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Polycarboxylic magnetic polydopamine sub-microspheres for effective adsorption of malachite green

Pan, Xihao, Zuo, Gancheng, Su, Ting, Cheng, Siyao, Gu, Yufan, Qi, Xiaoliang, Dong, Wei
Colloids and surfaces 2019 v.560 pp. 106-113
Fourier transform infrared spectroscopy, adsorbents, adsorption, chemical structure, coatings, colloids, iron oxides, kinetics, magnetism, malachite green, models, nanocrystals, pH, particle size distribution, sorption isotherms, transmission electron microscopy
Magnetic particle is a promising class of materials to absorb harmful contaminants for their easy collecting property with magnetic response. Here, we report a novel kind of polycarboxylic magnetic polydopamine sub-microspheres (Fe3O4@PDA-COOH) facilely synthesized by coating polydopamine (PDA) onto the surface of magnetic nanocrystal clusters (Fe3O4). Then the sub-microspheres were modified with mercaptosuccinic acid (MSA) to have polycarboxylic groups on their surface. Fourier transform infrared spectroscopy (FT-IR) was used to demonstrate the desired chemical structure. The unique morphology and particle size distribution were confirmed by Transmission electron microscopy (TEM). Malachite green (MG) was used as a model to test the adsorption capacity of the magnetic sub-microspheres. Besides, factors such as initial MG concentration, initial solution pH, and contact time were systematically studied for this adsorption process. Results showed that the maximum adsorption capacity of Fe3O4@PDA-COOH could reach up to 331.0162 mg/g (MG/ sub-microspheres), much higher than that of Fe3O4@PDA. The adsorption kinetics and adsorption isotherms could be well described by pseudo-second-order kinetic model and Freundlich isothermal model. Moreover, Fe3O4@PDA-COOH sub-microspheres can retain the high adsorption ability after five using-cycles. Therefore, the synthesized Fe3O4@PDA-COOH can be a high-efficiency adsorbent in the field of wastewater treatment.