Lanthanum-modified magnetic oyster shell and its use for enhancing phosphate removal from water

A lanthanum-modified magnetic oyster shell (La-Fe-OSP) was prepared by magnetization and lanthanum loading, and then its properties and phosphorus removal capability were studied. The results showed that La-FeOSP was magnetic, and the specific surface area and porosity increased remarkably compared with those before modification. La-Fe-OSP achieved a removal rate greater than 90% for various phosphate solutions (10-100 mg L-1) and could be successfully recycled by applying a magnetic field. The phosphorus adsorption process of La-Fe-OSP could be characterized by a pseudo-second order model and Langmuir model and displayed intraparticle diffusion properties. La-Fe-OSP could maintain the novel adsorption performance within the pH range of 3.0-8.0, and its adsorption capability was negligibly affected by coexisting ions and dissolved organic matter (DOM) in water. Moreover, the maximum phosphorus removal rates of La-Fe-OSP for the overlying water and the pore water were 96.4% and 41%, respectively. In addition, La-Fe-OSP application also slightly changed the order of various phosphorus forms in sediment and promoted the transformation of easily released iron-bound P (Fe-P) to hardly released occluded P (Oc-P). After five successive cycles, La-Fe-OSP still obtained 85.1% phosphate removal efficiency and thus showed excellent application prospects.

Automated summary

The lanthanum-modified magnetic oyster shell (La-Fe-OSP) exhibited high phosphorus removal efficiency, successful recyclability, and excellent adsorption performance under various conditions, making it a promising new type of phosphorus adsorbent with broad application prospects.