Phosphorus adsorption onto an industrial acidified laterite by-product: equilibrium and thermodynamic investigation

International audienceThe present research investigates the uptake of phosphate ions from aqueous solutions using acidified laterite (ALS), a by-product from the production of ferric aluminium sulfate using laterite. Phosphate adsorption experiments were performed in batch systems to determine the amount of phosphate adsorbed as a function of solution pH, adsorbent dosage and thermodynamic parameters per fixed P concentration. Kinetic studies were also carried out to study the effect of adsorbent particle sizes. The maximum removal capacity of ALS observed at pH5 was 3.68mg Pg(-1). It was found that as the adsorbent dosage increases, the equilibrium pH decreases, so an adsorbent dosage of 1.0gL(-1) of ALS was selected. Adsorption capacity (q(m)) calculated from the Langmuir isotherm was found to be 2.73mgg(-1). Kinetic experimental data were mathematically well described using the pseudo first-order model over the full range of the adsorbent particle size. The adsorption reactions were endothermic, and the process of adsorption was favoured at high temperature; the G and H values implied that the main adsorption mechanism of P onto ALS is physisorption. The desorption studies indicated the need to consider a NaOH 0.1M solution as an optimal solution for practical regeneration applications. (c) 2014 Curtin University of Technology and John Wiley & Sons, Ltd