Lanthanum chloride/eggshells modified diatomite for phosphorus recovery: Advanced performance and mechanisms study

In this study, a composite material (La/ES(m:n)-DE) was prepared by synchronously modifying diatomite with microwave irradiation and varying mass ratios of LaCl3.6 H2O and eggshells. La/ES(m:n)-DE was employed for efficient phosphorous recovery from water and utilized directly as a phosphate fertilizer. The results of adsorption isotherms indicate that the synthesized La/ES(m:n)-DE process for phosphorus recovery aligns more closely with the Langmuir model, with La/ES(7:3)-DE exhibiting the highest phosphorus recovery ability (98.79 mg P/g). Furthermore, the kinetic behavior of phosphorus recovery in the synthesized La/ES(m:n)-DE composite material conforms more closely to the pseudo-second-order kinetic model. The synthesized La/ES(7:3)-DE demonstrates outstanding phosphorus recovery performance in water with an initial pH ranging from 5.0 to 9.0. Apart from carbonate ions, common coexisting ions in water scarcely affect the phosphorus recovery efficiency of the synthesized La/ES(7:3)-DE. Most importantly, this synthesized composite material holds the potential to efficiently recover phosphorus from real water bodies. The synthesized La/ES(7:3)-DE primarily recovers phosphorus from water via electrostatic attraction, complexation and ligand exchange mechanisms. This composite material efficiently recovers phosphorus from water and can be directly utilized as a phosphate fertilizer, aiding in lettuce seed germination and seedling growth.