Production of Silk Fibroin Membrane for Heavy Metal Removal in Water

Abstract Thermodynamically driven salts and annealing processes developed the pure silk fibroin (SF) membranes from Bombyx mori cocoons. For more generation, the silk fibroin solution 5 wt% mixed the sodium chloride (NaCl) and polyethylene glycol (PEG). The top surface and cross-section of silk fibroin mixed with NaCl (SF/NaCl) showed pore in the surface membrane and hydrophilic property. The β-sheet content in the SF/NaCl membrane is higher than pure silk fibroin (SF) and the silk fibroin mixed with PEG (SF/PEG) membranes. Then cadmium (Cd), lead (Pb), and mercury (Hg) metals in water filtered pass through only SF/NaCl experimented. The pressure, pH, and temperature were effect by the flow rate efficiency of SF/NaCl membranes. The results showed that the highest % removal of Cd, Pb, and Hg were 45.36%, 61.43%, and 86.87%, respectively. The best condition of absorption capacity was 8.50, 6.42, and 41.14 mg/g for Cd, Pb, and Hg. As a natural biopolymer, SF/NaCl possibly apply for Hg removal for water treatment, its nontoxicity, excellent biocompatibility, and mechanical toughness.