title: Adsorption of Cd(II) by Mg-Al-CO3- and magnetic Fe3O4/Mg-Al-CO3-layered double hydroxides: Kinetic, isothermal, thermodynamic and mechanistic studies.
abstract: Understanding the adsorption mechanisms of metal cations on the surfaces of solids is important for determining the fate of these metals in water and wastewater treatment. The adsorption kinetic, isothermal, thermodynamic and mechanistic properties of cadmium (Cd(II)) in an aqueous solution containing Mg-Al-CO3- and magnetic Fe3O4/Mg-Al-CO3-layered double hydroxide (LDH) were studied. The results demonstrated that the adsorption kinetic and isotherm data followed the pseudo-second-order model and the Langmuir equation, respectively. The adsorption process of Cd(II) was feasible, spontaneous and endothermic in nature. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were used to explain the adsorption mechanisms. The characteristic XRD peaks and FTIR bands of CdCO3 emerged in the LDH spectra after Cd(II) adsorption, which indicated that the adsorption of Cd(II) by LDHs occurred mainly via CdCO3 precipitation, surface adsorption and surface complexation. Furthermore, the magnetic Fe3O4/Mg-Al-CO3-LDH can be quickly and easily separated using a magnet before and after the adsorption process.
authors.affiliation: School of Resources and Environment, University of Jinan, Shandong Provincial Engineering Technology Research Center for Groundwater Numerical Simulation and Contamination control, Jinan 250022, PR China.
authors.forename: Ran-ran
authors.initials: RR
authors.lastname: Shan
authors.affiliation: School of Resources and Environment, University of Jinan, Shandong Provincial Engineering Technology Research Center for Groundwater Numerical Simulation and Contamination control, Jinan 250022, PR China. Electronic address: yanyu-33@163.com.
authors.forename: Liang-guo
authors.initials: LG
authors.lastname: Yan
authors.affiliation: School of Resources and Environment, University of Jinan, Shandong Provincial Engineering Technology Research Center for Groundwater Numerical Simulation and Contamination control, Jinan 250022, PR China.
authors.forename: Kun
authors.initials: K
authors.lastname: Yang
authors.affiliation: School of Resources and Environment, University of Jinan, Shandong Provincial Engineering Technology Research Center for Groundwater Numerical Simulation and Contamination control, Jinan 250022, PR China.
authors.forename: Yuan-feng
authors.initials: YF
authors.lastname: Hao
authors.affiliation: School of Resources and Environment, University of Jinan, Shandong Provincial Engineering Technology Research Center for Groundwater Numerical Simulation and Contamination control, Jinan 250022, PR China.
authors.forename: Bin
authors.initials: B
authors.lastname: Du
keywords: Heavy metal wastewater treatment; Magnetic separation; Precipitation; Surface adsorption; Surface complexation