Effect of Manganese Oxide Sand Used in Water Treatment in Removing 222Rn and Mn2+, Fe2+, NH4+, and NO3− from Groundwater

In this study, the possibility of 222Rn removal through the deferrization/demanganization applied for water treatment was considered, assuming a sorption process. This study demonstrates the possible removal of dissolved radon from groundwater using manganese oxide sand (MnO2) employed in conventional water treatment systems. Four groundwater samples with varying chemical compositions were treated, and the simultaneous removal of 222Rn, Mn2+, Fe2+, NH4+, and NO3− was evaluated. Radon activity was quantified using a Lucas scintillation cell coupled with a Pylon AB-5 system, while inorganic ions were analyzed by ion chromatography. Structural characterization of MnO2 sand by XRD, SEM–EDS, and FTIR confirmed a heterogeneous oxide surface favorable for adsorption. The treatment achieved average removal efficiencies of 95% for 222Rn, 79% for Mn2+, 87% for Fe2+, 85% for NH4+, and 73% for NO3−. Equilibrium adsorption capacities increased with initial contaminant concentrations, indicating a multi-species uptake. Importantly, radon removal was largely independent of coexisting ions. These results reveal the benefit of MnO2-based water treatment, offering an effective solution for simultaneous radon and inorganic contaminant mitigation.