PORTUGALIAE ELECTROCHIMICA ACTA Experimental Investigation of Nickel Electrodeposits Brightness in the Presence of Surfactants: Modeling, Optimization and Polarization Studies

Abstract Nickel coatings were obtained from Watts bath containing sodium dodecyl sulfate (SDS) or polyvinylpyrrolidone (PVP) surfactants by direct current plating. The influence of electrolysis parameters, temperature, current density, concentration of surfactants and pH on the nickel deposits brightness is investigated through a multiple linear regression model with interaction. The models obtained fitted very well the experimental data. ANOVA statistical analysis shows that all design factors are significant, and the brightness of nickel deposits obtained from bath containing PVP is more sensitive to the changes in the factors levels. The electrochemical behaviour of baths was discussed; the results revealed an inhibitive effect exerted by both SDS and PVP. We have also found that the brightness and the inhibition are well linked and directly proportional. In addition, the corrosion resistance of the nickel coatings was slightly improved, especially with PVP. Finally, the optimization analysis showed that PVP could efficiently and eco-friendly substitute SDS as an additive of nickel electroplating

Simultaneous determination of 4-aminophenol and paracetamol based on CS-Ni nanocomposite-modified screen-printed disposable electrodes

In the present work, chitosan-coated nickel nanoparticles (CS-Ni) were successfully prepared onto screen-printed electrode (SPE) by electrodeposition method with the assistance of an anionic surfactant of sodium dodecyl sulfate (SDS) for the individual and simultaneous sensing of 4-aminophenol (4-AP) and paracetamol (PA). The as-prepared sensor was characterized via scanning electron microscopy, X-ray diffraction, and fourier transform infrared techniques. The electrochemical catalytic behaviors of the 4-AP and PA on the fabricated NiNPs-SDS/CS/SPE electrode were explored using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). The NiNPS-SDS/CS modified screen-printed electrode demonstrated excellent electrocatalytic activity for 4-AP and PA, indicating that nickel microstructures have a high specific surface area, excellent electrical conductivity, and high electrocatalytic activity. The results indicate that CV and DPV could be easily applied to determine 4-AP and PA using the fabricated sensor under optimized conditions. However, CV is preferred for both analysts’ sensing, with the largest linear range from 1 to 500 μM for 4-AP (R2 = 0.999) and 1 μM to 2 mM (R2 = 0.997) for PA, respectively. In terms of sensitivity and detection limit, DPVs response appeared to be a better technique choice, as it revealed the highest sensitivity values of 0.959 µA µM−1 cm−2 for 4-AP and 1.163 µA µM−1 cm−2 for PA, with the lowest detection limits of 0.06 and 0.04 μM for 4-AP and PA (S/N = 3), respectively. With a high recovery rate, good selectivity, excellent reproducibility, and strong anti-interference ability, the modified sensor was successfully applied to the simultaneous detection of 4-AP and PA in pharmaceutical tablets. It is expected to be widely used in actual sample detection