Anionic contaminant removal using

Chemical contaminants have widely varying affinities for sorbent surface and therefore the application of a selective sorbent seems to be an optimal method for contaminant removal. This justifies further research on active aluminium hydroxide (AAH), as a selective sorbent for specific anionic contaminant removal. The use of AAH as a sorbent involves both coagulation and ion-exchange mechanisms. 

Chemical pretreatment is often used to improve the performance of contaminant removal. The use of chemical flocculants is based on system efficiency, the specific DAF application and cost. Commonly used chemicals include trivalent metallic salts of iron, such as FeClj or FeSO or aluminum, such as AISO. Organic and inorganic polymers (cationic or anionic) are generally used to enhance the DAF process. 

In situ electrokinetic extraction (ISEE) is an in situ extraction technology that uses specialized lysimeter electrodes to remove anionic contamination from unsaturated soil. This technology is primarily used on soils with low permeabilities. During ISEE, a direct electric current is... 

Extract was prepared from the leaves and roots of two years old olive plants with water at room temperature. Internal standard as D-3-0-methylglucopyranose(MeGlu) was used and added In appropriate volume. Extraction was accomplished by shaking for 15 min and finally the suspension was centrifuged at 3000 rpm for 10 min. Before the injection the aqueous phase was filtered and passed on a cartridge OnGuard A (Dionex)to remove anion contaminants. 

Figure 27 Errors in electron affinities (as compared to experiment) for self-consistent B3LYP/aug-cc-pVTZ calculations, and also for cases where the B3LYP energies for the neutral molecule and the anion were evaluated using Hartree-Fock densities (HF-B3LYP). The dashed horizontal lines are mean errors, which include considerable cancellation between over- and underestimation of the experimental EAs. The data set is except that the CN molecule is removed because of spin contamination in the Hartree-Fock determinant. Adapted with permission from Ref. 313 copyright 2011 American Institute of Physics.

Lipoproteins may denature on heating and if present during pasteurization can result in the formation of haze or turbidity in the final product. This material was removed traditionally by filtration through asbestos (qv) sheets (6) however, health hazards associated with asbestos have led to its replacement by alternative filter materials (23,37,193). These media have been less effective than asbestos and further measures have been required to ensure the visual clarity of albumin products, eg, further filtration developments for Hpid removal (194), preferential denaturation of contaminants using in-process heat treatment, and anion-exchange chromatography (49). 

Biological activity can be used in two ways for the bioremediation of metal-contaminated soils to immobilize the contaminants in situ or to remove them permanently from the soil matrix, depending on the properties of the reduced elements. Chromium and uranium are typical candidates for in situ immobilization processes. The bioreduction of Cr(VI) and Ur(VI) transforms highly soluble ions such as CrO and UO + to insoluble solid compounds, such as Cr(OH)3 and U02. The selenate anions SeO are also reduced to insoluble elemental selenium Se°. Bioprecipitation of heavy metals, such as Pb, Cd, and Zn, in the form of sulfides, is another in situ immobilization option that exploits the metabolic activity of sulfate-reducing bacteria without altering the valence state of metals. The removal of contaminants from the soil matrix is the most appropriate remediation strategy when bioreduction results in species that are more soluble compared to the initial oxidized element. This is the case for As(V) and Pu(IV), which are transformed to the more soluble As(III) and Pu(III) forms. This treatment option presupposes an installation for the efficient recovery and treatment of the aqueous phase containing the solubilized contaminants. 

Ion exchange is effective for the removal of cationic or anionic heavy metal contaminants. It can also be used for water softening. Ion-exchange resins are usually regenerable with salt.65... 

Surface samples were collected in snow pits under ultra-clean conditions described elsewhere [13] with the exception that samples for anion analysis were collected in polystyrene cups precleaned without the use of acids. Ice core samples were cleaned to remove surface contamination using the "dry-core" procedure involving rinsing and melting of exterior surfaces with ultra-pure water [13]. Shallow-depth firn cores are permeable and the dry-core rinsing is unsuitable. Therefore an inner core of 2.5 cm diameter was taken from intervals of the 7.6 cm diameter South Pole firn core using a specially-built precleaned stainless steel corer within a -15 °C cold room. Prior to this coring, exposed ends of core sections were shaved away with precleaned stainless steel chisels. 

Several limitations on the synthetic techniques that can be employed are imposed by the need for rapidity and minimization of handling because of the radiation hazard, and the low concentration and small physical quantities of the compounds. Purification steps should be eliminated if possible by optimizing yields. Where purification is unavoidable, simple procedures are employed such as use of anion exchange columns to remove perrhenate (the most common contaminant in the final product). A variety of disposable sample preparation columns are well suited to this purpose and are available containing small quantities of anion or cation exchange materials (0.1 to 0.5 g typically) such as quaternary ammonium-, primary ammonium-, or sulfonate-derivatized silica. Reversed phase columns are also often used (C8 or C18-derivatized silica). The purification is often thus reduced to a simple filtration step which can be performed aseptically. 

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