Determination of trace level carbonate ion in Mg–Al layered double hydroxide: Its significance on the anion exchange behaviour

The presence of trace level (<1 ppm) carbonate ion in the interlayer space of MgAl-LDH has been estimated by ion chromatography technique using a novel inverse chemical suppression method using 0.5 mM H2SO4 as mobile phase and 25 mM LiCl as regenerating solution. The presence of carbonate ion in the LDH structure was found to affect the anion exchange capacity of MgAl-LDH. This has been illustrated by carrying out anion exchange of nitrate ion in the MgAl-LDH structure with chloride ion. The importance of this simple but accurate technique for the carbonate ion estimation is demonstrated and reported in this communication.