Maximizing the benefits of combining fibroin and sericin: Functionalized obsoleted silk cocoon shell for purifying oily wastewater containing Pb2+

Abstract

Based on the durability of fibroin and the biocompatibility of sericin, researchers are exploring ways to maximize their advantages by combining them in the biomedical field. Fortunately, silk cocoon shell (SC) offers a natural composite material of fibroin and sericin. However, the inherent hydrophobicity of SC, the random arrangement connection of fibers, and the protection provided by the outer sericin limit its application in purifying oil wastewater. In this work, a cost-effective method was developed to improve the hydrophilicity of SC and the mechanical properties of SC by utilizing obsoleted SC as a matrix as well as by dissolving portions of sericin proteins. The polydopamine particle (PDP) was utilized as the intermediate modification layer and a supramolecular gel (SMG) was introduced to the surface of SC, further improving the surface's hydrophilicity of SC. The study indicated that SC@P-SMG has excellent mechanical properties, favorable anti-fouling properties, and superior self-cleaning ability. Furthermore, when the SC@P-SMG was applied in water purification, it could achieve multifunctional applications such as purifying wastewater containing emulsified oil and Pb2+ ions, methylene blue (MB), and oil-water mixture separation. This work provided innovative ideas to maximize the benefits of combining fibroin and sericin.