Rationally designed functional macroporous materials as new adsorbents for efficient phosphorus removal

Novel phosphorus (P) adsorbents with a high adsorption capacity (up to 2.272 mmol g ^-1) and excellent adsorption performance in a low P concentration range of 1 mg L ^-1 have been successfully developed. The material achieves up to 96% P removal within 30 min with an initial concentration of 1 mg L ^-1. The adsorbents are prepared using macroporous ordered silica foams (MOSF) as the host. After modification by lanthanum species (La-MOSF), the two sides of the silica layer (∼5 nm in thickness) are coated by two layers of lanthanum oxide each with a thickness of ∼2.3 nm, forming a unique sandwich-like wall structure. Due to the very large pore size of La-MOSF (∼100 nm), after P adsorption the formed LaPO ₄ species are confined inside the pores without causing pore blocking, allowing for a high loading of lanthanum oxide and a high adsorption capacity. Moreover, the thin layer nature of lanthanum oxide facilitates the reaction between lanthanum oxide and phosphate ions, leading to the enhanced performance for the adsorption in low P concentration ranges. These rationally designed macroporous materials with outstanding performance have great potentials in water quality control and protection.