Efficient removal of phosphate through adsorption by acidified diatomite loaded with La2O2CO3

Phosphorus removal from wastewater is vital to mitigate the eutrophication of receiving waters. In this work, acidified diatomite (AD) was loaded with lanthanum carbonate (La2O2CO3) by a solvothermal method to prepare a series of composites, La2O2CO3@AD, which were used to adsorb phosphate. The La2O2CO3@AD materials have ordered structures and rich functional groups as verified by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, energy spectrum analysis (EDS), and scanning electron microscopy (SEM). Then, all La2O2CO3@AD were used as adsorbents for fast and efficient removal of phosphate from aqueous solution by batch equilibrium experiments. The experimental results demonstrate that the phosphate adsorption of La2O2CO3@AD is pH dependent, and completed within 360 min. The adsorption kinetics and isotherm data follow the pseudo-second-order equation and the Freundlich model, respectively. The adsorption mechanisms of phosphate are ascribed to the chemical bond force and ligand exchange.