The present study deals with the simultaneous removal of Brilliant Green and Crystal Violet by surfactant-modified nano-alumina. The utilization of alumina nanoparticles with an anionic surfactant (sodium dodecyl sulfate (SDS)) as a novel and efficient adsorbent is successfully carried out to remove two cationic dyes from aqueous solutions in binary batch systems. A first-order derivative spectrophotometric method is developed for the simultaneous determination of Brilliant Green and Crystal Violet in binary solutions. The influence of various parameters such as contact time (t), initial concentration of dyes (Ci) and sorbent mass (m) on the dye adsorption is investigated. A response surface methodology through performing the Box–Behnkendesign is utilized to optimize the removal of dyes by surfactant-modified nanoparticles alumina. The proposed quadratic model resulting from the Box–Behnken design approach fitted very well with the experimental data. The optimal conditions for dyes removal were: contact time t =50, Sorbent dose m = 0.036g, CBG (Initial BG concentration) =215 mg/L and CCV (Initial CV concentration) =170 mg/L. Furthermore, FT-IR analysis, the isotherms and kinetics of adsorption were also explored.