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

作者:Yuan, Ling; Qiu, Zhaofu*; Lu, Yunqing; Tariq, Muhammad; Yuan, Lin; Yang, Ji; Li, Zhen; Lyu, Shuguang
来源:Journal of Alloys and Compounds, 2018, 768: 953-961.
DOI:10.1016/j.jallcom.2018.07.230

摘要

A novel and highly effective adsorbent LHMS (lanthanum hydroxide loaded on molecular sieve) for phosphate (PO4) removal was investigated for the first time, possessing huge surface area (582.9836 m(2) 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 (LaPO4) 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 LaPO4 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 PO4 from real wastewater, and it would open the new avenues for the application of adsorbents in the field of wastewater treatment.