Master Student Hồ Thị Xuân Giang and Võ Kim Ngọc Successfully Defend Master’s Thesis

On the afternoon of December 30, 2024, the Faculty of Chemistry organized the master’s thesis defense session for graduate student Hồ Thị Xuân Giang and Võ Kim Ngọc, majoring in Theoretical Chemistry and Physical Chemistry. Under the academic supervision of Associate Professor Dr. Trần Văn Mẫn.

Thesis of Hồ Thị Xuân Giang student: “Study on corrosion of some lead alloys in sulfuric acid by electrochemical method”

In this thesis, various lead alloys were selected and optimized, focusing on new alloys or novel compositional ratios. The study investigated lead alloys containing additional elements such as Ca, Sn, Ag, Sb, and others. These trace elements were examined for their potential to enhance the corrosion resistance of lead. The research analyzed the effects of individual alloy components, evaluating how each alloying element influences corrosion mechanisms. Comparisons were drawn between new alloys and traditional ones, as well as between the corrosion resistance of the newly developed lead alloys and that of pure lead or commonly used alloys (e.g., Pb-Sb-Ag and Pb-Ca-Sn alloys). 

The objective of the thesis was to examine the electrochemical properties of selected Pb alloys, studying their electrochemical corrosion behavior as electrode frameworks in H₂SO₄ electrolyte solutions. Corrosion resistance was evaluated using electrochemical impedance spectroscopy and linear sweep voltammetry methods.

Thesis of Võ Kim Ngọc student: “Investigates the fabrication of electrodes and their application as cathodes in single-chamber microbial fuel cells (MFCs)”

This study investigates the fabrication of electrodes and their application as cathodes in single-chamber microbial fuel cells (MFCs): (1) Carbon C65-based electrodes were created and subsequently coated with MnO2 through an electrochemical deposition method, with 5, 10, and 15 minutes of deposition durations. The manganese (Mn) content on the electrode surface ranged between 1.22 and 1.85 mg/cm², as determined by atomic absorption spectroscopy (AAS). X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) analyses confirmed the presence of Mn and oxygen signals corresponding to manganese dioxide (MnO₂), validating the successful fabrication of 5-MnO₂/C65, 10-MnO₂/C65, and 15-MnO₂/C65 electrodes via electrochemical deposition. Scanning electron microscope (SEM) images displayed a flower-flake-like distribution of MnO₂, contributing to an increased specific surface area of the electrodes. Electrochemical measurements revealed that MnO2/C65 electrodes demonstrated catalytic activity for oxygen reduction, with 5-MnO2/C65 and 10-MnO2/C65 exhibiting comparable performance, surpassing that of the C65 electrode. (2) The constructed electrodes were then used as cathodes in single-chamber MFCs inoculated with Pseudomonas aeruginosa PR3, aiming to evaluate their performance in a glucose medium and bamboo biomass hydrolysate: Single-chamber microbial fuel cells (MFCs) featuring air cathodes were successfully established and operated as part of this study. The MFCs inoculated with Pseudomonas aeruginosa PR3 exhibited superior electrochemical performance compared to those without microbial inoculation. Notably, the 5-MnO2/C65-MFC system demonstrated the highest performance among the MnO2/C65-MFC electrodes, outperforming the C65-MFC samples in glucose medium and bamboo biomass hydrolysate. Specifically, the maximum open circuit voltage (OCV) recorded was 420 mV, 1.7 times greater than that of the C65-MFC. In terms of substrate degradation efficiency, after 72 hours, the 5-MnO2/C65-MFC consumed 90.7% of reducing sugars and achieved a 75.7% reduction in chemical oxygen demand (COD), compared to 87.3% and 68.6%, respectively, for the C65-MFC. Additionally, regarding MFC performance, the 5-MnO2/C65-MFC achieved a short-circuit current density of 198.1 mA/m² (1.43 times higher) and a power density of 13.7 mW/m² (2.04 times higher) than the C65-MFC.