Methods of ion exchange

The first level of treatment, with sand filters and chlorination to remove suspended matters and disinfection of pathogens, may be good enough for the low-cost water. The removal of discoloration and bad smell is accomplished by activated charcoal absorption. Ozone and ultraviolet treatments are much more expensive for the removal of microbes and organic matter, and should be considered only when necessary to solve a technical problem, or to satisfy an advertisement need. Reverse osmosis is the most effective method used to recover clean water from brackish water, and to remove inorganic minerals such as sodium, copper, iron, and zinc. The removal of calcium and magnesium ions can be accomplished by the method of ion exchange with sodium, which would also increase the sodium concentration, and could cause objections. Different levels of treatment require a variety of costs, and can produce different levels of customer satisfaction. 

The final answer came from the atomic pile. J. A. Marinsky, L. E. Glendenin, and C. D. Coryell at the Clinton Laboratories at Oak Ridge (20) obtained a mixture of fission products of uranium which contained isotopes of yttrium and the entire group of rare earths from lanthanum through europium. Using a method of ion-exchange on Amberlite resin worked out by E. R. Tompkins, J. X. Khym, and W. E. Cohn (21) they were able to obtain a mixture of praseodymium, neodymium, and element 61, and to separate the latter by fractional elution from the Amberlite column with 5 per cent ammonium citrate at pH 2.75. Neutron irradiation of neodymium also produced 61. 

After leaching, a concentration/pmification is done to get rid of other materials leached from the ore. This can be done by ion exchange or solvent extraction. In the ion exchange method, three steps are employed (a) the absorption of uranium from the leach liquor onto the resin, (b) the selective elution of uranium from the resin, and (c) the regeneration of the resin. Anion exchange is the preferred method of ion exchange with the relevant chemical reactions for acid leach being... 

Using methods of ion-exchange chromatography, trans-CHD have already been isolated from cultivation medium for analytical purposes ... 

The methods of ion exchange and subsequent reduction are also important in determining the final metal dispersion and hence the catalyst activity (77, 95-100). 

As mentioned previously, the analysis of amphetamines and other basic drugs was one of the first forensic applications of HPLC. Many analyses of basic drugs are still performed by the same method of ion-exchange chromatography on unmodified silica columns with an eluent buffered to about pH 9. Dissolution of the silica in the analytical column is prevented by using a pre-saturation column which is packed with a 40 pm particle size silica. This type of column is situated in the eluent line between the pump and the injection valve and should always be used when performing analyses with aqueous eluents on silica-based columns. By using these columns the lifetime of the analytical column can be extended considerably. 

Johansen, P.G. and Buchanan, A.S., An electrokinetic study by the streaming potential method of ion exchange at oxide mineral surfaces, Austr. J. Chem., 10, 392, 1957. 

General Explanation of Preparation Methods of Ion Exchange Membranes... 

Table 3.2 Classification of preparation methods of ion exchange membranes... 

K. Hayashi C. Kondo and J. Ueda, Preparation method of ion exchange membrane, Jpn. Pat. JP 39-19037 (examined application). 

In a related study, Khedr (2013) assessed the removal of radium, U, as uranyl cation, or carbonate complexes, and radon by reverse osmosis (RO) and nanofiltration (NF) in comparison with the conventional methods of ion exchange resins (lERs), chemical precipitation/softening, coagulation, and adsorption on surface active media. lERs and chemical softening achieved radionuclide rejection from 32 to 95%, but with loss of process efficiency due to undesired... 

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