Development of lanthanum hydroxide loaded on molecular sieve adsorbent and mechanistic study for phosphate removal.

Abstract A novel and highly effective adsorbent LHMS (lanthanum hydroxide loaded on molecular sieve) for phosphate (PO 4) removal was investigated for the first time, possessing huge surface area (582.9836 m2 g−1) and adsorption capacity (12.2158 mg g−1) under the circumstance of pH = 5 and 5 mg L−1 phosphorus solution. Adsorption capacity of the adsorbent showed up the increasing trend with the increase of La contents after mixing Ce, and decreased with the elevation of temperature. The adsorption process followed the pseudo-second-order kinetic model and Freundlich, as well as Termkin, isotherm model, indicative of the existence of chemisorption and strong intermolecular interactions (i.e. ligand exchange). The strong binding between La and phosphate (LaPO 4) could not be readily substituted by most anions and humic acid. The potential mechanism for the adsorption process by LHMS was explained based on the SEM-EDS, XRD, XPS, FTIR, and NMR analysis. Furthermore, the formation of LaPO 4 on account of ligand exchange reaction was considered to be the primary pathway for selective adsorption by the immobilized La(OH) 3. The above findings displayed that LHMS was deemed to be the promising adsorbent, efficiently removing PO 4 from real wastewater, and it would open the new avenues for the application of adsorbents in the field of wastewater treatment. Graphical abstract Image 1 Highlights • LHMS was the first La-based adsorbent composed of available molecular sieve. • Compared with Ce, loading La on MS was better adsorbent for PO 4 removal. • LaPO 4 was the main pathway by ligand exchange based on systematic characterizations. • LHMS has been proved to possess the practical application in real wastewater treatment. [ABSTRACT FROM AUTHOR]