Charge-Controllable Mussel-Inspired Magnetic Nanocomposites for Selective Dye Adsorption and Separation

Abstract

Magnetic polydopamine (PDA) nanocomposites were prepared with a facile synthetic method. The as-synthesized polymer-based hybrid composites inherited the intrinsic adhesiveness contributed by catechol and amino moieties of PDA as well as the magnetic property of Fe 3 O 4 . With the unique properties of PDA, the surface charges of Fe 3 O 4 @PDA could be easily tuned by pH for smart adsorption-desorption behaviors. To investigate the adsorption ability and universality of Fe 3 O 4 @PDA in textile wastewater treatment, four dyes with different structures and surface charges in solution were selected. It was found that the nanocomposites could successfully adsorb and desorb different dyes under appropriate conditions. The dispersed magnetic nanoadsorbents demonstrated the ease of collection from dye mixtures, and the possibility in recycling the composite materials. Selective dye separation was found to be achievable via simple charge control without large consumption of organic solvent and energy. These bio-inspired nanocomposite adsorbents have shown high potential in wastewater treatment and selective recovery of dye waste, especially for wastewater containing dyes of opposite ionic properties.

Keywords: Magnetic polydopamine, Charge control, Selective dye adsorption, Wastewater treatment