Klodian Xhanari

Green corrosion inhibitors for aluminium and its alloys: a review

This review summarises the research work published in the last two decades on the use of natural compounds as corrosion inhibitors for aluminium and aluminium alloys in different solutions. Herein, plant extracts, gums, drugs, and oils have been considered as green corrosion inhibitors. The advantages and disadvantages of the methods used to obtain green corrosion inhibitors are presented. Additionally, the inhibition effectiveness of these corrosion inhibitors, including the techniques used to evaluate them and the respective inhibition mechanisms, are discussed. Finally, a critical evaluation is presented together with the outlook as regards possible future improvements.

Organic corrosion inhibitors for aluminium and its alloys in acid solutions: a review

The aim of this review is to summarise the research work published in the last two decades on the use of organic compounds as corrosion inhibitors for aluminium and its alloys in acidic solutions. The focus is on HCl and H2SO4 solutions due to their extensive use in different applications, such as chemical and electrochemical etching, acid cleaning, anodising, and acid pickling of aluminium. Other acids are also reviewed. The inhibition effectiveness of numerous organic compounds and their possible inhibition type and mechanism are also discussed. Electrochemistry is mainly used to investigate inhibitor performance.

Novel ethanol-induced pectin–xanthan aerogel coatings for orthopedic applications

In this study, we developed a novel high methoxyl pectin-xanthan aerogel coating on medical-grade stainless steel, prepared by ethanol-induced gelation and subsequent supercritical drying. Two non-steroidal anti-inflammatory drugs, i.e. diclofenac sodium and indomethacin, were incorporated into the aerogel coating. Electrochemical analyses were performed on the coated samples using electrochemical impedance spectroscopy and cyclic polarization techniques. The results showed that all passivated samples were highly resistant to general corrosion. The release of both non-steroidal anti-inflammatory drugs was complete after 24h, as confirmed by the plateau in the drug release profiles as well as by IR spectroscopy after the final release point. The potential of samples for use in orthopedic applications was evaluated on a human bone-derived osteoblast cell and all samples were shown to be biocompatible. The increased viability of some samples indicates the high potential of the developed approach for future evaluation of possible clinical use.

The first electrochemical and surface analysis of 2-aminobenzimidazole as a corrosion inhibitor for copper in chloride solution

For the first time, 2-aminobenzimidazole (2-ABI) was tested as a corrosion inhibitor for copper in 3 wt% NaCl solution at 25 °C using cyclic voltammetry (CV), chronopotentiometry, electrochemical impedance spectroscopy (EIS), and potentiodynamic curve (PD) techniques. The EIS measurements indicated that the corrosion of Cu in the presence of 2-ABI followed kinetic- and diffusion-controlled processes. After 100 h of immersion, the potentiodynamic curves showed that 2-ABI acts as a mixed-type inhibitor, with a predominant action on the anodic corrosion reaction. ATR-FTIR confirmed the adsorption of 2-ABI on the Cu surface, which resulted in increased hydrophobicity of the copper surface and reduced its surface roughness.

A detailed electrochemical impedance spectroscopy study of a bismuth-film glassy carbon electrode for trace metal analysis

A systematic electrochemical impedance spectroscopy (EIS) analysis at different potentials of an in situ-prepared bismuth-film glassy carbon electrode (BiFE) in 0.1 M acetate buffer solution is reported. This electrode is employed in the square-wave anodic stripping voltammetry (SWASV) technique for the determination of trace amounts of the heavy metals Zn, Cd, and Pb. The method was first validated for detection limit, linear range, sensitivity, precision and accuracy to clearly prove the superior action of BiFE compared with the bare glassy carbon electrode (GCE). Next, in order to investigate the characteristics of this sensor, EIS measurements were carried out at slightly more negative potentials than the potentials at which each individual stripping signal is detected, after the deposition step at different deposition potentials. For comparison, EIS measurements were also performed at open circuit potential. The studied trace metal concentration range (5-20 ppb) did not significantly influence the capacitive and resistive behaviour of the BiFE which explains why the performance of this sensor is superior compared with the bare GCE. The higher sensitivity of the SWASV method for BiFE compared with the bare GCE was explained by the lower polarisation resistance values of the former. Moreover, the potential of zero charge was also determined, and an explanation whether the system is under kinetic- and/or diffusion-controlled process is given.

A combination of interdisciplinary analytical tools for evaluation of multi-layered coatings on medical grade stainless steel for biomedical applications

Graphical abstract Figure. No caption available. HighlightsCombination of interdisciplinary analytical tools for analysis of multi‐layered coatings.First use of photothermal beam deflection spectroscopy for coating evaluation.New testing platform for medical grade steel materials for biomedical applications. Abstract In this comprehensive study several analytical techniques were used in order to evaluate multi‐layered biomedical surface coatings composed of a drug (diclofenac) and a polymer (chitosan). Such a thorough examination is of paramount importance in order to assure safety and prove efficiency of potential biomedical materials already at the in vitro level, hence leading to their potentially faster introduction to clinical trials. For the first time a novel technique based on thermal diffusivity and conductivity measurements (photothermal beam deflection spectroscopy – BDS) was employed in order to analyse in a non‐destructive way the thickness of respective layers, together with their thermal diffusivity and conductivity. In addition to attenuated total reflection Fourier‐transform infrared spectroscopy (ATR‐FTIR), BDS confirmed successive surface layers of the prepared coatings. Scanning electron microscopy and atomic force microscopy were used to examine structural information on the macro‐ and micro/nano‐scale, respectively. Surface hydrophobicity was measured with the contact angle analysis, which clearly showed differences in hydrophobicity between coated and non‐coated samples. Considering the targeted application of the prepared coatings (as implant in orthopaedic treatments), the in vitro drug release was analysed spectrophotometrically to examine the coatings potential for a controlled drug release. Furthermore, the material was also tested by electrochemical impedance spectroscopy and cyclic polarisation techniques, which were able to detect even minor differences between the performance of the coated and non‐coated materials. As the final test, the biocompatibility of the coatings with human osteoblasts was determined.