Mussel-inspired polydopamine functionalized superhydrophilic coconut shells biosorbent for magnetically driven adsorption of methylene blue from aqueous solutions

The constraints faced by adsorbents in adsorbing dye wastewater include limited adsorption capacity, difficulties in regeneration with high costs, and the competition for adsorption as well as restrictions on conditions such as pH and temperature, all of which limit their wide application. Here we develop a novel adsorbent AC/Fe 3 O 4 @PDA with high adsorption capacity, rapid adsorption rate as well as magnetic property for efficiently adsorption organic methylene blue (MB). The surface morphology, crystal structure, chemical structure, elementals compositions, pore structure, magnetic property and wettability were all well characterized. It is proposed that an innovative superhydrophilic nanocomposite adsorbent based on highly magnetic and chemically stable biomass nanoparticles are covered by an adsorptive surface layer of PDA. Batch tests were performed to evaluate the influence of temperature, initial pH values, initial MB concentration and time on the performance of the target nanomaterial. The existence of open mesopores and macropores, three-dimensional cavity architecture, super-hydrophilic wettability and abundant amino/hydroxyl functional groups were all beneficial for well contact and chemical firmly bond with water-soluble toxic MB dye. After functionalized by mussel-inspired PDA modification, AC/Fe 3 O 4 @PDA, the active adsorbent could be easily removed from wastewater surface by a magnet. After adsorption, the three-dimensional pores of the carbon skeleton were well maintained. Super-hydrophilic and surface-adhering PDA coating make MB more tightly contact with AC/Fe 3 O 4 @PDA composite at aqueous media. More importantly, this strategy could be easily extended for fabrication of many other highly efficient magnetic adsorbents to solve the removing problem for the environmental applications of mussel inspired chemistry.