Study On The Synthesis Of Silver Loaded Porous Silica And Its Adsorption Behavior For Fission Product Iodide

First, the microcrystalline structure of silver halide(AgX, X=Cl, Br) was loaded onto a porous silica support by crystallization method in this study to synthesize a new AgX/SiO2(X=Cl, Br) adsorbents and its application to the removal of iodide anion from radioactive waste water was investigated. Second, Macroporous silica-based silver loaded adsorbent was synthesized by grafting the silver complexes of thiourea(AgTu3NO3) into the silica-based copolymer support(SiO2-P). While researching its behavior on iodide anions adsorption, comparative experiments with AgX/SiO2(X=Cl, Br) adsorbents were carried out from various aspects, such as kinetic, saturated adsorption capacity and so on.The characterizations of the adsorbents were investigated by methods such as SEM, XRD, BET, TG-DTA. The results confirmed the successful loading of silver onto the silica support. The synthesized adsorbents also showed excellent thermal stability.With the increasing of the concentration of the NaCl in aqueous solution, adsorption ability of AgX/SiO2(X=Cl, Br) for iodide anion decreased, but AgTu3NO3/SiO2-P suffered little from the effect of NaCl concentration. In static experiment, it took about 45 min for AgX/SiO2(X=Cl, Br) adsorbents to reach adsorption equilibrium in 0.6M NaCl solution, and the adsorption capacity was 0.2mmol/g. On the other hand, it took about 10 min for AgX/SiO2(X=Cl, Br) adsorbents to reach equilibrium in 0.6M NaCl solution, and the adsorption capacity was 0.07mmol/g. Both two kinds of adsorption process followed a typical Languir model and the results fitted quite well with pseudo-second kinetic order model. The breakthrough curve of iodide anion on AgTu3NO3/SiO2-P adsorbent had a S-shaped profile. The column efficiency was estimated to be over 90%.