Exchange equilibria on anion resins, 2. Effect of chemical structure of functional groups in macroporous polystyrene resins

Anion exchange equilibria were studied by the batch technique on macroporous polystyrene resins with the following functional groups: {article}{empty}{document}$ - { N}^ + { H}₂ { CH}₃ ({ M),} - { N}^ + { H(CH}₃ )_2 ({ DE),} - { N}^ + { (CH}₃ )_3 ({ TM),} - { N}^ + { H}₂ { CH}₂ { CH}₂ { OH (E),} - { N}^ + { H}₂ { (CH}₂ { CH}₂ { OH)}₂ ({ DE),} - { N}^ + { (CH}₂ { CH}₂ { OH)}₃ ({ TE),} - { N}^ + { CH}₃ { (CH}₂ { CH}₂ { OH)}₂ ({ MDE), and} - { N}^ + { (CH}₃ { )}₂ { CH}₂ { CH}₂ { OH (DME)}${document} . The selectivity order for these groups in slightly acidic, dilute solutions for the following anion systems: Br−/Cl−, I−/Cl−, and ClO4−/Cl− was found to be TM > DME > MDE > TE > DM > M > DE > E, but it was entirely reversed in the case of F−/Cl− system. These results are discussed in view of some known theories of ion exchange selectivity. It seems that the experimental data can be best explained in terms of the Chu‐Diamond‐Whitney theory which takes into consideration mainly changes of the water structure caused by counter‐ions, co‐ions, and functional groups of the ion exchanger.