In　this　paper,　how　chitosan　hydrogel　beads　were　modified　by　anionic　surfactants　(SDS,　SDOS,　SDBS,　AOT,　and　DTM-12)　and　then　used　for　the　adsorption　and　removal　of　an　anionic　dye　(congo　red)　from　aqueous　solutions　were　described.　The　effect　of　surfactant　concentration,　surfactant　ionic　head-group,　and　surfactant　hydrophobic　tail　were　investigated　in　detail.　The　result　revealed　the　modified　CS　beads　all　had　the　obviously　higher　adsorption　capacity　than　CS　beads.　Compared　to　the　ionic　head-group,　the　hydrophobic　tail　of　the　surfactant　plays　more　important　role　in　the　adsorption,　and　a　high　adsorption　capacity　was　observed　for　CS/AOT　beads　and　CS/DTM-12　beads　(both　with　two　hydrophobic　tails).　The　Sips　isotherm　model　showed　a　good　fit　with　the　equilibrium　experimental　data,　and　the　values　of　the　heterogeneity　factor　(n)　indicated　heterogeneous　adsorption.　The　adsorption　kinetics　analysis　indicated　that　the　pseudo-second-order　rate　model　could　better　describe　the　adsorption　process　than　the　pseudo-first-order　rate　model.　©　2017　Taylor　&　Francis.