Stability of Calcium Deficient Hydroxyapatite/Clay Mineral Nanocomposite in Solutions with Different pH

Gaseous Heptanethiol Removal by a Fe3+-Phenanthroline-Kaolinite Hybrid Material

Kaolinite functionalized by the μ-oxo Fe³⁺-phenanthroline complex (Fe⁺³Phen) was selected to test its ability to efficiently remove and store gaseous heptanethiol (HPT). Spectroscopic techniques, elemental analysis, and thermal analysis coupled with evolved gas mass spectrometry were employed to characterize the material before and after the exposure to the gas and to define the adsorption process. The amount of HPT trapped by the functionalized kaolinite after 60 days is 0.10940 moles per 100 g of kaolinite which, considering the amount of adsorbed Fe⁺³Phen (0.00114 moles per 100 g of kaolinite), means a thiol/Fe³⁺Phen molar ratio of about 100:1, a value much higher than those found in the past for Fe⁺³Phen functionalized montmorillonite and sepiolite. In addition, the process was found to be efficient also beyond 60 days. This significant removal of the smelly gas was explained by considering a continuous catalytic activity of Fe³⁺ toward the oxidation of thiol to disulfide.