Exchangers large scale application

Polystyrene has been used most often as the support for phase transfer catalysts mainly because of the availability of Merrifield resins and quaternary ammonium ion exchange resins. Although other polymers have attrative features, most future applications of polymer-supported phase transfer catalysts will use polystyrene for several reasons It is readily available, inexpensive, easy to functionalize, chemically inert in all but strongly acidic media, and physically stable enough for most uses. Silica gel and alumina offer most of these same advantages. We expect that large scale applications of triphase catalysis will use polystyrene, silica gel, or alumina. 

The first large scale application of ion exchange to effluent treatment was in the recovery of water, ammonia, and basic copper sulfate from the waste streams encountered in the cuprammonium rayon process. Originally a phenolic type condensation resin was employed, but more recently carboxylic acid acrylic-based exchangers have been introduced. A similar process exists for zinc recovery from the spinning acids of viscose rayon plants, except that in this operation a sulfonic acid resin is employed. 

Clearly, as is well known, heat transfer becomes a problem in large scale applications and external heat exchangers are often required. 

Hydrogen has two stable isotopes, protium and deuterium. According to the lUPAC classification, deuterium is denoted as or D. The natural abundance of deuterium is very low, about 156 ppm, and restricts the large-scale application of deuterium-exchanged compounds. However, deuterium-exchanged compounds are very useful and often easily obtainable model molecules for various investigations. 

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