Gas bubbles grown on solids are more than simple vehicles for gas transport. They are charged particles with surfaces populated with exchangeable ions. We here unveil a gateway for alkali metal ion transport between oxygen bubbles and semi-conducting (iron oxide) and conducting (gold) surfaces. This gateway was identified by electrochemical impedance spectroscopy using an ultramicroelectrode in direct contact with bubbles pinned onto these solid surfaces. We show that this gateway is naturally present at open circuit potentials, and that negative electric potentials applied through the solid enhance ion transport. In contrast, positive potentials or contact with an insulator (polytetrafluoroethylene) attenuates transport. We propose that this gateway is generated by overlapping electric double layers of bubbles and surfaces of contrasting (electro)chemical potentials. Knowledge of this ion transfer phenomenon is essential for understanding electric shielding and reaction overpotential caused by bubbles on catalysts. This has especially important ramifications for predicting processes including mineral flotation, microfluidics, pore water geochemistry, and fuel cell technology.

The electrochemical grafting of the “in-situ” prepared diazopyridinium salt have permitted the attachment of pyridine moieties onto platinum and glassy carbon surfaces. The modification of the electrode surfaces is observed by a redox probe. The ability of the film for the complexation of copper (II) ions is demonstrated by square wave voltammetry. After 45 min accumulation of copper (II) ions onto the grafted electrode surfaces, the electrode signal obtained by square wave voltammetry measurement served to discriminate the adsorbed heavy metal ions. Such measurements showed that the grafted pyridine has the ability to display complexing behavior toward some heavy metal ions. DFT calculations support a strong binding of the pyridine moieties onto the Pt surface. The most favorable complexation mode of copper (II) ions as suggested from DFT is the bidentate complex. This strategy is vital in constructing a wide range of different electrochemical sensors.

Surface modification is a hot topic in electrochemistry and material sciences because it affects the way materials are used. In this paper, a method for covalently attaching carboxyphenyl (PhCOOH) groups to a gold electrode is presented. These groups were grafted onto the electrode surface electrochemically via reduction of aryldiazonium salt. The resulting grafted surface was characterized using cyclic voltammetry (CV) before and after the functionalization procedure to validate the presence of the grafted layer. The grafting of PhCOOH groups was confirmed by analyzing electrode thickness and composition by ellipsometry and X-ray photoelectron spectroscopy (XPS). Density functional theory (DFT) calculations indicated that the grafted layers provide a stable platform and resolved, for the first time, their interactions with oxygen.

This study aimed to evaluate the discharge waters in the Nerodime River and the impact of the seasons on the quality of the surface waters in the Nerodime River. Research data were collected at six locations along the Nerodime River in three seasons of 2021. During this research, 14 physico-chemical parameters and total coliform bacteria were analyzed. Based on the study results, most of the tested parameters are above the maximum values allowed in conformity with the legislation in Kosova (Administrative Instruction (MMPH) No. 30/2014 and Administrative Instruction (MMPH) No. 16/2012). CCA (canonical correspondence analysis) indicates that Total coliform bacteria were in positive correlation with turbidity, color, chlorides, sulphates, and total coliform bacteria. This Poor quality is a consequence of anthropogenic activities including industrial water use and sewage discharge.