Sorption of uranium(VI) by Trapa bispinosa from aqueous solution: effect of pretreatments and modeling studies

In this study, the sorption of uranium(VI) from aqueous solution was investigated using Trapa bispinosa (Singhara) in batch system. Different physical and chemical treatments were given to native biomass for enhancing its sorption capacity for uranium(VI). The optimization of different experimental factors such as solution pH, dose of biosorbent, particle size, contact time, temperature, and initial uranium(VI) ion concentration was done. Maximum sorption (171mg g(-1)) was observed at pH (5.0), particle size (0.25mm), biosorbent dose (0.05g), temperature (50 degrees C), and initial uranium(VI) ion concentration (400mg L-1) in 90 min. The obtained data were analyzed by applying equilibrium, kinetic, and thermodynamic models. The uranium(VI) sorption equilibrium data were best fitted in Freundlich adsorption isotherm. The rate of biosorption process was effectively described by applying different kinetic models and the well-fitted model found to be pseudo-second-order. The evaluation of thermodynamic parameters represented that the uranium(VI) sorption process was exothermic, spontaneous, and favorable. The process was made more economical through recovery of uranium(VI) ions using HNO3. FT-IR analysis of biosorbent confirmed the involvement of functional groups like hydroxyl, carbonyl, and carboxylic groups in the sorption process.