Removal of long-lived minor actinides by means of solvent extraction with lipophilic chemically modified chitosan

Inoue, Katsutoshi*; Oto, Keisuke*; Yoshizuka, Kazuharu*; Naganawa, Hirochika  ; Tachimori, Shoichi*

Lipophilic chitosan containing functional groups of dithiocarbamate (DTC-lipophilic chitosan) was prepared and tested for the selective solvent extraction of minor actinides (MA) from large excess of lanthanides in dilute nitric acid solution. This reagent was found to be soluble not only in chloroform and toluene but also in kerosene, which is very favorable for practical purposes. Although solid chitosan gel chemically modified with functional groups of dithiocarbamate prepared according to the conventional method had exhibited no selectivity to MA over lanthanides, DTC-lipophilic chitosan exhibited high selectivity to americium over europium; i.e., the separation factor of Am/Eu was as high as 1227 in the extraction at pH = 4. In addition, it exhibited the same separation factor at the second solvent extraction test carried out one week after the first test, suggesting that it is chemically stable at least for one week contrary to Cyanex 301 and DPTP.