A　novel　magnetic　bioadsorbent　beads　composed　of　Fe3O4,　chitosan,　and　Al(OH)3　(Fe3O4/CS/Al(OH)3)　was　synthesized　by　a　modified　solvothermal　and　in-situ　reaction.　The　composite　adsorbent　was　characterized　by　Fourier-transform　infrared　spectroscopy,　X-ray　diffraction,　scanning　electron　microscopy,　energy　dispersive　X-ray　spectroscopy,　and　vibrating　sample　magnetometer,　respectively.　Adsorption　toward　F−　onto　Fe3O4/CS/Al(OH)3　was　investigated　as　a　function　of　Fe3O4　concentration,　initial　solution　pH,　adsorbent　dosage,　initial　fluorion　concentration,　co-existing　ions　in　water　and　initial　temperature.　The　addition　of　Fe3O4　could　enhance　the　adsorption　properties　of　CS/Al(OH)3.　The　saturated　adsorption　capacity　of　magnetic　Fe3O4/CS/Al(OH)3　calculated　from　the　Langmuir　isotherm　model　was　76.63　mg/g　at　298　K.　The　adsorption　isotherm　of　F−　followed　Langmuir　isotherm　model　and　the　adsorption　kinetics　fitted　better　to　the　pseudo-second　order　kinetic　model.　The　influence　of　temperature　confirmed　that　the　adsorption　was　spontaneous　and　endothermic.　The　magnetic　Fe3O4/CS/Al(OH)3　beads　could　be　easily　separated　from　water　under　a　low　magnetic　field.　©　2018　Elsevier　B.V.