The effect of pH

uranium concentration

contact time

particle size of tea waste and temperature on U(Ⅵ)adsorption by tea waste from aqueous solutions was studied by static adsorption experiments.The kinetic and thermodynamic characteristics of the adsorption process were analyzed

and the adsorption mechanisms were also discussed using data from SEM and FT-IR measurement.The results show that the pH affects greatly adsorption of U(Ⅵ)on tea waste

and U(Ⅵ)amount of adsorption were 13.90 and 43.19 mg·g-1 at pH 2 and 6

respectively.This adsorption process is slow

and it takes 12 h for adsorption equilibrium.The adsorption kinetics follows pseudo-second order equations rather than pseudo-first order.The amount of adsorption increases but the uranium recoveries decrease with the increasing initial uranium concentration.For example

uranium concentration increases from 10 to 100 mg·L-1

the U(Ⅵ)adsorption amount goes up from 9.40 to 70.05 mg·g-1

but uranium recoveries decrease from 94.04% to 70.05%.The adsorption equilibrium data fitted Freundlich isotherm better.The —OH

CO

—NO3

P—O

Si—O groups on the surface of tea waste are responsible for adsorption of U(Ⅵ).