Magnetic Core@Shell Fe₃O₄@Polypyrrole@Sodium Dodecyl Sulfate Composite for Enhanced Selective Removal of Dyestuffs and Heavy Metal Ions from Complex Wastewater

Abstract

Adsorption materials have demonstrated huge potential in treating sewage; however, it is a great challenge to fabricate an adsorbent effectively adsorbing multiple dyestuffs and heavy metal ions simultaneously. Here, a magnetic core@shell Fe₃O₄@polypyrrole@sodium dodecyl sulfate (Fe₃O₄@PPy@SDS) composite is prepared through the combination of a hydrothermal method, an <i>in situ</i> polymerization method, and modification, exhibiting enhanced selective removal of five dyestuffs (methylene blue (MB), malachite green (MG), rhodamine B (RhB), Congo red (CR), acid red 1 (AR1)), and heavy metal ions (Mn(VII)). The effects of adsorbent type, time, initial concentration of the adsorbate, and temperature on adsorption performances are investigated in detail. Kinetics and isotherm studies indicate that all adsorption processes are more in line with the pseudo-second-order kinetic model and the Langmuir model, the diffusion behavior is controlled by intraparticle diffusion and liquid film diffusion, and research of thermodynamics reveals a spontaneous endothermic behavior. The removal efficiency after five desorption-adsorption cycles can still reach more than 90%. The prepared Fe₃O₄@PPy@SDS composite is an efficient and promising renewable adsorbent for the treatment of dyestuffs and Mn(VII), exhibiting a wide range of applications in the field of adsorption.