Green synthesis of CaLaMnO with modulation of mesoporous and vacancies for efficient low concentration phosphate adsorption.

Phosphate concentrations in eutrophic surface waters are usually low, and efficient removal of low concentration phosphate remains a challenge. In this study, Ca-doped LaMnO synthesized at doping ratios, designated as CaLaMnO (x = 0, 0.2, 0.4, 0.7), were compared. It was found that, the adsorption capacity of CaLaMnO material reached 63.01 mg/g at pH = 5, increased by 63.6% over the undoped LaMnO perovskite. For long-term adsorption, CaLaMnO could constantly adsorb phosphate to avoid phosphate accumulation (<0.05 mg/L). This proves that CaLaMnO has the ability to control dynamic water eutrophication. Characterization and density functional theory results confirmed that CaLaMnO can increase the content of mesopores and oxygen vacancies, providing additional active sites. This reduces the adsorption energy of the La site, promotes electron transfer, and increases its affinity. It provides a new method for removing low-concentration phosphates.