Enhanced direct oxidation of diclofenac (DCF) at a carbon paste electrode (CPE) modified with cellulose and its biodegradability by Scedosporium dehoogii

A novel carbon paste electrode modified with cellulose fibers and dedicated to diclofenac electroanalysis was prepared, optimized, and used for the determination of the kinetic parameters of DCF biodegradation by a filamentous fungus. The electrochemical response of the modified CPE was compared to that of the unmodified. This study conducted by cyclic voltammetry and linear sweep voltammetry allowed the optimization of the cellulose fibers modified CPE in terms of absence/presence of cellulose fibers, accumulation time (250 s), and initial potential (- 0.4 V/Ag/AgCl). Interestingly, in these conditions, the limit of detection observed through linear sweet voltammetry was found to be as low as 0.020 µmol L-1. This electrode was then used to follow the degradation of DCF. Our results demonstrated that among species belonging to the Scedosporium genus, S. dehoogii displayed the best assets in our process in terms of growth temperature and ability to metabolize DCF. More precisely, DCF biodegradation using S. dehoogii in the process revealed a kinetic of order of 1, a kinetic constant k of 0.012 day-1 and a half time of 57.8 days for an initial concentration of DCF of 1.65 ± 0.05 mg L-1 and at a temperature of 25°C. This study constitutes a solid proof of concept for future developments of fungal wastewater treatments for bioremediation of DCF which is refractory to standard bacterial-based bioprocesses

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