Highly selective removal of organic dyes from aqueous solutions with recyclable Fe3O4@PDA-Ag magnetic microspheres

Fe3O4@PDA-Ag microspheres with excellent paramagnetic nature have been successfully prepared by a fast and straightforward strategy. The easily recycled Fe3O4@PDA-Ag microspheres were employed in the adsorptive removal of various dyes from aqueous solution. The results indicate that Fe3O4@PDA-Ag microspheres show excellent selectivity for cationic dyes adsorption and separation, and the adsorption efficiency is 98.2%, 97.8% and 96.9% for AH, MB, and MG in this work, respectively. Meanwhile, various influencing factors on the dyes adsorption have been explored. The results indicate that the adsorption rate strongly depends on the type of surfactant in solution and the pH value of the dye solution. Moreover, Fe3O4@PDA-Ag microspheres can be rapidly regenerated in 3 min using the saturated solution of NaCl in DMF as eluent, and display excellent reversibility in the process of the dye adsorption-release for at least 29 cycles. Overall, the experimental results showed that the Fe3O4@PDA-Ag microspheres had a great adsorption ability to remove cationic dyes in wastewater and can be applied for the separation of dyes mixtures.