Adsorption mechanism of rhein-coated Fe 3 O 4 as magnetic adsorbent based on low-field NMR
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RESEARCH ARTICLE
Adsorption mechanism of rhein-coated Fe3O4 as magnetic adsorbent based on low-field NMR Xu Sun 1 & Li Xu 2,3
&
Weina Jiang 4 & Yan Xuan 5 & Wen Lu 2,3 & Zhong Li 6 & Shilong Yang 5 & Zhenzhen Gu 2,3
Received: 16 April 2020 / Accepted: 16 August 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract In the present study, a magnetic adsorbent, rhein-coated magnetic Fe3O4 nanoparticle (RMNP), for Pb2+ and Mg2+ had been developed, and adsorption mechanism was studied via low-field NMR. RMNP was characterized by TEM, FTIR, and XRD. RMNP could adsorb and remove Pb2+ and Mg2+ from water and was successfully applied to remove Pb2+ and Mg2+ from wastewater, with satisfactory recovery rates and high adsorption capacities. The calculated maximum adsorption capacity for Mg2+ and Pb2+ was approximately 69.3 and 64.9 mg g−1 of RMNP, respectively, which was better than some results reported. Low-field NMR results showed that Pb2+ or Mg2+ enhanced the T2 relaxation time of RMNP, which suggested that RMNP selectively coordinated with Pb2+ or Mg2+ and led to the aggregation of RMNP, furthermore removal of Pb2+ or Mg2+ from water. The standard curves for △T2-cation concentration exhibited good line correlation. The linear ranges were from 4.2 × 10−6 to 2.0 × 10−4 mol L−1 for Pb2+ and from 5.0 × 10−6 mol L−1 to 1.0 × 10−4 mol L−1 for Mg2+, respectively. The limits of detection were 1.4 × 10−6 mol L−1 for Pb2+ and 2.1 × 10−6 mol L−1 for Mg2+, respectively. In short, low-field NMR could clearly display the interaction between RMNP and Pb2+ or Mg2+, even be used to detect Pb2+ or Mg2+ in suitable condition. Besides, this method could be expanded to study the interaction between other magnetic adsorbents and analytes. Keywords Low-field NMR . Fe3O4 nanoparticles . Pb2+ . Mg2+ . Remove . Magnetic adsorbent . Mechanism
Introduction With the social economic development, heavy metal ion pollution was becoming increasingly serious, which had a Responsible Editor: Tito Roberto Cadaval Jr * Li Xu [email protected] 1
College of Information Science and Technology, Nanjing Forestry University, Nanjing 210037, China
2
College of Science, Nanjing Forestry University, Nanjing 210037, China
3
Institute of Material Physics & Chemistry, Nanjing Forestry University, Nanjing 210037, China
4
College of Chemical and Biological Engineering, Nanjing Normal University Taizhou College, Nanjing 225300, China
5
Advanced Analysis and Testing Center, Nanjing Forestry University, Nanjing 210037, China
6
National Engineering Research Center of Biomaterials, Nanjing Forestry University, Nanjing 210037, China
significant impact on the environment and biological development. Since excessive heavy metal ions could induce serious harm to the environment and human health, it was necessary to study methods to detect and remove such ions (Jiang et al. 2019; Jiang et al. 2020; Kan et al. 2019; Song et al. 2019; Yuan et al. 2018; Zhu et al. 2019). In heavy metal ions, Mg2+ played a key role in biological, environmental, a
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