Removal Of Uranium From Aqueous Solutions Using Bio-sorbents

U(VI)is used on a commercial scale in different sectors such as nuclear power plants,national defense and agriculture.These sources slowly and gradually add U(VI)to the environmental water and soil.Both chemical adsorbents and bio-sorbents have been used to adsorb uranium from wastewater.However,bio-sorbents are cheap and show comparable adsorption capacity for U(Ⅵ)in wastewater.STL can be easily converted into a more effective adsorbent by only acid treatment,so as to obtain acid-treated spent tea leaves(ASTL).This study uses ASTL bio-sorbent to adsorb U(Ⅵ)from aqueous solutions.The BET surface area of ASTL is 35m2/g.Similarly,the pHpzc value was found to be 4.74.The adsorption capacity was pH dependent,and the highest adsorption capacity was found at pH 5.5.The adsorption was mainly due to electrostatic attraction.The adsorption capacity was proportional to the amount of ASTL,and the highest adsorption capacity was achieved at 2.0 g/L of ASTL.The kinetic data of U(Ⅵ)adsorption onto ASTL followed a pseudo-second-order kinetic model,which indicated that the adsorption of U(Ⅵ)on the ASTL surface was controlled by electrostatic interactions.Moreover,the adsorption data was in good agreement with the Langmuir isotherm model showing the single-layer adsorption mechanism,and the adsorption data at 25℃ was 120.74 mg/g.Thermodynamic studies have shown that the adsorption of U(Ⅵ)on ASTL is feasible,endothermic in nature and random at solid-liquid phase.The easily availability and high adsorption capacity emphasizes the commercial application of ASTL to remove U(Ⅵ)from wastewater.