Sorption, ion

A represents mechanical pump or steam ejector B, booster pump D, cryo, turbomolecular, sorption, ion, or trapped diffusion pumps. 

I expand treatment of sorption, ion exchange, and surface complexation, in terms of the various descriptions in use today in environmental chemistry. And I integrate all the above with the principals of mass transport, to produce reactive transport models of the geochemistry and biogeochemistry of the Earth s shallow crust. As in the first edition, I try to juxtapose derivation of modeling principles with fully worked examples that illustrate how the principles can be applied in practice. 

Humus/SOM enter into a wide variety of physical and chemical interactions, including sorption, ion exchange, free radical reactions, and solubilization. The water holding capacity and buffering capacity of solid surfaces and the availability of nutrients to plants are controlled to a large extent by the amount of humus in the solids. Humus also interacts with solid minerals to aid in the weathering and decomposition of silicate and aluminosilicate minerals. It is also adsorbed by some minerals. 

In natural waters, arsenic may exist as one or more dissolved species, whose chemistry would depend on the chemistry of the waters. Over time, arsenic species dissolved in water may (1) interact with biological organisms and possibly methylate or demethylate (Chapter 4), (2) undergo abiotic or biotic oxidation, reduction, or other reactions, (3) sorb onto solids, often through ion exchange, (4) precipitate, or (5) coprecipitate. This section discusses the dissolution of solid arsenic compounds in water, the chemistry of dissolved arsenic species in aqueous solutions, and how the chemistry of the dissolved species varies with water chemistry and, in particular, pH, redox conditions, and the presence of dissolved sulfides. Discussions also include introductions to sorption, ion exchange, precipitation, and coprecipitation, which have important applications with arsenic in natural environments (Chapters 3 and 6) and water treatment technologies (Chapter 7). 

Sorption, ion exchange, precipitation, and coprecipitation of arsenic in water 2.7.6.1 Introduction... 

Once arsenic dissolves in natural water, it may remain in solution for an extended period of time or participate sooner in abiotic or biotic reactions that remove it from solution. Depending upon the pH, redox conditions, temperature, and other properties of an aqueous solution and its associated solids, dissolved arsenic may precipitate or coprecipitate. Arsenic may also sorb onto solid materials, usually through ion exchange. Due to their importance in understanding the behavior of arsenic in natural environments (Chapter 3) and their applications in water treatment (Chapter 7), the sorption, ion exchange, precipitation, and coprecipitation of arsenic have been the subjects of numerous investigations. 

Besides phosphate, silica is known to commonly compete with As(V) for sorption/ion exchange sites on a wide variety of iron(III) and aluminum compounds (Clifford and Ghurye, 2002), 227 (Su and Puls, 2003), 2582 (Holm, 2002 Smith and Edwards, 2005 Zhang et al., 2004 McNeill, Chen and Edwards, 2002), 146. Silica may directly compete with arsenic for sites or polymerize on adsorbent surfaces and eliminate surface charges that are favorable for arsenic adsorption (Stollenwerk, 2003), 89. 

Another important factor is how pH may affect the competition between As(III) and As(V) for sorption/ion-exchange sites on ferrihydrites. As(III) has little effect on As(V) sorption at pH values below 6. However, As(V) sorption may significantly decrease above pH 6 because of preferential sorption of As(III). In turn, As(V) may interfere with As(III) sorption on ferrihydrites at pH conditions of 4-6, but has little effect on As(III) sorption at pH values above 9 (Stollenwerk, 2003, 79). As discussed in Chapters 2 and 3, these changes in sorption with pH are largely related to the presence or absence of charges on dissolved As(III) and As(V) species, and the surface charge of the ferrihydrite. 

Separation of individual species and element-specific detection (extraction, sorption, ion exchange, gas permeation, and electrolysis)... 

Sorption Ion Exchange Encapsulation Microencapsulation Macroencapsulation Embedment... 

On the basis of those discussed here, we can say that the thermodynamic parameters of ion exchange determined by linear isotherm equations are not correct. We determine the mechanism of sorption (ion exchange and/or adsorption) and then choose the isotherm equation. When simultaneous interfacial processes take place, the dominant process, if any, has to be selected or experimentally separated, or Equation 1.119 should be used. 

Current economic and ecological analyses of the various processes available for recovery of minerals from seawater (evaporation, solvent extraction, sorption, ion exchange, flotation, fractional precipitation, distillation, electrolysis, electrodialysis, and electrocoagulation) favor ion exchange and sorption technology. 

A new series of layered indium phosphate complexes have potential applications in the areas of sorption, ion exchange,... 

Sorption Ions or their complexes may be collected in microcolumns on activated carbon, hydrous iron(III) oxide or reversed phased silica based sorbents (Das et al., 1983 Mizuike, 1983 Fang, 1993). The techniques are easily automated. Either elution or direct analysis may be performed. However the problem with blank values (by direct analysis of the sorbent) deserves serious attention. 

Solvent extraction, solid-liquid sorption, ion exchange, and precipitation methods are commonly used for the separation or preconcentration of precious metals from various matrices. 

Niyazi, E. E., Maltseva, V. S., Burykina, O. V., and Sazonova, A.V. The Study to sorptions ion honeys from sewages natural carbonate rocks. The Chemistry in chemistry high school. MGTU N. E. Baumana, p. 151-154 (2010). 

Precipitation. - Electrochemical Deposition and Dissolution. - Sorption, Ion Exchange and Liquid Chromatography. 

The remarkable properties of the smectite clays are due to their relatively low layer charge. The interlayer cations are loosely held and therefore swelling via solvent sorption, ion exchange and intercalation of a variety of species is possible. 

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