Quaternary Ammonium Salts Immobilized on Silica Gel: Exchange Properties and Application as Potentiometric Sensor for Perchlorate Ions.

Ammonium chlorides immobilized on silica gel, SA(+)/Cl(-) and SE(+)/Cl(-), were obtained from silica previously modified with 3-aminopropyltriethoxysilane and N-[3-(trimethoxysilyl)-propyl]ethylenediamine, respectively. Both materials showed potential use as an anion exchanger: they are thermically stable (up to 413 K), achieve equilibrium rapidly in the presence of suitable exchanger ions, and are easily recovered. The exchange capacities observed for SA(+)/Cl(-) and SE(+)/Cl(-) are 0.