Renewable Energy from Livestock Waste Valorization: Amyloid-Based Feather Keratin Fuel Cells

Abstract

Increasing carbon emissions have accelerated climate change, resulting in devastating effects that are now tangible on an everyday basis. This is mirrored by a projected increase in global energy demand of approximately 50% within a single generation, urging a shift from fossil-fuel-derived materials toward greener materials and more sustainable manufacturing processes. Biobased industrial byproducts, such as side streams from the food industry, are attractive alternatives with strong potential for valorization due to their large volume, low cost, renewability, biodegradability, and intrinsic material properties. Here, we demonstrate the reutilization of industrial chicken feather waste into proton-conductive membranes for fuel cells, protonic transistors, and water-splitting devices. Keratin was isolated from chicken feathers via a fast and economical process, converted into amyloid fibrils through heat treatment, and further processed into membranes with an imparted proton conductivity of 6.3 mS cm −1 using a simple oxidative method. The functionality of the membranes is demonstrated by assembling them into a hydrogen fuel cell capable of generating 25 mW cm −2 of power density to operate various types of devices using hydrogen and air as fuel. Additionally, these membranes were used to generate hydrogen through water splitting and in protonic field-effect transistors as thin-film modulators of protonic conductivity via the electrostatic gating effect. We believe that by converting industrial waste into renewable energy materials at low cost and high scalability, our green manufacturing process can contribute to a fully circular economy with a neutral carbon footprint.

Copper Decontamination Using Feather Keratin Amyloid-Carbon Hybrid Membranes

“…Feather keratin is a relatively hydrophobic protein consisting of few charged groups . As Cu usually exists as a cation (Cu 2+ ) in aqueous solutions, the primary amino acids involved in binding with Cu 2+ are negatively charged aspartic (Asp) and glutamic acid (Glu) through electrostatic interactions of their carboxylate groups, and thiol-containing cysteines (Cys) through metal chelation. , At near-neutral pH condition, Asp and Glu (p K a ∼ 4) are mostly deprotonated and hold a negative charge, while Cys (p K a ∼ 8.4) is protonated.…”

“…The extraction and isolation process was adapted from ref . Chicken feathers obtained from a local farm were washed and added to a keratin extraction solution (8 M urea containing 5 wt % ammonium thioglycolate, pH adjusted to 9.8) at a ratio of 1:30 (w/v).…”

“…Among the many proteinaceous industrial waste byproducts, chicken feather keratins have the highest protein content and are the most abundant in cysteine (Cys) amino acid, which we hypothesized may be exploited to remove Cu from contaminated water through thiol–copper binding interactions. As previously demonstrated by us, keratin can be extracted and isolated from chicken feathers using a green process followed by self-assembly into amyloid fibrils under acidic heat treatment . In this work, we investigated the thiol–copper interactions of feather keratin amyloid fibrils at acidic pH by assessing their adsorption capacities, followed by the fabrication of hybrid keratin amyloid fibril/activated carbon membranes that exhibit high copper removal efficiency and reusability.…”

Sustainable Materials via the Assembly of Biopolymeric Nanobuilding Blocks Valorized from Agri-Food Waste

“…While I will not delve extensively into the intricacies involved due to the abundance of existing literature on the subject [20,23,[31][32][33][34], it is worth noting that the primary method for processing biopolymers (colloidal matter) involves using solvents [5,20,23,27]. This approach encompasses the assembly of macromolecules, coacervation [35], and various other techniques to produce capsules [35,36], membranes [37,38], hydrogels [39,40], aerogels [30], and fibers [41,42], offering a broad spectrum of potential applications in the energy and environmental fields, including water purification [28,37,38], bioplastics [13,17], and green bioelectronic and energy-related materials [18,43].…”

“…This not only shifts the carbon footprint of food waste from positive to negative [5], but also allows for the utilization of developed products and materials in tackling issues like water purification [12,15] and the production of bioplastics [16,17]. Furthermore, adding value to waste and elevating it to a high-commodity product will bring economic and industrial benefits [18,19].…”