Peels to Polymers: Food Waste Hydrogels as Low-Cost Alternatives to Commercial Hydrogels for Drought Resilience

Overview

To combat drought, runoff, and costly, synthetic commercial hydrogels, this project evaluates whether hydrogels derived from fruit waste, banana peels, orange peels, and apple pomace, serve as alternatives to commercial hydrogels, agar and sodium alginate, for improving soil water retention and drought resilience. Pectin was extracted from fruit peels using thermal extraction, filtered, and strengthened with sodium alginate and glycerol. A calcium chloride solution was added to form ionic crosslinks with sodium alginate, creating a stable network. Commercial hydrogels were prepared using agar or sodium alginate with glycerol. Hydrogels were incorporated into 100 g of soil at a 0.5% w/w concentration and tested for 25 days, with wet mass estimated using literature-based dry polymer yield values. Orange-based hydrogels demonstrated the highest water retention (29%) and pot mass growth, increasing it by 19 g (16.1%), as well as the highest cost-effectiveness of 0.0203L per $0 spent on raw materials. Banana-based hydrogels produced the most radish seedling growth, reaching an average height of 8.6 cm and leaf area of 4.18 cm². During drought, banana hydrogels achieved the lowest wilting score (2.6 on a 1–5 scale, where 5 indicates plant death) and delayed wilting to 7.8 days. During recovery, banana treatments reduced wilting by 1.2 points and increased plant height by 2 cm, while commercial hydrogels reduced wilting by 0.6–0.8 points. Fruit-waste hydrogels outperformed commercial options, demonstrating potential as a sustainable, scalable, and cost-effective solution for improving agricultural growth under drought conditions.

Competition history

• CSEF 2026 Earth & Environmental Sciences (Junior Division) · Entry J-08-26

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