Efficiently removing four cationic dyes from aqueous solution by magnetite@polypyrrole@2-acrylamido-2-methyl-1-propanesulfonic acid microspheres

Abstract

Water pollution caused by various cationic dyes is becoming more and more serious. A combination of magnetic materials, conductive polymers, and some strong adsorption groups is expected to solve this challenge. Herein, magnetite (Fe3O4)@polypyrrole@2-acrylamido-2-methyl-1-propanesulfonic acid (Fe3O4@PPy@AMPS) is fabricated as adsorbent for removing methylene blue (MB), rhodamine B (RhB), malachite green (MG), and crystalline violet (CV) from aqueous solution. The investigation of the factors including adsorbent type, adsorbent concentration, time, and temperature demonstrates that Fe3O4@PPy@AMPS has superior properties to adsorb the four cationic dyes. The maximum adsorption capacity of these dyes is separately 183.486, 215.054, 144.718 and 194.175 mg/g. Notably, although it goes through five cycles, the composite maintains a remarkable dye removal efficiency exceeding 95 %. Kinetic analysis reveals that the adsorption process conforms more closely to the pseudo-second-order kinetic model. The adsorption isotherm conforms to the Langmuir model, signifying monolayer adsorption of the dyes. Thermodynamic parameters also indicate that the adsorption process is endothermic and spontaneous. Furthermore, density functional theory (DFT) simulations affirm the molecular interactions between Fe3O4@PPy@AMPS and four dyes, elucidating the adsorption mechanism. The high efficiency and recyclable nature of the Fe3O4@PPy@AMPS composite underscores its significance in addressing dye wastewater pollution remediation.