Preparation and Characterization of Nano Silicotitanate Gel to be Used as a Base Material for 99Mo/99mTc and 188W/188Re Chromatographic Column Radionuclide Generators

Nano silicotitanate (SiTi) gel was prepared to test its sorption capacity for Mo(VI) and W(VI) and its performance as a base material for ⁹⁹Mo/^99mTc and ¹⁸⁸W/¹⁸⁸Re chromatographic column generators. X-ray diffraction analysis showed that SiTi is a crystalline material with a crystallite size of 5.5 nm. High-resolution TEM studies showed that the average particle size was 60 nm. According to field emission SEM studies, SiTi has a cloudy morphology with the presence of many cavities. As indicated by TGA and EDX studies, SiTi gel has the chemical formula SiTi₆O₁₁·7H₂O. Nitrogen chromatographic studies showed that SiTi has a BET surface area of 285 m²/g, total pore volume of 0.31 cm³/g, and average pore diameter of 3.7 nm. DLS studies showed that the hydrodynamic diameter distribution of SiTi particles is bimodal, with 86.5% of particles corresponding to the peak at 126.5 nm and 13.5%, to the peak at 724.4 nm. Electrophoresis studies indicated that SiTi gel has a zeta potential of –45.1 mV. According to Langmuir sorption isotherms, SiTi gel showed molybdate(VI)-⁹⁹Mo and tungstate(VI)-¹⁸⁸W maximum capacities in the ranges 162.87–192.31 and 67.93–196.85 mg/g, respectively, in the temperature range 25–60°C. The breakthrough capacities for ⁹⁹Mo and ¹⁸⁸W were found to be 69.8 mg Mo/g and 60 mg W/g, respectively. ⁹⁹Mo/^99mTc and ¹⁸⁸W/¹⁸⁸Re chromatographic column generators were prepared and successfully eluted to obtain ^99mTc and ¹⁸⁸Re with the average elution yields of 89.1 and 97.9%, respectively, and radiochemical purity of >97 % (as pertechnetate and perrhenate, respectively).