Preparation of Na specific absorbent and application of sodium removal from ammonium tungstate solution
(1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
2. Hunan Key Laboratory for Metallurgy and Material Processing of Rare Metals, Changsha 410083, China)
2. Hunan Key Laboratory for Metallurgy and Material Processing of Rare Metals, Changsha 410083, China)
Abstract: An adsorbent, Na1.6Al0.6Ti1.4(PO4)3 (or NATP), was prepared by controlled crystallization of glasses in the Na2O-Al2O3- CaO-TiO2-P2O5 system. The crystalline phases characterized by X-ray diffraction (XRD) show that the sample glasses crystallizes into two phases, i.e. NATP and Ca9Al(PO4)7, while the Ca9Al(PO4)7 phase can be leached selectively with HCl, leaving a massive number of pores in the material. Through the experimental research, the effects of contact time, solution pH, and the initial concentration of Na+ on the cation exchange properties were investigated. The batch sorption kinetics and equilibria can be described by Pseudo-second-order kinetic equations and Langmuir isotherm equations respectively. Furthermore, the experiments with an industrial solution show that the removal rate of sodium from industrial (NH4)2WO4 is higher than 97%. Cycle experiment also shows that the NATP has a good cyclic performance.
Key words: Na specific adsorbent; sodium removal; ammonium tungstate; purification