ION EXCHANGE 



391 



specific applications may best be found in the literature dealing with the 

 particular method. It is the intention here to present an over-all com- 

 mentary that may aid the inexperienced reader in the understanding and 

 application of the published procedures. 



KHj PO4 

 CjHjOH 



I 



Resin 



>/^/^^^/ 



K + 



Resin 



u 



3- 



PO 



r 



Resin 



CgH^OH 



HgO 



Deionized 

 solution 



Fig. 9-5. Use of cation and anion exchange in sequence to remove both potassium and 

 phosphate from solution. 



Apparatus. The operation may be carried out either by use of a col- 

 umn or by a batchwise procedure. Column methods are by far the most 

 widely used on account of their relatively high efficiency. However, in 

 a few instances, batch operations may offer an advantage, for example, 

 in a system where gas is produced in the resin bed which would interfere 

 with solution flow, or where the objective is the adjustment of pH or ion 

 concentration. As an example of concentration adjustment, a batch pro- 



