The increasing demand for rare earth elements in green technology, electronic components, petroleum refining, and agricultural activities has resulted in their scattering and accumulation in the environment. This study determined cerium, lanthanum and praseodymium in environmental water samples with the help of adsorptive differential pulse stripping voltammetry (AdDPSV) and inductive coupled plasma-optical emission spectroscopy (ICP-OES). A comparison of the results of these two analytical techniques was also made. The accuracy and precision of the methods were evaluated by spiking water samples with a known amount of REEs. The detection limit obtained for the stripping analysis was 0.10 μg/L for Ce(III), and 2.10 μg/L for combined La(III) and Pr(III). The spectroscopic method of determination by ICP-OES was applied to the same samples to evaluate the effectiveness of the voltammetry procedure. The ICP-OES detection limit obtained was 2.45, 3.12 and 3.90 μg/L for Ce(III), La(III) and Pr(III), respectively. The results obtained from the two techniques showed low detection limits in voltammetry; the ICP-OES method achieved better simultaneous analysis. This sensor has been successfully applied for the determination of cerium, lanthanum, and praseodymium in environmental water samples, offering good results.

This study assesses the physical and electrochemical changes of bimetallic Ag-Au nanoparticle-functionalized bentonite nanoclay. Nanoclay was studied to deduce a better sensing material/film. A chemical co-reduction method was used to synthesize bimetallic Ag-Au c nanoparticles, which were used to prepare a Ag-Au/PGV bentonite composite. Bimetallic Ag-AuNPs and their nanoclay composite were optically characterized using the scanning electron microscope, ultraviolet visible spectroscopy, X-ray diffraction, and Fourier transform infrared, whilst cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to ascertain their electrochemical activity and properties. The results of surface morphological inspection showed an average size of 10nm, in agreement with XRD. The bimetallic Ag-AuNPs UV/Vis characteristic wavelengths of 414nm and 516nm confirmed the presence of Ag and Au metals, respectively. XRD exhibited diffraction planes related to 2θ values of Ag and Au metals, whilst FTIR indicated mainly COO- functional groups from the citrate capping of bimetallic Ag-Au NPs. CV and DPV showed that bentonite nanoclay is largely insulated by silicates but exhibited a small electroactivity of Fe. The electroactivity of Ag-Au/PGV bentonite exhibited peak potentials due to Ag/Ag+ and Au/Au³⁺ redox couples at 0.19V/0.20V and 1.37V/0.42, respectively. The Ag-Au/PGV bentonite nanocomposite exhibited the highest surface concentration of 3.25×10⁻²cm², a diffusion coefficient of 2.36×11cm²/s, and an electron transfer rate constant (Ks) of 1.99×10⁻⁴cm². The outcome of these results indicated that the Ag-Au/PGV bentonite nanocomposite was more electroactive than PGV. Therefore, this study accentuates Ag-Au/PGV bentonite nanocomposite as a novel and promising platform for electrochemical sensing with higher sensitivity and efficiency than other sensing materials.

A study of nanosensor comprising of a glassy carbon electrode modified with a composite of multiwall carbon nanotube (MWCNT) and bimetallic (Ag‐PtNPs) for the determination of Nevirapine. The GCE/MWCNT/Ag‐PtNPs sensor had remarkable electrocatalytic properties with enhanced response towards Nevirapine under optimized conditions. The platform electrochemical characterisation in 0.01 M NaOH solution, with cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) is detailed. The limit of the detection (LOD) was 0.021 μM. The nanosensor was validated for real sample study using spiked pharmaceutical dose form, milk and urine samples, which showed acceptable recoveries (90‐ 112 %), good precision (RSD=3.3 %, N=3), reproducibility (RSD=4.3 %) and excellent selectivity towards Nevirapine from studied interferents.

Three different fractions of nanoclay (nanomer 1.44P) were functionalised with Ag forming silver nanoclay composites (Ag/nanomer 1.44P). The optical and electrochemical properties of the functionalised nanoclay were studied. Optical, morphology, and electrochemical techniques were used for the characterisation of the synthesised Ag/nanomer 1.44P nanocly composites. The presence and the absence of functional groups observed in the FTIR spectrum of Ag/nanomer 1.44P, compared with those found in the spectra of silver and pure nanomer 1.44P prove that a reaction occurred, thus a successful functionalisation of nanomer 1.44P nanoclay with silver. The XRD data of all composites showed four diffraction peaks within the silver spectrum range, with the intensity of silver decreasing with increasing concentration of nanomer 1.44P. SEM represented well-dispersed particles of different shapes with average particle sizes of 2.5, 27.5, and 5 nm with the enhanced concentration of nanomer 1.44P nanoclay. The decrease in diffusion coefficient values from 4.26 × 10⁻¹⁰, 2.50 × 10⁻¹³ , 1.40 × 10⁻¹³ cm² s⁻¹ and electron transfer rates of 1.50 × 10⁻⁵, 3.94 × 10⁻⁷, 2.86 × 10⁻⁷ cm s⁻¹ are respectively proportional to an increase in nanomer 1.44P concentration depicting changes in nanocomposites sizes.