Preparation and characterization of lanthanum(III) loaded granular ceramic for phosphorus adsorption from aqueous solution

A La(III)-loaded granular ceramic adsorbent, consisting mainly of different forms of metal oxide minerals, was developed for phosphorus removal from aqueous solution. Batch experiments were performed to investigate the effects of various experimental parameters, such as contact time (3–48 h), initial phosphorus concentration (5–25 mg/L), pH (2.0–12.0), temperature (20, 30 and 40 °C) and anions on phosphorus adsorption. The adsorption process was well described by a pseudo-second-order kinetic model and equilibrium was achieved at 30 h. The adsorption data closely fitted the Langmuir isotherm model at temperatures ranging from 20 °C to 40 °C. Thermodynamic study indicated a spontaneous, favorable and exothermic adsorption on the La(III)-loaded granular ceramic adsorbent. The optimum pH for phosphorus removal ranged from 7.0 to 9.0. Phosphorus adsorption was impeded by the presence of F−, followed by Cl−, SO42− and NO3− and the adsorption process appeared to be controlled by a chemical precipitation process. The mechanism may involve ion complexation during subsequent adsorption of phosphorus on lanthanum hydroxides.

► The novel La(III)-loaded granular ceramic adsorbents were prepared. ► Maximum adsorption of phosphate was achieved within the pH range 7.0–9.0. ► Adsorption process followed the pseudo-second-order kinetic model. ► Adsorption mechanism was investigated and assumed.