Treatment method of radioactive iodine-containing fluid

A treatment method of a radioactive iodine-containing fluid, comprising passing the radioactive iodine-containing fluid through an adsorbent for iodine consisting of a silver-containing binderless zeolite molded body having a silver content of 50 mass % or less, to adsorb the radioactive iodine on the adsorbent for iodine, wherein the binderless zeolite molded body constituting the adsorbent for iodine is either a binderless A-type zeolite molded body alone or a binderless X-type zeolite molded body alone, and wherein the binderless zeolite molded body includes a zeolite powder and zeolite fine particles wherein the zeolite powder has on a surface thereof the zeolite fine particles, and an average particle size of the zeolite powder is 2 μm or more and 8 μm or less wherein the average particle size of the zeolite powder is determined by measuring the size of randomly extracting 30 or more of independent smallest unit of particles having a particle size of 1.5 μm or less identifiable in a scanning electron microscope image at a measurement magnification of 10,000 to 15,000, and an average particle of the zeolite fine particles is 0.2 μm or more and 1.5 μm or less wherein the average particle size of the zeolite fine particles is determined by measuring the size of randomly extracting 30 or more of independent particles identifiable in a scanning electron microscope image at a measurement magnification of 1,500 to 3,000.