A research team led by Dr. Tizazu Mekonnen, professor of chemical engineering at the University of Waterloo, has developed a natural superabsorbent hydrogel that could replace the non-biodegradable materials currently used in disposable hygiene products. The material matches the performance of conventional absorbents while breaking down safely in soil within months, addressing a major source of long-term plastic waste.
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 diapers, menstrual pads, and tampons rely on superabsorbent polymers to capture and retain fluids. These polymers are typically petroleum-based and designed for durability, not degradation. As a result, billions of used hygiene products end up in landfills every year, where they can persist for centuries and contribute to microplastic pollution.
Dr. Tizazu Mekonnen, professor of chemical engineering at the University of Waterloo, stated,
“The potential benefits are threefold. Switching to biodegradable polymers would reduce long-term waste and microplastics, strengthen environmental sustainability and support compliance with emerging regulatory expectations.”
The new hydrogel, is made primarily from cellulose, a naturally abundant polymer found in plant matter. Mekonnen’s team combined two cellulose derivatives and used citric acid as a crosslinking agent to form a three-dimensional network capable of absorbing large volumes of liquid. All components were selected to ensure the material would remain biodegradable without compromising function.
According to the researchers, the hydrogel absorbs and retains fluid at levels comparable to, and in some cases better than, commercial synthetic absorbents. Importantly, when placed in soil, the material decomposes fully within approximately three months, leaving no detectable toxic residues. This contrasts sharply with conventional superabsorbent polymers, which can take hundreds of years to degrade.
To assess real-world performance, the team conducted tests designed to simulate conditions inside a diaper. They prepared synthetic urine containing salts and proteins and tested the hydrogel at body temperature. The material was evaluated for absorption capacity, retention under pressure, and resistance to leakage during movement. These tests were intended to reflect practical use cases, such as a baby sitting or crawling.
Safety was another key consideration. Dr. Evelyn Yim, a chemical engineering professor at Waterloo and co-author of the study, led biocompatibility testing by growing mammalian cells on the hydrogel surface. The results showed no signs of cytotoxicity, suggesting the material would be safe for prolonged contact with skin. Additional soil degradation studies confirmed that breakdown products did not harm the surrounding environment.
From an engineering perspective, the work addresses both materials design and manufacturability. The researchers focused on using low-cost, widely available raw materials and a synthesis process that could be scaled without specialized infrastructure. This approach increases the likelihood that the hydrogel could be integrated into existing manufacturing lines with minimal modification.
The research aligns with broader efforts to reduce the environmental footprint of consumer products, particularly those designed for single use. Global estimates indicate that hundreds of millions of disposable diapers are discarded daily, alongside large volumes of menstrual hygiene products. Replacing even a fraction of the absorbent material in these products with biodegradable alternatives could significantly reduce long-term waste accumulation.
The University of Waterloo team has filed a patent for the technology and is working with CTK Bio Canada, an industrial partner based in Vancouver, to explore commercialization pathways. Future work will focus on refining the material’s properties for different product formats and evaluating performance at pilot production scales.
Rather than proposing a radical redesign of hygiene products, the study offers a materials-level substitution that preserves functionality while reducing environmental impact. By demonstrating that high-performance absorbent polymers do not have to be persistent plastics, the work provides a practical example of how chemical engineering can contribute to more sustainable consumer goods.
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).
