In some embodiments, the present disclosure pertains to methods of capturing contaminants (i.e., radionuclides and metals) from a water source by applying an oxidatively modified carbon to the water source. This leads to the sorption of the contaminants in the water source to the oxidatively modified carbon. In some embodiments, the methods also include a step of separating the oxidatively modified carbon from the water source after the applying step. In some embodiments, the oxidatively modified carbon comprises an oxidized carbon source. In some embodiments, the carbon source is coal. In some embodiments, the oxidatively modified carbon comprises oxidized coke. In some embodiments, the oxidatively modified carbon is in the form of free-standing, three dimensional and porous particles. Further embodiments of the present disclosure pertain to materials for capturing contaminants from a water source, where the materials comprise the aforementioned oxidatively modified carbons.