Resins strong acid

Weakly acidic resins are used primarily for softening and dealkalization, frequently in conjunction with a strongly acidic polishing resin. Systems which use both resins profit from the regeneration economy of the weakly acidic resin and produce treated water of quality comparable to that available with a strongly acidic resin. 

Resins currently available exhibit a range of selectivity s and thus have broad application. As an example, for a strong acid resin, the relative preference for divalent calcium ions (Ca ) over divalent copper ions (Cu ) is approximately 1.5... 

Strong acid resins are so named because their chemical behavior is similar to that of a strong acid. The resins are highly ionized in both the acid (R-SOjH) and salt (R-SOjNa) form. They can convert a metal salt to the corresponding acid by the reaction ... 

Like strong acid resins, strong base resins are highly ionized and can be used over the entire pH range. These resins are used in the hydroxide (OH) form for water deionization. They will react with anions in solution and can convert an acid solution to pure water ... 

In an ion exchange wastewater deionization unit, the wastewater would pass first through a bed of strong acid resin. Replacement of the metal cations (Ni. Cu ) With hydrogen ions would lower the solution pH. The anions (S04. Cl ) can then be removed with a weak base resin because the entering wastewater will normally be acidic and weak base resins sorb acids. Weak base resins are preferred over strong base resins because they require less regenerant chemical. A reaction between the resin in the free base form and HCl would proceed as follows ... 

Approximate selectivity coefficients for the exchange of various cations for lithium ions on a sulphonated polystyrene, a typically strong acid resin, are given in Table 18.1. The values are relative to Li = 1.0. The selectivity coefficient between two ions is the ratio of their selectivities relative to lithium. Hence, for a sodium-hydrogen exchange ... 

Table 18.1. Selectivities on 8 per cent cross-linked strong acid resin for cations. Values are relative to lithium1-3 1...

An acid solution containing 2 per cent by mass of NaN03 and an unknown concentration of HNO3 is used to regenerate a strong acid resin. After sufficient acid had been passed over the resin for equilibrium to be attained, analysis showed that 10 per cent of resin sites were occupied by sodium ions. What was the concentration of HNO3 in the solution, if its density were 1030 kg/m3. 

Weak acid cation resins Here, the ionic group is a carboxylic acid (—COOH) and these resins behave as if they were weak organic acids. They have a much higher affinity than strong acid resins for hydrogen ions. Therefore, fewer amounts of acids are required in... 

The present study demonstrates suitability of sulphated zirconia for dehydration of carboxamides. It needs to be emphasised that the common inorganic acid catalysts are not sufficiently acidic to catalyst the reaction below 400°C while the strongly acidic resin catalysts are not structurally stable at temperature at which the reaction would occur at appreciable rate. Thus the sulphated zirconia appears to be a unique catalyst for this application. 

Resins with cation-exchange functionality are available either as strongly or weakly acidic ion exchangers. The strong-acid resins have sulfonic acid (—S03H) functional groups, whereas the... 

Table 3 Relative Affinities of Various Ions for the Strong-acid Resin Duolite 020 ...

Separator column strong base anion exchange resin suppressor column strong acid resin in hydrogen form eluting solvent 0.005 M sodium borate. 

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