Water treatment anion exchange

Encyclopedia of Separation Science (2000) eds C.F. Poole, M. Cooke and I.D. Wilson, Academic Press, New York J. Irving, p. 4469 - Water treatment Overview ion exchange W.H. H611, p. 4477 - Water treatment Anion exchangers ion exchange . 

Anion exchange resins. Should be conditioned before use by successive washing with water, EtOH and water, and taken through two OH"—H" "—OH" " cycles by successive treatment with N NaOH, water, N HCl, water and N NaOH, then washed with water until neutral to give the OH" form. (See commercial catalogues on ion exchange resins). 

Lipoteichoic acids (from gram-positive bacteria) [56411-57-5J. Extracted by hot phenol/water from disrupted cells. Nucleic acids that were also extracted were removed by treatment with nucleases. Nucleic resistant acids, proteins, polysaccharides and teichoic acids were separated from lipoteichoic acids by anion-exchange chromatography on DEAE-Sephacel or by hydrophobic interaction on octyl-Sepharose [Fischer et al. Ear J Biochem 133 523 1983]. 

Strongly basic anion exchangers (polystyrene quaternary ammonium resins). These resins (Duolite A113, Amberlite 400, etc.) are usually supplied in the chloride form. For conversion into the hydroxide form, treatment with 1M sodium hydroxide is employed, the volume used depending upon the extent of conversion desired two bed volumes are satisfactory for most purposes. The rinsing of the resin free from alkali should be done with de-ionised water free from carbon dioxide to avoid converting the resin into the carbonate form about 2 litres of such water will suffice for 100 g of resin. An increase in volume of about 20 per cent occurs in the conversion of the resin from the chloride to the hydroxide form. 

Anion-exchange sorbents are made by treatment of cation -exchange filters in H-form by water solution of polyethylenimine. Amine... 

Some approach to tailor a new natural anion exchanger from ODA-modified clinoptilolite was studied. We verified repeatedly clinoptilolite enhanced oxyanion uptake mechanism after regeneration and so far confirmed the feasibility at laboratory level. To set this process for water treatment in recycling operation, a pilot plant research is necessary to accomplish. In contrast to clay s properties, which surface have been usually... 

LDHs can take up anion species from solution by three different mechanisms surface adsorption, interlayer anion-exchange and reconstruction of a calcined LDH precursor by the memory effect . The memory effect [130] of LDHs, discussed in 2.3 above, is one of their most attractive features as adsorbents for anionic species. Calcination allows the recycling and reuse of the adsorbents with elimination of organic contaminants as CO2 and water [ 131]. The main advantages of LDHs over traditional anionic exchange resins are their higher AEG values and the fact that LDHs are resistant to high temperature treatments. 

Figure 15.20. Fixed bed ion exchange vessels and arrangements, (a) Typical design of a water softener, showing bed support, distributor, and effluent collector, (b) Vessel with radial-type distributors and collectors (Illinois Water Treatment Co.), (c) A double-dish underdrain system (Permutit Co.), (d) Some arrangements of vessels for cation and anion exchange.

AS Treatability and Environmental Concentrations. Studies of AS degradation in the environment or during actual sewage treatment have been limited because specific analytical methods to measure AS were not available until recently. We developed a method that isolated AS from water samples on a strong anion-exchange column. The AS were then hydrolyzed to a fatty acid and analyzed by gas chromatography with flame-ionization detection (GC-FID). The method has a detection limit of 5 xg/L per component (50). 

Interferences with arsenic adsorption and ion exchange Dissolved organics and anions may interfere with arsenic adsorption and ion exchange in both natural environments and water treatment systems. In some cases, chemical species directly compete with arsenic for adsorption sites. They may also desorb and replace arsenic. Vanadium is one element that could interfere with the adsorption of arsenic onto mineral surfaces. In most cases, vanadium is not abundant in water. However, alkaline (pH 7.0-8.8) groundwaters in the loess aquifers of La Pampa, Argentina contain up to 12mgL 1 of vanadium (Smedley et al., 2005). The vanadium readily hinders the sorption of As(V) onto iron (III) (oxy)(hydr)oxides (Chapter 3). 

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