Technical Faculty in Bor
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Electrochemical behavior of copper in chloride medium in the presence of pine cone macerate
(University of Belgrade - Technical Faculty in Bor, 2025) Grekulović, Vesna; Zdravković, Milica; Gorgievski, Milan; Štrbac, Nada; Marković, Miljan; Marković, Marina; Božinović, Kristina
The article presents the results of the study of the electrochemical behavior of copper during oxidation in a 0.5 mol/dm3 NaCl solution in the absence and presence of pine cone macerate of different concentrations. The electrochemical behavior of copper was investigated using the cyclic voltammetry method and the potentiostatic method. The results of cyclic voltammetry show that three current peaks appear on the anodic polarization curves, which correspond to the formation of copper chloride and copper oxide. Potentiostatic polarization was performed at 0.5 mV vs. SCE for 100 s and at 25oC. Potentiostatic curves show that the steady-state currents decrease with increasing concentration of macerate in the electrolyte. Microscopic images confirm that a protective layer has formed on the copper surface in the presence of the pine cone macerate, which prevents the corrosion process.
Extraction of bioactive compounds from nettle seeds as a potential inhibitor of metal corrosion
(University of Belgrade - Technical Faculty in Bor, 2025) Zdravković, Milica; Huseinović, Edina; Dedić, Jasmina; Horozić, Emir; Grekulović, Vesna
The aim of the research is to determine the effectiveness of ultrasonic extraction of nettle seeds (Urtica dioica) whose products can be used as potential metal corrosion inhibitors. Different solvents were used (water, methanol, ethanol, acetone) in terms of total phenol content (TPC), flavonoids (TFC) and antioxidant activity (DPPH and FRAP). The results show that the aqueous extracts have the highest TPC and antioxidant capacity in both tests. The high correlation between TPC and antioxidant activity (R ≈ 0.98) confirms that phenolic compounds are key contributors to antioxidant capacity. These findings suggest that nettle seeds can be examined as a potential metal corrosion inhibitor.
HPLC-DAD identification of compounds in corrosion inhibitor Salix alba bark extract and the hydrolate
(University of Belgrade - Technical Faculty in Bor, 2025) Zdravković, Milica; Savić Jovanović, Slađana; Grekulović, Vesna; Stanković, Dalibor
The compounds present in Salix alba bark (SAB) extract and its hydrolate were identified using highperformance liquid chromatography with diode array detection (HPLC-DAD). SAB extract and its hydrolate were obtained by evaporating a macerate of dried, ground white willow bark and hot distilled water. A total of 19 standard polyphenolic compounds were used for the HPLC analysis. Results indicate that only 4-hydroxybenzoic acid (4-HBA) was detected in the SAB hydrolate. In contrast, both gallic acid and caffeic acid were present in the SAB extract. The presence of 4-HBA indicates the potential possibility of using SAB hydrolate as a starting component for the synthesis of parabens and other 4-HBA derivatives. Additionally, the identification of gallic and caffeic acids in the SAB extract further confirms the effect as a cathodic inhibitor of copper corrosion in chloride environments, because both acids are proven cathodic inhibitors of copper in different corrosion environments.
ATR-FTIR characterization of the white willow bark extract used as a copper corrosion inhibitor
(University of Belgrade - Technical Faculty in Bor, 2025) Zdravković, Milica; Savić Jovanović, Slađana; Grekulović, Vesna; Stanković, Dalibor; Dimitrievska, Iva
As proved inhibitor of copper corrosion in saline environment, the white willow bark (WWB) extract was characterized using the Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy (ATRFTIR) method. By identifying the bands typical for phenolic profile of WWB extract, the anti-corrodic properties of WWB were explained. The hydrogen-bonded O-H stretching vibrations present in WWB extract is attributed to the phenolic hydroxyl groups and alcoholic hydroxyl groups within glycosides. The C-H stretching vibrations typical for salicin and for glucoside part of salicin aromatic were also identified, as well as the C=C ring stretching vibrations and C-O stretching vibrations that can be attributed to phenolic and alcoholic groups. The presence of these functional groups confirms the presence of a protective film of the WWB extract on the copper surface, protecting the metal from the corrosive effect of chloride ions.
On the leachability of copper from copper-iron minerals mixture
(University of Belgrade - Technical Faculty in Bor, 2025) Stanković, Velizar; Marković, Miljan; Gorgievski, Milan; Đorđievski, Stefan
Sulphuric acid leaching of the ore sample from the MCM (Mauritanian Copper Mine) was carried out. The achieved leaching degree was ≤ 38%. To improve copper leachability from the ore, TG (thermogravimetric), DSC (differential scanning calorimetry, and DTA (analyses differential thermal analysis) were conducted on the ore, and XRD (X-ray diffraction) analysis was performed on the leach residue. Thermal analysis has shown that goethite quickly transforms to hematite at ≈ 300 °C. The XRD pattern reveals the presence of four main minerals in the leach residue of the ore sample. Among them, the goethite peaks are the most intense. It seems as if the decomposition of goethite (thermally or chemically) could be a cornerstone in increasing the copper leaching degree. Both pathways were checked, and in both cases, a significant increase in the leaching degree was achieved.