Study On The Characteristics And Application Of High Performance Ammonium Removal Material Prepared From Midified Kaolin

This paper is the further research based on the precious work. The research studied on optimizing the pre-existing methods of prilling the modified kaolin to obtain the high performance ammonium removal material. Then the performance of removing ammonium, the regenerated method of the material and the isotherm, thermodynamics, kinetics of the ammnoium removal process were mainly studied.In the experiment of preparing particle mateiral, the paper focused on optimizing the binder and the molding process conditions of the modified kaolin powder so as to determine the optimal technological conditions to enhance the ion exchange capacity of the material. Eventually, we got the quite better results than the original kaolin that the exchange capacity is 68.0m2/g and the surface area is 76.3mg/g. The measurement result of SEM showed that the material had the well-developed microporous structure. We got from the XRD measurement result that the kaolinite of the high performance material was totally dissolved and a dissoluble and active alumino-silicate was formed.Then the effect of the particle dosage, contact time, pH, temperature and initial ammonium concentration of the solution on the exchange capacity and the removal efficiency was studied in this paper and the presence of K+, Na+, Ca²⁺ and Mg²⁺ could reduce NH4+ removal efficiency and the order followed K+>Na+>Ca²⁺>Mg²⁺. With comparison of different kinds of regenerated methods, the best regeneration solution was the mixture solution with NaCl and NaOH obtained at pH 12.5 and at initial concentration of 0.7 molNa+l-1. We could get the information from the futher studies on the isotherm, thermodynamics and kinetics of ammmoium removal process that Langmuir, Freundlich, Temkin, Redlich-Peterson and Koble-Corrigan isotherm models were all fitted to experimental equilibrium data and the Koble-Corrigan model gave the best fit, the thermodynamic constants revealed the ammonium uptake was an exothermic reaction; the effect of contact time at different initial concentration was fitted to pseudo-second-order model rather than pseudo-first-order model and both the surface adsorption and intra-particle diffusion contribute to the actual adsorption process.