Sorption performance of lithium-doped titanium vanadate for Sr²⁺, Fe³⁺ and Al³⁺ from polluted water

Abstract

Lithium-doped semicrystalline titanium vanadate (TV) with enhanced sorption properties was obtained using one step precipitation method. Employing this technique at different precipitation conditions produced two lithium-modified forms (LTVI and LTVII). The materials were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), simultaneous thermal analysis (DTA/TGA), and scanning electron microscopy (SEM). Stability of the materials was investigated. The XRD patterns of different vanadate forms revealed poor crystalline nature with minor changes. Distribution coefficient (K_d) of Sr²⁺, Fe³⁺, and Al³⁺ on different vanadate forms was studied and it was found that the selectivity order is Sr²⁺ > Fe³⁺ > Al³⁺. In addition, it can be seen that LTVI (of higher Li⁺ content) shows the higher sorption efficiency, mechanical, and chemical stability compared to the other forms. The dependence of sorption capacity of LTVI on annealing temperature was also studied. The study of binary separation of metal ions showed that LTVI can be potentially useful for analytical applications. Thermodynamic parameters of the exchange process employing the Van’t Hoff equation announced that the exchange reactions are endothermic and spontaneous. Langmuir and Freundlich isotherm models were applied to the experimental data to examine the exchange mechanism.

Keywords:

• Lithium-doped titanium vanadate
• Equilibrium studies
• Selectivity
• Thermodynamic