Researchers at the University of Waterloo, led by chemical engineer Dr. Tizazu Mekonnen, are addressing a long-standing materials problem in personal hygiene products by developing a biodegradable hydrogel designed to replace the petroleum-based absorbents used in disposable diapers, menstrual pads and tampons. The work focuses on reducing persistent plastic waste without sacrificing the performance standards required for products that manage large volumes of liquid under daily use.
Islam, M. S., Sproule, D., Yohans, J., Chenananporn, P., Yim, E., Gupta, A., & Mekonnen, T. H. (2025). Citric acid - crosslinked cellulose derivatives superabsorbent hydrogels (SAH) as sustainable alternatives for personal hygiene applications. Chemical Engineering Journal, 526, 170721. https://doi.org/10.1016/j.cej.2025.170721
Disposable hygiene products rely on superabsorbent polymers that can retain many times their own weight in fluid. These polymers are typically synthesized from fossil-derived materials and are engineered for stability, not degradation. As a result, they can persist in landfills for hundreds of years. Global waste estimates underline the scale of the issue, with hundreds of millions of diapers discarded every day and billions of menstrual products added to landfills annually. Researchers and policymakers have increasingly highlighted these materials as contributors to long-term plastic pollution and microplastic generation.
University of Waterloo, led by chemical engineer Dr. Tizazu Mekonnen, stated,
“We tested absorption capability and release under practical applications. We wanted to make sure it wouldn’t leak in real-life situations, such as a baby sitting and crawling in a wet diaper.”
The Waterloo team’s approach replaces synthetic polymers with cellulose-based components. Cellulose, an abundant plant-derived polymer, was chemically modified and crosslinked using citric acid to form a stable hydrogel network. According to the research, this structure allows the material to swell and retain liquid in a way comparable to, and in some tests exceeding, conventional superabsorbent polymers. At the same time, the hydrogel is designed to break down naturally in soil within a few months, leaving no harmful residues.
Laboratory testing focused on conditions that reflect real-world use rather than idealized benchmarks. To simulate diaper performance, the researchers used synthetic urine formulations at body temperature and measured absorption capacity, retention under pressure, and leakage during movement. These tests were intended to capture scenarios such as prolonged wear and mechanical stress. The material maintained liquid retention under compression, an essential requirement for hygiene applications.
Safety and environmental behavior were also central to the study. Cell culture experiments were conducted to assess biocompatibility, with results indicating no adverse effects on living cells. Degradation studies showed that as the hydrogel breaks down in soil, it does not release toxic by-products, addressing concerns about downstream environmental impact. Similar findings have been reported in related studies on cellulose-based absorbents, which have attracted attention for combining renewability with functional performance.
Beyond the laboratory, the research reflects a broader trend in materials engineering toward scalable, lower-impact alternatives for high-volume consumer products. Previous academic and industrial efforts have explored bio-based absorbents, but many have struggled with cost, performance consistency, or manufacturability. The Waterloo team emphasizes that their process was designed with large-scale production in mind, using widely available raw materials and relatively simple chemical steps.
Commercialization efforts are now underway. A patent has been filed, and the research group is working with an industrial partner to explore manufacturing pathways and integration into existing product lines. Regulatory pressures and sustainability targets are likely to accelerate interest in such materials, particularly as governments and manufacturers face growing scrutiny over single-use plastics.
While further testing and industrial validation will be required before the hydrogel appears in commercial products, the work illustrates how incremental advances in polymer chemistry can have broad environmental implications. By targeting a single but critical component of everyday products, the research highlights a practical route toward reducing persistent waste without requiring major changes in consumer behavior or product design.
Adrian graduated with a Masters Degree (1st Class Honours) in Chemical Engineering from Chester University along with Harris. His master’s research aimed to develop a standardadised clean water oxygenation transfer procedure to test bubble diffusers that are currently used in the wastewater industry commercial market. He has also undergone placments in both US and China primarely focused within the R&D department and is an associate member of the Institute of Chemical Engineers (IChemE).
