Electrochemical Sensing of Cadmium and Lead Ions in Water by MOF-5/PANI Composites.
Jadranka MilikićMarjetka SavićAleksandra Janošević LežaićBiljana ŠljukićGordana Ćirić-MarjanovićPublished in: Polymers (2024)
For the first time, composites of metal-organic framework MOF-5 and conjugated polymer polyaniline (PANI), (MOF-5/PANI), prepared using PANI in its conducting (emeraldine salt, ES) or nonconducting form (emeraldine base, EB) at various MOF-5 and PANI mass ratios, were evaluated as electrode materials for the electrochemical detection of cadmium (Cd 2+ ) and lead (Pb 2+ ) ions in aqueous solutions. Testing of individual components of composites, PANI-ES, PANI-EB, and MOF-5, was also performed for comparison. Materials are characterized by Raman spectroscopy, scanning electron microscopy (SEM) and dynamic light scattering (DLS), and their electrochemical behavior was discussed in terms of their zeta potential, structural, morphology, and textural properties. All examined composites showed high electrocatalytic activity for the oxidation of Cd and Pb to Cd 2+ and Pb 2+ , respectively. The MOF/EB-1 composite (71.0 wt.% MOF-5) gave the highest oxidation currents during both individual and simultaneous detection of two heavy metal ions. Current densities recorded with MOF/EB-1 were also higher than those of its individual components, reflecting the synergistic effect where MOF-5 offers high surface area for two heavy metals adsorption and PANI offers a network for electron transfer during metals' subsequent oxidation. Limits of detection using MOF/EB-1 electrode for Cd 2+ and Pb 2+ sensing were found to be as low as 0.077 ppm and 0.033 ppm, respectively. Moreover, the well-defined and intense peaks of Cd oxidation to Cd 2+ and somewhat lower peaks of Pb oxidation to Pb 2+ were observed at voltammograms obtained for the Danube River as a real sample with no pretreatment, which implies that herein tested MOF-5/PANI electrodes could be used as electrochemical sensors for the detection of heavy metal ions in the real water samples.
Keyphrases
- metal organic framework
- heavy metals
- aqueous solution
- health risk assessment
- electron transfer
- risk assessment
- health risk
- label free
- reduced graphene oxide
- gold nanoparticles
- sewage sludge
- hydrogen peroxide
- raman spectroscopy
- nk cells
- quantum dots
- visible light
- electron microscopy
- carbon nanotubes
- human health
- mass spectrometry
- network analysis