Ion-exchanged system

Waste Treatment. Environmental concerns have increased the need to treat Hquid discharges from all types of industrial processes, as well as mnoffs where toxic substances appear as a result of leaks or following solubilization (see Wastes, industrial). One method of treatment consists of an ion-exchange system to remove the objectionable components only. Another involves complete or partial elimination of Hquid discharges by recycling streams within the plant. This method is unacceptable unless a cycHc increase in the impurities is eliminated by removing all constituents prior to recycling. 

Ion exchangers exchange one ion for another, hold it temporarily, and then release it to a regenerant solution. In an ion-exchange system, undesirable ions in the water supply are replaced with more acceptable ions. 

The gels precipitated as described above are not useful in ion-exchange systems because their fine size impedes fluid flow and allows particulate entrainment. Controlled larger-sized particles of zirconium phosphate are obtained by first producing the desired particle size zirconium hydrous oxide by sol—gel techniques or by controlled precipitation of zirconium basic sulfate. These active, very slightly soluble compounds are then slurried in phosphoric acid to produce zirconium bis (monohydrogen phosphate) and subsequently sodium zirconium hydrogen phosphate pentahydrate with the desired hydrauhc characteristics (213,214). 

Ion Exchange Resins - Very good site for you to visit Contains cost comparisons between RO and ion exchange systems for several design cases. http //www. rohmhaas. com/ionexchange. 

Catalysts include oxides, mixed oxides (perovskites) and zeolites [3]. The latter, transition metal ion-exchanged systems, have been shown to exhibit high activities for the decomposition reaction [4-9]. Most studies deal with Fe-zeolites [5-8,10,11], but also Co- and Cu-systems exhibit high activities [4,5]. Especially ZSM-5 catalysts are quite active [3]. Detailed kinetic studies, and those accounting for the influence of other components that may be present, like O2, H2O, NO and SO2, have hardly been reported. For Fe-zeolites mainly a first order in N2O and a zero order in O2 is reported [7,8], although also a positive influence of O2 has been found [11]. Mechanistic studies mainly concern Fe-systems, too [5,7,8,10]. Generally, the reaction can be described by an oxidation of active sites, followed by a removal of the deposited oxygen, either by N2O itself or by recombination, eqs. (2)-(4). 

The ion exchange system will be capable of processing 200,000 lb/hr. A two-bed ion exchange unit will be specified. The minimum resin volume is 200 ft3. This was calculated on the basis of 2 GPM/ft3 resin.62 During the summer the extra wash water will be sent directly to the river. It does not appear to be warm enough to justify a cooling tower and should contain no pollutants. 

FIG. 16-66 Himsley continuous ion-exchange system. (Himsley and Farkas, Operating and Design Details of a Truly Continuous Ion Exchange System Soc. Chem. Ind. Corn., Cambridge, England, July 1976. Used by permission of the Society of Chemical Industry.)... 

Continuous inkjet (CIJ) printing, 9 222 Continuous ion-exchange systems,... 

Distributor system, in ion-exchange systems, 24 403-404 District heating, from biomass, 3 687... 

Semiconductor surfaces, 9 730-731 Semiconductor technology, 19 127 Semiconductor transport, 22 237-239 Semiconductor-vacuum interface, 22 241 Semicontinuous deodorizer, 10 815 Semicontinuous dyeing, 9 211-213 Semicontinuous ion-exchange systems, 14 403... 

Another ion-exchange system has recently been developed by Nippon Rensui [8]. The Nippon Rensui system employs an amphoteric ion-exchange resin called Diaion DSR01 which can be eluted with water. In the DSR01 system, the resin takes up the sodium chloride and rejects the sodium sulphate. Purified NaCl is then recovered from the resin by water elution. This seems like a difficult approach since it is necessary to take-up huge amounts of NaCl on the resin in order to separate out a relatively small amount of sulphate impurity. Excessive dilution of the purified brine may also be an issue with this process. 

While the DSR01 ion-exchange system appears to be reasonably efficient, resin cost with that system is a major maintenance cost item. The BDS system uses up to 95%... 

Reid, A. F. Multi-stage Ion Exchange System for the Fractionation of... 

A key finding is that Mo isotopes can be fractionated during elution in at least some ion exchange systems (Anbar et al. 2001 Siebert et al. 2001), similar to observations of Ca, Cu and Fe isotope effects (Russell and Papanastassiou 1978 Marechal et al. 1999 Anbar et al. 2000). Therefore, it is often necessary to ensure that yields through these chemical processes are essentially quantitative. 

I. Column and Eluent Selection in Suppressed Ion Exchange Systems... 

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