Immobilization of pyrazole compounds on silica gels and their preliminary use in metal ion extraction

A series of acyclic pyrazole derivatives was prepared by condensation reactions. These compounds were covalently immobilized on silica gel through a flexible 3-glycidoxypropyltrimethoxysilane spacer arm. These materials were used as sorbents for the recovery of heavy and alkali metal ions from aqueous solutions. They exhibit good selectivity between heavy metal ions and alkali ions with an affinity especially high towards mercury. The comparison with liquid-liquid extraction shows that the capacity is not affected by the grafting of the pyrazole rings on the surface of silica. In addition, the solid-liquid process is more convenient in terms of facility of use.