Superabsorbent polymers (SAPs) are fossil-based cross-linked polymer chains forming networks that can absorb large amounts of different fluids such as water, saline and blood. Due to their high liquid swelling capacities, SAPs are traditionally used in the daily-care industry, and some of the most relevant applications include single-use diapers and sanitary pads. SAP products correspond to ca. 2-3% of today's household waste production, and the market is expected to reach 12 million USD by 2023. The limited sustainability of current SAPs and the growing demand has promoted the utilization of biobased, sustainable SAPs. In this context, the functionalization of proteins from wheat gluten (WG) and potato concentrates (PPC) have increased their liquid uptake capacities by using harmless reagents. Here, the WG-based materials' absorption capacity has reached up to 30 grams of water per gram of dry material (g/g) and ca. 10 g/g of saline and defibrinated sheep blood. The functionalization of potato protein waste has also shown high liquid swelling, and the absorbent materials showed 50% biodegradability in regular soil after 15 days. The commercial SAP material did not show biodegradability even after 95 days of exposure to the soil. The protein-based materials could be post-processed using different techniques, i.e. lyophilization, extrusion, and ambient drying, and the result showed that the absorption could be tuned by having porous or particle structures. The results indicate that modifying these inexpensive and readily available product-stream proteins can be considered a potential alternative to fossil-based absorbing materials while having less environmental footprint.

Biodegradable absorbent materials from functionalized co-product proteins

ACS Fall 2021

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