Effect of adding dodecanol as modifier to N,N,N′,N′-tetra-n-hexyl-3,6-dithiaoctane-1,8-diamide silica-based adsorbent on the adsorption behaviors of platinum-group metals and other metals from simulated high-level liquid waste

To adsorb and separate platinum-group metals efficiently from simulated high-level liquid waste, two adsorbents, N,N,N′,N′-tetra-n-hexyl-3,6-dithiaoctane-1,8-diamide (THDTODA)/SiO2-P and (THDTODA + dodecanol)/SiO2-P, were prepared by impregnation of THDTODA with or without dodecanol into macroporous silica/styrene–divinylbenzene copolymer composite particles SiO2-P. The effect of the addition of dodecanol to THDTODA fixed silica-based adsorbents on the separation of platinum-group metals and other metals was evaluated by batch adsorption and chromatographic separation experiments. THDTODA/SiO2-P adsorbed Ru(III) and Rh(III) more than (THDTODA + dodecanol)/SiO2-P did in concentrated HNO3 solution. From the calculated thermodynamic parameters, dodecanol was considered to have little effect on the temperature dependence of the adsorptions of Ru(III), Zr(IV), Mo(VI), and Re(VII) onto the THDTODA adsorbents. Furthermore, in the results of column chromatography experiments, the effects of dodecanol addition on the separation properties were observed for Ru(III), Zr(IV), and Mo(VI), but little effect was observed for Pd(II) and Re(VII).