Preparation and characterization of immobilized [A336][MTBA] in PVA-alginate gel beads as novel solid-phase extractants for an efficient recovery of Hg (II) from aqueous solutions

► The PVA matrix gel beads entrapping the micro-droplets of tricaprylylmethylammonium 2-(methylthio) benzoate ([A336][MTBA]) were prepared and characterized by FTIR, SEM and TGA. ► The influence of the uptake conditions was investigated including aqueous pH, PVA/IL dosage, the content of [A336][MTBA] and initial mercury (II) concentration. ► Maximum Hg (II) adsorption capacity obtained was 49.89 mg g-1 at pH 5.8. ► The selectivity of the PVA/IL beads towards Hg (II), Pb (II) and Cu (II) was Hg > Pb > Cu.