Investigating the Absorption of Quaternary Ammonium Salt-Functionalized Silica Towards Vanadium in Hydrochloric Acid Solution.

A quaternary ammonium salt-functionalized silica based on N-benzyl-N-methylethanolamine (BMEA-SD) was prepared for the removal and recovery of pentavalent vanadium [V(Ⅴ)] from hydrochloric acid solutions. The impact of pH, contact time, ionic strength, competitive metal ions, and recyclability of the adsorption factors were investigated. The results showed that BMEA-SD was an effective V(Ⅴ) adsorbent with a maximum adsorption capacity of 51.42 mg g−1 at solution pH 3, contact time of 30 minutes, and temperature of 298 K. Characterization of BMEA-SD materials by TG, FTIR, SEM, and XPS. In addition, the adsorption kinetics followed a pseudo-second-order model, with film diffusion being the determined step. The Langmuir isotherm suggested that monolayer chemical adsorption occurred on the adsorbent surface, and thermodynamics data indicated that the V(Ⅴ) adsorption process was spontaneous and endothermic. Selective separation studies (βV/Cr = 109.87, βV/Mn = 1171.40) highlighted its potential for selective adsorption of V(Ⅴ) over hexavalent chromium [Cr(Ⅵ)] and divalent manganese [Mn(II)]. Desorption was most effective using HCl aqueous solution, and this material maintained good adsorption capacity after five cycles. The experimental results indicated that the adsorption behavior might stem from the interplay of electrostatic forces, redox transformations, and ligand-exchange. This investigation revealed the potential of the adsorbent as a promising, efficient, and renewable for enriching and recovering V(Ⅴ) ions from hydrochloric acid solution. [ABSTRACT FROM AUTHOR]