Laboratory Experiments on Electrochemical Remediation of the Environment. Part 2: Microscale Indirect Electrolytic Destruction of Organic Wastes

The objective of this experiment is to destroy, at the microscale level, a sample of surrogate organic waste by generating a powerful oxidizer at the anode of an electrochemical cell. This generated species oxidizes the waste to harmless products. The oxidizer can then be regenerated and recycled. Specifically, this experiment utilizes a redox mediator with a high standard potential (i.e., the Co (III/II) couple, E° = 1.82 V) to destroy a surrogate organic waste (e.g., glycerin or acetic acid) by converting it into CO2 and water. Students can observe the end of the reaction signaled by a color change of the electrolytic medium (from pink to gray-light purple) as well as the evolution of CO2 which precipitates CaCO3 from a Ca(OH)2 solution. The Co(II) solution and the electrodes can then be reused.