Batch adsorption and desorption investigations of Cs(I) and Sr(II) from simulated reactor waste by humic acid

Background: This work focused on cost-effective and collective adsorption of radionuclides followed by their subsequent selective desorption, which is necessary for separation. The potential of humic acid, a low-cost adsorbent, for the removal and recovery of Cs(I) and Sr(II) from simulated reactor waste, was investigated Basic Procedures: Experimental parameters like solution pH, adsorbent dose, contact time, and temperature were optimized. FT-IR of humic acid before and after adsorption was compared. Selective desorption of both the radionuclides was achieved with desorbing agents – citric acid and HCl Main findings: The process was governed by rapid kinetics where 91±2% of Cs(I) and 83±2% of Sr(II) was adsorbed within 10 min. Data modelling revealed that the process follows pseudo-second-order kinetics, and is spontaneous, feasible, and exothermic, with positive entropy indicating a high affinity of humic acid for the metallic ions. Maximum desorption of 97±2% was obtained for Sr(II), and 82±2% for Cs(I) Principal Conclusion: Thus, the adsorption of investigated radionuclides by humic acid and their desorption was time-efficient, economical and environmentally a benign alternative for the removal and recovery of Cs(I) and Sr(II).