Adsorption behavior of vanadium(V) by supported imidazolium-based difunctionalized ionic liquid

This study reports the functionalization of imidazolium-based ionic liquids (ILs) anions to synthesize novel supported imidazolium-based difunctionalized ILs (SIBD-ILs). Polystyrene [1-butyl-3-methylimidazolium][bis(2-ethylhexyl)phosphate] (PS[C4mim][D2EHP]) was used as an adsorbent to separate and enrich vanadium from vanadium-containing solutions. The effects of parameters such as the initial pH, liquid-solid ratio (L/S), reaction time, and reaction temperature on V(V) adsorption behavior were investigated. The adsorption capacity of 283.63 mg/g was reached under optimal conditions. V(V) adsorbed on PS[C4mim][D2EHP] was effectively desorbed using 3 mol/L NaOH solution and regenerated PS[C4mim][D2EHP]. After 10 adsorption-desorption cycles, the adsorption capacity was maintained at 95.36% of the initial value. The selective adsorption property of PS[C4mim][D2EHP] was studied in vanadium solutions containing Fe(III) and Al(III) ions. At pH = 2.0, the separation coefficients of towards Fe(III) and Al(III) were the highest, 62.05 and 38.69, respectively. The adsorption process of PS[C4mim][D2EHP] for V(V) conformed to Freundlich and pseudo-second-order kinetic models. SIBD-ILs were characterized by Fourier transform infrared, X-ray Photoelectron Spectroscopy, scanning electron microscopy, and energy dispersive spectroscopy. The results showed that PS[C4mim][D2EHP] was successfully prepared, and PS[C4mim][D2EHP] mainly adsorbed vanadium by ion association.