Abstract
In order to remove molybdenum (Mo) from the high-level radioactive liquid waste (HLLW), Pb-Fe based adsorbents were synthesized and their adsorption capacities were investigated. The adsorbent precursors were prepared with precipitation at various pH values by adding sodium hydroxide into a mixture of 1 mol/L lead nitrate and 1 mol/L ferric nitrate aqueous solutions, and each precipitate was then filtered, dried and ground to obtain a fine powder precursor. The precursors were also calcinated at various temperatures to obtain the Pb-Fe based adsorbents.
Two main parameters were considered when synthesizing the adsorbents, i.e. the pH value of precipitation of adsorbent precursor as well as the calcination temperature of the Pb-Fe based adsorbent. The experimental results indicated that the calcination temperature has a great influence on adsorption capacity of the Pb-Fe based adsorbent for Mo. It was found that when the precursor was precipitated at pH 9 and then calcinated at 500 °C, the sorbed amount of Mo by the adsorbent was the highest. In addition, the equilibrium sorption isotherm of Mo onto the adsorbent was estimated by the Langmuir, Freundlich and Redlich-Peterson sorption models. We found that the overall adsorption process was described well by Redlich-Peterson sorption isotherm equation.
