Plant-Based Amyloids from Food Waste for Removal of Heavy Metals from Contaminated Water

Water pollution is one of the major global threats brought about by industrial, agricultural, and any other anthropogenic activity. Heavy metals represent a large group of water pollutants that can accumulate in the human body, causing cancer and mutagenic diseases. Technologies currently used to treat polluted wastewaters of heavy metals employ chemical, ion-exchange, and membrane purification methods. However, high pressure and power requirements of membrane-based technologies require large energy input, making drinking water expensive and thus less affordable in developing countries. In this study, plant amyloid-carbon membranes consisting of sunflower and peanut amyloid fibrils were fabricated through a green and sustainable process and were used to remove toxic heavy metal pollutants to drinkable standards with negligible energy consumption. Protein-rich sunflower and peanut meals serve as low-cost raw materials obtainable from industrial oil production, from which proteins were extracted, isolated, and self-assembled into functional amyloid fibrils for heavy metal removal. These amyloid fibrils were incorporated into a carbon matrix to produce hybrid amyloid-carbon membranes, and were used to filter Pt-, Cr-, and Pb-containing water to produce water of drinkable standards containing < 10 ppb heavy metals with minimal energy input. This process can easily be upscaled due to its simplicity and minimal use of chemical reagents, pointing towards the future of low-cost yet efficient water treatment technologies.