Uranium(VI) remediation from aqueous environment using impregnated cellulose beads

Use of cellulose based adsorbents for post treatment of contaminated water provides significant removal and recovery of trace quantities of radioactive and highly toxic U(VI) ions. Efficiency of the adsorbent was enhanced by impregnation of nano Fe2O3. Variables considered for obtaining optimized process conditions were solution pH, adsorbent dosage, initial metal ion concentration, additive content and contact time. The batch adsorption study revealed highly pH dependent adsorption with 100% adsorption efficiency at pH 7 using 1.5 g of adsorbent impregnated with 6 wt% Fe2O3 for 50 mL solution capacity in 150 min. The adsorption capacity was noted to be 7.6 mg/g. The adsorption mechanism was studied at pH 7 maintained using dilute ammonia solution to prevent the effect of any interfering cation. Uptake of U(VI) was found to be predominately via an intraparticle diffusion mechanism following pseudo second-order kinetic model, which is clearly reflected from the non-spontaneous thermodynamics yielding a positive free energy value. Recovery of the adsorbed U(VI) ions was highly feasible using 0.05 N HNO3 and the regeneration of the adsorbent using 0.01 N NaOH.