From Waste to Wealth: An Integrated and Green Chemistry Experiment on Fabricating Smartphone-Based Fluorescent Sensors for Tetracycline Detection

This comprehensive experiment presents an innovative, multidisciplinary project designed for undergraduate students, integrating the principles of analytical chemistry, environmental protection, and digital literacy. Students turn waste orange peels into nitrogen-doped carbon quantum dots (N-CDs) via a facile hydrothermal synthesis. These N-CDs are then combined with Eu³⁺ ions to construct a fluorescent sensing system for the detection of tetracycline (TC), thereby enabling students to grasp the concept of waste valorization. The experiment culminates with the development of a portable, solid-state hydrogel kit, and students use a smartphone to perform quantitative RGB analysis, achieving a detection limit of 40.604 μmol·L^–1. Over the course of this project, students gain hands-on experience in nanomaterial synthesis, fluorescence spectroscopy, sensor design, and data analysis using modern digital technology. This comprehensive approach not only reinforces fundamental chemical concepts but also fosters critical thinking and highlights the role of chemistry in addressing real-world environmental challenges.