Sustainable Papermaking from Vegetable Waste: Turning Onion and Garlic Peels into Handmade Paper─An Educational Experiment in Green Chemistry and Circular Economy

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This laboratory experiment introduces undergraduate students to green chemistry and circular economy principles by converting onion (Allium cepa) and garlic (Allium sativum) peels, abundant in agricultural waste from local markets, into functional handmade paper. Students employ neutral autohydrolysis, mechanical fibrillation, and mild oxidative bleaching to produce paper sheets without harsh alkali treatment. The experiment requires one 3-h laboratory session plus overnight drying, and a subsequent ∼30 min characterization session the following day uses less than 50 rupees (∼\$0.60 USD) of materials per batch and provides hands-on experience with lignocellulosic chemistry, hydrogen bonding, and waste-to-wealth concepts. Pre- and post-lab assessment data from 24 undergraduate students showed improvement from 29% to 83% correct identification of hydrogen bonding in cellulose and from 33% to 79% correct explanation of autohydrolysis. The protocol is safe, reproducible, and suitable for introductory chemistry, environmental science, or materials science courses.