VSC Sorption onto Mg-Fe-F Layered Double Hydroxide and its Fluoride Release in Aqueous Solution

Abstract

Etiology of halitosis is often concerned with gram-negative anaerobic bacteria, which produce the malodorous compounds such as volatile sulfur compounds (VSC), hydrogen sulfide and methyl mercaptan. The absorbents for the malodorous compounds are expected to prevent the teeth from decaying and peiodontics disease. The VSC adsorption capabilities of layered double hydroxides, of which composition is A 1-x B x (OH) 2 C x/n ·mH 2 O, where A and B are Mg and Fe ions, and C are carbonate (CO 3 2- : MgFe LDH CO 3 ) and fluorine (F - : MgFe LDH F) ions in aqueous medium was studied by GC/FPD. The concentration of H 2 S rapidly decreased for first 1 hours of soaking in H 2 S water and fell to 0% in 4-5 h when MgFe LDH CO 3 was applied. MgFe LDH F was used, then the H 2 S concentration was quickly decreased the same as MgFe LDH CO 3 , and 8 mg/l of fluorine was released at a time. The iron ion was not detected in the H 2 S water after soaking for 18 hours. The MgFe LDHF are expected to be likely adsorbent for the fast removal of VSC from the mouth and fluorine releasing agent.