Optimization in Electrochemistry: New Methods in Sonoelectrochemistry, Electrochemical Separations, and Education

Optimization is a component critical to method development. Mathematical modeling of physical phenomena enables an efficient search for the parameters and conditions that optimize methods and systems. Here, optimization of methods in sonoelectrochemistry, electrochemical separations, electrochemical education, and assessment of diabetic status are discussed. Sonochemistry is widely used in applications that include catalysis, synthesis, nanoparticle formation, analysis, and plating. In classical sonoelectrochemistry (CS), a high power transducer delivers ultrasound to a bulk fluid that contains the working electrode. The high frequency ultrasound deposits sufficient energy at the electrode to enhance kinetic rates and increase mass transport. These enhancements are at the cost of a disrupted diffusion layer that disallows quantitative assessment of electron transfer kinetics. An alternative is thin layer sonoelectrochemistry (TLS) where ultrasound from a low power transducer (e.g., quartz crystal oscillator) delivers ultrasound into a thin fluid layer with thickness on the order of the ultrasonic wavelength. TLS is designed to focus and transduce energy at the electrode|solution interface. Experience has shown the difficulties in construction of a reliable and reproducible setup for TLS. Here, mathematical modeling and optimization of TLS is presented. The results indicate that input sound, amplified through constructive interference and resonance, achieves energy delivery commensurate with CS. A stepwise checklist of provided to improve setup reliability and reproducibility. Electrochemical separation is used for the extraction and purification of metals used in important technological devices (e.g., batteries and motors). Reliance of modern society on technological devices, has sharply increased demand for high purity materials. Traditional electrochemical separation relies on differences in thermodynamic formal or standard potentials that restrict separations to systems where formal potentials differ by several hundred millivolts. This difference disallows many important separations. Here, a mathematical model for electrochemical separation in a monolayer is discussed. The monolayer contains two species with identical initial concentration and formal potential but different standard heterogeneous rate constants. Standard heterogeneous rate constants characterize the rate of electron transfer between the electrode and redox species immediately at the electrode surface. Inclusion of the kinetics of deposition opens access to many separations previously considered impossible. A general optimal waveform enables kinetically based separations. To more easily implement the separation with common electrochemical devices an approximation comprised of only ramps and steps is provided. Educational demonstrations of diffusion are often complicated and require expensive laboratory equipment. Here, a demonstration of diffusion based on physical therapy putty is provided to address the deficiency in simple and inexpensive demonstrations in the literature. Physical therapy putty is nontoxic and can be acquired online from many commercial sources. The expansion of physical therapy emulates a diffusional process where the radius is an analog for the diffusion length. The difference between radial and linear diffusion is discussed and the arial rates for physical therapy putty are calculated and used to demonstrate the diffusion coefficient. Discussion questions are provided that are designed to encourage students to form a hypothesis, design an experiment, analyze data, and discuss the results. Type 1 Diabetes (T1D) is a disease that limits the ability of an individual to regulate blood sugar. T1D affects nearly 34.2 million people in the US where 11.7 million people are diagnosed globally each year. Without sufficient assessment and regulation of blood sugar, fatal complications can result. At present, assessment of diabetic status involves often invasive and painful extraction of a blood sample for use with a personal glucose meter. Recently, alternative body fluids (e.g., sweat, tears, and saliva) have been investigated for biomarkers that indicate diabetic status (e.g., lactate and blood ketones). Here, the initial studies for a non-enzymatic sensor for [beta]-hydroxybutyrate, a blood ketone, are presented. The feasibility of the method in development of a sensor is discussed. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]