Panyawut Cher Tonanon

Boron-doped diamond and titanium suboxides have been proposed as electrode materials for use as anodes in future electrochemical devices, most likely in remote locations for potable water purification, or for specialized disinfection applications in decentralized systems. A comparison is made between electrochemical purification strategies that do not require added chemicals and systems that do, with emphasis given toward Magnéli electrode-based electrochemical disinfection and iodine-based electrochemical disinfection systems. Both systems with and without added chemicals come with advantages and disadvantages. The outlook of these emerging processes concludes this review.

Two new techniques for analyzing praziquantel (PZQ), an effective antiparasitic drug used in fresh and saltwater aquariums, were optimized and compared statistically. , Two new techniques for analyzing praziquantel (PZQ), an effective antiparasitic drug used in fresh and saltwater aquariums, were optimized and compared. One method was based on voltammetry and the other method used gas chromatography combined with mass spectrometry (GC-MS), although both procedures utilized the same sample pretreatment strategy which involved the PZQ being quantitatively transferred into acetonitrile using solid phase extraction. GC-MS analysis led to lower limits of detection (0.32 μM, 0.10 ppm) and quantification (0.72 μM, 0.22 ppm) compared to voltammetry, although both methods gave acceptable quantification for levels of PZQ \textgreater 25 μM (7.8 ppm). GC-MS is preferred for the most accurate determination, but voltammetry may provide a cost-effective alternative for detecting PZQ where on site testing is required.

The electrochemical reduction of riboflavin (vitamin B2) in a dimethyl sulfoxide solvent was examined under a CO2 atmosphere and compared with results under an argon atmosphere. Variable-scan-rate cyclic voltammetry combined with controlled potential electrolysis (CPE) and analysis by UV–vis and EPR spectroscopies provided insights into the nature of interactions of reduced flavins with dissolved CO2. Reductive exhaustive CPE experiments under CO2 indicated an overall two-electron stoichiometry, compared to one-electron reduction under an argon atmosphere, due to the lowering of the formal one-electron reduction potential of the flavin radical anion to form the dianion, which can be rationalized by riboflavin–CO2 molecular interactions. UV–vis spectroscopic measurements confirmed complete chemical reversibility of the redox transformations over extended time scales. Digital simulation modeling of the voltammetric data enabled extraction of thermodynamic and kinetic parameters for the proposed mechanism, comprising multiple proton-coupled electron transfer steps, diamagnetic anions, radical anions, and neutral radical intermediates enroute to the fully reduced state, as well as evidence of a long-lived solution phase complex of the reduced riboflavin with CO2.

This thesis explores novel applications of analytical electrochemistry in addressing environmental challenges and advancing pharmaceutical analysis, focusing on three main areas: water disinfection, pharmaceutical compound detection, and carbon dioxide capture and utilization. In the first study, platinized titanium electrodes were investigated for their efficacy in inactivating Escherichia coli in water through electrochemical processes. The research elucidated the mechanisms underlying the disinfection process, particularly the generation and role of reactive oxygen species, demonstrating feasible rapid disinfection even at low electrolyte concentrations. The second study developed and optimized methods for detecting and quantifying praziquantel, an important antiparasitic drug, in water samples. Two techniques were compared: gas chromatography-mass spectrometry (GC-MS) and voltammetry, both utilizing solid phase extraction for sample preparation. While GC-MS showed lower detection limits, the voltametric method demonstrated comparable accuracy and precision, offering a potentially more cost-effective and portable alternative for on-site testing. The final study explored the electrochemistry of organic molecules, specifically quinones and flavins (vitamin B2), for potential applications in carbon dioxide capture and energy storage. The research investigated the molecular interactions between reduced organic species and CO2, as well as their electrochemical behavior under various conditions, providing insights into the development of novel carbon capture technologies and organic-based energy storage systems. Throughout these investigations, the thesis demonstrates the versatility and power of analytical electrochemistry in addressing diverse challenges in environmental remediation, pharmaceutical analysis, and sustainable energy technologies. The research contributes to the advancement of electrochemical methods and their practical applications in these critical areas.

This study explores the feasibility of using platinized titanium electrodes for the electrochemical inactivation of Escherichia coli (E. coli), with the aim of developing an efficient and sustainable water disinfection method in low ionic strength media similar to what exists in potable water. A comparative analysis between two-electrode and three-electrode configurations revealed the superiority of the three-electrode system in achieving higher current throughput and enhanced bacterial inactivation efficiency. This improvement is attributed to the potentiostat’s ability to compensate for solution resistance (IR drop) through the inclusion of the reference electrode, ensuring more stable and controlled electrochemical conditions. The inactivation of E. coli in various electrolyte solutions followed a logarithmic decay pattern (pseudo first-order), with no significant difference observed among the electrolytes tested, except for sodium chloride. The enhanced bactericidal activity in the presence of NaCl was attributed to the generation of chlorine species. These findings provide insights into optimizing electrochemical disinfection systems and highlight the potential of three-electrode configurations for practical water treatment applications in low-conductivity environments.