Shape‐Controlled Preparation of Basic Bismuth Nitrate Crystals with High Iodide‐Removal Capacities

Bismuth compounds have generated much interest as agents for the removal of radioactive iodine. In this work, we present the shape‐controlled preparation of basic bismuth nitrate crystals (BBN) in the form of Reuleaux triangles, hexagons, and deformed hexagon disks. Shape control was achieved through modulation of the effect of the shape‐directing agent 2,3‐bis(2‐pyridyl)pyrazine (dpp). The crystals were shown to be capable of iodide removal through reaction with I− to form BiOI. Depending on the degree of saturation, the resultant solids can exhibit colors ranging from yellow (unsaturated) to orange (saturated). Sedimentation of the products facilitates its removal after use. While the removal capacities did not depend on the crystal morphology, the Reuleaux triangle disks exhibited faster reaction rates than the other two shapes. With improved removal capacities of up to 3.6 mmol g−1, fast removal kinetics, good selectivity, and capture irreversibility, the BBN crystals show good potential as agents for radioactive iodine removal.