Abstract: Poly-Phosphate (Poly-P) is a group of very important inorganic phosphates, which exists widely in natural systems. Studying of the transport and transformation of Poly-P is critically essential to understand the biogeochemical cycling of phosphorus. Sorption reactions at mineral-solution interface control the transport and transformation of elements. In this research, the widely distributed hydrated alumina, Boehmite, was selected as the adsorbent to explore the behavior and mechanism of Poly-P sorption, as a function of initial P concentration and pH. Under the experimental conditions, the amounts of the sorbed Poly-P increase with P
concentration, whereas decrease with increasing pH. To further understand the mechanisms, we adopted several technologies, such as XRD, SEM and ³¹P solid-state NMR to characterize our samples. The results of 31P solid-state NMR indicate the occurrence of both adsorption and hydrolysis. The P-O-P bond in the middle of the long chain was randomly broken, generating short-chain Poly-P and orthophosphate, both of which were adsorbed as inner-sphere complexes on the surface of Boehmite.

Key words: Poly-Phosphate, Boehmite, solid-state NMR, adsorption