Dispersive solid phase extraction of precious metal ions from electronic wastes using magnetic multiwalled carbon nanotubes composite

Abstract

Rapid technological developments of electrical and electronic equipment raise a persistence demand for precious elements. The presence of precious metals (PMs) makes e waste recycling economically attractive. In the present study, magnetic multiwalled carbon nanotubes (Fe3O4-o-MWCNTs) were synthesized and utilized as a hydrometallurgical method for extraction of precious elements (Ag, Au, Pd and Pt) from e waste. MWCNTs were synthesized with chemical vapor deposition of acetylene using Ni-Fe-Co/Al2O3 catalyst, decorated with Fe3O4 nanoparticle via co-precipitation and characterized by multiple characterization techniques. Morphology shows that MWCNTs have been efficiently produced (having ~10–20 µm length and ~30 nm internal diameter) and successfully decorated with Fe3O4 nanoparticles. At optimized conditions the adsorbent shows 98% recovery with 3 mol/L nitric acid as eluent for Pd, Ag and Au. However, Pt elution was carried out with 1 mol/L sodium perchlorate. Maximum adsorption capacity calculated from Langmuir isotherm was found as 112, 57, 106 and 104 mg/g for Pd, Pt, Ag and Au, respectively. Results show that Fe3O4-o-MWCNTs composite is a good adsorbent material for extraction of precious metals from e waste due to its high efficiency, sensitivity, reusability and stability in acidic media.