Synthesis and characterization of silicon antimonate composites for the removal of alkali metal ions from solutions

A number of silicon antimonate composite extractants have been synthesized by hydrolysis and polycondensation of antimony pentachloride and tetraethox ysilane. The physical as well as chemical properties of the composite extra ctants show changes with variation in the amount of antimony in the composi tes. The significant feature of this work is that, for the first time, extr actants having a wide and continuous range of Si/Sb molar ratio i.e. 0.18 t o 2.72, have been synthesized and their physical and chemical properties,st udied. This work provides a guideline for synthesis of composite extractant s, with tailored distribution coefficient for alkali metal ions at a partic ular flow rate for their use in column operation. It was found that the amo unt of the uptake of each of the alkali metal ion in the same chemical envi ronment is directly proportional to the amount of antimony in the composite irrespective of the diversity in nature of the alkali metal ions. The sele ctivity sequences of the alkali metal ions for all the seven composites wer e found to be K+ > Na+ > Rb+ > Cs+ > Li+.