Efficient phosphate removal and recovery by using nanosized La(III) oxides anchored on aminated biomass waste

Abstract

Selective adsorption provides a promising solution for removing and recovering phosphate from contaminated waters. However, the development of an efficient, low-cost adsorbent with high adsorption selectivity for phosphate is still an important challenge. Here, a novel nanocomposite (SP-AE-La) was fabricated by anchoring La(III) oxide nanoparticles within a quaternary-aminated biomass waste, i.e., shaddock peel (SP-AE). The batch adsorption experiments suggested that SP-AE-La exhibited a high capacity for phosphate removal through the electrostatic attraction of quaternary ammonium groups and inner-sphere complexation of La(III) oxides; SP-AE-La could effectively and rapidly sequester phosphate over a wide range of pH values (3–10). Moreover, the nanocomposite exhibited significant selectivity for phosphate removal even in the presence of competitive anions (Cl-, SO42-) at high concentrations. The fixed-bed adsorption tests indicated that the treatable volume of the as-prepared nanocomposite was up to 2000 BV when the breakthrough point was set as 0.5 mg/L. Furthermore, the exhausted nanocomposite can be effectively regenerated by NaOH-NaCl solution for recycling use. All the results indicated that SP-AE-La nanocomposite can serve as a promising adsorbent for phosphate removal in a realistic application.