Biosorption of uranium(VI) using activated carbons prepared from agricultural wastes. To evaluate the potential of adsorption of uranium (VI) on porous carbons prepared from agricultural wastes, batch adsorption experiments were conducted. The effects of contact time, pH, initial U(VI) concentration and temperatures were investigated. Furthermore, adsorption capacity and adsorption isotherms were determined. In the experimental pH range (2-9), the amount of uranium adsorbed increased rapidly in the presence of H+ and decreased with an increase in pH. The maximum adsorption capacity of carbons is approximately 1.1 mmol/g at pH 4.3 and 25 degrees C. The adsorption data were analyzed using Langmuir and Freundlich adsorption models, which showed a good fit with the Langmuir isotherm model. The surface-functional groups may be responsible for the strong interaction between the adsorbent and uranium(VI) ions. Furthermore, the pseudo-second-order model is fitted to the experimental data well and better explains the rate of adsorption process than the pseudo-first-order model. The thermal treatment did not alter the adsorption capacity and adsorption mechanism of the carbons used in this study. However, high adsorption capacities were maintained at high temperatures.