Fixation Of Mercury Research Articles

Sustained-release of interlayer chloride in iron oxychloride for mercury oxidation from industrial flue gas

Conversion of gaseous elemental mercury (Hg0) to its higher valence state is essential for mercury control using the current air pollution devices from industrial flue gas. Traditional technologies often use selective catalytic reduction (SCR) units to enhance the Hg0 oxidation performance but highly depend on the high-temperature catalysts, the presence of HCl, and the downstream liquid absorption system. This study proposes a novel method coupled with a low-temperature catalyst and a dust removal device to realize mercury immobilization. The iron oxychloride (FeOCl) 2D-nanosheets are put into practice as the low-temperature catalyst. The results indicate superior Hg0 oxidation performance at low oxidizing conditions and a wide temperature window (100–300 °C). The FeOCl catalyst can further combine with MnO2 to achieve mercury fixation. The outstanding property is attributed to the chloride with high activity between the Van Der Waals layer of FeOCl. The oxidative products HgCl2(g) in high yield are attributed to the low Fe-Cl bonding energy in FeOCl relative to metal chloride. This study highlights the conversion process of gaseous Hg0 to HgCl2 in oxidized form and provides a new idea that can be used in conjunction with dust removal equipment to expand the removal method of flue gas mercury.

Interaction of Elemental Mercury with a Diverse Series of π-Organic Substrates Probed by Computational Methods: Is Mercury Fixation Possible?

A multitude of electronic structure computational methods has been employed to study the intermolecular adducts formed upon the interaction of elemental mercury, Hg0, with benzene and substituted benzenes of the general formula [Hg(η6-1,3,5-C3H3R3)], where R is either an electron donor substituent, such as −NH2, −OH, −SH, −NH(COCH3), −C≡CH, −S(CH3), −C═CH2, −CH3, −N(CH3)3, and −O(CH3)3 or an electron acceptor substituent, such as −COOH, −NO2, −CHO, −CO(CH3), −CN, −SO2H, −CF3, −C(CO)(NH2), −Cl, −F, and −C(CO)Cl. In addition, a set of neutral and negatively charged octupolar molecules, with alternating electron donor and electron acceptor groups in the 1,3,5 and 2,4,6 positions of the benzene ring, have been included in this study. The estimated interaction energies of Hg0 with these systems range from −2.6 to −13.7 kcal/mol. The interplay of electrostatic, dispersion forces and covalent interaction components constitute the Hg0···π-organic substrate interactions. In the [Hg(η6-1,3,5-C3H3R3)] adducts with e...

The fate of mercury in fluidized beds under oxy-fuel combustion conditions

Among the different pollutant gases released from oxy-coal combustion, mercury is the responsible for important operational issues in the CO2 processing unit, being able to cause material corrosion. Some studies concerning the fate of mercury during oxy-coal combustion are referred to pulverized coal (PC) boilers. However, the fate of mercury emissions in fluidized bed (FB) combustors has yet to be elucidated.In this work, mercury emissions from a 3kWth bubbling FB combustor operating under oxy-fuel combustion conditions have been evaluated. For this purpose, two Spanish Ca-based sorbents and two Spanish coals were used. The effects of type of Ca-based sorbent, the Ca/S molar ratio, temperature and recycled gases (NO, SO2 and H2O) typical in oxy-fuel combustion process on the distribution of mercury species have been analyzed.It was observed that the presence of Ca-based sorbents in the combustor favored mercury fixation as particle-bound mercury which exhibited a maximum at a temperature about 925°C corresponding to the highest degree of limestone sulfation. SO2 recirculation inhibited the Hg0 oxidation and thus the mercury fixation as particle-bound mercury decreased. However, neither NO nor steam recirculation affected mercury speciation.

Modelling of Hg0 Removal from Gaseous Streams and its Fixation in Hydroxyapatite-Based Adsorbents Modified with Copper Sulphide

In this work, a mathematical model of a fixed-bed process for elemental mercury removal from gaseous streams is proposed. Advective and diffusive processes were taken into account in the macroscopic mass balance along the bed, and diffusive process was considered in the microscopic mass balance inside the adsorbent particle in which the adsorption process occurs. In addition, a chemical reaction term was used to represent the mercury fixation by the adsorbent. The proposed model was implemented in the Environment for Modelling, Simulation and Optimization dynamic simulator. Model parameters were estimated based on experimental breakthrough curves, by minimizing the least-square function. The model satisfactorily described two experimental breakthrough curves of mercury removal using adsorbents with different preparation methods, both with high mercury fixation capacity. The proposed mathematical model was also able to consistently describe the mercury concentrations in the bed and in the particle.

Investigation of adsorption-enhanced reaction process of mercury removal from simulated natural gas by mathematical modeling

Hydroxyapatites modified with copper sulfide were studied as sorbents for mercury removal from gaseous streams containing low mercury concentration. A mathematical model was proposed to take into account adsorption, diffusion into the sorbent particle and chemical reaction inside the solid matrix. The chemical reaction mechanism for mercury fixation into the solid matrix is supported by XRD analysis results. The unknown parameters are estimated from experimental data by minimization of the unweighted least-squares function, using a hybrid of Newton-like and Particle Swarm Optimization methods. Results are shown for two hydroxyapatite sorbents developed in our lab. The model, with its optimized parameters, was used to study the dynamic behavior of a fixed bed adsorption process at different operational conditions. Simulation results show that the chemical fixation of mercury inside the solid matrix leads to an increase of mercury removal capacity and it provides insights about operational plant conditions.

Complexation of mercury(II) ions with humic acids in tundra soils

The interaction mechanisms of mercury(II) ions with preparations of humic acids (HAs) isolated from organic horizons of surface-gleyed soils (Haplic Stagnosol (Gelic, Siltic)) of shrub tundra and hydromorphic peat gley soils (Histic Cryosol (Reductaquic, Siltic)) of moss-lichen tundra have been studied. The particular features of the interactions between the mercury(II) ions and the HAs are related to the molecular structure of the HAs, the mercury concentration range, and the environmental parameters. The fixation of mercury(II) ions into stable coordination compounds is most efficient in the pH range of 2.5–3.5. At the element concentrations below 0.50 μmol/dm3, the main complexing sites of HAs are their peripheral aminoacid functional groups. Pyrocatechol, salicylate, and phenolic groups from the nuclear moiety of molecules interact in the concentration range of 0.0005–0.50 mmol/dm3; the physical sorption of mercury hydroxo complexes by the surface of HAs is the main process occurring in the system.

Mercury concentration in some calcareous soils of western Iran with a focus on pedological evolution and weathering process

The aim of this study was to evaluate total mercury concentration and its lithogenic and exogenic fractions in some calcareous soils of western Iran, where water contamination and bioaccumulation of mercury have been reported in the bottomland’s reservoir. In particular, we investigated soil physico-chemical properties and weathering conditions related to lithogenic and exogenic fractions of mercury for two groups of calcareous soils with a known comparative pedological evolution and weathering condition that was evident in the presence or absence of underlying layers of accumulated clay. Our results showed that the total mercury content of the studied soils ranged from 45.40 to 830.36 with a mean of 486.81 μg kg−1. Furthermore, calculation of mercury fractions revealed that lithogenic and exogenic fractions vary slightly according to the three reference elements (Fe, U and Nb) used in the calculations for the two groups of studied soils. The results also illustrated that most of the mercury content is of exogenic origin; therefore, total mercury variations are closely related to the content of exogenic mercury, while the lithogenic fraction exhibited no relationship with total mercury concentration. Moreover, application of the weathering indexes of Parker and the CaO/ZrO2 molar ratio supported the dependence of lithogenic mercury accumulation on weathering intensity in the studied calcareous soils. However, the significance of this relationship is stronger for more weathered calcareous soils; in such cases, fine-particle fractions are more developed, which encourages carrier phases such as organic materials and iron oxyhydroxides to become involved in more efficient fixation of mercury. Nevertheless, the formation of underlying layers of accumulated clay, i.e. argillic horizons, may restrain fixation of exogenic mercury by limiting its atmospheric input.

Leaching of Mercury from Carbonated and Non-Carbonated Cement-Solidified Dredged Sediments

This study investigated traditional cement-based and non-conventional (using accelerated carbonation) solidification/stabilization to treat 2 dredged sediments contaminated with mercury from two different locations in UK. Canal and estuarine-derived sediments were mixed with blended binders and powdered activated carbon. Fresh mixtures of sediment and cement were exposed to gaseous carbon dioxide and were allowed to carbonate for fixed time periods, after which they were cured for 28 days. Following curing, samples were leach tested to evaluate the fixation of mercury in the treated products. The results obtained indicated that both conventional and accelerated carbonated treatments were capable of reducing the concentration of mercury in the eluates to acceptable limits.

Mercury Fixation in Contaminated Sediments as a Management Option at Albany, Western Australia

Water overlying mercury contaminated sediments in Princess Royal Harbour, Albany, was found to contain up to 0.8 µg/L of mercury. Using contaminated sediments and water from Princess Royal Harbour experiments were carried out to remove the mercury from the waterbody and fix it to the sediment. Treatment with metallic iron reduced the mercury concentration of the water to less than 0.1 µg/L within 2 minutes and any potential visual pollution from the oxidation of iron was prevented by a sand overlay. The sand did not interfere with the lasting effectiveness of the iron. A field trial was conducted to test the system under wind and tidal conditions in shallow waters of Princess Royal Harbour. It was established that due to the sedimental rework, the overlay thickness would have to be increased for the shallow waters. For deeper waters (>2 m), the system is expected to give good results over sand bottoms. Seagrass covered areas are expected to yield staining problems due to ineffective sand overlay.

Mechanisms of metal stabilization by cement based fixation processes

The mechanism of zinc and mercury fixation by cement/silicate stabilization processes has been assessed from leaching, scanning electron microscopy, X-ray diffraction and porosimetry studies. The results of these tests correlate closely and suggest two separate mechanisms operating in the interaction between these metals and the cement/silicate system. The presence of zinc has a significant effect upon the hydration and final physical properties of cement. The chemical interaction between mercury and cement/silicate is minimal and the hydration process of cement proceeds normally. Zinc appears to be chemically stabilized by cement based fixation processes through the formation of insoluble compounds at high pH. Mercury and related metals which do not form precipitates at elevated pH levels are held in pore solution. Mobility depends largely upon physical encapsulation by the cement matrix and leachability of these materials is expected to be closely related to porosity of the final product.

Contamination d'une chaine trophique experimentale par le methylmercure: Importance du systeme ‘producteur-consommateur primaire’

Within the framework of methylmercury bioaccumulation and bioamplification along an experimental food chain with four links, the contamination procedure of the first two trophic levels, Chlorella vulgaris and Daphnia magna is accurately defined. After developing the chosen methodology and the constraints inherent in each link, the main results showing the primary producer are presented from the toxicological point of view (inhibition rate of Chlorella growth). A sublethal concentration is defined for each species in our model (1 μg litre −1 in the environment) and the dynamics of mercury fixation for Chlorella vulgaris and Daphnia magna are quantified at three temperatures (10, 18 and 26°C) over contamination periods of 24 and 96 h, respectively. The study enabled us to show the great fixation capacity of algae for mercury. Therefore, the first consumer level is essentially contaminated trophically. The results obtained underline the temperature factor effect on Daphnia magna accumulation processes; moulting, in relation to temperature, partly explaining the differences observed. The high values of the pollutant concentration factors relative to the ‘water- Chlorella-Daphnia’ system confirm the importance of the inclusion of an autotrophic link at the base of an experimental trophic chain. On the other hand, the accuracy of the measurement shows the high level of reliability and reproducibility of the procedure chosen.

Fluorescamine, a fluorescence probe for amino groups in histochemical studies of plant cells and the effect of mercury fixation.

When fixed in mercuric chloride solutions and stained with Fluorescamine, histological plant specimens emit a strong fluorescence. The fluorophore distribution is topologically identical to the staining pattern revealed by visible light methods for nucleoproteins, but the fluorescence mode of viewing preparations gave greater sensitivity and contrast than transmitted light absorption methods. The parameters that influence the formation of the fluorescent image in plant cells are discussed. The results obtained indicate that the mercury-Fluorescamine reaction is an ideal histochemical procedure for collecting qualitative and analytical information on plant nuclei and on the changes of nucleolar architecture that occur during the cellular developmental cycle.

In Vivo Inhibition of Grey Partridge (Perdrix Perdrix) Creatine-Kinase by Methoxy Ethyl Mercury Silicate

In grey partridge, methoxy-ethyl-mercury is a potent reversible inhibitor of muscular creatine-kinase. This effect is probably the result of a fixation of mercury by the thiol groups of the enzyme molecule.

Experimental studies on detoxication of mercury salts by means of ethylenediaminetetra-acetic acid

It was experimentally proved that mercury may be fixated with the aid of ethylendiaminetetraacetic acid. The latter, likewise, promotes excretion of mercury from the body. It was established in experiments on isolated frog's heart that the ratio of the quantity of sublimate and ethylendiaminetetraacetic acid should be 1 : 120 for total fixation of mercury. However, it was impossible to fixate mercury in the intact organism, even in presence of this ratio.

The Seven Follies of Science: a Popular Account of the most famous Scientific Impossibilities and the Attempts which have been Made to Solve Them

THESE “Follies” are the squaring of the circle, the duplication of the cube, the trisection of an angle, perpetual motion, the transmutation of metals, the fixation of mercury, and the elixir of life; we miss from this list the flattening of the earth. The author is an American; he writes for ordinary readers, and makes his subject interesting; he seems to make no mistakes. He dwells at much greater length upon the first and fourth of the follies than the rest. In addition to these seven classical ones he gives an account of four others: perpetual lamps, the alkahest or universal solvent, palingenesy (the revival of a plant or animal from its ashes), and the powder of sympathy. He adds a division on the fourth dimension of space and some paradoxes, micrography, illusions of the senses, and two tricks. The book finishes with an account of some arithmetical problems and the fulcrum of Archimedes which are probably “curious” to the ordinary reader. The Seven Follies of Science: a Popular Account of the most famous Scientific Impossibilities and the Attempts which have been Made to Solve Them. By John Phin. Pp. viii + 178. (London: Archibald Constable and Co., Ltd., 1906.) Price 5s. net.

On the action of platina and mercury upon each other

Mr. Chenevix, in the month of May 1803, presented to the Royal Society a paper, which was printed in the Philosophical Transactions for that year, respecting the nature of a metallic substance which had been offered to the public as a new simple metal, under the name of Palladium. In that paper he not only attempted to prove that the said substance, instead of being a simple metal, was merely a compound of platina and mercury, but he also described certain processes by which he had been enabled to produce it. He now expresses his mortification to learn that the processes he there recommended, as the least likely to fail, have been generally unsuccessful; and confesses he has reason to believe “that the nature of palladium is considered by most chemists as unascertained, and that the fixation of mercury by platina is by many regarded as visionary.” In France, he says, the compound nature of palladium has been more generally credited; M. Guyton, who was appointed by the National Institute to make a report upon Mr. Chenevix’s experiments, having repeated some of them, and having been led by the results to the same general conclusions as Mr. Chenevix.

V. On the action of platina and mercury upon each other

On the 12th of May, 1803,I had the honour of presenting a Paper to the Royal Society, the object of which was to discover the nature of palladium, a substance just then announced to the public as a new simple metal. The experiments which I had made for this purpose led me to conclude that palladium was not what it had been stated to be, but that it was a compound of platina and mercury. It was natural to suppose that a subject so likely to spread its influence throughout the whole domain of chemistry, and which tended even to the subversion of some of its elements, would awaken the attention of philosophers. We find accordingly, that it has become a subject of enquiry in England, France, and Germany; but the experiments which I had recommended as the least likely to fail, have been found insufficient to insure the principal result; and I have had the mortification to learn that they have been generally unsuccessful. I have even reason to believe that the nature of palladium is still considered by chemists, at least with a very few exceptions, as unascertained; and that the fixation of mercury by platina is by many regarded as visionary.