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

Abstract

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.