Methylammonium cation exchange

Thermal Decomposition Patterns in Methylammonium Cation-Exchanged Y-Type Faujasites... 

The separation of the same charged compounds were also accomplished on an ethyl-pyridine bonded silica surface and 30 0% methanol/C02 mobile phases without the need of added sulfonate modifier. Anionic compounds did not elute from the ethyl-pyridinium surface that lead the authors to hypothesize that the surface was positively charged. To further test this hypothesis, the separation of the same compounds on a strong anion exchange column, silica-based propyltri-methylammonium cationic surface, which exhibits are permanent positive charge was attempted. The same retention order was observed on the strong cation exchange surface. 

Methylammonium Ion Exchange. The observed extent of exchange (70%) of MM A cations was to be expected since 16 of the Na cations (31% ) initially present are located in the small-pore system (23), into which these MA cations cannot pass. Bulkiness of the cations further limits the number of Na cations that can be replaced (2) in the large-pore system, decreasing with increase in size of the MA ion. The degree of exchange of various MA cations in this study agrees with earlier results (2,26). 

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