Effect of pH,fulvic acid and temperature on the sorption of uranyl on ZrP_2O_7

摘要

The sorption of UO22+ onto ZrP2O7 was studied using the batch technique and the point of zero charge of ZrP2O7 was obtained through mass titration.The results indicated that sorption of UO22+ onto ZrP2O7 was strongly affected by pH,solid-to-liquid ratio (m/V),the species of electrolyte in solution and fulvic acid (FA),but was insensitive to ionic strength.The sorption of UO22+ increased with increasing pH and m/V.The presence of FA enhanced UO22+ sorption onto ZrP2O7 at low pH.The presence of phosphate or sulfate caused opposite effects on the sorption of UO22+ onto ZrP2O7.Addition of citrate also significantly affected UO22+ sorption.The sorption of UO22+ increased as the temperature of the system increased.The Langmuir and Freundlich models were used to simulate the sorption isotherms of UO22+ onto ZrP2O7 at different temperatures.The results indicated that the Freundlich model described UO22+ sorption better than the Langmuir model.Thermodynamic parameters for the sorption process were calculated from the temperature dependent sorption isotherms.The results suggested that the sorption process of UO22+ onto ZrP2O7 is spontaneous and endothermic.The desorption process of UO22+ from ZrP2O7 was also investigated and it was found that sorption onto ZrP2O7 was irreversible.