Functionalized mesoporous materials for phosphate removal with high efficiency and minimized sludge treatment or disposal problems have been developed. Biocompatible lanthanum adsorbents were loaded into a mesoporous silica SBA-15 which can be transformed to LaPO₄ species with very low K_sp. La species were immobilized in the mesopores of La-SBA-15 by controlling the calcination temperature to avoid the leaching of functional component. By adjusting the pore size of the mesoporous support to control the nucleation and growth site, the phosphates can diffuse into the pore channels and react with La species. The nucleation of LaPO₄ species takes place inside the pore and they further grow from inside to the outside of the pore channels, thus the phosphates can be adsorbed in the adsorbent. The designed nanoporous material has the highest phosphate removal capacity compared to literature reports and commercial products, which can prevent the excessive growth of blue green algae and thus have great potential in water body quality control and protection.