Disposable diapers, sanitary pads, napkins, and incontinence products have become an essential part of modern life. They offer convenience, hygiene, and comfort, but their environmental cost is growing rapidly. Most conventional absorbent products depend heavily on petroleum-based plastics, synthetic fibers, and superabsorbent polymers that are difficult to break down after disposal.
Now, research led by Agnes Juge and her team points toward a promising alternative: biodegradable absorbent materials made entirely from protein blends obtained from industrial coproducts. The approach combines zein and gluten proteins to create porous structures that can absorb and retain liquids while offering significantly better end-of-life properties than conventional plastic-based materials.
The Growing Environmental Problem of Disposable Sanitary Products
The widespread use of disposable sanitary products creates an enormous amount of waste. From infancy to old age, people may rely on products such as diapers and incontinence pads for years.
The scale of the problem is considerable. A single newborn can generate up to one ton of diaper waste during the diaper-using period. Similarly, a care home with only 20 residents may generate around 90 liters of waste every day from incontinence diapers.
Sanitary pads and other disposable hygiene products also contribute substantially to greenhouse gas emissions. In the United Kingdom, sanitary pads have been estimated to contribute around 6,600 tonnes of CO₂-equivalent emissions.
The problem goes beyond waste volume. Conventional sanitary products commonly contain polyethylene, polypropylene, polyurethane, and superabsorbent polymer gels. These petroleum-derived materials can remain in the environment for long periods. Research has also raised concerns about substances that may migrate from disposable sanitary products, including certain potentially harmful chemicals and microplastics.
As global population increases and disposable hygiene products become more widely used, finding sustainable replacements is becoming increasingly important.
Turning Industrial Protein Coproducts Into Useful Materials
One promising solution is to replace petroleum-based materials with biopolymers derived from renewable resources.
The research by Juge and her colleagues focuses on proteins that can be obtained as coproducts of industrial processes. Instead of depending on virgin resources such as cotton or petroleum-based polymers, the researchers use zein and gluten to develop porous absorbent structures.
Zein is a protein associated with corn processing, while gluten is a high-molecular-weight protein that can provide strong binding and structural properties.
The important innovation is not simply using proteins as an absorbent. The team developed a formulation that can be processed using established polymer-processing technologies, including extrusion and compression.
This makes the approach particularly interesting from a manufacturing perspective.
Why Zein and Gluten Work Well Together
The performance of the material comes from the complementary properties of the two proteins.
Gluten has a relatively high molecular weight and can act as an effective binder. It can also be cross-linked, helping the material maintain its structure.
Zein, on the other hand, has lower viscosity and can function as a processing aid. It makes the protein mixture easier to process and thermoform, even at relatively low temperatures.
When combined, the two proteins create a synergistic system. Gluten provides structural strength, while zein improves processing behavior.
This combination allows researchers to produce continuous porous extrudates with relatively homogeneous pore structures—something that has been challenging in previous protein-based absorbent materials.
Creating Different Forms From One Formulation
One of the strongest advantages of the new approach is its versatility.
The same zein-gluten formulation can be manufactured into several different structures, including:
Liquid-absorbent pellets
Compressed absorbent pads
Continuous porous extrudates
Porous film structures
Multilayer absorbent components
This flexibility could be important for developing different types of sustainable sanitary products.
For example, an absorbent core could be produced using the porous protein material and then combined with additional permeable layers. Such a design could eventually allow the development of complete sanitary products rather than simply replacing one component of an existing plastic-based product.
Porosity Is the Key to Absorption
The researchers found that the porous structure plays a central role in the material's ability to absorb liquids.
The interconnected pores allow liquid to move through the material through capillary-driven absorption. This structure supports liquid uptake, spreading, and retention.
Tests showed that the protein-based materials could absorb saline solutions and blood, making them potentially suitable for applications where liquid management is essential.
Importantly, the material can be designed as part of a multilayer structure, similar in function to conventional sanitary products. The prototype demonstrated free-liquid absorption, spreading, and retention properties comparable to those expected from traditional absorbent systems.
Lower-Temperature Processing Could Reduce Energy Use
Another important feature is the processing temperature.
The protein formulations can be processed at temperatures lower than those commonly required for many commercial plastics used in sanitary products. The researchers also found that extrusion speed, plasticizer content, and foaming-agent concentration strongly influenced the formation of continuous structures with uniform porosity.
Because the approach uses conventional industrial processing equipment, it may not require completely new manufacturing infrastructure.
That could make scaling the technology easier and potentially reduce the investment required to move from laboratory experiments toward larger-scale production.
A Major Advantage: Biodegradability
Perhaps the most important environmental benefit is the biodegradability of the protein-based materials.
According to the reported results, the protein-blend products achieved up to 70% hydrolytic degradation in less than five weeks.
This is dramatically different from the behavior of many conventional petroleum-based sanitary materials, which can persist in the environment for much longer periods.
The protein materials can ultimately break down into simpler, potentially less harmful molecules. This creates the possibility of a safer end-of-life pathway and reduces dependence on materials that can contribute to long-term plastic pollution.
The researchers suggest that this biodegradability could eventually support new approaches to disposal, potentially including flushable sanitary materials if future product development, safety testing, and infrastructure requirements are successfully addressed.
Toward Plastic-Free Sanitary Products
The broader significance of this work is that it moves beyond simply creating a biodegradable absorbent.
A conventional sanitary product is a complex combination of an absorbent core, synthetic nonwoven layers, films, and other components. Replacing only the absorbent core does not necessarily make the entire product sustainable.
The protein-based approach offers the possibility of producing 100% protein-based porous structures that can be assembled into multilayer products.
This could eventually support applications such as sanitary pads, diapers, medical patches, and other disposable absorbent products.
Supporting a Circular Bioeconomy
The concept also fits into the growing idea of a circular bioeconomy.
Instead of relying on virgin petroleum resources or agricultural materials that may compete directly with food production, industrial protein coproducts can become valuable raw materials for new products.
This creates an opportunity to convert industrial costreams into useful, higher-value materials while reducing waste.
At the same time, the materials can be processed using established manufacturing technologies and designed for biological degradation at the end of their useful life.
The Road Ahead
The research does not mean that conventional diapers, pads, or medical absorbents can immediately be replaced. Commercial products must meet demanding requirements for safety, durability, comfort, absorption capacity, shelf life, manufacturing consistency, and disposal.
However, the study demonstrates an important proof of concept.
The combination of zein and gluten provides processability, structural stability, porosity, liquid absorption, and biodegradability in a single material platform. The ability to manufacture the same formulation in multiple shapes further strengthens its potential for industrial applications.
A Promising Step Toward Cleaner Disposable Products
Disposable sanitary products provide important benefits, but their dependence on persistent plastics has created a serious environmental challenge. The work of Agnes Juge and her team demonstrates how industrial protein coproducts could provide a fundamentally different route.
By combining zein and gluten, researchers have created porous absorbent structures that can be processed using conventional equipment, absorb liquids effectively, and biodegrade within weeks.
The concept offers more than a new absorbent material. It represents a potential pathway toward plastic-free, biodegradable, and resource-efficient sanitary products.
As research continues, protein-based biopolymers could become an important part of the transition from today's disposable, plastic-heavy products toward a more circular and environmentally responsible future.
Reference: Jugé A, Moreno-Villafranca J, Perez-Puyana VM, Jiménez-Rosado M, Sabino M, Capezza AJ. Porous Thermoformed Protein Bioblends as Degradable Absorbent Alternatives in Sanitary Materials. ACS Appl Polym Mater. 2023 Aug 25;5(9):6976-6989. doi: 10.1021/acsapm.3c01027.
Comments
Post a Comment