Recovery of gold(III) and iridium(IV) using magnetic layered double hydroxide (Fe3O4/Mg-Al-LDH) nanocomposite: Equilibrium studies and application to real samples

N. Raphael Biata, Silindokuhle Jakavula, Geaneth Pertunia Mashile, Azile Nqombolo, Richard M. Moutloali, Philiswa N. Nomngongo

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)

Abstract

In this study for the first time, a magnetic Fe3O4/MgAl-layered double hydroxide (LDH) nanocomposite was used as an adsorbent for recovery of gold and iridium from soils around the mining area. The morphological and structural properties of the obtained Fe3O4/MgAl-LDH was characterized by transmission electron microscopy, Brunauer-Emmett-Teller, scanning electron microscopy coupled with energy dispersive spectroscopy and X-ray diffraction. The adsorption performance of the magnetic adsorbent was evaluated using isotherm and kinetic models. The equilibrium data best fitted to Langmuir, Sips and pseudo-second order kinetic models. The maximum adsorption capacities of gold(III) and iridium(IV) were found to be 124 mg g−1 and 115 mg g−1, respectively. The selectivity of the nanoadsorbent in the presence of diverse common ions and other platinum group metals (PGMs) were investigated. The adsorbent demonstrated relatively high selectivity towards Au(III) and Ir(IV) ions. The recovery of Au(III) and Ir(IV) ions from the adsorbent was achieved using 2.0 mol L−1 H2SO4 solution. Recoveries ranging from 80% to 109% were obtained and the adsorbent was found to be reusable up to ten cycles of adsorption/ desorption processes. The repeatability of the method expressed as relative standard deviation (%RSD) ranged from 2.5–4.9%. The nanocomposite was successfully applied for the recovery of Au(III) and Ir(IV) in South African Reference material (SARM 186, platinum group metal (PGM) concentrate) soil samples collected from a gold mine.

Original languageEnglish
Article number105447
JournalHydrometallurgy
Volume197
DOIs
Publication statusPublished - Nov 2020

Keywords

  • Adsorption isotherm
  • Adsorption kinetics
  • FeO@MgAl-LDH adsorbent
  • Magnetic separation
  • Recovery of PGMs

ASJC Scopus subject areas

  • Industrial and Manufacturing Engineering
  • Metals and Alloys
  • Materials Chemistry

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