Protein-based foams are potential sustainable alternatives to petroleum-based polymer foams in e.g. single-use products. In this work, the biodegradation, bioassimilation, and recycling properties of glycerol-plasticized wheat gluten foams (using a foaming agent and gallic acid, citric acid, or genipin) were determined. The degradation was investigated at different pH levels in soil and high humidity. The fastest degradation occurred in an aqueous alkaline condition with complete degradation within 5 weeks. The foams exhibited excellent bioassimilation, comparable to or better than industrial fertilizers, particularly in promoting coriander plant growth. The additives provided specific effects: gallic acid offered antifungal properties, citric acid provided the fastest degradation at high pH, and genipin contributed with cross-linking. All three additives also contributed to antioxidant properties. Dense beta-sheet protein structures degraded more slowly than disordered/alpha-helix structures. WG foams showed only a small global warming potential and lower fossil carbon emissions than synthetic foams on a mass basis, as illustrated with a nitrile-butadiene rubber (NBR) foam. Unlike NBR, the protein foams could be recycled into films, offering an alternative to immediate composting.

Styrofoams are widely used as floats and are likely to be damaged by burrowing animals in mariculture. However, the fate of fragmented Styrofoams and their interaction with organisms are not clear in coastal environments. In the present study, field investigations were conducted in 14 sites along the coast of China from July 2023 to October 2024. Results showed that Styrofoams were buried by sand or soil at a depth of up to 50-60 cm in patchy and belted distribution patterns. The abundances of Styrofoams in the deep layer of sediments ranged from 94 to 3042 items/kg. The buried Styrofoams were bunched by roots of six plant species in three ways, i.e., wrapping, crossing, and clinging. The abundance of bunched foams ranged from 1 to 495 items/plant. Simulation experiments in the laboratory showed that plant roots could interact with Styrofoams after 14 days of exposure and tended to cross through the gaps of foam materials. Our study indicates that the fragmented Styrofoams coming from mariculture floats could remain in the sediments due to the physical and biological factors, providing new insight into the biogeochemical cycle of plastic debris.

Frequent and severe wildfires have led to increased application of fire suppression products (long-term fire retardants, water enhancers, and Class A foams) in the American West. While fire suppressing products used on wildfires must be approved by the U.S. Forest Service, portions of their formulations are trade secrets. Increased metals content in soils and surface waters at the wildland-urban interface has been observed after wildfires but has primarily been attributed to ash deposition or anthropogenic impact from nearby urban areas. In this study, metal concentrations in several fire suppression products (some approved by the U.S. Forest Service, and some marketed for consumer use) were quantified to evaluate whether these products could contribute to increased metal concentrations observed in the environment postfire. Long-term fire retardants contained concentrations of toxic metals (V, Cr, Mn, Cu, As, Cd, Sb, Ba, Tl, and Pb) 4-2,880 times greater than drinking water regulatory limits, and potentially greater than some aquatic toxicity thresholds when released into the environment. Water enhancers and Class A foams contained some metals, but at lower concentrations than fire retardants. Based on these concentrations and retardant application records, we estimate fire retardant application in the U.S. contributed approximately 380,000 kg of toxic metals to the environment between 2009 and 2021.

The production of biodegradable gluten-based protein foams showing complete natural degradation in soil after 26 days is reported, as an alternative to commercial foams in disposable sanitary articles that rely on non- biodegradable materials. The foams were developed from an extensive evaluation of different foaming methodologies (oven expansion, compression moulding, and extrusion), resulting in low-density foams (ca. 400 kg/ m3) 3 ) with homogenous pore size distributions. The products showed the ability to absorb 3-4 times their weight, reaching ranges for their use as absorbents in single-use disposable sanitary articles. An additional innovative contribution is that these gluten foams were made from natural and non-toxic wheat protein, glycerol, sodium and ammonium bicarbonate, making them useful as fossil-plastic-free replacements for commercial products without the risk of having micro-plastic and chemical pollution. The impact of different processing conditions on forming the porous biopolymer network is explained, i.e., temperature, pressure, and extensive shear forces, which were also investigated for different pH/chemical conditions. The development of micro-plastic-free foams mitigating environmental pollution and waste while using industrial co-products is fundamental for developing large-scale production of single-use items. A sanitary pad prototype is demonstrated as an eco-friendly material alternative that paves the way for sustainable practices in manufacturing, and contributes to the global effort in combating plastic pollution and waste management challenges, Sustainable Development Goals: 12, 13, 14, and 15.