(377p) Study of Lanthanum Carbonate Modified Microfibrous Composite for Phosphate Adsorption in Wastewater

In this study, a novel lanthanum carbonate modified microfirous composite (LC-MC) adsorbent is synthesized for phosphate adsorption in wastewater. Box-Behnken design method is used to optimize the parameters of preparation process and a linear model is demonstrated to describe the relationship between adsorption capacity and preparation parameters. It was predicted that under conditions of 0.19 mg/L initial La concentration, 93.13 molar ratio of urea and La and 20.92 h synthesis time, the best adsorption capacity is 54.63 mg/g, similar to the actual value (55.2 mg/g). The phosphate adsorption experiments on LC-MC in batch reactor show that 6-9 is the best pH range for phosphate adsorption with low La leakage, and ionic strength has no obvious effect on the performance of LC-MC. The adsorption isotherm data are fitted well by Freundlich isotherm and the adsorption kinetic data are described well with the pseudo-second order model, and the adsorption achieves equilibrium at about 300 min. The adsorption can be divided into three steps according to Intraparticle diffusion model, including intra-particle diffusion, surface film diffusion and equilibrium. The presence of co-existing anions has little effect on the removal. The LC-MC exhibited an ideal regeneration performance in phosphate adsorption with 80% adsorption capacity remained after 5 cycles. Finally, the adsorption mechanism indicates that electrostatic attraction and ligand exchange are both involved in the phosphate adsorption process.