Abstract:

In this study, we develop an innovative and comprehensive method for extracting Au from electronic scrap. Au recycling from electronic waste is a popular topic for chemistry students and the general public. To implement the latest scientific knowledge and methods, herein, Au recovery via the reaction of α-cyclodextrin with [AuBr₄]^- is used as the basic principle. The procedure used to recycle Au from electronic waste comprises four steps: dilute nitric acid is used to decrease the unwanted metal content of electronic waste (Au enrichment); Au is subjected to mild oxidation using a potassium bromide-acetic acid-nitric acid system (Au dissolution); α-cyclodextrin is reacted with [AuBr₄]^- (Au extraction); Au(Ⅲ) is reduced to Au(0) using sodium metabisulfite, a non-toxic and non-metallic reducing agent (Au formation). The experiments involve multi-disciplinary principles, such as inorganic, supramolecular, and analytical chemistry concepts. Furthermore, they cover the basic operations of synthesis and analytical experiments including reaction monitoring, structural characterization, and purity analysis. The experimental results are conspicuous, the experiments are repeatable, and the purity of Au is above 90%. Moreover, the time required to perform the experiments ranges between 6 and 8 h. Therefore, the experiments are suitable for undergraduate comprehensive chemistry laboratory teaching. In addition, green chemistry concepts and experimental methods are incorporated as the reagents are environmentally friendly and safe to handle. This experiment demonstrates the critical role of chemistry in solving national economy problems and improving the livelihood of humankind. Through a thorough teaching approach comprising online and offline modules, this experiment cultivates the scientific thinking patterns and innate curiosity of students, improves the ability of undergraduate chemistry students to solve complex synthetic chemistry problems, and consolidates the knowledge of chemistry trainees.

Key words: Innovative comprehensive experiments, α-cyclodextrin, Supramolecular recognition, Electronic waste, Green Au extraction