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Perchlorate contamination of drinking water and groundwater is a worldwide concemed issue,and technologies are needed for the treatment of aqueous perchlorate.In this study,activated carbon fibers (ACFs) and quaternary-ammomum-chloride-surfactant modified ACFs were tested for perchlorate removal from aqueous solution.The ACFs modified by cetyltrimethyl ammonium chloride (CTAC) exhibited the best performance on perchlorate adsorption.Batch experiments were performed to investigate the equilibrium,thermodynamics,kinetics and mechanism of perchlorate adsorption onto CTAC-ACFs.The results showed that the spontaneous perchlorate adsorption process followed the Langmuir isotherm and pseudo-second-order kinetics.Perchlorate adsorption onto CTAC-ACFs was enhanced as the initial perchlorate concentration,contact time and solution temperature increased.Alkaline pH and higher ionic strength did not favor the adsorption of perchlorate.Ion exchange between the perchlorate and carried chloride was the major adsorption mechanism,but other adsorption processes (e.g.electrostatic attraction and physical absorption) may also play an important role for the adsorption.The CTAC-ACFs adsorbents showed a relatively high adsorption capacity of 26.74 mg/g (at initial perchlorate concentration of 20 mg/L).