Abstract An agricultural by-product, wheat straw (NWS), was soaked in 1% a cationic surfactant (hexadecyl trimethyl ammonium bromide, CTAB) solution for 24h (at 293K) and modified wheat straw (MWS) was obtained. Then MWS was used as adsorbent for the removal of Congo red (CR, anionic dye) from aqueous solution. The experiment was performed in column mode at room temperature (293K) and effects of initial CR concentration, flow rate, bed depth and common salt existed in solution on breakthrough curves were presented. The breakthrough curves became flatly at lower flow rate, lower CR concentration and higher bed depth and these conditions were advantageous of CR removal from solution. There is no significant effect of CR adsorption capacity at 0.1mol/L sodium chloride solution. Thomas model and modified dose–response model were used to fit the column data using nonlinear analysis method and the fitted results were presented. Modified dose–response model was better to predict the breakthrough curves. 0.1mol/L sodium hydroxide solution can elute CR adsorbed on MWS in column. The results implied that MWS can be selected as an inexpensive, effective and environmentally friendly adsorbent to remove CR from aqueous solution.