Scientists have turned invasive aquatic weeds into high-performance biodegradable sanitary napkins, demonstrating how sustainable materials can reduce plastic waste while maintaining menstrual hygiene safety.
Research: Biodegradable menstrual pads from hydrophilic weeds: sustainability assessment, absorption performance, and microbial safety. Image credit: Joel 100×35 Por.Ahi.PR / Shutterstock
A recent study published in the journal Processes developed a laboratory-scale approach to produce a biodegradable absorbent material for sanitary napkins from water hyacinth.
Effective menstrual protection is essential to the physical, mental and economic well-being of the approximately 300 million people who regularly menstruate. Access to safe, hygienic and affordable menstrual products is critical to preventing infectious diseases, supporting education and professional engagement, and maintaining dignity.
Modern menstrual protection methods have evolved to provide reliable and comfortable hygiene. Over the years, the use of disposable sanitary napkins has increased due to improved health literacy, social awareness, and government initiatives. Although these products are essential for health, they are poorly biodegradable and have a significant environmental impact if disposed of improperly.
Common sanitary napkins are made from non-biodegradable materials such as polyethylene, polypropylene, superabsorbent polymers, and polymer films. These substances remain in the environment for long periods of time and cause pollution. Widespread use of petroleum-based polymers will further increase carbon emissions, as petroleum-based polymers can persist for centuries and contribute to environmental pollution, including the potential production of harmful by-products such as dioxins and methane during certain waste treatment or disposal processes.
The synthetic fibers found in sanitary napkins, such as polyester and polypropylene, break down into microplastics due to environmental stress. Microplastics accumulate in ecosystems, contaminate water and soil, and enter the food chain, posing risks to living organisms and public health.
Research is increasingly focusing on biodegradable plant-based absorbents such as bamboo, banana fiber, corn husk, and agricultural residues to improve absorption and reduce environmental impact. However, much of this research has primarily focused on biodegradability and absorbability, with relatively limited investigation of antimicrobial performance during actual product use, which is important for microbial control and odor management.
Development of hyacinth-based biodegradable sanitary napkins
Water hyacinth (Eichhornia crassipes) is an invasive aquatic plant known for its rapid growth and high biomass, often posing significant environmental and economic challenges. Despite these problems, cellulose-rich, porous, renewable fibers exhibit excellent liquid absorption capacity. Previous studies have suggested that this plant contains compounds with natural antimicrobial activity, making it attractive for use in absorbent hygiene products.
Manufacturing process of sanitary napkins based on water hyacinth. The figure shows a series of steps including collection of Echhornia crassipes, fiber extraction and alkaline pretreatment (washing and neutralization), pulping and formation of cellulose sheets, and assembly of polymer-based layers. The final multilayer structure consists of a water hyacinth fiber sheet as the top layer, a composite absorbent core of cellulose and cotton, and a cornstarch-based biodegradable polymer film as the barrier layer.
Researchers developed sanitary napkins by blending cotton and water hyacinth fibers, creating a product that is effective, comfortable, safe, and environmentally sustainable. Cellulose-rich water hyacinth petioles were thoroughly washed and pulped using sodium hydroxide at 90 °C to produce absorbent fibers. These fibers were processed into absorbent sheets without the use of bleach or synthetic additives during sheet manufacturing.
The resulting sanitary pad featured a multilayer structure consisting of a top sheet of water hyacinth fibers in contact with the skin, an absorbent core to retain body fluids, and a biodegradable barrier to prevent leakage. By replacing some of the traditional synthetic components with soft, breathable and compostable water hyacinth fibers, this design improves both user comfort and environmental sustainability.
The alkali-treated fibers are powdered to increase surface area, increase absorbency, and ensure superior liquid absorption. A cornstarch-based barrier and canvas paper support provided leak protection and structural integrity, while heat sealing eliminated the need for synthetic adhesives and further made the product biodegradable.
Absorbency, an important property of menstrual pads, was evaluated by applying a fixed 10 mL methylene blue dye solution to the pads and recording the absorption time, thereby assessing the efficiency of the pads in managing menstrual flow. Biodegradability was determined by burying the pads in soil for 90 days at room temperature and measuring weight loss over time.
Improving the performance of hyacinth-based sanitary napkins
Absorbency testing demonstrated that both the water hyacinth and cotton pads absorbed 111 mL of liquid in this laboratory comparison, whereas the commercially available pads evaluated retained 71 mL under the same experimental conditions. This superior absorbency highlights the benefits of natural fiber products, as materials such as cotton and bamboo can absorb several times their weight, often outperforming some commercially available synthetic products in controlled laboratory tests.
Blending water hyacinth fibers with cotton further improves liquid retention and outperforms commercially available pads included in the comparison. Optimized material processing and fiber processing were key to achieving maximum absorbency with these natural fiber pads.
The pH level of sanitary napkins plays an important role in user comfort and vulvar health. The vagina maintains an acidic environment (pH 3.5 to 4.5), and sanitary napkins must have a pH of 6.0 to 8.5 to meet safety standards. The newly developed water hyacinth-based pad consistently exhibited a pH of 6.87, well within regulatory guidelines.
Bioburden testing, which measures microbial contamination in pads, showed that hyacinth-based sanitary napkins contained 360 CFU/g of bacteria and less than 1 CFU/g of yeast, both well below safety standards. This low presence of microorganisms confirmed the safety and quality of the product.
Make sure your sanitary napkins are free of pathogens such as: Staphylococcus aureus, Essential for user safety and skin compatibility. Tests have confirmed that water hyacinth pads are completely free of harmful substances. Staphylococcus aureus and other microbial growth has been observed, indicating excellent pathogen safety and suitability for prolonged skin contact.
Statistical analysis verified the pad’s skin-compatible pH, minimal microbial load, and absence of harmful bacteria, confirming compliance with safety standards.
Characterization and biodegradability of hyacinth-based sanitary napkins
Scanning electron microscopy (SEM) analysis revealed that untreated water hyacinth fibers were coated with lignin, pectin, and hemicellulose, making individual fibers difficult to see. After alkali treatment, these impurities were removed, producing a rougher fiber surface and stronger fiber-to-fiber interactions.
Fourier transform infrared (FTIR) spectroscopy confirmed that the chemical treatment increased the relative cellulose content and decreased the signals associated with hemicellulose and lignin components. This was evident from a prominent cellulose absorption band and a decrease in signal from non-cellulosic components.
X-ray diffraction (XRD) analysis demonstrated that chemical treatment increased the crystallinity of water hyacinth cellulose from 53.21% to 62.56%, which reflected the removal of amorphous material and improvement of structural order. Increased crystallinity improves the mechanical properties and stability of biodegradable products.
Biodegradability tests showed that the sanitary napkins degraded rapidly, reaching 70% degradation in 40 days and approximately 95% degradation in 60 days. This broke down significantly faster than common petroleum-based sanitary products, which break down much more slowly under natural conditions. This rapid decomposition is due to the pad’s high cellulose and hemicellulose content and low lignin levels, making it highly compostable and environmentally friendly. Additionally, the use of water hyacinth supports sustainable management of this invasive species.
conclusion
This study highlights that sanitary napkins made from water hyacinth fibers combine effective performance and significant environmental benefits, making them a promising and sustainable alternative to conventional products. Because sanitary napkins have been manufactured and evaluated at laboratory scale under controlled experimental conditions, further development, user trials, and validation at industrial scale are required to improve these materials and processes and support widespread adoption of more environmentally friendly menstrual hygiene products.
Reference magazines:
- Vijayakumar, G., Bhaskar, S., Raghupathy, S., and Rangarajuru, S. K. (2026). Biodegradable menstrual pads made from hydrophilic weeds: sustainability assessment, absorption performance, and microbial safety. process. 14(6). DOI: 10.3390/pr14060918, https://www.mdpi.com/2227-9717/14/6/918
