Hemp-derived cellulose offers superior absorption and eco-friendly solutions

The manufacture and discard of traditional superabsorbent materials — typically made from synthetic polymers, primarily polyacrylate-based compounds — are affecting the planet. Purdue University researchers are developing biodegradable materials that retain water in a cleaner, more sustainable way and have much less environmental impact.

Senay Simsek leads a team of researchers in Purdue’s College of Agriculture using cellulose extracted from hemp and refined through a sequence of treatments to create the patent-pending, superabsorbent materials. Simsek is a professor in and the head of the Department of Food Science, and holds the Dean’s Chair in Food Science.

“We are passionate about the potential of our product to make a significant environmental impact,” Simsek said. “By introducing a commercial product that helps save our planet, we aim to lead the way in sustainable innovation — helping to heal the planet one application at a time.”

 

Drawbacks with traditional superabsorbent materials

Traditional superabsorbent materials are used around the globe in multiple applications including disposable diapers, feminine hygiene products and agricultural water retainers.

“This widespread use exacerbates their environmental impact due to the volume of waste generated and the universal nature of the problems they cause,” Simsek said.

Production of traditional superabsorbent polymers often requires significant energy inputs, which contributes to their overall environmental footprint. Also, they are made from raw materials derived from nonrenewable resources, like petroleum-based products, which also are used to make plastics and various chemicals.

“The reliance on petroleum-based materials in their production is a further concern, as it ties these products to fluctuating oil prices and geopolitical tensions,” Simsek said, noting that this also leads to the depletion of limited resources. “Transitioning to materials like hemp-based cellulose could mitigate this issue by utilizing a renewable resource to produce superabsorbent materials.”

Finally, the waste from used, nonbiodegradable, disposable diapers alone is impacting the planet’s health. The World Economic Forum reported in August 2023 that over 300,000 disposable diapers are incinerated or taken to landfills each minute. Babies use between 4,000 and 6,000 diapers before they are potty-trained. Those numbers don’t include the billions of menstrual pads and tampons discarded annually in the U.S. alone.

 

Purdue innovative materials

Simsek said hurds and bast are two parts of the hemp plant that offer unique benefits for sustainable material development, particularly in absorption technologies.

“Hemp hurds, found in the inner woody core of the hemp stalk, are highly absorbent due to their high cellulose content and low lignin levels. This makes them an excellent alternative for superabsorbent applications,” she said. “Hemp bast, the fibrous outer layer, while less absorbent, provides strength and durability.”

She added, “The cellulose extracted from these parts is particularly effective because its molecular structure can be modified to enhance its water retention capabilities, making it ideal for products requiring high absorbency.”

Simsek said the Purdue process to refine the cellulose extracted from hemp involves a carefully designed sequence of treatments.

“The treatments break down the natural structure of the cellulose, increasing its surface area and porosity. This enhancement allows the cellulose to absorb and retain more water,” she said. “A fitting analogy would be turning a compact sponge into a more open, fluffy one. This alteration dramatically improves its ability to soak up and hold moisture, which is crucial for applications that demand high absorbency. The uniqueness of our technology lies in its versatility, making it highly tunable for diverse applications of superabsorbent materials across various industries.”

Along with diapers and hygiene products, the Purdue-developed material could be applied to water retention in agriculture.

“For water retention in agriculture, the improved water efficiency helps maintain crop health during droughts, offering a sustainable alternative to traditional superabsorbents that can harm the soil and plant growth,” Simsek said. “Our approach conserves water and supports the ecosystem by providing a biodegradable solution that integrates seamlessly into natural cycles.”

Another application is biosensors used in a variety of industries.

“These include glucose strips and pregnancy tests,” Simsek said. “The versatility stems from the material’s ability to respond dynamically to environmental changes. This trait is essential for timely and accurate biosensing.”

 

Validation and next steps

Simsek and her team tested the Purdue superabsorbent materials made from hemp using standardized absorbency tests, which compared them against traditional superabsorbent materials such as polyacrylate-based products.

“The hemp hurd, due to its enhanced surface area and porosity from our refining process, showed significantly higher absorption capacity than both hemp bast and many traditional materials,” she said. “This validation underscores not only the effectiveness of our technology but also its potential to replace less sustainable options in the market, offering a biodegradable and renewable alternative.”

Simsek said the next step to bring the superabsorbent materials to the market is to scale up the technology to industrial levels.

“This scaling phase is vital not only for refining our process but also for demonstrating the practical applications of our innovation in agriculture and food packaging, areas where sustainable solutions are urgently needed,” she said.

“We are passionately pursuing further collaborations with industry leaders who share our vision of replacing traditional superabsorbents with our biodegradable, sustainable alternative,” Simsek said. “This support will be instrumental in helping us meet regulatory requirements and achieve widespread adoption, ultimately allowing us to provide future generations with a cleaner, more sustainable way to retain water and reduce environmental impact.”

Simsek disclosed the superabsorbent hemp-based materials to the Purdue Innovates Office of Technology Commercialization, which has applied for a patent from the U.S. Patent and Trademark Office to protect the intellectual property. Industry partners interested in developing or commercializing the work should contact Dipak Narula, assistant director of business development and licensing — physical sciences, at dnarula@prf.org about track code 70273.