A POSS-Phosphazene Based Porous Material for Adsorption of Metal Ions from Water.

The development of adsorptive materials continues to be an important area of research for removal of heavy metal ions from waste water. The adsorption capacity can be modulated by both physical and chemical modification of the adsorbent. Herein, we combine the unique properties of polyhedral oligomeric silsesquioxane (POSS) and organocyclophosphazene as the building units to synthesize a hybrid porous material, abbreviated as PN-POSS. The synthetic method follows a Heck reaction between hexa(4-bromophenoxy)cyclotriphosphazene and octavinylsilsesquioxane (OVS). The Brunauer-Emmett-Teller (BET) analysis shows that the material possesses micro- and mesopores of 1.5 and 3.8 nm size and a surface area on the order of 500 m2  g-1 . These attributes in combination with the donor ability of the phosphazene units qualify the material for high adsorption of Pb2+ , Hg2+ and Cu2+ ions with maximal adsorption capacities on the order of 1326, 1927 and 2654 mg g-1 , respectively. The adsorbent exhibits a good regeneration performance and can be effectively used for water treatment.