Fabrication of core–shell Fe3O4@polypyrrole@sodium dodecyl benzene sulfonate composite for high-performance adsorption of methylene blue and malachite green in water

Magnetic core–shell Fe3O4@PPy@SDBS composite is successfully fabricated by the combination of hydrothermal method, in situ polymerization method and surface modification method, exhibiting maximum adsorption capacity for MB and MG of 124.07 mg/g and 73.10 mg/g, and after five desorption-adsorption cycles the removal rates for MB and MG still more than 80% and 90%. [Display omitted] •Magnetic core–shell Fe3O4@PPy@SDBS composite is successfully fabricated.•It exhibits maximum adsorption capacity for MB and MG of 124.07 mg/g and 73.10 mg/g, respectively.•After five desorption-adsorption cycles, its removal rates for MB and MG can still exceed more than 80% and 90%.•The excellent adsorption performances are attributed to the synergistic effect of electrostatic interactions, hydrogen bonding interactions and π-π interactions. In this study, a novel composite material with a core–shell structure, Fe3O4@PPy@SDBS, was synthesized through a combination of hydrothermal, in situ polymerization, and surface modification methods. The primary objective was the removal of methylene blue (MB) and malachite green (MG) dyes from aqueous solutions. The influence of adsorbent type, time, initial adsorbent concentration, and temperature on the adsorption behavior of MB and MG was comprehensively investigated. The experimental results revealed that the adsorption kinetics of both MB and MG adhered to the pseudo-second order kinetic model, while the isotherm data were best described by the Langmuir isotherm model. Furthermore, the adsorption process exhibited characteristics of a spontaneous heat-driven reaction. The maximum adsorption capacities were determined as 124.07 mg/g for MB and 73.10 mg/g for MG, respectively. Remarkably, even after undergoing five desorption-adsorption cycles, the removal efficiencies for MB and MG remained above 80% and 90% respectively. These promising outcomes were attributed to the collaborative effects of electrostatic interactions, hydrogen bonding, and π-π interactions mediated by PPy and SDBS, in addition to the magnetic properties imparted by Fe3O4. Consequently, the Fe3O4@PPy@SDBS composite exhibited high potential as a proficient and reusable adsorbent. Beyond its efficient removal capabilities, the incorporation of magnetic properties and diverse adsorption mechanisms within these composites presents compelling opportunities for advancements in adsorption and separation processes.