Environmental pollution caused by industrial wastewater is at its alarming rate. Benzene falls under the category of those contaminants that most commonly found in produced water from chemical industries. To get rid of this carcinogenic compound, the present study proposed an environmentally benign method to modify the commercially activated carbon by means of 1-Hexyl-3-methylimidazolium bis (trifluoromethylsulfonyl)imide. This green functionalization attempts to simultaneously maximize the removal efficiency of adsorbent by elevating the surface area and pore volume of the modified adsorbent and reduce the overall cost of the process. The activated carbon in pristine and functionalized forms was characterized by using, N 2 adsorption/desorption, FTIR, Thermogravimetric analysis, Raman spectroscopy, XRD analysis and Scanning Electron Microscopy. Batch adsorption experiments were performed and modified activated carbon exhibited higher adsorption capacity compared to that of pristine AC. The Pseudo second order model and Langmuir isotherm model best fitted the data of the adsorption of benzene. Thus, modified activated carbon managed to enhance the benzene removal efficiency up to 87. © Published under licence by IOP Publishing Ltd.