 3 and a heavy metal chloride. Also, the decay time of Eu 3+ ions ( τ) in Eu 3+–Cu +, Eu 3+–Cu 2+ system was shorter than that of only Eu 3+ system ( τ 0). The linear relationship between the concentration of copper ions (Cu + or Cu 2+) and τ 0/ τ reflected the dynamic quenching, as predicted by the Stern–Volmer equation. The method proposed appears the detection of heavy metal ions in environmental waters.

Accelerated corrosion of pure Fe, Ni, Cr and several Fe-based alloys induced by ZnCl2–KCl at 450°C in oxidizing environment

Corrosion problems in waste incinerators are usually rather severe, also due to the presence of low-melting point heavy and alkali metal chlorides. In this paper, the corrosion behavior of several Fe-based alloys with different Cr content, as well as three pure metals Fe, Cr, and Ni, was studied at 450 degreesC beneath ZnCl2-KCl deposits in flowing pure oxygen. All the materials suffered from accelerated corrosion characterized by an important separation and spallation of the oxide scales. The Cr-containing alloys did not exhibit better corrosion resistance to this environment due to the poor adherence of the scales to the matrix, while higher Ni content could improve the corrosion resistance. Chlorine was always enriched on the substrate surface beneath the scale, and in some cases chlorine-rich corrosion products were also present within the alloy matrix. For the HP heat-resistant steel, Cr-rich Cr7C3 carbides were preferentially attacked in comparison to the matrix. The effect of Cr is discussed with respect to the nature of the scales. (C) 2002 Elsevier Science B.V. All rights reserved.

Sharp dose- and time-dependent toxicity of mercuric chloride at the cellular level in sea urchin embryos

Sea urchin embryos ( Sphaerechinus granularis) offer the opportunity to analyse toxicity towards cell division and stages of early development. Mercuric chloride (HgCl(2)) arrested early development at the level of the first cell cycle. The toxic effect occurred in a very sharp concentration range around 7 microM HgCl(2). At sub-toxic concentrations of HgCl(2), the morphology and kinetics of early development were comparable to control embryos. The time-dependence of toxicity was short; a 5-min exposure to the toxic concentration of 10 microM HgCl(2) was sufficient to provoke developmental dysfunction whereas continuous exposure to 5 microM HgCl(2) allowed development to occur normally. The effects on early development over this range of concentrations were specific to HgCl(2) toxicity since other heavy metal chlorides had no effect at 30 microM. Thus, the sea urchin model may provide new clues to the molecular mechanisms of HgCl(2) toxicity.

The Corrosion of Various Materials under Chloride Deposits at 623-723K in Pure Oxygen

Corrosion problems in waste incinerators or in other advanced combustion power generation systems are usually rather serious due to the deposition of ashes composed of heavy and alkali metal chlorides or sulfates of metals such as Zn, K, Pb etc. This paper presents the individual and combined effects of ZnCl2 and KCl on the corrosion behavior of some heat-resistant steels, the M38G Ni-based alloy, 2205 duplex steel and several other Fe-based alloys as well as pure metals were examined at 623K and 723K in pure oxygen. All the materials tested suffered from accelerated corrosion due to the formation of non-protective porous oxide scales and in many cases from local attack in the alloy matrix induced by chlorine. The Cr addition to the alloys can hardly provide sufficient corrosion resistance against such environments as a result of the bad adherence of Cr2O3 to the alloy matrix. This detrimental effect is discussed on the basis of thermodynamic considerations.

In-situ study of the effect of operating conditions and additives on alkali emissions in fluidised bed combustion

In this work, alkali concentrations were determined in a realistic industrial flue gas by an in-situ laser spectroscopic method, excimer laser induced fragmentation fluorescence (ELIF). An excitation wavelength of 193 nm (ArF-excimer laser) was used to photofragment the alkali species and fluorescence signals from the atomic metal fragments were detected at 589 (Na) and 766 nm (K), respectively. These signals provide a measure of the alkali compounds in the flue gas. In the actual flue gas measurements, which were performed at the atmospheric pressure fluidised bed combustor of DMT, the flue gas alkali concentrations were observed to vary, e.g., with bed temperature and with the rate of fuel supply. Data taken following a hot gas filter in the flue gas line gave significantly reduced levels of alkali species compared to those before the filter. The addition of sodium or potassium acetate to the coal leads to increases of up to a factor of two in flue gas alkali concentrations. In some experiments, small quantities of heavy metal chlorides were added to the coal fired and this resulted in very strong increases in flue gas alkali concentrations. A possible explanation for this effect may lie in reactions with the mineral matter to form heavy metal aluminosilicates and consequent release of alkali.

Relative Volatility of (Oxy)chlorides of Light, Heavy, and Superheavy Transition Metals of Groups IV-VI

Analysis of the gas-chromatographic and thermochromatographic behavior of transition metal (oxy)chlorides shows that the compounds of elements 104-106 are more volatile than those of their lighter homologs. The ionic radii of elements 104-106 are also smaller than those of the lighter homologs. These facts are due to the influence of the relativistic effect on the properties of superheavy elements.

Changes in the photosynthetic apparatus of broad bean leaves as dependent on the content of heavy metals in the growth medium

The content of chlorophyll, the rate of O2 evolution, the slow phase of fluorescence induction, and photoinduced changes in the intensity of electron paramagnetic resonance (EPR) signal I from the reaction center of photosystem I (P+700) were studied in leaves of Vicia faba L. grown in 10–7–10–3 M aqueous solutions of CdCl2, SnCl2, CuCl2, and MgCl2. At low concentrations of heavy metal (Cd, Sn, and Cu) chlorides, the content of chlorophyll per fresh weight decreased. However, the rate of O2 evolution calculated per chlorophyll basis, ΔO2/(Δt chlorophyll), increased. High concentrations of heavy metals significantly suppressed plant development and inhibited photosynthetic O2 evolution. In contrast, plant treatment with MgCl2 (10–5–10–3 M) resulted in an increase in the content of chlorophyll and a stimulation of leaf photosynthetic activity. A positive correlation between the FM/FT ratio and ΔO2/(Δt chlorophyll) (r = 0.89, P > 0.999) was found. We observed a negative correlation between the values of P/P0 of EPR signal I (white/far-red light) and ΔO2/(Δtchlorophyll) (r = – 0.89, P > 0.999). The data obtained indicate nonspecific and nonmonotone changes in the photosynthetic apparatus of plants treated with heavy metals: low concentrations of heavy metals (10–7–10–6 M) stimulated photosynthetic activity, whereas high concentrations (10–4–10–3 M) suppressed it.

Transfer of xenobiotics through cell membranes of luminous bacteria.

The influence of some chemical substances on luminous bacteria was studied to elucidate the interrelation between the xenobiotics action on bacterial luminescence and cell ultrastructure. Such substances as quinones, phenols, chlorides of heavy metals (in concentrations of substances inhibiting luminescence by 50%) resulted in damaging effects upon bacteria: a lot of cells had damage of membranes due to changes in their permeability. It was found that the high concentration of EDTA and toluene decreased the luminescence and caused the condensation of DNA-fibrils and the cell damage after long-term and short-term action. The low concentration of EDTA and toluene did not decrease the bacterial luminescence; the noticeable damage of cell membranes did not take place during short-term treatment. However, the long action of these substances changed the membrane permeability resulting in increased sensitivity of bacterial luminescence to some toxic substances.

Transfer of xenobiotics through cell membranes of luminous bacteria

The influence of some chemical substances on luminous bacteria was studied to elucidate the interrelation between the xenobiotics action on bacterial luminescence and cell ultrastructure. Such substances as quinones, phenols, chlorides of heavy metals (in concentrations of substances inhibiting luminescence by 50%) resulted in damaging effects upon bacteria: a lot of cells had damage of membranes due to changes in their permeability. It was found that the high concentration of EDTA and toluene decreased the luminescence and caused the condensation of DNA-fibrils and the cell damage after long-term and short-term action. The low concentration of EDTA and toluene did not decrease the bacterial luminescence; the noticeable damage of cell membranes did not take place during short-term treatment. However, the long action of these substances changed the membrane permeability resulting in increased sensitivity of bacterial luminescence to some toxic substances. Copyright © 1999 John Wiley & Sons, Ltd.

Corrosion Prevention of Waterwall Tube by Field Metal Spraying in Municipal Waste Incineration Plants

Abstract Fireside corrosion factors in high-temperature corrosion of waterwall tubes in waste incineration boilers were investigated. Factors accelerating corrosion were considered to be heavy metal (zinc and lead) chlorides, unburned carbon in deposits, and reduction of the gas atmosphere formed by the increase of unburned gas components and the decrease of oxygen (O2). Laboratory tests confirmed that increasing these factors increased the corrosion rate of carbon steel (CS). These tendencies were in good agreement with those in actual furnaces. A gas spray coating of two-layer Al/80% Ni-20% Cr, selected after laboratory corrosion tests, was applied to waterwall tubes at the test site. The Al/80% Ni-20% Cr spray coating maintained excellent durability for > 3 years, and its effectiveness in corrosion prevention was confirmed. This coating system has been applied at seven plants. Main deterioration factors affecting the coating layer were considered to be formation of corrosion scale and a decrease in bon...

Reactions between gas phase, deposits and metallic materials in chlorine containing atmospheres

Laboratory experiments were carried out in simulated waste incineration atmospheres at 500°C on 2.25Cr-1Mo-steel covered by deposits. In He-5 vol.% O2 enhanced corrosion takes place due to the formation of chlorine from the reaction of chlorides in the deposit with the oxide scale of the material. The Cl2 diffuses through cracks and pores of the oxide scale and FeCl2 is formed at the metal/scale interface. By evaporation and outward diffusion through the oxide scale, FeCl2 oxidizes to Fe2O3 (‘active oxidation’). In He-5 vol.% O2−500 vppm HCl catastrophic corrosion occurs; the sulfates in the deposits are converted to (K, Na)Cl and heavy metal chlorides (PbCl2, ZnCl2). Additions of SO2 (1000 vppm SO2) retards the corrosion process due to stabilization of the sulfates in the deposits. Experiments on 2.25Cr-lMo and Fe-32Ni-27Cr (AC 66) covered with PbCl2 indicates a deleterious effect of heavy metal chlorides on the corrosion process.

5454914 Method of removal of heavy metal from molten salt in IFR fuel pyroprocessing : Gay Eddie Park Forest, IL, United States Assigned to The United States of America as rep. by the United States Department of Energy

The pyrometallurgical process for recycling spent metal fuels from the Integral Fast Reactor (IFR) involves electrorefining spent fuel in a molten salt electrolyte (LiCI-KCI-U/PuCI3) at 500°C. The total heavy metal chloride concentration in the salt will be about 2 mol %. At some point, the concentrations of alkali, alkaline earth, and rare earth fission products in the salt must be reduced to lower the amount of heat generated in the electrorefiner. The heavy metal concentration in the salt must be reduced before removing the fission products from the salt. The operation uses a lithium-cadmium alloy anode that is solid at 500°C, a solid mandrel cathode with a ceramic catch crucible below to collect heavy metal that falls off it, and a liquid cadmium cathode. The design criteria that had to be met by this equipment included the following: (1) control of the reduction rate by lithium, (2) good separation between heavy metal and rare earths, and (3) the capability to collect heavy metal and rare earths over a wide range of salt compositions. In tests conducted in an engineering-scale electrorefiner (10 kg uranium per cathode), good separation was achieved while removing uranium and rare earths from the salt. Only 13% of the rare earths was removed, while 99.9% of the uranium in the salt was removed; subsequently, the rare earths were also reduced to low concentrations. The uranium concentration in the salt was reduced to 0.05 ppm after uranium and rare earths were transferred from the salt to a solid mandrel cathode with a catch crucible. Rare earth concentrations in the salt were reduced to less than 0.01 wt % in these operations. Similar tests are planned to remove Plutonium from the salt in a laboratory-scale (100-300 g heavy metal) electrorefiner.

Schwermetall- und chloridhaltige Filterst�ube. I. Phasenanalysen und Modellversuche zum Recycling

Flue Dusts Containing Heavy Metal Ions and Chloride.I. Phase Analysis, Model Experiments for Recycling Four flue dusts from a cement factory, an electric-furnace steelmaking plant and a municipal waste plant were analyzed by powder diffraction methods. Chloride combines above all with alkali ions or heavy metal ions, especially yielding PbCl2 and KPb2Cl5. The controlled sublimation of these chloride compounds in open crucibles was developed and optimized in our laboratory. Between 850°C and 1150°C and at reaction times from 30 min up to 12 h, the chloride content decreases to below 0.1 wt-%. The sublimed phase mainly consists of alkali and lead chloride. Zinc is found in the flue dust as oxide and is enriched during this process. Recent investigations with a small waelz kiln give analogous results. With our procedure, the manufacturer by himself is able to exploit flue dusts containing a large amount of heavy metal elements and chloride which cannot be deposited. The remaining product contains mainly zinc oxide which can be recycled in the zinc industry or returned to the production process. The sublimed chloride compounds may be recycled in the potash industry.

Effect of low pH, heavy metals and anions on chlorophyll degradation in the lichen Ramalina duriaei (de not.) bagl.

Lichen thalli were soaked in water adjusted to pH 1.0–12.0 to study the influence of different pH conditions on the integrity of the photobiont's chlorophyll. The ratio OD 435 nm/OD 415 nm, used to estimate the chlorophyll degradation, decreased after a 30 min treatment in water acidified to pH 1.0–2.0. Thalli were exposed to solutions containing potassium or heavy metal chlorides, sulfates and nitrates under acidic conditions, all of which exerted different degrees of chlorophyll damage. The chlorophyll integrity was especially affected following treatment of the thalli with Cu, Zn, Mn, Pb, Fe(II) and Fe(III) salts under pH 2.0. Under the same pH, SO 4 2− combined with K + proved more harmful to the photobiont chlorophyll than Cl − anions. After a treatment with CuCl 2, a very low OD 435 nm/OD 415 nm ratio was obtained.

Immunological detection of an embryogenic-cell protein (ECP31) during stress-induced somatic embryogenesis in carrot

The accumulation and localization of ECP31, an embryogenic cell protein with a molecular weight of 31 000, was examined with immunoblotting and immunohistochemical analysis during stress-induced somatic embryogenesis in carrot (Daucus carota). ECP31 was not detected in apical tip segments of 7-day-old carrot seedlings. However, it accumulated in the apical tip segments on which somatic embryos had formed after treatment with 0.5 mM NiCl2 or CdCl2 and successive culture on Murashige and Skoog's agar medium without the heavy metal chlorides. ECP31 was localized in proembryo-forming cells located in the periphery of the NiCl2 treated carrot segments but not in developing somatic embryos on these segments. Key words: carrot (Daucus carota), ECP31 (carrot embryogenic cell protein with molecular weight 31 000), embryogenic competence, stress-induced somatic embryogenesis.

Induction of somatic embryogenesis in carrot by heavy metal ions

A new method for the induction of somatic embryos has been demonstrated. Somatic embryos were formed without a visible interventing callus stage when apical tips from 1-week-old seedlings of carrot (Daucus carota cv. US-Harumakigosun) were cultured for 1–3 weeks on Murashige and Skoog's medium without growth regulators but containing heavy metal chlorides, such as CoCl2, NiCl2, ZnCl2, and CdCl2, and then transferred to Murashige and Skoog's medium. These results suggest that the stresses caused by these chemicals trigger the induction of somatic embryogenesis in carrot. Key words: Daucus carota, somatic embryo, stress, tissue culture.