Adsorption of cadmium using teak leaves powder (Tectona grandis sp.): embedding Mahaffy's tetrahedral concept in undergraduate chemical engineering capstone lab project

Chemical engineering education can be aptly structured on four central components: macroscopic, particulate, symbolic, and human element domains; known as the Mahaffy's tetrahedral concept. This paper discusses the application of the concept of undergraduate chemical engineering capstone projects. The capstone was carried out as an undergraduate final laboratory project to investigate the adsorption of heavy metal, namely cadmium (Cd), using powder of teak leaves (Tectona grandis sp.). The lab experiment was environmentally safe, completed at ambient temperatures and that the experimental data collection was easy. It was actively guided by lecturers in a way to encourage meaningful lab experience as proposed in the Mahaffy's tetrahedral idea. Three experimental variables were investigated: initial pH solution, adsorbent dosage, and initial concentration of Cd. The results were analyzed to determine the diffusion mechanism and kinetics through Weber-and-Morris intra-particle diffusion model. The experimental results agreed with most published literature which gave satisfaction on both students and lecturers. To assess learning outcomes, pre- and post-evaluations in regard the Mahaffy's tetrahedral idea was employed. The post-test scores were significantly higher than those of the pre-test indicating that the learning outcomes were achieved. The lab project was also found to increase the student's writing and presentation skills. (paper)