Ionic Liquid-Laden Mesoporous Silica for Ultrafast Gold Recovery Via Nanoconfined Interfacial Anion Exchange

Recovery of Au from electronic waste is fundamentally a physicochemical problem of selective ion transfer across liquid interfaces under strongly acidic, multicomponent conditions. Although water-immiscible ionic liquids can exchange their resident anion counterions with AuCl₄^-, their practical use is kinetically limited by slow interfacial transfer and sluggish diffusion within the highly viscous ionic-liquid phase. Here, we report ionic liquid-laden mesoporous silica particles (IL-MS) as a nanoconfined ion-exchange platform that couples favorable chlorometalate/ionic-liquid interactions with shortened diffusion paths and enlarged aqueous/ionic-liquid interfacial area. This mesopore-confined architecture enables complete capture of AuCl₄^- from water within less than 10 s, with an equilibrium uptake corresponding to a 1:1 molar ratio with the resident anion Cl^- counterions. The practical applicability of IL-MS was further demonstrated using real waste printed circuit board leachate, from which Au was selectively recovered and converted into metallic Au with a purity of 99.6%. These results establish nanoconfined interfacial anion exchange as an efficient strategy for rapid and selective Au recovery from complex e-waste-derived streams.