Adsorption performance and mechanism for phosphate removal by cerium hydroxide loaded on molecular sieve

Abstract

Abstract Cerium hydroxide loaded on molecular sieve (CHMS) was investigated for phosphate (PO4) adsorption. As the initial phosphorus concentration was set as 5 mg L−1, CHMS possessed high PO4 adsorption capacity at 25 °C compared with COMS (ceria loaded on molecular sieve) and MS (molecular sieve), and can be extensively applied in wide pH range (4–11). Based on kinetics and isotherms analysis, the adsorption process was mainly chemisorption and multilayer adsorption procedure. In addition, most of the coexisting ions had little effect on PO4 adsorption, in spite of 2 orders of magnitude higher levels than PO4. CHMS showed the excellent regeneration (at least 5 times recycling) ability with 1 M NaOH. The proposed mechanisms were explicated by various analytical techniques XRD, TG, XPS, and NMR analysis and found that Ce(HPO4)2 and Ce3(PO4)4 were the main pathways after adsorption, and the activated site of adsorbent was dependent on the presence of cerium hydroxide. Consequently, CHMS was a promising adsorbent for PO4 removal from wastewater.