Electrochemical recovery of low concentrated platinum (Pt) on nickel hexacyanoferrate nanoparticles film

Abstract

The nickel hexacyanoferrate (NiHCF) nanoparticles film coated electrode was firstly used to recover low concentrated Pt(II) (∼ppm) from the dilute solution electrochemically. The film showed compact nanoparticles structure, high redox-active sites (4.6 mmol/g), characterised by Cyclic Voltammetry (CV), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FE-SEM). There was a prominent recovery effect of Pt(II) on NiHCF film in a well-stirred solution. The recovery of Pt(II) was improved with the potential decreasing but decreased with the background electrolyte concentration rising. And its recovery capacity was up to 498.62 mg/g at -0.6 V (vs. SCE), about occupying 56% of redox-active sites, which was significantly higher than the conventional adsorption process. The presence of Co2+ greatly enhanced the Pt(II) recovery from the dilute solution, since Co2+ inserted into availble Ni-NC-Fe-CN- sites, resulting in a drecrese of static electrostatic field and an increase of boundary laryer effect. Conversely, Ni2+ had an insignificant effect on Pt(II) recovery in agreement with the results of energy dispersive X-ray (EDX). The kinetic considerations indicated that the adsorption process was controlled by a multistep mechanism, and the whole process possibly involved the chemisorption of Pt(II) on NiHCF film firstly and then Pt(II) was reduced into Pt(0).