Fe3O4@Polydopamine Core-Shell Nanocomposite as a Sorbent for Efficient Removal of Rhodamine B from Aqueous Solutions: Kinetic and Equilibrium Studies

In this work, a Fe3O4@polydopamine core-shell nanocomposite (Fe3O4/PDA) was synthesized through an in situ self-polymerization methods and was applied as a sorbent for Rhodamine B (RhB) removal. The synthetic procedure is simple and involves no organic solvents. The as-prepared Fe3O4/PDA nanocomposite was characterized by transmission electron microscope, Fourier transforms infrared spectra, and X-ray photoelectron spectroscopy. Due to the catechol and amine groups, the polydopamine (PDA) polymer provided multiple interactions in combination with RhB. The removal ratios of the RhB by Fe3O4/PDA were all above 98% at the optimum experimental conditions, suggesting that the Fe3O4/PDA nanocomposite was an excellent sorbent for acid dyes removal from aqueous solution. The kinetic studies revealed that sorption follows a pseudo-second order kinetic model which indicates chemisorption between sorbent and adsorbate molecules. The Langmuir adsorption models were applied to describe the equilibrium isotherms, and the isotherm constants were also determined. The maximum adsorption capacity derived from the Langmuir model was 195.3 mg/g.