Effect of ionic radius on Ti (IV), Zr (IV), and Hf (IV) adsorption by RB biomass

For the first time, sorption characteristics and mechanisms of group4 elements were investigated and compared in extremely acidic solutions (4 M HCl) by rice bran (RB) biomass. Numerous instrumental strategies and hardsoft acidbase (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 4.79 m2.g−1 as determined by BarrettEmmetTaller analyzer (BET). Deposition of planned metal ions on the biomass was determined through a scanning electron microscope (SEM) with energydispersive Xray spectroscopy (EDS). The linkage of C=O, OH, and NH functional groups of biomass with metal ions became clear with Attenuated total reflection Fourier transform infrared (ATRFTIR) 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 highaffinity of rubidium to sorption of zirconium and hafnium ( gt;99%) was owing to their lower hydrated ionic radius. From all the results obtained, exhaustinghard interactions and electrostatic complexation mechanism were diagnosed between hardfunctional groups of RB biomass and hard cations of Ti(IV), Zr(IV), and Hf(IV).