Iron(III) removal from acidic solutions using mesoporous titania microspheres prepared by vibrational droplet coagulation

Abstract

The removal of contaminants, such as Fe(III) from acidic leachates, is often needed as its presence as a contaminant hinders the recovery of the desired metals. An inorganic adsorbent of interest for the removal of Fe(III) is titania due to its high specific surface area and good chemical stability. However, besides the material properties, also the macroscopic shape of the adsorbent is important for its implementation. In this study we have shaped monodisperse titania microspheres using vibrating nozzle technology. In a first step, a suspension containing titania nanopowder and sodium alginate is broken up into monodisperse droplets. The droplets are then solidified through ionotropic gelation of the alginate binder molecules with the calcium ions used as solidification species. The thermally treated microspheres had an average diameter 518 µm, a specific surface area 97 mm2 g−1 and an average pore size of 19 nm. These titania microspheres were employed as an adsorbent to remove Fe(III) from acidic solutions (pH 2). A maximum adsorption capacity of 13.2 mg g−1 was found. A high selectivity (kD 449 mL g−1) was observed towards Fe(III) removal in an acidic leachate originating from a spend automotive catalyst. The titania microspheres could be easily separated and regenerated using a 0,1 M EDTA solution which was demonstrated for up to 5 cycles.