Preparation of the Lanthanum-Aluminum-Amended Attapulgite Composite as a Novel Inactivation Material to Immobilize Phosphorus in Lake Sediment

摘要

In this study, a green solvent-free drying production method was used to prepare an attapulgite clay/lanthanum and aluminum (ACLA) composite as a novel phosphorus (P) sorbent to immobilize P in lake sediment. The prepared sorbent contained around 5% La and 2% Al. The maximum P sorption capacity of ACLA can reach as high as 34.6 mg P/g and is higher than most clay-based P sorbents. The addition of ACLA into sediment can effectively reduce sediment mobile P and simultaneously induce elevated inert P forms of HCI-P and NaOH-rP, which also can increase the stability of P in sediment. Long-term sediment core incubation indicated that 72.2% of total phosphorus and 90.7% of soluble reactive phosphate (SRP), as well as 44.2% SRP fluxes, can be reduced with a dosage of 466 mg/m~2 of ACLA when compared with the control treatment. The P binding mechanism by ACLA is assigned to the intersphere P complexes and is mainly because of the formation of rhabdophane and aluminum phosphate precipitation on ACLA. This is confirmed by results of the XPS and P NMR spectroscopy, which indicate that the La/Al coexisting novel P inactivation agents are a promising sorbent for lake sediment P control.