Selective removal of radioactive iodine from water using reusable Fe@Pt adsorbents.

Environmental damage from serious nuclear accidents should be urgently restored, which needs the removal of radioactive species. Radioactive iodine isotopes are particularly problematic for human health because they are released in large amounts and retain radioactivity for a substantial time. Herein, we prepare platinum-coated iron nanoparticles (Fe@Pt) as a highly selective and reusable adsorbent for iodine species, i.e., iodide (I-), iodine (I2), and methyl iodide (CH3I). Fe@Pt selectively separates iodine species from seawater and groundwater with a removal efficiency ≥ 99.8%. The maximum adsorption capacity for the iodine atom of all three iodine species was determined to be 25 mg/g. The magnetic properties of Fe@Pt allow for the facile recovery and reuse of Fe@Pt, which remains stable with high efficiency (97.5%) over 100 uses without structural and functional degradation in liquid media. Practical application to the removal of radioactive 129I and feasibility for scale-up using a 20 L system demonstrate that Fe@Pt can function as a reusable adsorbent for the selective removal of iodine species. This systematic procedure is a standard protocol for designing highly active adsorbents for the clean separation and removal of various chemical species dissolved in wastewater.

Determination of HPGe peak efficiency for voluminous gamma-ray sources by using an effective solid angle method.

A code called EXVol has been developed to obtain the absolute peak efficiency for an extended or voluminous γ-ray source. The method is based on the concept of effective solid angles. Several efficiency curves that have been determined semi-empirically for voluminous sources are compared with the experimental values based on certified reference volume sources. To study the geometric and matrix effects, standard γ-ray sources of several media, volumes and shapes were measured using HPGe detectors with three different efficiencies. For the n-type detector of 32% relative efficiency, the relative deviations are less than ±10%; this performance is similar to that of existing programs for similar purposes. The EXVol code is able to calculate the detection efficiency within approximately five minutes or less. Systematic errors based on EXVol input parameters, which are mainly due to the inherent uncertainty in the detector's characteristic dimensions provided by the vendor, are studied to obtain more accurate specifications of the detectors.