Preferable uptake of phosphate by hydrous zirconium oxide nanoparticles embedded in quaternary-ammonium Chinese reed

Phosphate capture from aqueous was conducted using hydrous zirconium oxide (HZO) embedded in quaternary-ammonium Chinese reed (CR-N⁺-HZO), and the characteristics of adsorbent was determined. HZO was dispersed as nanoparticles or nano-clusters on the external or inside the networking pores of CR-N⁺-HZO. The surface of CR-N⁺-HZO was heterogeneous with multiple adsorption sites, HZO nanocomposite and N⁺(CH₂CH₃)₃Cl^-, which both contributed to the adsorption process. The phosphate uptake by CR-N⁺-HZO was optimal at pH 3.0 and phosphate uptake by HZO nanocomposite was greatly inhibited at alkaline pH. Kinetics studies suggested that both the intra-particle mass-transfer and external resistances were likely to be the rate controlling steps. The Q_max (maximum adsorption capacity) of phosphate uptake by CR-N⁺-HZO and CR-N⁺ (30°C) calculated based on Langmuir model was about 59.2mg(P)/g(CR-N⁺-HZO) and 30.4mg(P)/g(CR-N⁺). A high usage efficiency of Zr in CR-N⁺-HZO was observed with calculated molar ratio of P/Zr to be 3.07.