Teaching Practical Sonochemistry: Synthesis of Magnetic Nanomaterials

In this work, a practical experience that introduces the use of sonochemistry for nanomaterials synthesis is proposed with the aim of incorporating ultrasound concepts and their relationship with chemical reactions into chemistry undergraduate curricula. The proposed experience involves the synthesis of magnetic nanomaterials (bare and composite), followed by an evaluation of their characteristics, for example, average size and distribution, and relating them to theoretical aspects of ultrasound energy. Nanoparticle synthesis was carried out by the students following the procedures provided by the instructor. Students were required to interpret the results and create spaces for group discussion. Open discussion can be more productive for obtaining conclusions than answering closed questions. Students could observe that sonication provides shorter reaction times and increased reaction yield. In comparison to the conventional co-precipitation synthetic route, the ultrasound-assisted procedure reduces particle agglomeration and allows the formation of smaller particles. Changes in the size distribution, reaction time, and reaction yield were ascribed to physical effects (e.g., microjets and shockwaves) and chemical effects (e.g., generation of reactive free radicals) of ultrasound energy. The proposed practical experience could therefore contribute to consolidate theoretical aspects of ultrasound and experimental tasks that are specific to the area of sonochemistry synthesis, for a more comprehensive understanding of the different ultrasonic effects.