Lignocellulosic date stone for uranium (VI) uptake: Surface acidity, uptake capacity, kinetic and equilibrium

Surface acidity is an important for prediction of affinity between sorbent and sorbate and it is expressed by pH of zero point charge (pHzpc). In this study, pHzpc of lignocellulosic date stone was investigated by potentiometric mass titration and solid addition methods. The capacity of date stone for U(VI) sorption was studied at different experimental conditions and the optimum conditions were pH = 6, dose = 8 g L−1 and time = 1 h. Kinetic models were fitted by first order, second order and intra-particle diffusion models and the equilibrium were described by Langmuir and Freundlich isotherms. Date stone surface before loading and after was characterized by Fourier Transform Infrared Spectroscopy (FT-IR) and scanning electron microscope (SEM). The reported method may be used to remove U(VI) in water at economic level.