Voltammetric Determination of Pb(II) Ions at a Modified Kaolinite-Carbon Paste Electrode

We report a novel application of a carbon paste electrode modified with sodium dodecyl sulphate (SDS) intercalated kaolin clay for the electrochemical detection of Pb²⁺in aqueous medium using square wave voltammetry. SDS was used to modify a chemically purified kaolin clay via intercalation process to prepare a carbon paste electrode. The SDS kaolin clay was obtained by intercalation of SDS into the interlayer spaces of kaolinite in the presence of heat. The purified kaolinite and its SDS intercalate were characterised using techniques such as X-ray powder diffraction (XRD), X-ray fluorescence (XRF), thermogravimetric analysis (TGA), attenuated total reflection Fourier transform infrared (ATR-FTIR), scanning electron microscopy (SEM), BET and CHNS elemental analysis. These techniques proved the successful intercalation of SDS into the interlayer spaces of the clay adsorbent. Various parameters affecting the electrochemical detection of Pb²⁺ were optimised. A linear current response was obtained in the concentration range of 1–100 ppb. The limit of detection was found to be 2.48 ppb. The proposed sensor also demonstrates good reproducibility after series of 10 repetitive measurements with a relative standard deviation (RSD) of about 6.30%. The interfering effects of some ions on the detection of Pb²⁺ were evaluated. The proposed sensor was applied for the determination of Pb²⁺ in a real water sample. [Figure not available: see fulltext.]