Polyacrolein　(PA)　was　prepared　by　photoinduced　free　radical　polymerization　for　adsorption　of　congo　red　(CR).　The　structural　and　physicochemical　properties　of　PA　were　characterized　using　BET,　zeta　potential　measurements,　SEM,　FT-IR　and　XPS.　The　adsorption　process　of　CR　accorded　with　the　pseudo-second-order　kinetics,　while　the　adsorption　isotherm　conformed　to　be　the　Langmuir　model　and　the　adsorption　was　proved　to　be　the　spontaneous　and　endothermic　process　(ΔG0　0　＞　0).　Electrostatic　attraction,　hydrogen　bond　and　chemical　reaction　(formation　of　imine)　were　the　critical　driving　forces　of　adsorption.　The　good　removal　efficiency　obtained　during　the　five　executed　cycles　suggested　a　good　reusability　of　PA.　It　was　noteworthy　that　salts　in　CR　solution　could　promote　the　adsorption　capacity　of　PA,　in　which　Ca　(II)　could　obviously　improve　the　adsorption　capacity　and　shorten　the　time　to　reach　adsorption　equilibrium.　These　results　have　provided　very　useful　information　for　removing　CR　and　enhanced　our　understanding　of　the　adsorption　mechanism　of　PA　on　CR.　©　2020　Elsevier　B.V.