Ion Exchange 441 Table 17. Oxidation of Polystyrene and Polylamine Resins in a One-Week Accelerated Test at 90CE Besin Backbone EunctionaL Groun Capacity meala) During test%) Polystyrene R-CH2N(CH3)2 Polystyrene R-CH2N(CH2CH3)2 17 Polydially lamine N-H 8.3 37 ially lamine N-C3H7 As would be expected, the combination of thermal and osmotic shocks has been shown to have a large effect on the osmotic strength of anion resins. [85] This is illustrated in Fig. 27, where the decrease is shown to be over 15% in just 150 cycles. The important processing point to remember from this is that if the regeneration of a resin is performed at a temperature more than 20 C different from the temperature of the operating(loading)stre it is advisable first to adjust the temperature of the resin with distilled water until it is at the temperature of the regenerant 5.8 Safety Considerations Safety considerations in the use of ion exchange systems include nderstanding the reactions which will take place during the contact of resin and solution being treated. The possibility of reactions being catalyzed in the presence of the hydrogen form of a strong acid cation or of the hydroxide form of the strong anion must be studied. These resins produce acid or base, respectively, during treatment of salt solutions If reactants or products of the ion exchange reaction are hazardous appropriate protective equipment should be included in the system design For example, during the demineralization of metal cyanide by-products, hydrogen cyanide solution is an intermediate formed in the cation exchange unit. The processing equipment must be designed to ensure containment of this solution until it has passed through the anion exchange unit which picks up the cyanide ions
Ion Exchange 441 Table 17. Oxidation of Polystyrene and Polylamine Resins in a One-Week Accelerated Test at 90°C[831 Polystyrene Polystyrene Polystyrene Polydiallylamine Polydiallylarnine Polydiallylamine Initial Base R-CHzN(CH3)z 4.4 R-CH~N(CHZCH~)~ 4.5 R-CH~N(CZH~OH)~ 3.6 N-H 8.3 N-CHzCHs 7.3 N-CaH7 6.7 Base Capacity Lost 1 2 17 37 37 31 As would be expected, the combination ofthermal and osmotic shocks has been shown to have a large effect on the osmotic strength of anion resins.[85] This is illustrated in Fig. 27, where the decrease is shown to be over 15% in just 150 cycles. The important processing point to remember from this is that if the regeneration of a resin is performed at a temperature more than 2OoC different from the temperature of the operating (loading) stream, it is advisable first to adjust the temperature of the resin with distilled water until it is at the temperature of the regenerant. 5.8 Safety Considerations Safety considerations in the use of ion exchange systems include understanding the reactions which will take place during the contact of resin and solution being treated. The possibility of reactions being catalyzed in the presence ofthe hydrogen form of a strong acid cation or of the hydroxide form of the strong anion must be studied. These resins produce acid or base, respectively, during treatment of salt solutions. If reactants or products of the ion exchange reaction are hazardous, appropriate protective equipment should be included in the system design. For example, during the demineralization of metal cyanide by-products, hydrogen cyanide solution is an intermediate formed in the cation exchange unit. The processing equipment must be designed to ensure containment of this solution until it has passed through the anion exchange unit which picks up the cyanide ions
442 Fermentation and Biochemical engineering handbook 1.5 DowE /sd 1,4 1.3 12 1.4 WOFATIT Ro 1.3 1,2 1,1 ME圳40 1.1 1,0 1.6 LEWATIT H500 XR-Ow 80160240320400480 № MBER OF CYCLES Figure 26. Dependence of the strong base capacity on the number of cycles between 20%C and80°Cs4
442 Fermentation and Biochemical Engineering Handbook I I I I I WIW AI 1.3 I I I I Figure 26. Dependence of the strong base capacity on the number of cycles between 20°C and 80°C.[841