Contrasting effect of zirconium-, iron-, and zirconium/iron-modified attapulgites capping and amendment on phosphorus mobilization in sediment

Environ Sci Pollut Res Int. 2021 Oct 24. doi: 10.1007/s11356-021-16979-5. Online ahead of print.ABSTRACTIn this research, the sorption characteristics and mechanism of phosphate on zirconium-modified attapulgite (Zr-ATP), iron-modified attapulgite (Fe-ATP), and zirconium/iron co-modified attapulgite (Zr/Fe-ATP) prepared by a simple impregnation method were studied, and the impacts of Zr-ATP, Fe-ATP, and Zr/Fe-ATP amendment and capping on the migration of phosphorus (P) from sediments to overlying waters were investigated. The results showed that Zr-ATP and Zr/Fe-ATP possessed stronger adsorption ability for phosphate in aqueous solution than Fe-ATP. The ligand replacement of the hydroxyl group with the phosphate anion to form the inner-sphere phosphate complex played a crucial role in the adsorption process of phosphate on Zr-ATP, Fe-ATP, and Zr/Fe-ATP. Most of the phosphate ions bound by Zr-ATP and Zr/Fe-ATP were in the form of caustic soda solution-extractable inorganic P (NaOH-IP) and residual P (Res-P), and it is hard for these P species to be re-released into water under the circumstances of reducing environment and normal pH (5-9). The ratio of mobile P to total P of Fe-ATP loaded with phosphate was much higher than those of Zr-ATP and Zr/Fe-ATP loaded with phosphate, indicating that Fe-ATP-bound phosphate has a higher re-releasing risk than Zr-ATP-bound and Zr/Fe-ATP-bound phosphate. Zr-ATP, Fe-ATP, and Zr/Fe-ATP amendment all can reduce the releasing risk of P from se...
Source: Environmental Science and Pollution Research International - Category: Environmental Health Authors: Source Type: research