Saeed Kakaei - Radiation Application Research School, Nuclear Science & Technology Research Institute, P.O. Box ۱۱۳۶۵-۳۴۸۶, Tehran, Iran
Elham Sattarzadeh Khameneh - Radiation Application Research School, Nuclear Science & Technology Research Institute, P.O. Box ۱۱۳۶۵-۳۴۸۶, Tehran, Iran
Akbar Monji Boveiri - Radiation Application Research School, Nuclear Science & Technology Research Institute, P.O. Box ۱۱۳۶۵-۳۴۸۶, Tehran, Iran

For the first time, sorption characteristics and mechanisms of group-۴ elements were investigated and compared in extremely acidic solutions (۴ M HCl) by rice bran (RB) biomass. Numerous instrumental strategies and hard-soft acid-base (HSAB) theory were applied to investigate the sorption features and mechanisms of Ti(IV), Zr(IV), and Hf(IV). The specific surface area of the raw biomass was ۴.۷۹ m۲.g−۱ as determined by Barrett-Emmet-Taller analyzer (BET). Deposition of planned metal ions on the biomass was determined through a scanning electron microscope (SEM) with energy-dispersive X-ray spectroscopy (EDS). The linkage of C=O, O-H, and N-H functional groups of biomass with metal ions became clear with Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectrum analysis. The role of C=O functional group of ammonium oxalate/ammonium carbonate in metal ions desorption was confirmed by elution experiment. The experiments showed that the high-affinity of rubidium to sorption of zirconium and hafnium (>۹۹%) was owing to their lower hydrated ionic radius. From all the results obtained, exhausting-hard interactions and electrostatic complexation mechanism were diagnosed between hard-functional groups of RB biomass and hard cations of Ti(IV), Zr(IV), and Hf(IV).

Agricultural byproduct, Bio separation, Chemical Interaction, hard cations, tetravalent metal