Zirconium phosphate dispersed on a cellulose fiber surface:: Preparation, characterization, and selective adsorption of Li+, Na+, and K+ from aqueous solution

Highly dispersed zirconium phosphate was prepared by reacting Cel/ZrO2 (ZrO2 = 6.7 wt%; 0.56 mmol g(-1) of zirconium atom per gram of the material) with phosphoric acid. High power decoupling magic angle spinning (HPDEC-MAS) P-31 NMR and X-ray photoelectron spectroscopy data indicated that HPO42- is the species present on the fiber surface. The X-ray diffraction patterns showed that zirconium hydrogen phosphate particles were amorphous and bad an ion-exchange capacity, determined by ammonia gas adsorption, of 0.30 mmol g(-1). The ion-exchange capacities for Li+. Na+, and K+ ions were determined from ion-exchange isotherms at 298 K and showed the following values (in mmol g-1): Li+ = 0.01, Na+ = 0.23, and K+ = 0.30. The higher affinity of the surface hydrogen phosphate particles for Na+ and K+ is due to its lamelar structure which permits easier diffusion of these two ions whose hydrated radii are smaller than that of Li+. (C) 2002 Elsevier Science (USA).