Effect of magnetic iron-zirconium modified zeolite on the different phosphorus forms in river sediment under aerobic and anoxic condition

In this study, a magnetic iron-zirconium modified zeolite (FeZrMZ) was synthesized. Through sediment culture experiments, the influence of the addition of modified materials on the migration and transformation of phosphorus in river sediments was investigated. The results show that the modified zeolite can not only effectively reduce the phosphorus concentration in the overlying water, but also significantly reduce the phosphorus concentration in the pore water of sediments. The addition of modified zeolite makes the unstable weakly adsorbed phosphorus (NH4Cl-P) and redox phosphorus (BD-P) transform into the more stable metal oxide bound phosphorus (NaOH-P) and very stable residual phosphorus (Res-P).The four types of bioavailable phosphorus (BAP), including water-soluble phosphorus (WSP), readily desorbable phosphorus (RDP), algae-available phosphorus (AAP), and NaHCO3 extractable phosphorus (Olsen-P). Under anoxic conditions, they were reduced by 53.5%, 14.1%, 23.8%, and 49.9% respectively. Under aerobic conditions, they were reduced by 23.2%, 16.6%, 32.1%, and 50.0%. Obviously, the addition of magnetic iron-zirconium modified zeolite can reduce the release potential of phosphorus in sediment, and it can be recovered through the action of an external magnetic field, so it can be used as an effective sediment modifier to control the sediment the release of phosphorus.