Undergraduate students were exposed to hands-on novel desalination laboratory experiments in an attempt to generate interest towards research in the broad field of environmental engineering and specifically in the field of water desalination. The laboratory exercises were designed to introduce desalination techniques, enhance their learning experiences, generate interest among them, and prepare them as potential researchers in laboratory settings. The hands-on experience of capacitive deionization (CDI) based laboratory experiments provided foundational and working knowledge of the CDI concept and allowed students to learn basic methodology followed in environmental laboratories to arrive at technical conclusions.
Students were given opportunity to desalinate water solutions using commercially available carbon aerogel fiber/paper electrodes at various conditions. Different parameters such as applied voltage, ambient temperature, initial concentration, flow rate, ion radius were varied and effects on desalination performance were observed. The teams were assigned one of these variables and asked to explore the effect its variation on desalination in using a semi-batch mode CDI experiment set up.
Students used conductivity meters to develop salinity vs conductivity calibration curves for a given salt type. Each team was asked to prepare and use their calibration curve to measure the salinity levels of 2 to 3 solutions of unknown salinity of the same salt. Each team was asked to adopt a basic CDI reactor and were provided with basic material, equipment and supplies and guidelines for the project. A salt solution was pumped through the reactors in a continuously re-cycled (multi-pass) mode. The conductivity was measured in a reservoir. Students were asked to do mass-balance calculations on total quantity of the salt removed using initial and final concentrations, and the volumes of the solutions used in their experiments. Students explored the effects of various operating conditions on desalination.
The hands-on experience focused on design-build-operate approach starting from preparation of solutions of varying concentrations, preparing calibration curves, adopting a reactor with a basic design and operating it under variable conditions exposed students to fundamentals of experimental research. Pre/post-activity surveys were conducted to measure the students' experiences on specific aspects of the laboratory assignments and their change of interest in environmental engineering. The results have been encouraging and provide deeper insight into the whole process.
This experience made a positive impact on students. General trend, based on pre/post activity surveys, shows that students are more interested in environmental engineering post activity and feel more confident about their abilities to solve real-world problems in water related issues. Students liked the format of group activities. Some of them are interested in pursuing a graduate degree and/or career in environmental engineering because project related activities provided them a good exposure and generated greater interest.
- Water filtration,
- CDI cell
Available at: http://works.bepress.com/sanjay-tewari/14/