Clean Mercury Research Articles

Potential Combination of Phytoremediation Plants and Compost in Remediation of Hg in Ex-Gold Mine Soil Contaminated Mercury (Hg)

Heavy metal mercury pollution in the environment can have negative impacts on both surrounding ecosystems and human health. Sources of mercury pollution often come from mining activities, particularly from many unlicensed gold mines (PETI) that use the mercury amalgamation method to extract gold. Due to the persistent, bioaccumulative, and toxic nature of mercury, contamination in the soil has increased. One effort to reduce mercury toxicity is the application of absorption methods using phytoremediation plants and compost as regulating factors. The aim of this study is to review sources of information related to the use of phytoremediation plants and the application of compost as remediators to clean mercury (Hg)-contaminated soil. To reduce levels of heavy metal contamination, plants employ five phytoremediation mechanisms: phytoextraction, phytostabilization, rhizofiltration, phyto degradation, and phytovolatilization. Therefore, selecting hyperaccumulator plants that have the ability to accumulate mercury (Hg) at levels 100 times higher than ordinary plants is crucial for effective remediation. Additionally, the use of compost as a source of organic material can enhance mercury mobility. The addition of organic materials such as compost can increase C organic content, cation exchange capacity (CEC), pH, and Hg-chelate formation, thereby maximizing mercury absorption by plants. This combination has a positive impact on reducing mercury levels in the soil and is environmentally safe.

Gaseous mercury capture using seaweed biochars modified by clean ultraviolet/hydrogen peroxide advanced oxidation process

Seaweed-based biochars stemmed from the solid wastes of seaweed-based biomass pyrolysis were used to reduce the emission of elemental mercury. An environmentally-friendly ultraviolet/hydrogen peroxide advanced oxidation process modification method was used to increase the active species over seaweed-based biochars for elemental mercury adsorption. Results suggest that the elemental mercury capture performance of seaweed-based biochars is greatly improved after the ultraviolet/hydrogen peroxide advanced oxidation process modification. The optimum adsorption temperature and hydrogen peroxide concentration are 120 °C and 4%, respectively. The characterization results display that the clean ultraviolet/hydrogen peroxide advanced oxidation process modification greatly enhances the rising of oxygen functional group on seaweed-based biochars surface. In particular, the presence of CO and COOH/COOC groups is conducive to Hg0 capture. The process of elemental mercury capture over the tested seaweed-based biochars accords with pseudo-second-order adsorption kinetic equation. Chemical sorption is the pivotal controlling link of the whole mercury capture process. The preparation costs of Sargassum-based biochar and Enteromorpha-based biochar are lower than that of chitosan adsorbent and commercial AC. In addition, the modified seaweed biochars have good regeneration performance, which is conducive to greatly reducing the cost of mercury removal. This research can provide new inspiration for the green modification of biochar and the development of clean mercury removal adsorbent.

Reduction of oxygen and hydrogen peroxide on electrodes with adsorbed monolayer of aliphatic compounds

Cathodic reduction of oxygen and hydrogen peroxide on amalgamated platinum electrodes, which are coated with monolayers of long-chain aliphatic compounds cetyl alcohol (CA) and stearic acid (SA), is retarded as compared with the same reactions on clean mercury (or amalgam) surface. The oxygen reduction kinetics differ from that on mercury. The difference is explained by that oxygen diffuses into the monolayer and is reduced in it at a certain distance from the metal surface and only at the limiting current the reaction is forced onto the monolayer surface. In contrast to the oxygen reduction, the hydrogen peroxide reduction kinetics on electrodes with SA and CA monolayers is much closer to that on mercury, but with some quantitative distinctions. All results favor the H2O2 reduction at the monolayer/solution interface. The difference in the behavior of O2 and H2O2 is explained by different polarity of these molecules: it is significantly more difficult to penetrate the hydrocarbon monolayer for polar H2O2 molecule than for nonpolar O2 molecule.

Fabrication of protein crystalline films on mercury

A fabrication method to form two-dimensional (2D) crystalline films of protein particles is reported. The key innovation in this fabrication is the spreading wetting process which uses a clean mercury surface where protein solutions are spread to yield a wetting film. The thin liquid film of protein solution leaves a monolayer state of protein molecules, namely 2D crystalline films, after solvent removal by evaporation. The significance of the film fabrication lies in its active nature to harness certain directional transport of particles driven by spreading and convection flow of the solution. This seems to be a unique character which exclusively effects thin liquid films on flat substrate. Owing to this active nature of particle assembling, hexagonally packed 2D crystals can grow within a short period.

Surfactant monolayers on a clean mercury surface: Apparatus and experiments

A Langmuir trough for studying monolayers on a mercury surface was constructed usingT. Smith's design. The surfactant (long-chain alkyl-trimethylammonium compounds) in aqueous solution were spread on a clean mercury surface in an atmosphere of helium, and the surface pressure re-areaA and thickness of surface filmd-areaA curves were obtained. Theπ-A curves were characterized by the appearance of multiple inflection points and plateaus, being explained as stepwise dense surface packing of molecules, and the formation of multilayers by film compression with long axes of molecules lying flat on the mercury surface.

Anisotropic molecules forming a monomolecular layer on a strongly adhesive substrate: a scaled particle treatment

Long chain fatty acids and large, rigid, aromatic molecules form a monomolecular layer on the surface of clean mercury. The surface pressure isotherms of these systems have been measured previously. In this paper, the scaled particle theory is applied to such monolayers with a number of simplifying assumptions. With a single adjustable parameter, the interaction of the molecules with the substrate and the general features of the surface pressure isotherms of the long chain fatty acids, anthracene, naphthalene, and cholesterol at intermediate liquid densities are fairly well reproduced.

Some properties of polyvinyl acetate films cast from methanol, acetone and chloroform as solvent

Polyvinyl acetate was cast into films on a clean mercury surface from its solution in either methanol, acetone or chloroform. Some mechanical properties of the films, exposed at 20 °C and 65% r.h., and 45 and 60 °C in air ovens, were studied. They were found to be highly dependent on the solvent used for film casting and the time of exposure of film at each of the temperatures. The initial modulus, yield stress, tensile strength and work to rupture of the polymer films were greater for those cast from acetone than those cast from chloroform, and for all the films these properties increased with exposure time, with an induction period in some cases. The elongation at break decreased with exposure time from an initial value which was higher for the chloroform-cast than the acetone-cast films. Films cast from methanol were found to be too brittle for testing. The results are interpreted on the basis of interactions between the solvent molecules and those of the polymer. Of the three solvents, chloroform produced polyvinyl acetate films with the most constant mechanical properties over the longest period of exposure which depended on the temperature of exposure, decreasing as the temperature increased. Hence chloroform is recommended for casting films of polyvinyl acetate. Methanol is practically unsuitable while acetone could be used where chloroform is not available.

Properties of Anchored Cathode Spots of a Dc Mercury Vacuum Arc

Ensembles of anchored cathode spots of a dc mercury vacuum arc have been studied by fast framing and streak photography. From these photographs, several statistical properties of the cathode spots have been determined: distribution functions for their diameters, velocities, and displacements, as well as spot shape and average values for the spot current and its density. The measurements showed that the anchored cathode spots were quasi-stationary. No indications of a microstructure within the individual cathode spots were found at an optical resolution of 0.37 ?m. Strong evidence is presented that the dc cathode spot parameter values reported here are typical for a clean mercury surface, and that those reported in the earlier literature are typical for impurity-covered surfaces.

The maximum boiling superheat of water

Boiling of water without a solid heating surface was carried out by submerging a water drop under a layer of immiscible liquid on top of clean mercury. It was found that the boiling superheat without an active nucleation site decreased with the increase of the size of the water body. It agrees with that predicted by the nucleation therries when the water body is very small and reaches a constant value if it is sufficiently large. This asymptotic value should be used to predict the incipient boiling superheat for flooded heating surface.

The density of states of liquid mercury

Photoemission measurements from clean liquid mercury are reported for photon energies up to 21 eV. The results are consistent with a dip in the density of states close to the Fermi level. In addition, a new value for the binding energy of the 5d core levels has been derived from the data.

Adsorption of normal alkanes on Hg: Experimental check of gibbs adsorption equation and theoretical contact potential

Simultaneous surface tension, contact potential, and ellipsometric measurements of pentane, octadecane, and dotriacotane on mercury have been made at 24°C. These measurements for pentane have been used to experimentally verify the Gibbs adsorption equation within 6%. It is demonstrated that the experimental contact potential and dielectric constant of the adsorbed films can be theoretically predicted over the range of adsorption (Γ = 0 to 5.5 × 10 14 molecules/cm 2) with no adjustable parameters. the electric field 2.1 Λ above a clean mercury surface is 1.35 × 10 7 volts/cm. The dipole moment induced in CH bounds by the electric field is 0.0292 D per CH if the chain is parallel to the surface. The eneregy to change molecules from a horizontal orientation to a vertical orientation is equal to the difference between the heat of adsorption on Hg and the heat of vaporization from the liquid alkane. This energy per CH bond proves to be 0.15 × 10 −13 ergs. A most probable model for molecular orientation is revealed as a function of surface density.

Ellipsometry for Measurements at and below Monolayer Coverage

Ellipsometer, surface-tension, and contact-potential measurements were made simultaneously at and below monolayer coverage (θ = 1 to 0.05) on a clean mercury surface at room temperature. It has been demonstrated with molecules of known dimensions (caproic, lauric, stearic, behenic, and adamantane-carboxylic acids, and α bromonaphthalene and pentane) that the classical Drude equation for the relationship between the phase shift ( Δ¯ − Δ) of reflected polarized light and the average effective film thickness d is valid below monolayer coverage. This is so even though the Drude equation was derived for thick films that are considered to be a continuum with index and density independent of thickness. The equation for the three-dimensional model is Δ¯ − Δ = αd, where for less than monolayer coverage d is the hypothetical thickness the film would have if it were a continuum with index and density independent of d. The equation for the 3-D model remains valid below monolayer coverage, where the continuum property is not approximated, because the 2-D model gives essentially the same equation Δ¯ − Δ = αd0θ. In the 2-D model, the molecules are contained between the substrate surface and a plane d0Å above the surface, where d0 is the molecular diameter. The phase shift ( Δ¯ − Δ) decreases as the fraction of the surface covered (θ) decreases because the index of refraction is a function of the surface density. Values of α, calculated with the bulk-liquid index of refraction (sodium D line) and the first-order Drude relation (for films with only a real part of the refractive index) can be used to calculate d (0.05d0 to d0) or θ (0.05 to 1) within a few percent with the equations above. The same values are obtained if the relationship between α and the film index (based on the 2-D model) is used to calculate α. The ellipsometer measurements indicate changes of orientation of the molecules on the surface. A technique is described for automatically recording ellipsometer measurements for very thin films (0–30 Å).

Optical Constants of a Clean Mercury Surface as a Function of Temperature

The optical constants of Hg have been measured as a function of temperature (23°–115°C) on a surface that was demonstrated to be atomically clean (fraction of contamination monolayer ~0.004). The measurements were made at an angle of incidence of 70° and a wavelength of 5461 Å, in He atmosphere and in a vacuum. The equations relating n and κ with temperature are n=[0.00036T+1.593]±0.004, κ=[−0.00165T+2.995]±0.012, where T is °C (range 23°–115°) and the optical constants are defined by N=n(1−iκ).

Amalgam exchange separation of radiothallium

A method is presented for the rapid separation of radiothallium. The solution is made basic by addition of ammonia, then sodium fluoride and ethylenediamine are added and the mixture is shaken with 3% thallium amalgam. A rapid exchange takes place and the bulk of the activity is concentrated in the amalgam. The amalgam is diluted with clean mercury and shaken with acidic cobalt nitrate solution which back-extracts thallium. About 90% of the thallium activity is recovered.

A New Microwave Harmonic Generator

IF my estimate1 of up to 107 amp./cm.2 for the emission current density of free cathode ‘spots’ on a clean mercury surface is accepted, the mercury arc may be regarded as an indestructible point-contact rectifier with interesting microwave properties. At high rates of growth of current (that is, in excess of 6 × 107 amp./sec.) the cathode emission appears to be unable to follow the rising current by its normal method of increasing size1 and presumably (at microwave frequencies) must either change its emission density or become unstable, or both. In either case a ‘non-linear’ current-voltage relationship is still to be expected.

The Statistics of Liquid Spray and Dust Electrification by the Hopper and Laby Method

The electric charges created upon individual microscopic particles of an aerosol during its generation have been determined by the Hopper and Laby oil drop method. In the spraying of nonconducting liquids, the charges produced upon droplets in the diameter range 2–50 microns are found to follow a normal distribution with the average charge zero and the mean square charge proportional to droplet volume. This result favors the electrification mechanism of statistical fluctuation of electrolytic ion concentration among the droplets rather than the more prominent Lenard mechanism. The charge distribution among clean mercury droplets in the diameter range 1–6 microns sprayed from a glass sprayer is asymmetric because of contact effects at the mercury-glass interface: the average droplet charge is positive, relatively large, and increases with droplet diameter. The dependence of dispersive dust charging upon particle surface roughness is illustrated by observations made with relatively smooth microscopic glass spheres and compared with data for rough crushed quartz particles.

Active nitrogen of long duration, law of decay, and of increased brightness on compression

1-Active Nitrogen-Influence of Vessel Walls on the Duration The length of time for which the afterglow associated with active nitrogen remains perceptible varies very greatly under different experimental conditions; and, what is more important, if we start from a given luminosity per cc of the gas, the integrated amount of light emitted before the luminosity sinks to zero varies also. This is connected with the fact that the walls of the certain gaseous impurities may have an unfavourable effect. In other words, the active nitrogen may go out of existence either by a luminous or a non-luminous reaction. If it is desired to study the homogeneous luminous reaction, then it becomes important to eliminate the other as far as possible. So far as I am aware, no systematic attempt has ever been made to do this, though many writers have referred to the subject. The electrodelss ring discharge at low pressures is suited for the production of active nitrogen, and it has the advantage that no metal electrodes need be introduced. An oxidized copper surface, even of very small area, immediately destroys the afterglow when introduced into it, and a clean (freshly formed) mercury surface is attacked with formation of nitride. In view of these facts it seemed best to avoid metal, though more information would be desirable.

The pH and the CO2 Content of Cerebrospinal Fluid in Epilepsy.

Although considerable work has been done on the acid-base relationships in epilepsy, the evidence presented thus far has been conflicting and indecisive. Because of the importance of this phase of the problem, we have determined the pH and CO2 content of the cerebrospinal fluid in 125 epileptics and 30 non-epileptic control subjects by procedures which eliminate errors due to loss of CO2.1, 2The colorimetric method of McQuarrie and Shohl1 used for determining the pH may be briefly described as follows: The clear fluid is drawn into a special glass sampling burette over clean mercury after all air in the connecting tubes has been eliminated by means of a 3-way stop-cock. In preparation for taking the sample a number of tenths of a cc. of 0.0075% phenol red equal to the number of cc. of fluid to be taken is measured into the apparatus. After the spinal fluid is mixed with the dye in this concentration, it is read directly at 38°C. against the bicolor standards of Hastings and Sendroy in a simple comparator ...

Floating Mercury on Water

IN a letter in NATURE of Mar. 16, Mr. N. K. Adam describes the floating of small globules of mercury on a water surface, even when the latter was considerably contaminated. He concludes that for equilibrium to be possible, the mercury-air tension must have been reduced by the order of one or two hundred dynes. It is not necessary to suppose such a decrease. It appears that the part played by curvature of the surfaces in determining conditions for the equilibrium or the spreading of one liquid on another has been neglected. Experimentally, we have the observations of Burdon (Proc. Roy. Soc., 38, 2, 154; 1926), who found that water would spread over the surface of a large, clean mercury drop, but that its progress was stopped when the curved edge of the drop was reached, where acceleration ‘downhill’ would be expected.

Apparatus and Methods for Preparing Very Clean Mercury

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text Duane Roller, "Apparatus and Methods for Preparing Very Clean Mercury," J. Opt. Soc. Am. 18, 357-359 (1929) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article