Adsorption of mercury

Fig. 15-17 The effect of chloride on adsorption of mercury by hydrous iron oxide at constant total mercury concentration of 3.4 x 10 M. The lines represent the predicted adsorption assuming that Hg-Cl complexes do not sorb at all. (Reprinted with permission from P. V. Avotins, Adsorption and coprecipitation studies of mercury on hydrous iron oxides," 1975, Ph.D. dissertation, Stanford University, Stanford, CA.)...

On the surface of metal electrodes, one also hnds almost always some kind or other of adsorbed oxygen or phase oxide layer produced by interaction with the surrounding air (air-oxidized electrodes). The adsorption of foreign matter on an electrode surface as a rule leads to a lower catalytic activity. In some cases this effect may be very pronounced. For instance, the adsorption of mercury ions, arsenic compounds, or carbon monoxide on platinum electrodes leads to a strong decrease (and sometimes total suppression) of their catalytic activity toward many reactions. These substances then are spoken of as catalyst poisons. The reasons for retardation of a reaction by such poisons most often reside in an adsorptive displacement of the reaction components from the electrode surface by adsorption of the foreign species. 

Underpotential Deposition of Mercury on Cold Electrodes Earlier studies of UPD of mercury were carried out applying only classical electrochemical methods and polycrystalline electrodes. The results have shown that UPD of Hg is accompanied by adsorption of mercury ions. 

Adsorption of mercury. All chemicals used were Merck or Baker analytical quality reagents, unless stated otherwise. From the commercially available adsorbents the following were used silica gel 60 A porosity, 0.063-0.200 mm particle size (Merck) charcoal 0.3-0.5 mm particle size, gas-chromatographic quality (Merck) alumina R Woelm hydrous zirconium oxide HZ0-1, 100-200 mesh, (Bio-Rad). Except for zirconium phosphate, which was prepared according to Amphlett ( ), all other sorbents were prepared by coating (precipitation) on acid-purified silica gel, as described in (1 ). The Si0 -NH was prepared according to Leyden et al (11). L... 

Figure 3. Adsorption of Mercury Vapor Emanating from the Bioreactor...

Mercury binding leads to an increase of mass of the gold layer which can be detected by electro-acoustic transducers based on quartz microbalance (QMB the abbreviation QCM = quartz crystal microbalance is also widely used), surface acoustic waves (SAW)—devices [20] or microcantilevers [21,22], Adsorption of mercury vapour increases resonance frequency of shear vibrations of piezoelectric quartz crystals (Fig. 12.2). This process can be described by Sauerbrey equation [23]. For typical AT-cut quartz, this equation is... 

Another plasmon resonance approach for detection of mercury vapour is based on localized plasmon resonance in gold nanoparticles deposited on transparent support (Fig. 12.4, right). Changes of the refractive index of gold nanoparticles due to adsorption of mercury should lead to modification of the gold plasmon band of optical adsorption spectra. This approach has been applied successfully for investigation of interaction of biomolecules however, to our knowledge there is still no report on its applications for detection of mercury vapour. 

Adsorption of mercury atoms onto thin gold film leads to scattering of conduction electrons at the gold surface resulting in an increase of surface electrical resistance. This phenomenon is used for preparation... 

The sensor is based on high affinity of gold to mercury and on chemo-resistive properties of ultrathin gold layers adsorption of mercury leads to increase in the surface resistance [1,2]. However, this effect is not selective similar changes are caused by adsorption of water vapor and sulfuric compounds. The use of monomolecular layer of alkylthiols as a filter excludes this interference completely [3]. Sensor calibration is performed by thermoinjection of nanogram-amount of mercury quantitatively deposited by electrochemical reduction [4],... 

Figure 2 shows a comparison of nitrogen adsorption isotherms at 77 K for the organic-inorganic hybrid materials developed for adsorption of mercury ions. The shape of the nitrogen adsorption isotherms indicates that the mesostructure was preserved after chemical modification of the surface. Evaluation of the shift of the capillary condensation step and reduction of its height provide information about formation of the chemically bonded layer inside mesopores. 

Watson C. M., Dwyer D. J., Andie J. C., Bruce A. E., and Bruce M. R. M. (1999) Stripping analyses of mercury using gold electrodes irreversible adsorption of mercury. Anal. Chem. 71, 3181-3186. 

DBU has been quaternized with chloromethylated polystyrenes to give new ion-exchange resins (84BCJ1108). The chloride forms of these ion-exchange resins were effective as ion exchangers for bulky anions such as sulfate, oxalate, hexacyanoferrate(II) and (III), and tris(oxalato)ferrate(III). The adsorption of mercury(II) and copper(II) chlorides and iodides on these resins was also investigated. 

Appreciable interest has been generated in the use of activated carbons for flue gas cleanup, especially for the removal of SOx and NO the adsorption of mercury from flue gases was discussed earlier. From the environmental point of view, emissions from the combustion of fossil fuels in power plants and similar industrial processes are major contributors to a lowering of air quality. The flue ga.ses carry traces of SOi and NO, which can be oxidized and converted to their acid forms in the presence of atmospheric water vapor, and they may also combine with other volatile organics to form ozone and smog. Similarly, low level SOj and NOx emissions from automobiles, while insignificant for individual vehicles, become a large source of pollution when multiplied by the millions of vehicles that are on the roads. 

Care must be exercised to ensure that the analysis of methylmercury levels in hair are not confounded by adsorption of mercury vapors or inorganic mercury onto the hair (Francis et al. 1982)... 

Tiffreau, C., Liitzenkirchen, J., and Behra, P. (1995). Modehing the adsorption of mercury (II) on (Hydr)oxides. I. Amorphous iron oxide and a-quartz. /. Colloid Interface Sci., 172, 82-93. 

Bonnissel-Gissinger, P. et al.. Modeling the adsorption of mercury(II) on (hydr) oxides II 0(-FeOOH(goethite) and amorphous silica.. 1. Colloid Interf. Sci., 215, 313, 1999. 

It must be stressed that the co-adsorption of mercury (from the vacuum line) could lead to mercury photosensitization of the adsorbed gas and great care must be taken to distinguish sensitization by the surface or other substances on the surface with mercury sensitized decomposition. The use of low pressure mercury resonance lamps which produce the 253.7 nm mercury line... 

R.W. Joyner and M.W. Roberts. Auger Electron Spectroscopy Studies of Clean Polycrystalline Gold and the Adsorption of Mercury on Gold. J. Chem. Soc. Faraday... 

Mercer, T.T. (1979) Adsorption of mercury by gold and silver. Anal. Chem., 51, 1026-1030. 

Chitosan from different sources was used in the form of beads and flakes and the adsorption capacity for Cu(II) was almost unaffected by the physical form of the polymer while dye adsorption was much higher on beads than on the flakes. Langmuir isotherm was found to fit the adsorption process (Wu et al. 2000). Chitosan and some of its derivates have been used effectively for the adsorption of mercury(II) (Cardenas et al. 2001, Babel and Kumiawan, 2003). Radiation-cross-linked chitosan has been used recently for the treatment of wastewater contaminated with Cr(VI) (Ramnani and Sabhaewal 2006). 

Baba, Y., Matsumura, N., Shiomori, K., and Kawano, Y. 1998. Selective adsorption of mercury (II) on chitosan derivatives from hydrochloric acid. Anal. Sci. 14 687-690. 

Adsorption of toxins from skin or internally by clay organic interaction processes, adsorption of mercury and other heavy metals by ion exchange (Eyton s Earth, 2006), use as an alkalizing agent, supplying alkali exchangeable cations, etc. 

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