Study On Recovery Mechanism Of Uranium Resources In Wastewater By Modified Carbonized Sawdust

With the adjustment of energy structure in China,nuclear power has been greatly developed as a clean energy source.As a necessary fuel for the development of nuclear power,the demand for uranium is increasing year by year.At present,the production capacity of natural uranium in China is far from meeting the demand,and the supply of natural uranium is under great pressure.However,the low concentration of uranium in the large amount of uranium-containing wastewater produced in the process of uranium mining and smelting is not fully recovered,therefore,it is necessary to find a material with wide source,low cost and strong adsorption and desorption ability to recover uranium from wastewater.Organic carbon materials have been widely used in the treatment of uranium-containing wastewater due to their excellent properties such as large adsorption capacity,radiation resistance,corrosion resistance and chemical stability.Sawdust is a common organic material in daily life,which has the advantages of wide source,simple preparation and low price.In this study,the sawdust was carbonized with concentrated sulfuric acid and modified for the adsorption of uranium.The adsorption mechanism of MCS?modified carbonized sawdust?on uranium was studied by studying the factors affecting the adsorption of uranium,as well as the kinetics and thermodynamic behavior of the adsorption process.And through dynamic adsorption,in situ desorption and regeneration experiments,the adsorption ability of MCS on uranium,the desorption property of uranium on MCS and the regeneration ability of MCS were further explored.It provides a theoretical basis for the recovery of uranium resources from uraniumcontaining wastewater.The results showed that MCS with NaHCO₃ had the best adsorption effect on uranium.The adsorption of uranium by MCS had little effect on the temperature,but it was affected by the pH value of solution.When the pH value of the solution was 4.5,the adsorption effect was the best,and the contact time reached the adsorption equilibrium around 30 min.The adsorption process is in accordance with the pseudo-second-order model and the Freundlich adsorption isotherm model.the adsorption process is endothermic reaction and the increase of temperature is beneficial to the adsorption process.,and the randomness of solid/liquid interface increased during the adsorption process.The analysis of SEM and FT-IR showed that the surface of MCS became relatively flat after adsorption,and there were surface complexation adsorption in adsorption process and the functional groups involved in adsorption were mainly amine group,carboxyl group,aldehyde group and other groups on surface of MCS.The experimental results of dynamic adsorption,in situ desorption and regeneration showed that the dynamic adsorption of uranium in standard uranium solution by MCS can reach 99.47 mg / g;The adsorption column is eluted in situ by 0.5mol/L H₂SO₄ solution.The desorption rate of the first eluted uranium can reach 97.03%;Moreover,the regeneration effect of the adsorption column is better,and the adsorption rate of the second stage can reach 96.4%,which can be used for the recovery of uranium resources in wastewater theoretically.Moreover,the regeneration effect of adsorption column is better,the second stage adsorption rate can reach 96.4%.In theory,MCS can be used to recover uranium resources in wastewater.