Calorimetric Approach for the Detection of Modified Silica Efficiency as Chelating Agent for Heavy Metal Ions

Chelating molecules with carboxyhydrazide functional group was immobilised on silica surface. The functional group was covalently bonded to the silica surface by sequential reactions of silica with dibromobutane, malonic ester and hydrazine in different media. The grafting reaction was confirmed by elemental analyses and thermal stability analysis (TGA). The flow microcalorimeter (FMC) was used as an approach to assess the performance of modified silica sorbent toward heavy metal ions. The FMC results show that this modification enhances remarkably the silica ability to retain a series of heavy metal ions on its surface. The selectivity of adsorption on modified silica was determined and the strength of the chemical bonding between metal ions and modified silica was quantified.