One-step electrochemical elaboration of SnO2 modified electrode for lead ion trace detection in drinking water using SWASV.

A facile method was proposed for the elaboration of an electrochemical sensor for heavy metal's trace detection by using square wave anodic stripping voltammetry (SWASV); this method is based on a simple anodic conversion of tin electrode into Sn/SnO2 modified electrode. Both electrochemical and physico-chemical techniques were used to confirm the modification process and better understand the electrode's behavior. Then, depending on the operating conditions, the response signal was studied and adjusted in order to obtain optimal sensor performance. When optimized, the proposed method reached a lowest detection limit (LOD) of 2.15 µg L-1 (0.0104 µM), and quantification limit (LOQ) of 5.36 µg L-1 (0.0259 µM), in linearity range between from 6.2 and 20.7 µg L-1. Additionally, after having used the elaborated electrode for ten successive measurements, the repeatability remains very high with an RSD of approximately 5.3%; furthermore, ten other species appear to have very slight effect on Pb(II) detection. Finally, for the method validation, the proposed electrode was able to sense different lead concentration integrated in a local bottled spring water by showing recovery levels ranging from 103.8 to 108.4%.

Efficient removal of the antibiotic Cefixime on Mg0.3Zn0.7O under solar light: kinetic and mechanism studies.

The heterogeneous photocatalysis is known to provide significant degradation and mineralization of emerging contaminants including antibiotics. For this, nanosized Mg0.3Zn0.7O (MZO) was prepared by nitrate route to be used as photocatalyst. The single-phase was confirmed by X-ray diffraction with a crystallite size of 33 nm. The morphology was visualized by scanning electron microscope/energy-dispersive X-ray analysis. The physicochemical properties were studied by the FTIR, XPS, and optical analyses. The diffuse reflectance gives a direct forbidden band of 3.26 eV. The electrochemical characterization showed an n-type semiconductor with a flat band of - 0.56 VAg/AgCl. The photodegradation of Cefixime (CFX) was carried out under solar light; the operating parameters such as the catalyst dose, solution pH, and initial CFX concentration (Co) were optimized. The best performance occurs at neutral pH ~ 6 within 4 h with an abatement of 94% for an initial CFX concentration of 5 mg/L and MZO dose of 0.75 g/L. The photodegradation follows a first-order kinetic with an apparent rate constant of 0.012 min-1. The effects of scavenging agents indicated the dominant role of hydroxyl •OH followed by the holes (h+). The results showed the potentiality of MZO as an environmentally friendly photocatalyst for CFX photodegradation.