Mussel-inspired polydopamine-modified silk nanofibers as an eco-friendly and highly efficient adsorbent for cationic dyes

Abstract

The development of environmentally friendly and biodegradable adsorbent materials to remove organic dyes from wastewater has been a hot topic in environmental protection. In this work, waste natural mulberry silks from the textile industry were used as substrates to fabricate a novel adsorbent with excellent adsorption capacity for cationic dyes. Silk nanofibers (SNFs) with an average diameter of 187 nm were firstly fabricated by swelling and mechanical splitting treatment. Then, the polydopamine (PDA)-modified SNFs (SNFs@PDA) were achieved by in situ polymerization. Characterization results showed that the SNFs were uniformly coated with a layer of PDA with a thickness of several tens of nanometers. The adsorption results revealed that the SNFs@PDA composites had an adsorption capacity of up to 3256 mg g⁻¹ for methylene blue (MB), which outperformed most adsorbents reported in the literature for the removal of MB. In addition, the nanocomposite could be easily separated from the purified water and desorbed efficiently, maintaining a good adsorption efficiency of more than 90% after 5 cycles. It is believed that this nanocomposite based on natural materials and a mussel-inspired strategy with ultra-high adsorption capacity is a very promising adsorbent for dyeing effluent.