title: Kinetic, isotherm and thermodynamic investigations of phosphate adsorption onto core-shell Fe₃O₄@LDHs composites with easy magnetic separation assistance.
abstract: In this study, three different magnetic core-shell Fe3O4@LDHs composites, Fe3O4@Zn-Al-, Fe3O4@Mg-Al-, and Fe3O4@Ni-Al-LDH were prepared via a rapid coprecipitation method for phosphate adsorptive removal. The composites were characterized by XRD, FTIR, TEM, VSM and BET analyses. Characterization results proved the successful synthesis of core-shell Fe3O4@LDHs composites with good superparamagnetisms. Batch experiments were conducted to study the adsorption efficiency of phosphate. Optimal conditions for the phosphate adsorption were obtained: 0.05 g of adsorbent, solution pH of 3, and contact time of 60 min. Proposed mechanisms for the removal of phosphate species onto Fe3O4@LDHs composites at different initial solution pH were showed. The kinetic data were described better by the pseudo-second-order kinetic equation and KASRA model. The adsorption isotherm curves showed a three-region behavior in the ARIAN model. It had a good fit with Langmuir model and the maximum adsorption capacity followed the order of Fe3O4@Zn-Al-LDH>Fe3O4@Mg-Al-LDH>Fe3O4@Ni-Al-LDH. Thermodynamic analyses indicated that the phosphate adsorption process was endothermic and spontaneous in nature. The three Fe3O4@LDHs composites could be easily separated from aqueous solution by the external magnetic field in 10s. These novel magnetic core-shell Fe3O4@LDHs adsorbents may offer a simple single step adsorption treatment option to remove phosphate from water without the requirement of pre-/post-treatment for current industrial practice.
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: 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.
authors.forename: Tao
authors.initials: T
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: Jing
authors.initials: J
authors.lastname: Wei
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: Shu-jun
authors.initials: SJ
authors.lastname: Yu
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: Hai-qin
authors.initials: HQ
authors.lastname: Yu
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: Fe(3)O(4)@LDHs composites; Layered double hydroxides; Magnetic separation; Phosphorus removal; Wastewater treatment